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The vote count in the itself tells me it has 2 upvotes and 0 downvotes. But the "achievements" drop-down pane shows +8, which would typically indicate 2 upvotes and 1 downvote. Indeed, the reputation section of my profile says 2 upvotes and 1 downvote. I remember that prior to posting this question, I had 1990 reputation. So it looks like the downvote hasn't been counted in my reputation. But I remember that it was counted at one point, because my reputation went from 1995 to 1993. I was doing several edits to this question, so it's possible that the downvoter changed his/her mind and removed it or upvoted. Does this have something to do with caching or something? I wouldn't guess that, since I'm used to votes appearing in all three places immediately. Feel free to tag this with if it's appropriate. | A question in my reputation tab shows two downvotes, and my reputation total reflects this: However, the question itself shows only one downvote: The downvotes were cast several hours ago, so I don't think I should blame caching. What's going on? |
So i have this application in which I am storing Sockets in an ArrayList on the Server side. When the client closes its application the socket must close as well but It doesnt reflect the changes in the ArrayList in the server. class arrays { public static ArrayList<Socket> online_buyer=new ArrayList<Socket>(); public static ArrayList<Socket> online_seller=new ArrayList<Socket>(); public static ArrayList<String> buyer_prod=new ArrayList<String>(); } public void seller_display() { while(true) { if(flag==1) { synchronized(sock) { for(int i=0;i<arrays.online_buyer.size();i++) { System.out.println(arrays.buyer_prod.get(i)); } flag=0; } } check2(); } } public void check2() { for(int i=0;i<arrays.online_buyer.size();i++) { try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } **while(!arrays.online_buyer.get(i).isConnected())** { arrays.online_buyer.remove(i); arrays.buyer_user.remove(i); arrays.buyer_add.remove(i); arrays.buyer_prod.remove(i); arrays.time.remove(i); arrays.buyer_no.remove(i); flag=1; System.out.println("RECORD DELETED"); } } } public void run() { get_details(); } } Now the statement while(!arrays.online_buyer.get(i).isConnected()) must be while(!false)=true. When i close the socket from the client side as isconnected()method must return false. But this statement never runs to be false even if i close the socket from client. | As a follow up to a , I wonder why it is impossible in Java, without attempting reading/writing on a TCP socket, to detect that the socket has been gracefully closed by the peer? This seems to be the case regardless of whether one uses the pre-NIO Socket or the NIO SocketChannel. When a peer gracefully closes a TCP connection, the TCP stacks on both sides of the connection know about the fact. The server-side (the one that initiates the shutdown) ends up in state FIN_WAIT2, whereas the client-side (the one that does not explicitly respond to the shutdown) ends up in state CLOSE_WAIT. Why isn't there a method in Socket or SocketChannel that can query the TCP stack to see whether the underlying TCP connection has been terminated? Is it that the TCP stack doesn't provide such status information? Or is it a design decision to avoid a costly call into the kernel? With the help of the users who have already posted some answers to this question, I think I see where the issue might be coming from. The side that doesn't explicitly close the connection ends up in TCP state CLOSE_WAIT meaning that the connection is in the process of shutting down and waits for the side to issue its own CLOSE operation. I suppose it's fair enough that isConnected returns true and isClosed returns false, but why isn't there something like isClosing? Below are the test classes that use pre-NIO sockets. But identical results are obtained using NIO. import java.net.ServerSocket; import java.net.Socket; public class MyServer { public static void main(String[] args) throws Exception { final ServerSocket ss = new ServerSocket(12345); final Socket cs = ss.accept(); System.out.println("Accepted connection"); Thread.sleep(5000); cs.close(); System.out.println("Closed connection"); ss.close(); Thread.sleep(100000); } } import java.net.Socket; public class MyClient { public static void main(String[] args) throws Exception { final Socket s = new Socket("localhost", 12345); for (int i = 0; i < 10; i++) { System.out.println("connected: " + s.isConnected() + ", closed: " + s.isClosed()); Thread.sleep(1000); } Thread.sleep(100000); } } When the test client connects to the test server the output remains unchanged even after the server initiates the shutdown of the connection: connected: true, closed: false connected: true, closed: false ... |
I made an array containing 24 elements. I want to iterate a loop 24 times, each time taking all the elements from the array and making a unique sequence. For example: for(int i=0; i<4 ; i++) array = [a,b,c,d] The output I want is: iteration1: abcd iteration2: acdb iteration3: bacd iteration4: dcab The specific order is not important. What's important is the sequence for each iteration must be unique. Can somebody recommend a way to this? Perhaps there is some function for randomisation in C#? | What is the best way to randomize the order of a generic list in C#? I've got a finite set of 75 numbers in a list I would like to assign a random order to, in order to draw them for a lottery type application. |
I need to read a file given to me in a script i made, the file can be any name, the input is as follows ./Naloga1.sh tocke < somefile.txt This is the code i have: while read line do echo $line done < The problem is, firstly if i put the script name at the done, it will read all the lines in my file - the last one. And secondly how can i acess the files name to then output it? If i echo $1 $2 $3, $1 comes as tocke and $2 and $3 dont exist | I have a complex command that I'd like to make a shell/bash script of. I can write it in terms of $1 easily: foo $1 args -o $1.ext I want to be able to pass multiple input names to the script. What's the right way to do it? And, of course, I want to handle filenames with spaces in them. |
Here we encounter a strange thing about waves; a very simple thing . . .namely, we cannot define a unique wavelength for a short wave train. Such a wave train does not have a definite wavelength; there is an indefiniteness in the wave number that is related to the finite length of the train. . .$^\text{1}$ Now, why can't we define a unique wavelength for a wave packet? $^\text{1}$ Lectures on Physics by Feynman, Leighton , Sands. | My textbook and the following extract from feynman's lectures present the same idea regarding wavetrains and uncertainty in their wavelengths. Why is it that a wavetrain confined to some space has an uncertainty in its wavelength or the wave number? Is not a confined wave-train equivalent to a burst of successive pulses which can have a definite wavelength according to their origin or nature of origin. Next, i understand that the De Broglie relation relates the uncertainty in wavelength to the uncertainty in momentum but what links the finiteness of the wave-train to the uncertainty in position? |
I'm using lstinputlisting to include code examples in my thesis, but as I'm working on the text and the code simultaneously, the code is not yet fixed in length. Is there any way that I can define a range of lines in my code dynamically so that the imported lines will be updated if I change the code (somehow as I'd do in iPython)? At the moment I'm only using as in this script example: \lstinputlisting[language=Python, firstline=135, lastline=145]{code/inv1.py} But when I add a line to my script, the range is out-of-phase with some funny results. A dream scenario would be something like this pseudo code: \lstinputlisting[language=Python, firstline=label{#loop2}, lastline=label{#end_loop2}]{code/inv1.py} Can minted or another listing package be the solution? My code and scripts are in C# and Python. | Is there a way to input particular sections of source code using \lstinputlisting (from the listings package) in a flexible way? It's possible to use the firstline and lastline options to input particular line ranges, but this isn't robust to changes to the source file. For example, suppose that the input source file is: int square(int x) { return x * x; } int cube(int x) { return x * x * x; } In my LaTeX document, I can include the cube procedure using the command \lstinputlisting[firstline=5,lastline=7]{source.c}. But suppose I later decide to rewrite the cube procedure. The input source file becomes: int square(int x) { return x * x; } int cube(int x) { int x2; x2 = square(x); return x * x2; } Now my LaTeX document will not show the final two lines of cube because the listing uses only lines 5-7. I could manually update the line range, but this is tedious and error-prone. Is there a way to mark sections of source code with some kind of label so that the listing will be robust to these sorts of changes? For instance, perhaps the input source file would be something like int square(int x) { return x * x; } /**\beginlabel{lst:cube} **/ int cube(int x) { int x2; x2 = square(x); return x * x2; } /**\endlabel{lst:cube} **/ so that I could use something like \lstinputlisting[lines=lst:cube]{source.c} to include the section that I want and remain robust to changes. I am open to using other packages for source code listings (e.g., minted) if helpful. |
R1 = 2Ω R2 >= 22kΩ D2 = 1N4148, or 1N400x (x is a number) U1 = (MIC4452YN is the through-hole version) Q1 = So basically I want to run the circuit from a NE555 timer because I don't have the MIC4452 to drive the MOSFET. I will be using an MOSFET. I have no clue how to wire everything up ... and other components I need. If someone could walk me through the connections for the circuit... ? | Hi I am trying to run a slayer exciter using a MOSFET. Tells to use these parts R1 = 2Ω R2 >= 22kΩ D2 = 1N4148, or 1N400x (x is a number) U1 = Q1 = Except I don't have a MIC4452 to drive the MOSFET. I think I might be crazy - I have no idea what I am doing. Can a NE555 run a MOSFET? How would I do that? Maybe another way without using a gate driver? |
I'm writing this with a throwaway account, for obvious reasons; if this is inappropriate or runs counter to the rules of the site in some way, please let me know. I'm an undergraduate student in the UK, and am planning on applying to PhD programs next year. For context, I'm looking primarily at programs in the US, and am hoping to specialize in applications of model theory to algebra and geometry. For the past year or so, I have been a reasonably active contributor on ; at present I am self-studying some material, and so have been asking occasional questions when getting stuck on a proof or exercise in the textbook I'm reading, but for the most part I enjoy answering questions on the site, generally in algebra or logic. (I'll avoid specificity, again for obvious reasons.) Most of the questions I've answered are pretty standard, with a handful of (at least for me) less obvious ones, but my activity on the site has been largely well-received, at least as far as I can tell. So, in short, my question is whether a stackexchange profile can be a worthwhile inclusion in graduate school applications. I see a few pros and cons; on the one hand, I'm (embarrassingly) a bit proud of my contributions here! I really enjoy sharing my love of math and helping people resolve questions (teaching is one of the things I'm most excited for in the future), especially questions that are particularly interesting or thought-provoking. I also enjoy mathematical writing, and one of my favorite parts of the site is that it's an excellent venue for sharpening one's expository abilities. These are important things to me, and I feel that including the math.SE profile in an application would be a good way of indicating this. I also believe (read: hope) that the questions I've posted are worthwhile, and indicate a good understanding of and level of thought about the material I'm studying. On the other hand, I'm concerned an application committee might see the time spent on the site as frivolous or wasted, somehow; the site is certainly a source of procrastination for me, and my involvement may give an undesirable impression of being too vested in virtual things. Furthermore, while I'm generally happy with my contributions to the site, I'm also aware that one's own view of such things may be very different than the view of an experienced mathematician; what if my answers seem overcomplicated or my questions seem silly? In any case, these are some of the things I've been thinking about; any thoughts would be greatly appreciated. | I think contributions to StackExchange constitute a valuable thing for an academic to do. In many cases such contributions are directly related to the aims of an academic department: community engagement, building new knowledge, etc. This is particularly clear for sites that directly align with a particular academic discipline (e.g., , , ). However, many people in academia have not heard of StackExchange. They often won't have heard about the reputation system. They may not be aware of the high quality content that often appears. Thus, as an academic, how should you share your achievements on the StackExchange network in contexts where how your performance is evaluated has material consequences? (e.g., a CV, job interview, grant application context, promotion context) |
My battery is broken, so it's always at 0%. How can I remove the annoying notify-send with beep warning about low battery? Things I've tried so far: Altering /etc/UPower/UPower.conf dconf-editor → org → gnome → settings-daemon → plugins → power (which seems to save settings to file UPower.conf) service upower stop service acpid stop Various GUI power related options in System Settings Nothing seems to stop the damn popup. | I have the low battery alarm disabled in the BIOS settings on my Lemur laptop, but the alarm still sounds when the battery is low. The sound is a very loud and annoying beep that repeats every couple seconds. The laptop will last another 20 minutes without being plugged in so the battery level isn't properly being detected anymore anyways. I found that if I mute my audio then the beep stops but I obviously cannot listen to anything anymore. If i turn the volume back on even to just 1% the battery alarm is audible again at full volume. I remember there used to be a mixer somewhere that could control the internal speaker and so if I could find that again then maybe i could mute that and fix this problem. I have Ubuntu 14.04. Note that I'm not talking about a low battery notification, which is something through gnome; as opposed to a low battery ALARM which is this very loud beep every couple seconds coming through the internal speaker. Nevertheless, here are my gnome power settings: $ gsettings list-recursively org.gnome.settings-daemon.plugins.power org.gnome.settings-daemon.plugins.power button-power 'interactive' org.gnome.settings-daemon.plugins.power critical-battery-action 'nothing' org.gnome.settings-daemon.plugins.power percentage-low 1 org.gnome.settings-daemon.plugins.power priority 0 org.gnome.settings-daemon.plugins.power lid-close-suspend-with-external-monitor false org.gnome.settings-daemon.plugins.power idle-dim false org.gnome.settings-daemon.plugins.power button-hibernate 'hibernate' org.gnome.settings-daemon.plugins.power sleep-inactive-ac-type 'suspend' org.gnome.settings-daemon.plugins.power button-sleep 'suspend' org.gnome.settings-daemon.plugins.power button-suspend 'suspend' org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout 0 org.gnome.settings-daemon.plugins.power time-low 1200 org.gnome.settings-daemon.plugins.power lid-close-ac-action 'nothing' org.gnome.settings-daemon.plugins.power notify-perhaps-recall true org.gnome.settings-daemon.plugins.power percentage-critical 1 org.gnome.settings-daemon.plugins.power percentage-action 1 org.gnome.settings-daemon.plugins.power sleep-inactive-battery-type 'suspend' org.gnome.settings-daemon.plugins.power time-action 120 org.gnome.settings-daemon.plugins.power lid-close-battery-action 'nothing' org.gnome.settings-daemon.plugins.power idle-brightness 30 org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 0 org.gnome.settings-daemon.plugins.power time-critical 300 org.gnome.settings-daemon.plugins.power active true org.gnome.settings-daemon.plugins.power use-time-for-policy false $ |
My name is invisible. I can't write my user name when I join an online server, it says invalid name! How do I fix this? | I am having trouble getting onto a server in Minecraft PE on iOS. When I tap on the person's server it just says invalid name: I have tried turning off and restarting the iPad, going to home screen and logging back into the server but I have had no luck and no change. Is there a reason why this is so? |
"The diamagnetic materials repel the materials which produces magnetic field, so putting these materials in the proximity of the magnetic field generating materials produces the effect of the diamagnetic levitation." I read this statement somewhere and I got confused with it. I know that when magnetic field is applied to a current carrying loop an electric potential is induced in the circuit which is proportional to rate of change of the magnetic flux through the loop. This induced potential gives raise to a current flow in such a direction so that the magnetic field generated because of this new current is in opposition of the applied magnetic field which is diamagnetism. I want to know what happens to the diamagnetic material when it is kept in a constant magnetic field. Since the field is constant now, there would not be any flux change and hence no induced magnetic field to oppose the constant applied field. So will in that case be no diamagnetic effect or any other effect? | When we put a diamagnetic material in the presence of an external magnetic field $\vec B_0$, the magnetic field inside the material decreases to $$\vec B=(1+\chi_m)\vec B_0,$$ where the magnetic susceptibility $\chi_m$ is a small negative number. I am assuming the material is linear and isotropic. On the other hand the diamagnetism is explained in terms of Lenz law. When we change the magnetic flux of the external field over the material, atomic currents generate an induced magnetic field trying to restore the flux. But then the induced field could have any sign (in the appropriated direction), depending if we are increasing or decreasing the flux of the external field. It seems diamagnetism is a dynamic effect. How come the sign of $\chi_m$ is always negative? Moreover, the magnitude of $\chi_m$ should depend on how large is the variation of the flux but I do not see any suggestion of this when looking at tables of $\chi_m$. |
Is there a word for using a word twice to imply something different? eg. Are you done, or are you done done? | What is the term when a word is used consecutively twice, with intentional stress placed on the first word, as a means to alter the severity of the word's meaning? I am not referring to a (had had) or a (that that), but to the slightly sarcastic use as demonstrated in shows like Seinfeld. Sample sentences, with emphasis: I know we're going out to eat, but I am only going to pick at an appetizer because I'm not hungry hungry. Don't wear something so formal to the party; I don't think you need to be dressed dressed. Of personal note, some of my relatives decided a few years ago to nick-name the term a "Celaine" (a combination of their names) due to their own frequent use of it. Note: This question explicitly requests the term of art used by linguists and English scholars when discussing this phenomenon. This question is different from a which requests a historical explanation for the phenomenon described by this term. None of the answers to the suggested duplicate provide the term. The author of the similar question requests the term for the pattern in a comment, but does not receive an acceptable answer. The only mention of an acceptable term is in a comment made by the author of this question, in response to the author of the similar question, directing back to this very question. |
I had Schengen visa four years ago through Latvia, and it was revoked due to limitation on my visa, pls can I apply with my new passport as new applicant through another Schengen country. I would like to know if my previous information won't have any effect on my new application. With another Schengen. | When certain nationalities of people want to travel in the Schengen zone, they are required to apply for a Schengen visa. This is a straight-forward process for most, but when an applicant has had problems with removals or refusals they may be reluctant to apply because they want to avoid the complexities of serial visa refusals. This reluctance may lead some into wondering how their history can be expunged, and this line of thought inevitably leads to the idea of getting their passport replaced with a new one. This sounds like a great formula for people who have had prior refusals or removals. In essence they can become 'reincarnated' as a first-time traveller and hence avoid the unpleasantness of revealing their prior interactions with the Schengen authorities. The relevant parts of the application form are shown here... Nothing asks about a prior removal or refusal, and the applicant is left with simple denials for 3 questions in order to present themselves as a first-time traveller. Assuming the person is happy to set aside the moral issues associated with denying their history, are there any holes to this strategy? This question is scoped to Schengen visa applications so that it will not be unmanageably broad, but answers from other regimes (particularly the affluent Commonwealth and the USA) are acceptable as long as the main points are relatively consistent with Schengen. |
I found this in a previous years iit paper. It seems really interesting, but incredibly difficult. Can someone please help $$ \sum_{i = 1}^\infty \arctan\frac{1}{2i^2} $$ This whole expression is equal to $t$ Find $\tan(t)$ | I am solving this problem. If $$\sum\limits_{i=1}^{\infty} \tan^{-1}\biggl(\frac{1}{2i^{2}}\biggr)= t$$ then find the value of $\tan{t}$. My solution is like the following: I can rewrite: \begin{align*} \tan^{-1}\biggl(\frac{1}{2i^{2}}\biggr) & = \tan^{-1}\biggl[\frac{(2i+1) - (2i-1)}{1+(2i+1)\cdot (2i-1)}\biggr] \\\ &= \tan^{-1}(2i+1) - \tan^{-1}(2i-1) \end{align*} and when I take the summation the only term which remains is $-\tan^{-1}(1)$, from which I get the value of $\tan{t}$ as $-1$. But the answer appears to be $1$. Can anyone help me on this. |
I have my own self-signed SSL certificate for a website I need to keep relatively secure. I've been able to install my client SSL certificate just fine, but I can't seem to install the server's certificate to the Android trusted list, so I always get a warning when trying to access my site in Chrome from the device. How do I install a PEM or CRT file for a self-signed server certificate? | I am trying to install the self-signed certificate for my web server in Android 4.3. I have the .crt file in the root of the SD card (which is actually emulated as I have no SD card in the slot). To install the certificate I go to Setting -> General -> Security -> Credential Storage -> Install from device storage. I get a dialog box showing the name of the certificate (the filename minus the .crt extension) which I can modify (but don't), a "used for" pull down with "VPN and apps" selected and text at the bottom of the dialog which informs "Package contains: one user certificate". Everything looks okay, so I click "Ok". The dialog goes away and a toast message pops up with "[name] installed". However if I immediately go to "Trusted credentials and select "User" there is nothing there! The new cert is also not under "System" but I would not expect it there. If I go to a browser after this and try going to my web site, I still get the warning that the site's certificate is not trusted. I have also tried rebooting, but it doesn't make a difference. What am I doing wrong? The complete lack of error messages isn't helpful. Is it possible my certificate is in the wrong format? I have tried using the .crt file in the server's ssl directory and I have tried converting it to DER format. Update: I read somewhere that Android requires certificates to be in p12 format, so I converted the Apache2 certificate to p12 using the following command: openssl pkcs12 -export -inkey server.key -in server.crt -out ~/server.p12 I then repeated the above steps, got the same success message, and then proceeded to still not see the certificate in the user credentials and I still get the untrusted certificate error from the mobile browser. |
Let X a continous variable and Y a binary variable with joint distribution : $$p(x,y;\beta,\rho_1,\rho_2,\phi_1,\phi_2)=\frac{1}{Z(\beta,\rho_1,\rho_2,\phi_1,\phi_2)}\exp(-0.5 \beta x^2+1_{y=0}\rho_1 x+1_{y=1} \rho_2 x+1_{y=0} \phi_1+1_{y=1} \phi_2)$$ with Z a normalising constant. The conditional of X given Y is a Gaussian depending on Y and the conditional of Y given X is a Bernoulli variable whose probability $P(Y=1)$ is depending on X. Is it possible to use Gibbs sampling? | For a project, I need to simulate from a joint distribution with both continuous and discrete variables that are dependent. The conditional distribution of any variable given the rest is known. I decided to simulate with the help of Gibbs sampling. My question is: Is it possible to simulate from a joint distribution containing both continuous and discrete variable with Gibbs sampling? |
I am trying to do something that I feel should be more straightforward or maybe my Java knowledge is interfering, but I can't figure it out. All I want to do is make a vector<A> as {aa, bb, cc} where bb and cc are child instances of the base class, A. Each Child class uses the same function name but has a different implementation. So what I want to do is call that implementation during the iteration. Here's my attempt. #include <iostream> #include <vector> class A { public: virtual ~A() = default; }; class B: public A { public: int h() { return 2; } }; class C: public A { public: int h() { return 3; } }; int main() { std::cout << "hello world" << std::endl; // Inheritance A aa; B bb; C cc; std::vector<A> as {aa, bb, cc}; for (A child: as) { if (typeid(B) == typeid(child)) { std::cout << "child is a B" << std::endl; B* child_b_p= static_cast<B*>(&child); std::cout << child_b_p -> h() << std::endl; } if (typeid(C) == typeid(child)) { std::cout << "child is a C" << std::endl; C* child_c_p= static_cast<C*>(&child); std::cout << child_c_p -> h() << std::endl; } } return 0; } I expect child is a B 2 child is a C 3 I only see hello world. What is a possible workaround for object slicing in this case? | Someone mentioned it in the IRC as the slicing problem. |
I've got an online discussion forum as part of a (mostly in person) university course that I'm teaching. I've been using the university-provided Blackboard forum software which is ... well, I won't use the words that I want to use to describe its quality. In the future, I'm going to use some other software for this purpose, and it won't be hard to find something better than Blackboard. However, the best forum software I've ever used is StackExchange. It's incredible. Any way I could make use of it for teaching? | Is the Stack Exchange engine that powers Stack Overflow available to download or install internally for an enterprise or company? I think Stack Exchange's engine is very great and could be very cool to use for internal enterprise patterns and practices, like the engine of Wikipedia. |
Recently I set a password containing small c cedilla (ç) and now I can't type it on login menu because it doesn't use the Spanish but English keyboard and types a slash, resulting in wrong password. How could I login? | I'm working on a Ubuntu system, and my client has completely forgotten his administrative password. He doesn't even remember entering one; however it is there. I've tried the suggestions on the website, and I have been unsuccessful in deleting the password so that I can download applets required for running some files. Is there a solution? |
Two-part question: Neural Networks(NN) can be looked at as stacked units of logistic regression classifiers (LRC). A basic requirement of an activation function is to be non-linear. When LRC is a neuron, sigmoid function is the activation function and is said to bring non-linearity to NN. Q1:) If this is true, why is LRC still a linear classifier even when it uses non-linear sigmoid function? Further, if the activation function is a linear function(e.g. an identity function), the NN can no longer learn non-linear decision boundaries. Q2:) Does this mean that the depth of a neural network plays no role in making it non-linear? I have scanned similar threads for this question. But not convinced yet! | What is the purpose of a neural network having a non-linear activation function? Is it correct to say that the non-linear activation function's main purpose is to allow the neural network's decision boundary to be non-linear? I've read in other StackOverflow answers that the activation function "", but that is rather vague. Another posting states that an answer in the context of , but again that is not exactly what I'm asking. |
I'm trying to make a very abstract PDO select function, but for some reason, I'm getting an empty array returned. function listAllProducts () { return select('products', '', ''); } function select( $tableName, $property, $value ){ switch($tableName) { case "products": $tbl = 'products'; break; case "cart": $tbl = 'cart'; break; } switch($property){ case "id": $property = 'id'; break; case "name": $property = 'name'; break; } $db = new PDO('mysql:host=localhost;dbname=ecom;charset=utf8', 'root', 'PASSWORD'); if( strcmp($value, '') != 0 ){ //if $value is not empty $query = "SELECT * FROM $tbl WHERE $property = :value"; $stmt = $db->prepare($query); //bind params $stmt->bindValue(':value', $value); } else{ $query = "SELECT * FROM $tbl"; $stmt = $db->prepare($query); } //execute try{ $stmt->execute(); $result = $stmt->fetchAll(); return $result; } catch(Exception $e){ return $e; } } Is there something simple I'm missing? EDIT: Thanks for the help, but after adding a switch and removing table and columns from my bound params, I'm still getting an empty result set :( EDIT 2: I've found a somewhat convoluted solution, added it above, but it looks like it's working for now! More testing is necessary. | Why can't I pass the table name to a prepared PDO statement? $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) { var_dump($stmt->fetchAll()); } Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do $sql = "SELECT * FROM $table WHERE 1" |
I'm new in ubuntu and when I try every time to install a program sometimes I install the program by apt-get command or by snap so, please anyone can tell me when I should use snap or apt-get? thank you | This is not a duplicate of the following questions because: My question specifically states that I am interested in end-user experience, not ease or efficiency of development, which is what the other question largely refers to. As has been noted, development/deployment affects end-user experience, but it is not all there is to it, and neither of the referenced questions address issues that directly impact an end-user's ability to use the application (e.g. trouble accessing data on other partitions, sluggishness, etc.) Maybe "compelling" wasn't the right word to use; my intent was to ask about real-world, experiential consequences, i.e., things that happen or don't happen, as opposed to theoretical/architectural statements that, while presumably accurate, don't appear to be backed up with any real-world examples to support the statement. I should have stated more directly that my intention was to get answers that consider the balance of "advantages" to snaps against the real-world downsides experienced by end-users. The "duplicate" question is largely theoretical, and doesn't discuss end-user experience at all. The "duplicate" question makes no mention of anything remotely similar to the example I used here, i.e., that there is an end-user downside to snaps (in this case, lack of access to data on other partitions and snap app performance) that isn't discussed in any available documentation that I can find. While I understand that snap has a big advantage in making apps more widely available, is there any compelling reason to choose snap over apt, if the app is available for my distro/version via an apt package? I am curious because I've been doing some reading about snaps, and all the excitement about the method seems to be about things that are advantageous for app developers, but I've seen virtually nothing on how this makes life easier for end users (aside from the obvious; that they may be able to install apps that aren't otherwise available on their distro/version). I installed snapd and installed a couple of snaps and was really frustrated and disappointed. The snap apps are slow and it's difficult, if not impossible, to access files on other partitions from within the snap. While I've seen plenty of info that says snaps are "faster," "easier," "safer," etc., I haven't been able to find anything that explains why or how this is actually the case. Being very new to Linux, I am wondering if maybe I'm just missing something obvious? To be clear, I understand why the technology might be useful overall, but I can't find anything that explains whether/why it is a better option even when the app in question is available for install via a more traditional method, and all dependencies are met. |
When I try to change a sudo password, it say it doesn't work even running the mount -rw -o remount / When you run that command it would say i worked from the root menu but would still be invalid when you logged in. | If I change the password for the root user is that going to automatically change the password for the user account? I found this link for root: How do I change the user account password? |
I am trying to turn my standard shifting bicycle into an automatic shifter using a motor to increase and decrease the tension in the shifter cable. The problem is that a lot of torque is required to do this, so I was considering cutting the return spring off. I know this is permanent, so I want to make sure that I am doing the right thing before making the cut. I am planning on installing a spring with a much lower spring constant on the cable itself (see image). This is another thread with a similar topic. Móż suggested cutting this spring. I am really new to bicycle engineering, so please excuse my lack of knowledge on the topic. | I am planning to build an electronically controlled automatic bike transmission for my senior design project. I'm personally more of an electrical guy, so dealing with the mechanics is somewhat new to me. I would have loved to use an off-the-shelf electronic derailleur, but alas, they are too cost prohibitive (the school has allotted a budget of $115 per student and we're a group of two, so we have $230 to spend). So I'm going to need to make my own like several other people have done. I am planning on using the bike's current derailleurs and replacing the hand shifters with motors of some sort to pull on the cables. Of course, we're going to need a certain amount of torque to shift up (and much less for shifting down) and a holding torque to ensure that we don't accidentally slip down a gear. I have not bought a bike yet, I'm looking at a Diamondback bike that I found on Craigslist (it looks like a hybrid bike). So I'm wondering if there are any average measurements for the required torque. And of course, I'm sure there are many people more experienced in bicycling than I am. So if you have a better solution, please feel free to shout it out. I'm all ears. |
I'm using jQuery and Laravel's session flash data to show a notification after every CRUD action. For example: /* * * Update code goes here */ return Redirect::route('profile')->with('flashMessage', 'Profile updated'); The flash data is by definition available only for the next request. However, if I go to another page (directly after the notification was shown) and hit the browser back button, the flash data is still there, causing the notification to show up again, but this time with no logical reason. Is there a way to prevent this? I'm testing in Chrome. | So the SMEs at my current place of employment want to try and disable the back button for certain pages. We have a page where the user makes some selections and submits them to be processed. In some instances they have to enter a comment on another page. What the users have figured out is that they don't have to enter a comment if they submit the information and go to the page with the comment and then hit the back button to return to the previous page. I know there are several different solutions to this (and many of them are far more elegant then disabling the back button), but this is what I'm left with. Is it possible to prevent someone from going back to the previous page through altering the behavior of the back button. (like a submit -> return false sorta thing). Due to double posting information I can't have it return to the previous page and then move to the current one. I can only have it not direct away from the current page. I Googled it, but I only saw posts saying that it will always return to the previous page. I was hoping that someone has some mad kung foo js skills that can make this possible. I understand that everyone says this is a bad idea, and I agree, but sometimes you just have to do what you're told. |
I'm running the following SQL on SQL Server 2000: exec sp_trace_create @options = 2, @tracefile = N'h:\\trace.trc', @filecount = 2 and am getting the following error and can't understand why: Procedure expects parameter '@tracefile' of type 'nvarchar(128)' If I pass all of the parameters in like so: declare @id int exec sp_trace_create @id output, @options = 2, @tracefile = N'h:\\trace.trc', @filecount = 2, @maxfilesize = 5, @stoptime = '2013-8-15' I get the error: Procedure or function sp_trace_create has too many arguments specified. | The first batch of the following script calls stored procedure with parameters in documentation order; the second batch swaps the positions of parameters @tracefile and @options: DECLARE @new_trace_id INT; EXECUTE master.dbo.sp_trace_create @trace_id = @new_trace_id OUTPUT, @options = 0, @tracefile = N'C:\temp\TestTrace'; SELECT @new_trace_id AS [@new_trace_id]; EXECUTE master.dbo.sp_trace_setstatus @trace_id = @new_trace_id, @status = 2; GO DECLARE @new_trace_id INT; EXECUTE master.dbo.sp_trace_create @trace_id = @new_trace_id OUTPUT, @tracefile = N'C:\temp\TestTrace', @options = 0; EXECUTE master.dbo.sp_trace_setstatus @trace_id = @new_trace_id, @status = 2; GO The first batch creates a new trace, selects its id, and then closes the trace. One result set is returned: @new_trace_id 2 The second batch fails with an error: Msg 214, Level 16, State 3, Procedure sp_trace_create, Line 1 Procedure expects parameter '@tracefile' of type 'nvarchar(256)'. Why does parameter order affect the output of stored procedure sp_trace_create? And why does it fail with such a misleading error message? |
I'm currently trying to see if the date value is set to today's date or greater. var date = document.getElementById("inputDate").value; var varDate = new Date(date); //dd-mm-YYYY var today = new Date(); if(varDate >= today) { //Do something.. alert("Working!"); } Date format dd-mm-YYYY The current code above won't work. | Can someone suggest a way to compare the values of two dates greater than, less than, and not in the past using JavaScript? The values will be coming from text boxes. |
I have a bootstrap table where I list among other things some links that trigger a jQuery action based on CSS class selector. The past couple of days been struggling to understand why my selector does not trigger once the sorting of the table is changed (eg any type of sorting, or changing pagination etc). Calling the action like so would only work until the table is re-sorted but not after that: $('.class_selector').on('click', function(e) { ... }); Calling it like so appears to work all the time: $(document).on('click', '.class_selector', function(e){ ... }); I'm guessing the 1st approach attaches the event to the selector whereas the 2nd actually attaches it to the document and thus perform a search for the selector every time the action (ie click) is performed on the selector (ie document)? And then something happens to the document when the bootstrap table is re-sorted? Could anyone please explain the difference between the two methods above? I've no idea how to begin searching for answers and I cannot find any reference in the documentation for the 2nd approach. Thanks Answer: I think I can answer this now for myself? You can delegate events either for selectors that exist at the time of parsing (1st approach), or you can bind them to selectors that might be later added dynamically (2nd approach). | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
Can anyone help me identify this component? It just says 0 or D on it (I think it's a zero). I tested it for conductivity with a multimeter - doesn't seem to have any (tried both polarities in case it's a diode). Tested for resistance: nothing (i.e. infinite resistance), although I'm not 100% sure I was touching the contact points correctly, so don't take this as an ultimate measurement. Thanks in advance! | It is used on a small board RFID antenna circuit based on the TMS3705: At the first check it seems to be a 0 ohm resistor, but the dimension 4x4mm its strange. Any ideas? L. |
I have a default sphere and created ornamental design. I want to coil or wrap on the sphere. I tried shrinkwrap modifier but it did not work. Is there any other i can coil or wrap the design on the sphere. Similar to like this Below Aladdin lamp is my model and i want to wrap on that lamp. Any suggestion or help. Thanks | I have base of the machine and the button separate model. I want the button to be bend and shrink so that it fix on the top of the machine. I tried shrinkwrap and bend option but its not working. With bend option i got this result With shrinkwrap option i got this result I want to achieve this result |
I have been given this task to design a single 8x4 memory chip using only 2x1 memory chips. I have been searching everywhere on google for some decent information or example of how this is done, but sadly came up empty handed. Can anyone please help me out or at least point me in the right direction? | Construct an 8k X 32 ROM using 2k X 8 ROM chips and any additional required components. Show how the address and data lines of the constructed 8k X 32 ROM are connected to the 2k X 8 chips. I tried to solve it but I am not sure if I got the correct answer. Could anyone check my drawing and correct me? |
How do I find binary path of Firefox ? I'm using the dev edition and the solution I found here didn't help as the command which firefox outputted nothing. whereis firefox outputted the lib location within the system which lead me to firefox's plugins. which firefox-dev outputted nothing as well. Any ideas ? | Mozilla released the Firefox Developer Edition! How do I install it on Ubuntu? Source: |
1) One-third of the population of sub-Saharan Africa is undernourished. 2) Nearly 70 percent of the population still live in the countryside. 3) One-third of the residents live below the poverty level. Why is a singular verb "is" used after "One-third of the population" while a plural verb "live" is used after "70 percent of the population"? Why is a singular verb "is" used after "One-third of the population" while a plural verb "live" is used after "One-third of the residents"? | Does a percentage require a singular or plural verb, for example, do we say ten percent "go" or "goes"? |
Given n objects held by n people, how to find the total number of valid exchanges, where a valid exchange means that all persons hold different objects after the exchange? eg for 4 objects 1 2 3 4: valid exchanges are: 2 1 4 3 2 3 4 1 2 4 1 3 3 1 4 2 3 4 1 2 3 4 2 1 4 1 2 3 4 3 1 2 4 3 2 1 Therefor the total number of valid exchanges are 9. | I understand the whole concept of Rencontres numbers but I can't understand how to prove this equation $$D_{n,0}=\left[\frac{n!}{e}\right]$$ where $[\cdot]$ denotes the rounding function (i.e., $[x]$ is the integer nearest to $x$). This equation that I wrote comes from solving the following recursion, but I don't understand how exactly the author calculated this recursion. $$\begin {align*} D_{n+2,0} & =(n+1)(D_{n+1,0}+D_{n,0}) \\ D_{0,0} & = 1 \\ D_{1,0} & = 0 \end {align*} $$ |
This is core of the function i am currently writing. #include <cstdio> #include <cstdlib> #include <cctype> #include <ctime> #include <cstring> const char *words[] = { "pigu", // "third", // "country", // "human", // "define", }; #define word_count (sizeof(words) / sizeof(char *)) const char *allowed_chars = "abcdefghijklmnopqrstuvwxyz"; const char *get_random_word() { return words[rand() % word_count]; } char *copy(const char *origin) { char *str = NULL; str = (char *)malloc(sizeof(origin)); strcpy(str, origin); return str; } int run() { const char *selected_word = get_random_word(); char *active_word = copy(selected_word); char *placeholder_word = copy(selected_word); char *left_chars = copy(allowed_chars); free(active_word); free(placeholder_word); free(left_chars); return 1; } int main(int argc, char *argv[]) { srand(time(NULL)); while (run()) { } printf("\n"); return 0; } I have stripped out other code and managed to locate the problem to run function, which in this case will run infinitely, however while debugging I have set break points inside run function. Turns out that after running the function run for second time, the program crashes when it tries to execute free(placeholder_word);. Why is this happening and how could i prevent it. | First off, here is some code: int main() { int days[] = {1,2,3,4,5}; int *ptr = days; printf("%u\n", sizeof(days)); printf("%u\n", sizeof(ptr)); return 0; } Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)? |
I am running Ubuntu 16.04 LTS. I added Japanese as a supported language but it is not the top one and no other apps appear in Japanese. How can I get Synaptic to display in English? Output from locale command: LANG=en_US.UTF-8 LANGUAGE=en_US:en LC_CTYPE="en_US.UTF-8" LC_NUMERIC=en_US.UTF-8 LC_TIME=en_US.UTF-8 LC_COLLATE="en_US.UTF-8" LC_MONETARY=en_US.UTF-8 LC_MESSAGES="en_US.UTF-8" LC_PAPER=en_US.UTF-8 LC_NAME=en_US.UTF-8 LC_ADDRESS=en_US.UTF-8 LC_TELEPHONE=en_US.UTF-8 LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=en_US.UTF-8 LC_ALL= Here is the output from /etc/default/locale. Looks like we might have found the culprit! Thank you! How do I change these values? # File generated by update-locale LANG="ja_JP.UTF-8" LANGUAGE="ja:en_US:en" LC_NUMERIC="en_US.UTF-8" LC_TIME="en_US.UTF-8" LC_MONETARY="en_US.UTF-8" LC_PAPER="en_US.UTF-8" LC_IDENTIFICATION="en_US.UTF-8" LC_NAME="en_US.UTF-8" LC_ADDRESS="en_US.UTF-8" LC_TELEPHONE="en_US.UTF-8" LC_MEASUREMENT="en_US.UTF-8" | I have a remote server which I installed and have been trying to unsuccessfully change the locale to french for a few hours. Below are the contents of my locale files: /etc/default/locale: LANG="fr_FR.UTF-8" LANGUAGE="fr_FR.UTF-8" LC_CTYPE="fr_FR.UTF-8" LC_NUMERIC="fr_FR.UTF-8" LC_TIME="fr_FR.UTF-8" LC_COLLATE="fr_FR.UTF-8" LC_MONETARY="fr_FR.UTF-8" LC_MESSAGES="fr_FR.UTF-8" LC_PAPER="fr_FR.UTF-8" LC_NAME="fr_FR.UTF-8" LC_ADDRESS="fr_FR.UTF-8" LC_TELEPHONE="fr_FR.UTF-8" LC_MEASUREMENT="fr_FR.UTF-8" LC_IDENTIFICATION="fr_FR.UTF-8" LC_ALL="fr_FR.UTF-8 /var/lib/locales/supported.d/local: fr_FR.UTF-8 UTF-8 en_US.UTF-8 UTF-8 en_GB ISO-8859-1 en_GB.UTF-8 UTF-8 en_GB.ISO-8859-15 ISO-8859-15 fr_BE.UTF-8 UTF-8 fr_CA.UTF-8 UTF-8 fr_CH.UTF-8 UTF-8 fr_LU.UTF-8 UTF-8 fr_FR ISO-8859-1 Everything is still defaulting to english dates and the $ currency in my web app. Is there something else I'm overlooking? I should also mention that I have dpkg re-configured and restarted the server after changes were made. |
I am sure this will be easily spotted, but it is late here. Here is my The desired outcome is that the user will have some feedback when they click on the active calendar links. You can tell the active ones, as the calendar numbers are darker, and they have an 'active' class on them. Rendered markup: <td class="active"><a href="#">23</a></td> Right now, nothing happens when you click on any of the links. I feel like it must be my selector, but I'm not capturing it. There is already an event in the js (line 9), and I am just trying to trip the debugger to be sure I've triggered the event. JS listener: $('td.active').on('click', function(e) { debugger; }); I've tried a number of selectors, and I can't seem to figure out the right syntax for this. I feel pretty certain it is just my selector, but I'm open to suggestion. Please tell me what I'm missing. I could use some help. Thanks. | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
I suspect that this exact integral has been asked about before, but finding it among the sea of questions title "difficult integral" is daunting. I am trying to compute $$\frac{1}{\sqrt{2\pi}}\int_{-\infty}^{\infty}e^{-\frac{x^{2}}{2}+x}dx$$ This integral showed up when I found myself needing to compute the expected value of $e^{X}$ where $X$ is a standard normal random variable. Wolfram says that the integral evaluates to $\sqrt{e}$, but I haven't been able to get it to work out. Any help would be appreciated. | Problem: Let X be a nonnegative random variable and $log X \sim N(0,1)$, prove that $\mathbb{E}[X^k] = e^{\frac{k^2}{2}}$. I'm self learning probability in order to understand some theorems in number theory, and this problem came in a book I'm reading. I know that $\mathbb{E}[X^k]=\mathbb{E}[e^{klog X }]=\int_{-\infty}^{\infty} e^{klog(x)}f_{X}(x)$. Now, I'm pretty lost in the $f_{X}(x)$ part. I suppose the question is how can I link the logX which its distribution is known and the X but Im not sure what is allowed to use in these cases. Any help would be really appreciated. Thanks! :) |
Disclaimer: I haven't reviewed in ages. I just see 55k and think, What's the point? This leads me to wonder if it might not make a psychological difference (and maybe calm the robo-reviewers?) If there was just a simple 'There is something to review' message, and no indication of 'pressure'. (Just imagine if the had said "2,352,342 images left to label", would you have played?) | Today, the size of the close-votes queue is 55k questions and growing. Is that a problem? Which action could be taken to clean it up? It seems to be growing faster than Stack Overflow members are capable to handle it. |
I would like to check whether a number is in a list and make a decision in the calculation of a macro. I found a neat solution to check the membership of a number, and it works as long as I don't use it inside my decision macro. However, I have not been able to use it in the macro \processNum in the code below. \documentclass[tikz, border=0mm]{standalone} \usepackage{tikz,xfp} \usepackage{xstring} \newcommand\IfStringInList[2]{\IfSubStr{,#2,}{,#1,}} % Adapted from https://tex.stackexchange.com/a/260909/23594 \newcommand{\singleBox}[4]{% \fill(\fpeval{#1}mm,\fpeval{#2}mm) rectangle (\fpeval{#1} mm + \fpeval{#3} mm,\fpeval{#2} mm - \fpeval{#4} mm); } \newcommand{\processNum}[5] % { \fpeval{ \IfStringInList{#1}{1,17,130,109}{1}{0} ? #3 + 39 + (#4 + #5) + (#2-1) : \IfStringInList{#1}{4,11,100,189}{1}{0} ? #3 + 39 + (#4 + #5)*2 + (#2-1) : \IfStringInList{#1}{9,19,124,167}{1}{0} ? #3 + 39 + (#4 + #5)*3 + (#2-1) : 0 } } \begin{document} \IfStringInList{17}{1,17,130,109}{1}{0} % Works just fine. [for debugging purposes]. \IfStringInList{16}{1,17,130,109}{1}{0} % Works just fine. [for debugging purposes]. \begin{tikzpicture} \draw[draw=black] (0mm,0mm) rectangle (300 mm, 400 mm); \singleBox{100}{200}{24}{13} % This works just fine. [for debugging purposes] \singleBox{\processNum{1}{1}{0}{2}{1.46}}{200}{24}{13} % Fails at this line. \end{tikzpicture} \end{document} The error message is: Undefined control sequence. ...convertNum{1}{1}{0}{2}{1.46}}{200}{24}{13} | Is there any way to check whether an integer is a member of a list of integer numbers and return a boolean? I found this neat solution, that does a great job. It checks whether a string exists in a list of strings: \documentclass{article} \usepackage{xstring} \newcommand\IfStringInList[2]{\IfSubStr{,#2,}{,#1,}} \begin{document} \IfStringInList{Paul}{George,John,Paul,Ringo}{True}{False} \end{document} However, it does return a string not a boolean "true" or "false" and caused me some difficulty which is posted . Let's call the macro I would like to have \ISMEMBER. My goal is to use \ISMEMBER and examine whether an integer is in the list and depending on whether it is or not, perform some tasks, as an example: \fpeval{ \ISMEMBER{1}{1,2,3,4,5} ? \MACRO_FOR_MEMBERS : \MACRO_FOR_NON_MEMBERS } Is such functionality possible? |
I'm learning about the "coding to an interface to hide implementation details" design principle, and I'm confused over this idea. In my example, I have a WorkoutRoutine class that has a List of RoutineStep. By following the coding to an interface principle, my getWorkoutRoutine() method will return the List interface so that the implementation details of which list is used is hidden from the client. What if I decide to change the implementation from a List of RoutineStep to an array of RoutineStep, won't disclosing the return type as List reveal to the client that a list was implemented and not an array, tree, graph, or any other data structure? How can I best encapsulate my data structure for holding a collection of RoutineStep, such that I can change the implementation of the data structure without the client code breaking if the List was changed to an array, tree, graph, etc? public class WorkoutRoutine { private List<RoutineStep> workoutRoutine; public List<RoutineStep> getWorkoutRoutine() { //What if I later decide to change the data structure from a List to an array, tree, //graph, set, map. What approach should I take so that the client code doesn't break //as they would have already coded to receive a List but after changing the //implementation from a list to an array or any other data structure, their code would //break. } } | I have seen this mentioned a few times and I am not clear on what it means. When and why would you do this? I know what interfaces do, but the fact I am not clear on this makes me think I am missing out on using them correctly. Is it just so if you were to do: IInterface classRef = new ObjectWhatever() You could use any class that implements IInterface? When would you need to do that? The only thing I can think of is if you have a method and you are unsure of what object will be passed except for it implementing IInterface. I cannot think how often you would need to do that. Also, how could you write a method that takes in an object that implements an interface? Is that possible? |
I'm wanting to remove a compressor from a fridge, I need to release the gas(r600a - safe) first. Initially I thought you had to cut or pierce the copper piping attached to the compressor but I've watched a video where he cuts the capillary pipe. Cutting the capillary would be easier and safer than the larger copper pipes. Will this release all the gas? | Can I safely cut a fridge compressors copper pipes if it uses r600a gas. I've read of people taking out fridge compressors but I want to check whether it's safe to cut the pipes like this? |
In my project I reference a managed dll, that references other unmanaged dlls. I would like to know how I can embed these unmanaged dlls instead of putting them in the application's directory. I can not embed them as I would with a regular managed dll since they can not be added as a reference in my project. Thanks | I have a managed C# dll that uses an unmanaged C++ dll using DLLImport. All is working great. However, I want to embed that unmanaged DLL inside my managed DLL as explain by Microsoft there: So I added the unmanaged dll file to my managed dll project, set the property to 'Embedded Resource' and modify the DLLImport to something like: [DllImport("Unmanaged Driver.dll, Wrapper Engine, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null", CallingConvention = CallingConvention.Winapi)] where 'Wrapper Engine' is the assembly name of my managed DLL 'Unmanaged Driver.dll' is the unmanaged DLL When I run, I get: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)) I saw from MSDN and from that's supposed to be possible... |
I am writing to data in excel , My process is : Get data from website Store data into Array Write into excel Problem : It writes data first time perfectly , But second time when it reaches to Write() function , it fires null pointer exception. I have checked by debug that data is in array but not writing second time. Code : public static void Write_To_Excel() throws IOException { int lastrow = 0; FileInputStream input = new FileInputStream("E:\\Data.xls"); Workbook wb = new HSSFWorkbook(input); Sheet sh = wb.getSheet("sheet1"); Row row = sh.getRow(0); lastrow = sh.getLastRowNum(); for(int c=0;c<URLs.size();c++) { System.out.println(URLs.get(c).toString()); //driver.findElement(By.cssSelector("body")).sendKeys(Keys.CONTROL +"\t"); driver.get(URLs.get(c).toString()); String Name = driver.findElement(By.id("ProductOverrideName")).getAttribute("value"); String Manufacturer = driver.findElement(By.id("ManufacturerName")).getAttribute("value"); String MPN = driver.findElement(By.id("ProductManufacturerPartNumber")).getAttribute("value"); String Size = driver.findElement(By.id("SizeName")).getAttribute("value"); String Color = driver.findElement(By.id("ColorName")).getAttribute("value"); String Option = driver.findElement(By.id("OptionName")).getAttribute("value"); String Mkeywords = driver.findElement(By.id("ProductOverrideMetaKeywords")).getAttribute("value"); String Mdesc = driver.findElement(By.id("ProductOverrideMetaDescription")).getAttribute("value"); driver.switchTo().frame(0); String Desc = driver.findElement(By.xpath("/html/body")).getText(); driver.switchTo().defaultContent(); ProductData = new ArrayList<String>(); ProductData.add(Name); ProductData.add(Manufacturer); ProductData.add(MPN); ProductData.add(Size); ProductData.add(Color); ProductData.add(Option); ProductData.add(Mkeywords); ProductData.add(Mdesc); ProductData.add(Desc); lastrow = sh.getLastRowNum(); Row newrow = sh.getRow(lastrow); newrow = sh.createRow(lastrow+1); for(int d=0;d<ProductData.size();d++) { try{ System.out.println(ProductData.get(d).toString()); Cell cell = newrow.createCell(d); cell.setCellValue(ProductData.get(d).toString()); }catch(Exception E) { E.printStackTrace(); } } input.close(); try{ FileOutputStream webdata = new FileOutputStream ("E:\\Data.xls"); wb.write(webdata); wb.close(); }catch(Exception E) { E.printStackTrace(); } } } First time everything works fine , When it comes second time at wb.write(webdata); , It fires null pointer exception. | What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely? |
My book says that $\subset$ is used to represente any subset, proper or improper, needing in this case to show the anti symmetric property of sets. ($A = B \iff A \subset B \, \, \wedge \,\, B \subset A)$ And $\subseteq$ is used specifically to represent improper subsets. (In other words, $A \subseteq B \iff A = B) $ But i saw so many articles using $\subseteq$ and not $\subset$ then i am kinda suspicious about this definition. If this definition is correct, why $\subseteq$ it's so used? Just because it helps to prove the equality betwen the sets? Thanks for the help. | Inspired by the confusion in the comments on : I always thought that the standard was to read $\subset$ as "is a strict subset of", and $\subseteq$ could mean proper or improper inclusion. Was I wrong? |
I was taking a look at this post which details the database schema for the Stack Exchange Data Explorer. I had one question about the Posts data set: what are the reasons that the FavoriteCount column has elements that are not available? At first, I thought that this could be completely explained by the PostTypeId column--after all, if the post wasn't a question, it can't be favorited. However, I noticed that there are some questions that have a NA value, even though they're questions. Why is this? | I was when I noticed some questions have a favourite count of 0, while the majority have a favourite count of NULL. What's the reason behind this? For the questions with a count of 0, did somebody add it as a favourite in the past and removed it later (possibly even when their account was removed)? Looking at , it might very well be the case. This behaviour seems to happen on all sites in the network, not just Meta. I've already checked migrations as a possible cause, but nope. Here are two queries to view more examples: A related issue is . While this behaviour makes writing some niche queries slightly more complex than needed, it's far from being a bug and this question is also to satisfy my curiosity. |
When I was initially learning to use LaTeX, the professor who taught me the basics instructed me to use \\ as a way to end a previous line and start a new line of text. However, many of the veteran users on this forum are opposed to this method. Is there a method that is objectively better (and not just preferred) over the others and why? | What is the difference between \par, \newline, \\ and blank lines? When should I use which one? |
I had an issue with flickering on chrome and I saw what seemed to be a fix on the following thread: so I did the following: sudo nano /usr/share/X11/xorg.conf.d/20-intel.conf Paste this: Section "Device" Identifier "Intel Graphics" Driver "intel" Option "AccelMethod" "sna" Option "TearFree" "true" Option "DRI" "3" EndSection Save (CTRL + O) and reboot." Except than on reboot, after I enter my encryption password, I have a black screen. I'am on 16.04 and my computer is an Asus UX305F. I would be very grateful for any help. Thanks a lot. | I am trying to boot Ubuntu on my computer. When I boot Ubuntu, it boots to a black screen. How can I fix this? Table of Contents: |
In one part of my site, some accent characters (é,à...) are replaced by black question marks. It is for sure some encoding character but the thing is that everywhere the site displays well, except for the $html variable whose accent are corrupted and which is set this way $html = <<<EOF <div>... <header>... EOF; What is weird is that on my local machine, everything goes well but on my remote machine, it is failing. For information, I correctly set this <meta charset="utf-8"> | I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1. Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur? This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2. |
Now I cannot add any menu entry to my main menu structure, possibly because I attempted to modify it using a cache plugin. Anybody knows how I can fix that and make the menu editable again? Thank you | Suddenly I cannot add any menu entry via the "Menu" settings option (....wp-admin/nav-menus.php). Any new menu I set results in de-selecting the currently selected menu and saving a "null" menu structure in my homepage! Any help would be greatly appreciated because my home page is affected/ Thank you |
When I was in my teens, I think (if so it must have been in the seventies or early eighties), I read a short story about a single person landing in a space ship on a hostile military planet, and then driving everyone mad there with paradoxes. In this way he managed to beat them, or get out safely or something like that. Maybe even engender a revolution. The reason I would like to find this story again, is that it ends with a description of him back in his ship and on his way, trying to think of a cardinality between those of the natural numbers and the real numbers. This clearly was about the continuum hypothesis, although I don't think it was named like that in the story. And then the story ends with something like "... and then he did not look stable at all." This might have been a Robert Sheckley story, but I searched for a long time and haven't found it, so this may not be the case. | I read the really funny story about 30-40 years ago, probably around the 1970's to 1980's. It was a short that tells how 3 races (one human, one insect-like and one ???) land together on a new planet with a species that is really annoyed that the strangers just sit on the ledge of the door of the spaceship instead of attacking them. Eventually they take the human and imprison him. While he's there, the insect flies inside to work out the plan to get this planet to cooperate with them. |
I don't understand assigning workers in this game. I have a bunch of crops that need tending, but not many of them are getting the attention needed. I have tried to assign one person to do it. Do I have to click assign on each individual plant? Or do I just click 'Command' and then look at the items I want to assign? | When building various structures such as the guard post or the scavenger workbench, you're prompted to assign a worker to the resource object: However... I'm not seeing any indication of how I'm meant to achieve this, and without assigning a worker the structure doesn't operate... How do I assign a worker to a resource object? |
Via this i studied the single layer Perceptron convergence proof (= maximum number of steps). In the convergence proof inside this document , the learning rate is implicitly defined as 1 . After studying it, by myself i tried to re-do the proof inserting this time a generic learning rate $\eta $. The result is that the result remains the same: $k\leq \frac{R^{2}\left \| \theta ^{*} \right \|^{2}}{\gamma ^{2}}$ that is the learning rate $\eta$ cancelled out in the proof. Is it possible , or i make mistakes in my proof ? | The convergence of the "simple" says that: $$k\leqslant \left ( \frac{R\left \| \bar{\theta} \right \|}{\gamma } \right )^{2}$$ where $k$ is the number of iterations (in which the weights are updated), $R$ is the maximum distance of a sample from the origin, $\bar{\theta}$ is the final weights vector, and $\gamma$ is the smallest distance from $\bar{\theta}$ to a sample (= the margin of hyperplane). Many books implicitly say that $\left \| \bar{\theta} \right \|$ is equal to 1. But why do they normalize it ? |
The book 'English Grammar in Use, Murphy' contains the following exercise under the Present perfect/Present perfect continuous chapter: Are you OK? You look as if ____ (you / cry). I have not found any explanations why 'have been crying' is the correct answer. Based on my understanding, the action has already been completed (the person has cried and now we're asking her by focusing on the result of the action). Other words, I can't imagine a situation when we're asking someone who's crying right now by focusing on the activity and not the result. Would anyone explaining the Present Perfect Continuous choice here? | Non-native speakers often get confused about what the various tenses and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter. I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be incorporated into the diagram. Nota bene: What this is not is a discussion of whether there are more than two tenses in English. , to which this question is not intended to supply arguments one way or the other. Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better. Breaking News There is now an excellent ELU blog article titled . It is highly recommended reading. |
I'm writing a Terms of Use page using , which is contained within a card-panel. I find that 'as-is', the spacing at the top is too much: Here, the margin-top of the h4 element get added to the padding of the containing card-panel, which is 24px. I think the former is actually sufficient spacing by itself from the top of the shadowed box, so I tried setting padding-top of this card-panel to zero using the following SCSS rule: .lucy-terms { .card-panel.lucy-card-panel { padding-top: 0; } } However, with this enabled, I find that the spacing becomes too small: When I highlight it, it seems like the margin-top of the h4 element falls outside the box. Shouldn't the margin of the element fall within the containing element? How can I fix this? I've included the relevant snippet below. body { background-color: #f3f3f3; } .card-panel.lucy-card-panel { padding-top: 0; } <html> <head> <!-- Materialize.css --> <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/1.0.0-beta/css/materialize.min.css"> <script src="https://cdnjs.cloudflare.com/ajax/libs/materialize/1.0.0-beta/js/materialize.min.js"></script> </head> <body> <div class="container lucy-terms"> <div class="row"> <div class="col s12 m12"> <div class="card-panel lucy-card-panel"> <div class="card-content"> <h4 class="center-align">Terms of Use</h4> <p class="flow-text uppercase">PLEASE NOTE THAT YOUR USE OF AND ACCESS TO OUR SERVICES (DEFINED BELOW) ARE SUBJECT TO THE FOLLOWING TERMS. IF YOU DO NOT AGREE TO ALL OF THE FOLLOWING, YOU MAY NOT USE OR ACCESS THE SERVICES IN ANY MANNER.</p> <p class="flow-text">Effective date: April 2, 2018</p> </div> </div> </div> </div> </body> </html> | So essentially does margin collapsing occur when you don't set any margin or padding or border to a given div element? |
I have been thinking of this sentence: All these factors culminated in my choosing [some life decision]. Is the usage of my choosing correct? | I assume that the following sentences are grammatically correct: He resents your being more popular than he is. Most of the members paid their dues without my asking them. They objected to the youngest girl's being given the command position. What do you think about his buying such an expensive car? We were all sorry about Jane's losing her parents like that. I'm still getting used to this possessive gerund structure. It sounded so weird to me at first. Is the structure used in both formal and informal contexts? Are there any alternative structures that result in the same meaning and are more frequently used? (Examples taken from ) |
I have a problem with encoding Polish letters in TeXmaker. What I mean by this is that: when I write Polish letters in TeXmaker they are visible as Polish letters: ą, ę, ć and so on yet after compilation what I get in dvi or pdf are just question marks similarly, if I open tex file written in TeXmaker and containing Polish letters in WinEdt, what I get are question marks as well if I produce a file containing polish letters in TeXmaker, close it and re-open in TeXmaker — again question marks I know there must be some problem with encoding, yet I have no idea how to solve it. The question has been marked as duplicate, however the original answer which was pointed to me does not concern the problem of Polish signs in TeXmaker and in a source file. Texenthusiast's answer below helped me to solve that problem as well. | How to type these special letters from European languages in latex? ä, é, and L'? |
I have Windows XP SP2 installed on my laptop, its been infected by a virus, which creates autorun.inf in each of my drives as read-only, hidden and system file attribute being set, and which generates some EXE file and PIF file. I tried some free versions of anti-rootkit, anti-malware, registry scanning softwares but of no use. For most of them it denies installation. I also tried online scanning but it disconnects the process. Then I deleted them using Live Ubuntu running on a bootable USB. But after rebooting the laptop in Windows XP they were autogenerated again. I think the registry is being affected by the virus which is restoring them. I dont want to format my laptop. Earlier the safemode was also being disbled but anyhow I enabled it then, I tried deleting the autorun.inf files from there Is there any way to check what is causing them to be autogenerate. | What should I do if my Windows computer seems to be infected with a virus or malware? What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware? This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits. |
I'm trying to return a 2d array but it gives me the errors: could not convert brace-enclosed initializer list to int cannot convert 'int ()[(((sizetype)(((ssizetype)terrainSize) + -1)) + 1)]' to 'int' in return #include <windows.h> #include <stdio.h> #include <gl/glut.h> #include <gl/gl.h> int* terrainGenerator(int terrainSize){ int tArray[terrainSize][terrainSize]; tArray[0][0] = {1,1}; return tArray; } int main(){ terrainGenerator(1); } | I am trying to return an array Data Member from one smaller 2D Array Object, and trying to insert the array into a larger 2D array object. But when attempting this, I came into two problems. First problem is that I want to return the name of the 2D array, but I do not know how to properly syntax to return 2D Array name. This is what my 2D Array data member looks like private: int pieceArray[4][4]; // 2D Smaller Array and I want to return this array into a function, but this one causes a compiler error: int Piece::returnPiece() { return pieceArray; //not vaild // return the 2D array name } I tired using this return type and it worked: int Piece::returnPiece() { return pieceArray[4][4]; } But I am unsure if this is what I want, as I want to return the array and all of it's content. The other problem is the InsertArray() function, where I would put the returnPiece() function in the InsertArray()'s argument. The problem with the InsertArray() is the argument, heres the code for it: void Grid::InsertArray( int arr[4][4] ) //Compiler accepts, but does not work { for(int i = 0; i < x_ROWS ; ++i) { for (int j = 0; j < y_COLUMNS ; ++j) { squares[i][j] = arr[i][j]; } } } The problem with this is that it does not accept my returnPiece(), and if i remove the "[4][4]", my compiler does not accept. Mostly all these are syntax errors, but how do I solve these problems? Returning the whole pieceArray in returnPiece() The correct syntax for the argument in InsertArray() The argument of InsertArray() accepting the returnPiece() These 3 are the major problems that I need help with, and had the same problem when I attempt to use the pointer pointer method. Does anyone know how to solve these 3 problems? |
How do I find the symmetry point for a graph based on a quadratic equation? | I'm taking a course on Basic Conic Sections, and one of the ones we are discussing is of a parabola of the form $$y = a x^2 + b x + c$$ My teacher gave me the formula: $$x = -\frac{b}{2a}$$ as the $x$ coordinate of the vertex. I asked her why, and she told me not to tell her how to do her job. My smart friend mumbled something about it involving calculus, but I've always found him a rather odd fellow and I doubt I'd be able to understand a solution involving calculus, because I have no background in it. If you use something you know from calculus, explain it to someone who has no background in it. Because I sure don't. Is there a purely algebraic or geometrical yet elegant derivation for the $x$ coordinate of a parabola of the above form? |
Ok here is the code snippet that I am having the problem with (class name has been changed due to work reason) const std::map<A*, std::pair<int, B*> > &aMap = ot->getAMap(); A *a = getAFromSomewhere(); B* b = aMap[a].second; //The line that the compilation error points to. Error: The operation "const std::map<A*, std::pair<int, B*>, std::less<A*>, std::allocator<std::pair<A*const, std::pair<int, B*>>>>[A*]" is illegal. anyone has any idea why this is so? | Is there a reason why passing a reference to a std::map as const causes the [] operator to break? I get this compiler error (gcc 4.2) when I use const: error: no match for ‘operator[]’ in ‘map[name]’ Here's the function prototype: void func(const char ch, std::string &str, const std::map<std::string, std::string> &map); And, I should mention that there is no problem when I remove the const keyword in front of std::map. If I've been instructed correctly, the [] operator will actually insert a new pair into the map if it doesn't find the key, which would of course explain why this happens, but I can't imagine that this would ever be acceptable behavior. If there is a better method, like using find instead of [], I'd appreciate it. I can't seem to get find to work either though... I receive const mismatched iterator errors. |
I am a bit of a novice when it comes to Blender and I'm having trouble fixing a very noticeable seam on a mirrored object (a head). I've checked to see if there's vertices that haven't been merged near the seam to no such luck. I've changed the order of the modifiers (mirror and subdivision surface). "Clipping" and "Merge" are both enabled within the mirror modifier too. I've even copied and pasted one side of the head, flipped it and then tried to merge the vertices but that won't work either. I hope this isn't a silly question, but I'm only a university student and would really appreciate the help! Thank you! :) | I was practicing with modeling a leaf using a image reference. Everything went fine and I finished modeling my leaf, but I wanted to make it more realistic (I'll add textures later), I saw lots of people using the Subdivision Surface modifier but it doesn't work for me. My model: My model when I add the Subdivision Surface modifier |
On the Activity section of the profile page, there's a little blue hat in the top-right corner of the badge section. When I receive a badge, it gets partially covered by a congratulatory message. When I press "Let us pick" to dismiss the message, or dismiss it by any other means, the blue hat in the corner disappears entirely. The fact that the message partially covers the hat seems like it is probably an intentional feature, . The fact that the hat disappears after dismissing the message seems like it is a separate issue, and probably unintentional/undesired. | Normally the hat picker is on top of the "Badges" box in your activity tab, but when there's a "Congratulations" there, the hat picker appears behind it: Also, as @MikeMiller mentions, the hat disappears after you click "let us pick". |
I recently tried my LVL20 free to play account again and noticed that when I was in PVP, I actually became LVL29. The item levels of my gear were also scaled to 34 or 35. Now I am stuck with the following problem: because items change upon entering PVP, I don't know how to compare them anymore. For Items that I already have I could just try them all, but I just have no idea what to hunt for now. So, my question is: Given an item, how can I determine in advance how good it will be for PVP? I have already looked for a guide or database, but didn't find one that took this mechanism into account. I have also not found any formula to use. | I am trying to figure out the algorithm/formula for item stat scaling in WoW. If you play in battlegrounds or arenas, your item's stats increase to the highest possible level in that bracket. So if you're level 10 your items will be boosted to level 19 in that bracket. 20 will be 29 and so on. I have an example here: This item is level level 20 and has 10 armor, 7 agility, and 7 stamina. When you join the arena or battleground, it will increase to this: I am trying to figure out this algorithm/formula, so I can enter any item's item level and stats, which will then figure out the stats when in a battleground or arena. How would I approach that? I've tried a few isolation equations, but it won't really work :( Thanks in advance! |
I play a game and need a word for the following situation. What do you call a person who asks, and begs multiple times daily and impatiently for items (gear, weapons, weapon upgrades, runs through dungeons) and swears loyalty to your guild or raids team to help and or pay for items later but does nothing in return? Then when you confront that person, they ‘unfriend’ you and leave your guild. | What would you call someone who isn't afraid to ask for money or any kind of favor or who misinterprets someone's generosity for a consistent resource for what they need? |
My Prt Sc button is on the same button as my Home button. The Prt Sc is circled and under the word Home. I assume that you push Shift+Home to get Prt Sc to work. That is how it has worked in past iterations of Windows, my current version being Windows 7. So, I press Shift+Home and open Paint, Photoshop and Word. I then press paste and nothing comes out. I've done it repeatedly with the same results. I've looked up the process with Windows Help and it tells me to do exactly what I have done. In addition, somewhere in here, it was suggested to open Windows Media Player and take the screen print from there, which I have done, with the same results. I have also tried taking screen prints from VLC media player. The version of Firefox I am using when I screen print from YouTube is 37.0.2. Any help I can receive is well appreciated. Thank you in advance. | I am trying to take a screenshot of a YouTube video in fullscreen. When I pause the video and wait a moment, only the bottom UI bar (play/pause/seek) disappears. The top UI bar (Like/Share/More Info) stays there. So when I press PrintScreen on the keyboard, the screenshot is polluted by this top UI bar. Is there any way to remove it while the video is on pause? |
I have just installed Ubuntu 18.04.3. And I wanted to update by running sudo apt update. I got Get:1 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB] Get:2 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB] Hit:3 http://archive.ubuntu.com/ubuntu bionic InRelease Get:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB] Fetched 252 kB in 28s (8,883 B/s) Reading package lists... Done Building dependency tree Reading state information... Done 4 packages can be upgraded. Run 'apt list --upgradable' to see them. After that I ran apt list --upgradable, I got Listing... Done libsnmp30/bionic-updates 5.7.3+dfsg-1.8ubuntu3.3 amd64 [upgradable from: 5.7.3+dfsg-1.8ubuntu3.1] linux-generic-hwe-18.04/bionic-security,bionic-updates 5.0.0.36.94 amd64 [upgradable from: 5.0.0.23.80] linux-headers-generic-hwe-18.04/bionic-security,bionic-updates 5.0.0.36.94 amd64 [upgradable from: 5.0.0.23.80] linux-image-generic-hwe-18.04/bionic-security,bionic-updates 5.0.0.36.94 amd64 [upgradable from: 5.0.0.23.80] After this, I ran sudo apt-get upgrade, I got Reading package lists... Done Building dependency tree Reading state information... Done Calculating upgrade... Done The following packages have been kept back: linux-generic-hwe-18.04 linux-headers-generic-hwe-18.04 linux-image-generic-hwe-18.04 The following packages will be upgraded: libsnmp30 1 upgraded, 0 newly installed, 0 to remove and 3 not upgraded. Need to get 929 kB of archives. After this operation, 1,024 B of additional disk space will be used. Do you want to continue? [Y/n] y Err:1 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 libsnmp30 amd64 5.7.3+dfsg-1.8ubuntu3.3 403 Forbidden [IP: 91.189.88.173 80] E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/n/net-snmp/libsnmp30_5.7.3+dfsg-1.8ubuntu3.3_amd64.deb 403 Forbidden [IP: 91.189.88.173 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? Here my repository: deb http://security.ubuntu.com/ubuntu/ bionic-security multiverse main restricted universe deb http://archive.ubuntu.com/ubuntu bionic-updates multiverse main restricted universe deb http://archive.ubuntu.com/ubuntu bionic main universe restricted multiverse deb http://archive.ubuntu.com/ubuntu bionic-backports multiverse main restricted universe How to fix with it? | The first thing I did after installing 16.04 LTS was to change my update server to Main Server. I can not find a similar option in Ubuntu 18.04. How do I change it? |
since I am new to JS / jQuery it is probably a obvious problem (but no exception thrown). I read that I can't use .onclick so i tried this approach with .on("click"...) I try to build a table that adds new lines under the clicked line. This should also work for the newly created lines. My html: <tbody> <tr id="line1"><td>Stuff1</td><td>Stuff</td><td>Stuff</td><td>Stuff</td><td>Stuff</td></tr> <tr id="line2"><td>Stuff2</td><td>Stuff</td><td>Stuff</td><td>Stuff</td><td>Stuff</td></tr> <tr id="line3"><td>Stuff3</td><td>Stuff</td><td>Stuff</td><td>Stuff</td><td>Stuff</td></tr> <tr id="line4"><td>Stuff4</td><td>Stuff</td><td>Stuff</td><td>Stuff</td><td>Stuff</td></tr> </tbody> My JS: <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script> <script> $(document).ready(function(){ $("tr").on("click",function(){ var childId = $(this).attr("id")+1; if($("#"+childId).length){ $("#"+childId).toggle(); }else{ $(this).after('<tr id="'+childId+'"><td>Stuffxxxx</td><td>Stuff</td><td>Stuff</td><td>Stuff</td><td>Stuff</td></tr>'); //AJAX } }); }); </script> Thanks for your help! :) | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
When I try to run the .exe file, this error notice comes up. Archive: /media/DWA-140/DWA140.exe [/media/DWA-140/DWA140.exe] End-of-central-directory signature not found. Either this file is not a zipfile, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive. zipinfo: cannot find zipfile directory in one of /media/DWA-140/DWA140.exe or /media/DWA-140/DWA140.exe.zip, and cannot find /media/DWA-140/DWA140.exe.ZIP, period. Is there any steps I can take to get this to run? Thanks! | So, I just built my PC today, and am only using Ubuntu until I get Windows installed (sorry, guys!) But when I go to click on any .exe file, nothing happens. It just sits there. No error message, nothing. I've seen other people with similar problems, but they all get an error message. But not me... Whats going on? How do I fix this? Help? |
In my program, I'm trying to set x and y values to game.getWidth() so that I can access those variables elsewhere. The issue is that when I run the program those variable declarations throw a NullPointerException. I'm not sure exactly why these are causing an error. Is there a way I can fix it? package data; import java.awt.Color; import java.awt.Graphics2D; public class Star { private float mass; public Star(Game game) { this.game = game; } private Game game; //These variables cause the NullPointerException private int x = game.getWidth() / 2; private int y = game.getHeight() / 2; public void paint(Graphics2D g) { g.setColor(Color.WHITE); g.fillOval(x, y, 12, 12); g.setColor(Color.BLACK); } public float getMass() { return mass; } public void setMass(float mass) { this.mass = mass; } public int getX() { return x; } public void setX(int x) { this.x = x; } public int getY() { return y; } public void setY(int y) { this.y = y; } } | What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely? |
Let $A,B \in {M_n}$ and suppose $tr(A^k) = tr(B^k)$ for all $k$=$1,2,...$ . Why do $A$ and $B$ possess the same characteristic polynomial? | Let $M,N$ be $n \times n$ square matrices over an algebraically closed field with the properties that the trace of both matrices coincides along with all powers of the matrix. More specifically, suppose that $\mathrm{Tr}(M^k) = \mathrm{Tr}(N^k)$ for all $1\leq k \leq n$. The following questions about eigenvalues is then natural and I was thinking it would be an application of Cayley-Hamilton but I am having trouble writing out a proof. How do we show that $M$ and $N$ have the same eigenvalues? Added (because this question is now target of many duplicates, it should state its hypotheses properly). Assume that all the mentioned values of $k$ are nonzero in the field considered; in other words either the field is of characteristic $0$, or else its prime characteristic $p$ satisfies $p>n$. |
I'm running 18.04. When I try to upgrade to LTS version 20.04 using Software Updater I get message that 19.10 is available. I've set the upgrade line to "any new version". I've also tried using the command line in the terminal with same results. This has persisted since April 23rd - date 20.04 was released. My system is up to date | Update appear to have been updated recently (as of writing this the last update appears to have taken place on 3rd of June) to include the following statement: The -d switch is necessary to upgrade from Ubuntu 18.04 LTS as upgrades have not yet been enabled and will only be enabled after the first point release of 20.04 LTS. Also note that . TLDR (as of 15 Aug 2020): is the canonical tracking document for the first Focal Fossa point-release (20.04.1). It’s a live document. The Ubuntu release team will be updating it as we work on releasing 20.04.1. […] Upgrades from 18.04 to 20.04.1 are still disabled as we are working through a few upgrade blockers Edit The answers (so far) do not answer the question. The question is pretty simple. Ubuntu.com points to a "FinalRelease", which turns out to be a "Development Release", see evidence below. I'm not asking how and when to upgrade. I'm pointing out what seems to me to be an apparent inconcistency (in semantics, linguistics, logic) in the way Ubuntu names or labels its releases. From an answer to the question I'd except someone to pick up and acknowledge this inconsistency. An answer could start with a "Yes, ..." or a "No, ...", for starters. (Moreover, a good answer could distinguish between the release being in dev stage and/or the upgrade process (e.g. from LTS to LTS) being in dev stage, if appropriate.) This question, as I see it, is not a duplicate. Futher, I think it is a question which deserves a non-patronizing answer. Thanks. indicates that today (23rd April 2020) the new Ubuntu 20.04 LTS is to be released. See "condensed screenshot" here: Indeed, it seems that that's what happened, see and : However, when following the instructions to upgrade (from 18.04 LTS to 20.04 LTS) found and elsewhere (edit: actually , too!), even prior to the July point release, I'm a bit confused to see that the instruction is to use update-manager -d which also points to the "Development Release" (see screenshot below) rather than the "FinalRelease" (see screenshot and link above). Is the "Final Release" (which I'm after) the/a "Development Release"? Why isn't it called something like "Production Release" or "Final Release"? When will it no longer be referred to as "Development Release"? In July? I'm confused :( |
When using pipes for example sudo cat /dev/sda | strings | less I can move around the lines of strings of my sda device. But are the contents of the sda device loaded fully and outputed to the output stream of cat? Or are the new lines evaluated whenever a program requests output from cat ? ( i.e. i press j on the less pager) | Does anything symbolic happen in chaining bash commands via a pipe or is it all compute-pass-compute-pass? For example in head t.txt -n 5 | tail -n 2, is head t.txt -n 5 getting computed and then tail -n 2 executes over it. Or first there is some abstraction to tell the shell that lines 3 to 5 are to be read? It might not make a difference in this example, but I guess can in other scenarios. |
I want to try something new. I used Windows for a long time. I have sistem: сore i5-4460 Asus 1050. I was thinking of installing Ubuntu, just her. But amd is written on the installation file, can it work for me? Which system might work for me? I also use PHPStorm, Photoshop,Steam , FileZilla and OpenServer. What can you suggest and advise. Thank you so much! | For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and such as: with a lighter desktop than the usual Gnome and Unity with the even lighter LXDE desktop Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements? |
Im trying to find the exact value of the infinite sum : 3 + 1/3 + 1/27 + 1/243 + 1/2187 + ... I can see that to generate new terms we take the previous term and divide by 9 or multiply by 9. Not exactly sure if one way or the other makes it any easier. This is what i have come up with to solve the series is this correct and where do i go from here? $\sum_{k=3}^\infty= K_0 + K_n(1/9)\\ $ | How can I find the closed formula for the sum $$1/3 + 1/27 + 1/243 + ...?$$ |
Say, if we have two trucks travelling towards eachother at 60m/s, and those two trucks carry the same payload, and are the same model (aka they're exactly the same), will the collision force be as if just one truck crashed into a wall at 120m/s? Theoretically the forces will balance each other out, but it won't always be this way. | I was watching a youtube video the other day where an economist said that he challenged his physics professor on this question back when he was in school. His professor said each scenario is the same, while he said that they are different, and he said he supplied a proof showing otherwise. He didn't say whether or not the cars are the same mass, but I assumed they were. To state it more clearly, in the first instance each car is traveling at 50mph in the opposite direction and they collide with each other. In the second scenario, a car travels at 100 mph and crashes into a brick wall. Which one is "worse"? When I first heard it, I thought, "of course they're the same!" But then I took a step back and thought about it again. It seems like in the first scenario the total energy of the system is the KE of the two cars, or $\frac{1}{2}mv^2 + \frac{1}{2}mv^2 = mv^2$. In the second scenario, it's the KE of the car plus wall, which is $\frac{1}{2}m(2v)^2 + 0 = 2mv^2$. So the car crashing into the wall has to absorb (and dissipate via heat) twice as much energy, so crashing into the wall is in fact worse. Is this correct? To clarify, I'm not concerned with the difference between a wall and a car, and I don't think that's what the question is getting at. Imagine instead that in the second scenario, a car is crashing at 100mph into the same car sitting there at 0mph (with it's brakes on of course). First scenario is the same, two of the same cars going 50mph in opposite directions collide. Are those two situations identical? PS: This scenario is also covered in an of . |
To be clear I want to know if the hand could be arranged that way; the cards do not to come out in that order. They could also take the form AABABCB. Ex. (3,hearts)(3,clubs)(3,spades)(jack,diamonds)(jack,spades)(jack,hearts)(5,spades) And that would also qualify. | What is wrong with my method of find the probability of a 2 pair? For the first card we have 52 choices, one this is picked( call it A) we have 3 choices(different suite than A but this same value) for the second card, ( lets call this card B). Now we have AB, to we have to throw away 2 more cards so we don't have 3 of a kind or a four of a kind. Therefore one our third card we have 48 choices and on our fourth card we have 3 choices again similar to above. On our last card we only have 44 choices left. So the probablity of getting a 2 pair should be (52*3*48*3*44)/(52 choose 5). But this isn't correct. Note: I edited this to "2 pair"; the original version was wrong. |
I want to format numbers using JavaScript. For example: 10 => 10.00 100 => 100.00 1000 => 1,000.00 10000 => 10,000.00 100000 => 100,000.00 | I would like to format a price in JavaScript. I'd like a function which takes a float as an argument and returns a string formatted like this: "$ 2,500.00" What's the best way to do this? |
Story: While browsing through Reopen reviews, I've clicked at "Leave Closed" button and I was presented with a modal dialog asking me to "Nominate the post for reopening / OK / Cancel". I've pressed "Cancel" and the case was resolved as I wanted: LeftClosed. I do not know what happens if I'd pressed "OK". I've not checked that in case it would interpret it as "Reopen" vote. Bug/suggestion: As far as I remember, the popup was related to "Reopen" button, not to "Leave closed" one. For "Leave closed" it makes a little sense. I think that 'back then' there was no popup dialog at all when voting for leave-closed, so I think that this dialog should be simply skipped for that button. Repeatability: 100% over two 'leave closed' votes today. | This is rather difficult to describe with fancy pictures with red circles but it's easily reproducible. Whenever I click Leave Closed in the re-open queue on MSO the "nominate this question for re-opening" pop-up appears. I normally press escape out of shock and a leave closed vote is recorded. This is the latest review it's happened to me on: You can also test it on , I clicked reopen this time and a leave closed vote was recorded but I also got a red popup stating that an error had occurred. This is also occurring when the Edit & Reopen button is clicked, the edit box opens for a second before being overridden by the popup. |
There is a string variable that has a path like /app/something/xx/4/profile besides there is an array of string like ** const arr=[ {name:'xx',etc...}, {name:'yy',etc...}, {name:'zz',etc...} ] I want to find the first index of array that the string variable has the name in simplest way. | What is the most concise and efficient way to find out if a JavaScript array contains a value? This is the only way I know to do it: function contains(a, obj) { for (var i = 0; i < a.length; i++) { if (a[i] === obj) { return true; } } return false; } Is there a better and more concise way to accomplish this? |
To my best knowledge Java uses pass by value. but if you look below I passed a list and added a Integer to it. Desired output : list before [] and after should be [] Resultant output : list before [] and after is [20] Also, if I initialize the list inside static function that my desired output is achieved . Can i know the reason for this phenomenon please import java.util.ArrayList; import java.util.List; public class NormalTest { public static void testMethod(Integer testInt, List<Integer> sampleList) { testInt *= 2; System.out.println(" Inside testInt :: " + testInt); sampleList.add(testInt); } public static void main(String[] args) { Integer testInt = 10; List<Integer> sampleList = new ArrayList<>(); System.out.println(" Before testInt :: " + testInt); System.out.println(" Before sampleList :: " + sampleList); NormalTest.testMethod(testInt, sampleList); System.out.println(" After testInt :: " + testInt); System.out.println(" After sampleList :: " + sampleList); } } | I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation? |
I am a student of biology at a State school in New York (SUNY), and my school is very liberal arts focused, I am also a racial minority. I also have a poor GPA, 2.7ish currently, due to failings of a previous major(in computer science i received F's for 2 classes, and a D for one). I am trying to do undergrad research, but only have 2 potential presentable results up and coming. Do grad schools typically fund students like me to get their tuition totally waived and a possible small stipend? What can I do to better my odds at securing such a position? It is the only way I could even consider grad school. | When applying to a PhD program in the US, how does the admissions process work? If an applicant is weak in a particular area, is it possible to offset that by being strong in a different area? Note that this question originated from this . Please feel free to edit the question to improve it. |
I am looking for correlations between certain measures of brain structural integrity (fractional anisotropy, given as ratio between two hemisphere ==> rational data range 0-1, normally distributed) and behavioral parameters from stroke patients which are not normal but in part extremely leftskewed. Having read numerous posts on assumptions of GLZM which I'd like to apply to assess the data, I still struggle with the assumption of non-normality of Y. ; ; ; ; For instance, it reads ".... In normal circumstances, the question isn't 'are my errors (or conditional distributions) normal?' - they won't be, we don't even need to check. A more relevant question is 'how badly does the degree of non-normality that's present impact my inferences?" I suggest a kernel density estimate or normal QQplot (plot of residuals vs normal scores). If the distribution looks reasonably normal, you have little to worry about. In fact, even when it's clearly non-normal it still may not matter very much, depending on what you want to do (normal prediction intervals really will rely on normality, for example, but many other things will tend to work at large sample sizes)...." Moreover, here it says: ".... Strictly speaking, neither, though the second is the thing you check. What is assumed normal is either the unobservable errors, or equivalently the conditional distribution of Y at each combination of predictors. The unconditional distribution of Y is not assumed to be normal. – Glen_b May 30 '13 at 13:38 " or "....Since the residuals are just the y values minus the estimated mean (standardized residuals are also divided by an estimate of the standard error) then if the y values are normally distributed then the residuals are as well and the other way around. So when we talk about theory or assumptions it does not matter which we talk about because one implies the other." So my question is: Is a GLZM applied to my data valid if the residuals look normally distributed but the Y is not? Would a non-significant Shapiro-Wilk test on the residuals together with a reasonable QQ plots allow to trust the confidence intervals estimated incl. the p-vals? I would be very grateful if somebody could help and clarify how to face this problem of non-normality in a generalized linear model. Having talked to two colleagues more familiar with modelling I got two different perspectives, A saying that normality of Y is crucial, B saying look at the residuals, GZLM should be robust to non-normal distributions. Now I am confused with discrepant views on assumptions of GZLM. " | I have made a generalised linear model with a single response variable (continuous/normally distributed) and 4 explanatory variables (3 of which are factors and the fourth is an integer). I have used a Gaussian error distribution with an identity link function. I am currently checking that the model satisfies the assumptions of the generalised linear model, which are: independence of Y correct link function correct scale of measurement of explanatory variables no influential observations My question is: how can I check that the model satisfies these assumptions? The best starting point would seem to be plotting the response variable against each explanatory variable. However, 3 of the explanatory variables are categorical (with 1-4 levels), so what should I be looking for in the plots? Also, do I need to check for multicollinearity and interactions amongst explanatory variables? If yes, how do I do this with categorical explanatory variables? |
I bought a large joint of beef which I roasted on Sunday. On Monday I made a stew from leftovers. From a food hygiene/bacterial growth perspective am I ok to reheat the stew after freezing/refrigeration? I wouldn't do this with ordinary leftovers but I wonder if the boiling for 1.5Hrs kills any bacteria in the leftovers. Thanks | I am defrosting a cooked chicken to use in a curry it will be thoroughly heated at a high temperature. If I have too much curry will i be able to freeze it, as the cooked chicken was frozen before? |
So i have this code: <div class="row"> <?php $sql = $koneksi->prepare("SELECT * FROM lapangan ORDER BY id_lap DESC"); if($sql->rowCount() == 0){ echo "There is no product!"; }else{ while($data = mysqli_fetch_assoc($sql)){ ?> <div class="span4"> <div> <table> <tr> <td> <img src="<?php echo $data['lap_img']; ?>" style="max-width: 300px" /> <div style="max-width: 300px"> <ul data-role="listview" data-inset="true"> <li data-role="list-divider" data-theme="a"><?php echo $data['lap_name']; ?></li> <li><p><?php echo $data['lap_ket']; ?></p></li> </ul> </div> </td> </tr> <tr> <td> <a href="detail.php?id_lap=<?php echo $data['id_lap'];?>" data-theme="a" data-iconpos="notext" data-role="button">Detail</a> <a href="detail.php?id_lap=<?php echo $data['id_lap'];?>" data-theme="g" data-iconpos="notext" data-role="button">Lokasi</a> </td> </tr> </table> <hr> </div> </div> <?php } } ?> </div> I wanted to change mysqli_fecth_assoc into PDO. I've searched through some tutorials and it doesn't give me an answer (maybe, because its using loops?). Can anyone help me? | I'm slowly moving all of my LAMP websites from mysql_ functions to PDO functions and I've hit my first brick wall. I don't know how to loop through results with a parameter. I am fine with the following: foreach ($database->query("SELECT * FROM widgets") as $results) { echo $results["widget_name"]; } However if I want to do something like this: foreach ($database->query("SELECT * FROM widgets WHERE something='something else'") as $results) { echo $results["widget_name"]; } Obviously the 'something else' will be dynamic. |
Using the law of cosines for sides: $\cosh(a) = \cosh(b) \, \cosh(c) - \sinh(b) \, \sinh(c) \, \cos(\alpha) $ I have to show that $\alpha + \beta + \gamma < \pi$ Unfortunately I find no ansatz for this question. | I am hoping that someone can help me see understand a proof that the sum of angles of a hyperbolic triangle $\triangle ABC$ is strictly less than $\pi$. I want to stick to the upper-half-plane model $\mathbb H:=\{z\in \mathbb C : Im (z)>0\}$ of hyperbolic geometry where lines are either vertical lines or semicircles centered on (but excluding) the $x$-axis. To simply things, by using an LFT we can take one vertex $A$ to be the point $i$ and another $B$ to be $(0,k)\in \mathbb H$ for some $k>0$. Now, call the third vertex $C$. We have the other two sides $AC$ and $BC$ as arcs of the circles $C_1 =(x-a)^2+y^2=r_1^2$ and $C_2=(x-b)^2+y^2=r_2^2$, respectively, so that $x^2+1=r_1^2$ and $x^2+k^2=r_2^2$. In my class notes, there is a brief mention of how this simplification can help us with the proof. However, I do not see at all how this helps us get the result that $\triangle ABC$ sums to less than $\pi$. Therefore, any help is very appreciated. P.S., My knowledge is elementary, so I am hoping for a proof using basic tools. |
If I run $(</dev/stdin) Then type echo hello world, press enter, then Ctrl-D We get hello world But why? When I think of I/O and redirection in bash, it only makes sense to me when there's an actual command. I don't understand the behavior when there's no command, and it's just < my_file Could someone help explain/point me to a primary source that explains this further? Thanks! | I am trying to understand how exactly Bash treats the following line: $(< "$FILE") According to the Bash man page, this is equivalent to: $(cat "$FILE") and I can follow the line of reasoning for this second line. Bash performs variable expansion on $FILE, enters command substitution, passes the value of $FILE to cat, cat outputs the contents of $FILE to standard output, command substitution finishes by replacing the entire line with the standard output resulting from the command inside, and Bash attempts to execute it like a simple command. However, for the first line I mentioned above, I understand it as: Bash performs variable substitution on $FILE, Bash opens $FILE for reading on standard input, somehow standard input is copied to standard output, command substitution finishes, and Bash attempts to execute the resulting standard output. Can someone please explain to me how the contents of $FILE goes from stdin to stdout? |
What my problem is, is that I want to install windows xp on my laptop where ubuntu is installed on, I cannot run the disc because it is an .exe and you can't run that on ubuntu. I tried several things and searched for like an hour on the internet, I hope someone knows how to help me. Sorry for my bad english, I am dutch. [edit] The answer wich some of you linked is not an answer to my question because I have a black screen after I try to boot with the disc | I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows. How do I remove Ubuntu and reinstall Windows? Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot. |
I create a span using PHP like this. if ($subnetkey == 1 ) { echo ("<span class='subnetkey'>S/N of: $subnetnum</span>&nbsp;&nbsp;");} It works, and shows the correct data on screen. Additionally if I look at it using 'Inspect Element' its properly formatted. <span class="subnetkey">S/N of: 780</span> I have this script at the top of the page. I've also tried it at the bottom. <script> $(document).ready(function(){ $(".subnetkey").click(function() { alert("subnet click mode"); }); }); </script> When I click the span, nothing happens. I get no errors, and of course I don't see the alert fire. It seems like this is a timing issue between building the page dynamically and using the page. But in case thats not it, what can I do to make the function fire? | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
I have seen this behavior lately when I go to edit a question if it is editing by some one else the white page coming with the message saying "There is a pending suggested edit in the queue, try again in a few minutes.". But the page coming with this message was different with an ajax message before as I can remember. Is this normal? | I just tried to edit a post on Stack Overflow but when I pressed the 'edit' button it showed me this message on a white page. I know what the message means but I don't think it is supposed to show up in a white page. So, is this a bug or is it something else? |
The police station public works project just became available in my town. There are two of them - modern and classic. What are the differences / similarities between the two, and are there things exclusive to either that the other one doesn't offer? | A villager requested that I create a police station as our next public works project, which I would be happy to oblige... but I've got some questions first. That conversation unlocked the "modern police station" and "classic police station" and both will cost 264,000 to construct. Is there any functional difference between the two? Can I build both, or will I be restricted to one or the other? Is one better to have than the other? |
Context: Want to automate a process which requires a connection to Linux vm machine from code running on AWS cloud. Code Snippet: #!/bin/sh ssh -i LinuxVM.ppk testuser@<ipadress> 'df -h'. Result: When I am running the above shell script I am getting an error "Enter passphrase for key 'LinuxVM.ppk':" The same PPK file I am using to connect the remote vm through 'putty' and I am through. While creating the PPK from puttygen file I have not given any phrases. | I'm having some issues SSH'ing to a server when logged into a particular VM. From my local PC, I can log in to the server just fine using the command ssh -i .ssh/[my private key] username@domain. If I then SSH into another unrelated server which also has the same private key and run the above command it will also log in just fine in to the server. But, when I SSH into a particular OpenStack VM (again has the same private key) on the unrelated server and then SSH in to the server from there I start getting prompted for a passphrase. But a passphrase hasn't been set for the key so inevitably I get a "Permission denied (publickey)." error. To double check, I removed the private key from the VM and scp'd the private key from my PC into it again and tried the same command I still get prompted for a passphrase. In other words: PC - SSH - Server1 = Works fine PC - SSH - Server2 - SSH - Server1 = Works fine PC - SSH - Server2 - SSH - Virtual Machine - SSH - Server 1 = Asks for a passphrase What could be the reason behind this? It's definitely the right private key I'm using and it has the appropriate permissions. Edit - Output of ssh -v -i .ssh/[my private key] username@domain as requested OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 58: Applying options for * debug1: Connecting to xxx.xxx.xxx.xxx [xxx.xxx.xxx.xxx] port 22. debug1: Connection established. debug1: key_load_public: No such file or directory debug1: identity file /.ssh/[my private key].ppk type -1 debug1: key_load_public: No such file or directory debug1: identity file /.ssh/[my private key].ppk-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_7.4 debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 pat OpenSSH* compat 0x04000000 debug1: Authenticating to xxx.xxx.xxx.xxx:22 as '[my username]' debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: algorithm: [email protected] debug1: kex: host key algorithm: ecdsa-sha2-nistp256 debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none debug1: kex: [email protected] need=64 dh_need=64 debug1: kex: [email protected] need=64 dh_need=64 debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ecdsa-sha2-nistp256 SHA256:ZiugTjR5fM0E3evOwHoePFKspDQChA0Ab6L0q88KP/g debug1: Host 'xxx.xxx.xxx.xxx' is known and matches the ECDSA host key. debug1: Found key in /home/centos/.ssh/known_hosts:2 debug1: rekey after 134217728 blocks debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: rekey after 134217728 blocks debug1: SSH2_MSG_EXT_INFO received debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512> debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Trying private key: /.ssh/[my private key].ppk Enter passphrase for key '/.ssh/[my private key].ppk': Enter passphrase for key '/.ssh/[my private key].ppk': Enter passphrase for key '/.ssh/[my private key].ppk': debug1: No more authentication methods to try. Permission denied (publickey). |
I need a little bit of help (just a hint, please) with an induction proof on this sequence, which I need to prove is bounded above by 3. $$ a_1 = \sqrt{2} $$ $$ a_{n+1} = \sqrt{2 + a_n} $$ My attempt: $$ a_k < 3 $$ $$ a_k + 2 < 5 $$ $$ \sqrt{a_k + 2} < \sqrt{5} $$ $$ a_{k+1} < \sqrt{5} $$ ... and I don't know where to go from here. If I were to find a limit of this sequence, which way would I have to go? Should I try to rewrite the sequence into a formula? | Setting $a_n=\sqrt{2+\sqrt{2+\sqrt{2+}}}\ $ I get that $$a_{n+1}=\sqrt{2+a_n} \quad \quad a_1=\sqrt{2}.$$ Clearly all numbers in the sequence are positive and we see that $a_n<a_{n+1} \ \forall \ n$ which implies that the sequence is strictly increasing. To show that it's convergent, I need to show that it's bounded above. We can use the help-function $f(x)=\sqrt{2+x}$ such that $a_{n+1}=f(a_n).$ But since $$f'(x)=\frac{1}{2\sqrt{2+x}}=0\Leftrightarrow\text{no real solutions,}$$ $f(x)$ never flattens out or decreases, so it can't be convergent? |
If I open Firefox or Thunderbird or any other application twice, they stack on top of each other in the dock. I run GNOME 3.36 on Ubuntu 20.04.1 LTS. How can I duplicate the icons of the applications that I open, on the dock? This is especially useful when using multiple screens, so that I can easily switch between opened apps without having to select which Firefox instance I want to show on the main screen, since the second one always runs on the second screen. The dconf-editor did not seem to have any option that allows me to run multiple icons instead of stacking the icons. | I want to make Ubuntu dock like Windows taskbar Ubuntu: Windows: (as you see Windows has three Explorer icons and Ubuntu has only one Files icon Is it possible to uncombine/ungroup apps in Ubuntu? |
Suppose a sound is produced behind you. You can easily tell that the sound came from behind. Our ear lobes face towards the front and hence traps the sound waves which come from the front. Yet, we can detect that the sound came from behind. How does the ear/brain manage to identify the sources of sound accurately? | Pretty self descriptive, without being able to view the source of the noise how can we tell the difference between a sound in front of us and a sound behind us if pitch, volume and distance are all the same. Also assume that it is not biased to one side more than the other, e.g its not to your left or right but directly in front or behind. I'm interested in knowing if it is a part of the ear that makes this distinction, or a function of the brain. |
My wife is a naturalised UK citizen from Gambia. Her brother is 17 and in Italy with a Permesso di Soggiorno. Would he need a visa or would he be able to join us in the UK immediately? If he arrived in the UK with the residence permit and a Gambian passport and evidence that they are brother and sister would he be allowed in? Would he be allowed to board an aircraft in Italy without a visa stamp in his passport? We are trying to do it quickly before he turns 18 in July. | I am from Non-EU country (from Nepal to be precise) and recently moved to Germany for work. I am applying for BlueCard. I would like to travel to UK later this year, can I go there without visa as I am resident in another EU country? I can't find this information online. Any links/references will be much appreciated. |
I accidentally created a flag as duplicate for this question: I was in the input to select a duplicate. Typed some words and pressed enter. It automatically selected the first entry. It didn't ask me anything and created the flag. That said, I believe it could be good to be able to cancel our own flags. I see it as active in when I click the flags I created but there is no way to remove it. As I see it, it should be possible to remove our own flags as long as they are active. When the flag get rejected or accepted, it should not be possible to cancel it. One other way to handle flags could be to show a flash popup just after a flag has been created with a link to cancel it. If you let the flash message go away, then it won't be possible to cancel it or you'll have to go in your profile to remove (it if such feature could be added). | I'm wondering (since it just happened to me), is it possible to "cancel" ("undo", "delete", "retract", whatever) a flag I just raised if I misclicked it, so the mods won't waste time? I looked everywhere, but I can't find such a feature. |
How do I set the font size to 11.5? 12 is too large and 11 is too small. I used \documentclass[titlepage,11.5pt]{article} but it still gives me size 11 | I may be wrong, but it seems to me that I cannot obtain non-integer (or non-preloaded) font sizes (say, 9.876pt) using \fontsize. If this is true, how do I do this in LaTeX? Do I have to resort to the \font ... at ... primitive? (The reason I need this is that I'd like to implement a more LaTeXy way to do the \diminuendo macro from .) |
Weinberg uses the LSZ reduction formula to introduce field renormalization,and on page 441, he says: As this discussion should make clear: the renormalization of masses and fields has nothing to do with the presence of infinities, and would be necessary even in a theory in which all momentum space integrals were convergent. I believe weinberg is right , but I can't convince other people: how is renormaliztion needed without infinities? What does it have to do with the LSZ formula? I want answers to make clear the field renormalization with LSZ reduction formula. so maybe the question is different , because I am asking weinberg's book. | Michael Brown made the following comment : The modern understanding of renormalization (due to Kadanoff, Wilson and others) is hardly controversial and has nothing really to do with infinities. It is necessary even in completely finite theories, but the fact that it fixes infinities in QFT is a bonus. Can anyone explain what this means? |
Running Ubuntu on a Dell XPS, dual-booting with Windows that I hardly use. I encrypted my home folder when installing 16.04, and now Dropbox won't sync anymore as they no longer support .ecryptfs. What's the simplest solution so that I can keep using Dropbox? (I would consider switching but I share folders with other people who use it so it's more convenient to stick with it.) I came across this solution: , but I'm worried that I might erase the dropbox folder I already have. I'm still a bit of a newbie and get a bit nervous when messing around with filesystems, so I'd appreciate any detailed tips. Thanks in advance. | Some time ago Dropbox began to warn me about supporting ext4 as FS only. As a happy BTRFS user I wasn't happy, but have done this: dropbox stop dd if=/dev/zero of=~/dropbox.img bs=1M count=4096 mkfs.ext4 ~/dropbox.img echo "${HOME}/dropbox.img ${HOME}/Dropbox ext4 rw,async 0 2" | sudo tee -a /etc/fstab rm -rf ~/Dropbox/* sudo mount "${HOME}/Dropbox" sudo chown "${USER}:" "${HOME}/Dropbox" Everything worked without errors, but Dropbox still says that I should use ext4 for its folder. What am I doing wrong? |
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