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I have installed ubuntu 14.04 in my Lenovo G505s Laptop and now I also want to install Windows 8 Pro. I have already done an ntfs partition through gParted Partion Editor in ubuntu. This is the same partition where I want to install my Windows 8 Pro. I want to do a dual boot. Please Help. | I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go for UEFI only! |
Let $A$ be a countable set, and let $f : A \to B$ be a function. Prove that $f(A)$ is at most countable. Therefore $A$ is bijective with positive integers. Since the function is defined, it is clear that every elements in $A$ will not map to a different elements in $B$, i.e., for every $a\in A$ there exists a unique $b\in B$. So we don't care much whether the function is bijective or whatever. I also know that $f(A)$ is at most countable if it is either finite or countable. I think that $f(A)$ if proved as finite, should be a key to this proof, and to show if it is finite we may need to show something on the line that $|f(A)| < |A|$. I don't know how all these pieces fit together to construct a proof. Please help! Thank you. | Is there anybody who can help me to prove that if $D$ is countable, and $f$ is a function whose domain is $D$, then $f(D)$ is either finite or countable? |
So, I am making a safe house in Minecraft, and I want to make it so if you go to y=10, you get weakness 5, or at least it detects that you are a y 10 so I can add a second command block that gives you weakness. I did commands like /testfor @a [y=10], but it completely ignores the [y=10] part. Please help! (Edit, I figured it out, but I still need help making it not only just work for the x and y coords of the command block, so it can detect your y pos anywhere.) | I am trying to test for any player that is on Y level 118. Here is the command I am using: /testfor @a[y=118] The problem is, the command isn't working as expected. In my chat when I type this command, it reads: Found Boomcrasc078 The problem is, I am not on y=118 when I run this command. What could be the problem? I have also tested with a space: /testfor @a [y=118] but it still doesn't work. |
I am looking for the server's RSA public key string. I do not have permission to go to /etc/ssh and further so I can't read the actual public key. I do not have access to any packet sniffing tools like WireShark. Having these limitations, is it possible somehow to get the server's public key string? | Is there a way to programmatically obtain a SSH server key fingerprint without authenticating to it? I'm trying ssh -v user@host false 2>&1 | grep "Server host key", but this hangs waiting for a password if key based auth is not setup. |
I am trying to understand why the provided sentence makes sense. I understand a grammar rule: the pronoun in the sentence should match the noun in the sentence. However, how can we use "they" for "a prisoner"? Even if a prisoner has committed a serious crime, they deserve humane treatment. To me, the following sentences make more sense based on the grammar rule. Even if a prisoner has committed a serious crime, she or he deserves humane treatment. Even if prisoners have committed a serious crime, they deserve humane treatment. | Is it good English to say "They have just left", when talking about a single person (perhaps someone you don't know the gender of)? (I am a native English speaker, I'm looking for the view held by lexicographers). |
I have a few sentences with a lot of footnotes. Currently my tex code looks like this: This is One% % \footnote{ Footnote text 1 }% % , Two% % \footnote{ Footnote text 2 }% % ~and Three% % \footnote{ Footnote text 2 }% % . The code is obviously very hard to read and also error prone with regard to the commas, points and whitespaces following the footnote. I have added the comment lines for better readabilty, but it only helps a little bit. Is there a way to decouple the footnotes from the main text? I know that there are the commands \footnotemark and \footenotetext, but when I write This is One\footnotemark, Two\footnotemark and Three\footnotemark. \footnotetext{ Footnote text 1 } \footnotetext{ Footnote text 2 } \footnotetext{ Footnote text 3 } all the footnote texts refer to the last footnotemark. I also know that I could use the number parameter (and thereby making the footnote indexes static), but then I would get a problem if I have to add footnoes before or between the existing footnotes. How can I achieve a code like in the second example, but at the same time keep the footnote indexes dynamic? | I would like to use footnotes without cluttering the container paragraph. Something like: This is a very long complex\footnote[a] sentence. \foottext[a]{So complex that I would prefer to pull out the footnote text.} The idea comes from the [linktext][1], [1]: http://url.com markdown syntax. |
I am new and learning JavaScript from Udemy Question is age variable is declared globally so the second console.log should be 23 which is outside the function what am i doing wrong ? but the console.log is taking the variable from the function ! | What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally? |
My home town has a charity which maintains our parks - called the “Parks Trust”. I recently got involved in a Facebook debate as I’ve always maintained that it should be “Parks’ Trust”. My main opponent argued that as the parks belonged to the trust (which I’m not sure they actually do) rather than the other way round the apostrophe wasn’t necessary. Was either of us correct? | I was trying to write “I was using the lecture's flow of logic”, as to say that I was following the logic that was in the lecture. But I am corrected by a spell-checker. I tried to google it, but this leads me to another much more silly question. How do you call that “..'s” that designates ownership / association? I really did try to google it, but since “'s” is such a bad search term, and any formation for "What do you call that 's you add to designate ownership" I could think of, yielded anything but the answer I was looking for. So my question is twofold. What is the name of that 's thing? I guess it is not the "ownership 's" :) Is it perhaps called officially the ‘possessive s’? Is saying "lecture's" (pertaining to the lecture) valid English grammar? Or is it valid grammar but people just don't say it this way? |
I have installed another new different copy of windows 7 on a different hard drive in my computer running a win7 version.I am seeing both my win 7 files in different drives and intact. But what I found that my previous win7 version is not showing in startup boot menu. All I find that the last installed version boots up be default without giving any options for selecting desired OS. Is it possible I can manually add my previous windows entry (E:\Windows) in this boot menu? | I'd like to add an entry to the Windows 7 boot menu, but it seems that it is not as simple as editing the boot.ini file. How to I add a new entry? I'm trying to install using the instructions . |
I have the following situation: $ ls 0.txt aaa.txt a-.txt a.txt b.txt ddd.txt -hello.txt libs -.txt ,.txt !.txt ].txt \.txt $ ls [-a]*.txt ls: opzione non valida -- "e" Try 'ls --help' for more information. $ ls [a-]*.txt ls: opzione non valida -- "e" Try 'ls --help' for more information. The dash (-) creates some problems. How can I find a file starting with -? | How do you remove a file whose filename begins with a dash (hyphen or minus) -? I'm ssh'd into a remote OSX server and I have this file in my directory: tohru:~ $ ls -l total 8 -rw-r--r-- 1 me staff 1352 Aug 18 14:33 --help ... How in the world can I delete --help from a CLI? This issue is something that I come across in different forms on occasion, these files are easy to create, but hard to get rid of. I have tried using backslash rm \-\-help I have tried quotes rm "--help" How do I prevent the minus (dash or hyphen) character to be interpreted as an option? |
So avoiding the obvious reason the Joker wasn't in The Dark Knight Rises, what was the reason in the film for The Joker not appearing? Is he locked up in Arkham? Clearly it's not Blackgate due to the breakout. | In Dark Knight Rises, we see a bit of history of what has happened to Gotham in the past 8 years. Batman in seclusion, criminals being locked up for being part of organized crime, and Gordon's guilt from what happened with Dent. However, there seems to be absolutely no mention of the Joker at all during the movie, not even a hint at what happened to him after being apprehended. In comparison, Crane has been seen across all three movies and given some sort of wrap-up. Granted, it is a tad hard to film anything new with the death of the actor. But is there any reason Nolan gave on why he wouldn't at least give us a visual hint at the Joker being locked up (example being a pan across a door reading EXTREMELY DANGEROUS) or him escaping into hiding (example: Gordon saying to a fellow officer that "The Madman still got away")? |
I would like to studying linear algebra and set theory. Does anyone have a a good recommendation of books/resources/etc.? | I'm looking for a book to learn Algebra. The programme is the following. The units marked with a $\star$ are the ones I'm most interested in (in the sense I know nothing about) and those with a $\circ$ are those which I'm mildly comfortable with. The ones that aren't marked shouldn't be of importance. Any important topic inside a unite will be boldfaced. U1: Vector Algebra. Points in the $n$-dimensional space. Vectors. Scalar product. Norm. Lines and planes. Vectorial product. $\circ$ U2: Vector Spaces. Definition. Subspaces. Linear independence. Linear combination. Generating systems. Basis. Dimesion. Sum and intersection of subspaces. Direct sum. Spaces with inner products. $\circ$ U3: Matrices and determinants. Matrix Spaces. Sum and product of matrices. Linear ecuations. Gauss-Jordan elimination. Range. Roché Frobenius Theorem. Determinants. Properties. Determinant of a product. Determinants and inverses. $\star$ U4: Linear transformations. Definition. Nucleus and image. Monomorphisms, epimorphisms and isomorphisms. Composition of linear transformations. Inverse linear tranforms. U5: Complex numbers and polynomials. Complex numbers. Operations. Binomial and trigonometric form. De Möivre's Theorem. Solving equations. Polynomials. Degree. Operations. Roots. Remainder theorem. Factorial decomposition. FTA. Lagrange interpolation. $\star$ U6: Linear transformations and matrices. Matrix of a linear transformation. Matrix of the composition. Matrix of the inverse. Base changes. $\star$ U7: Eigen values and eigen vectors Eigen values and eigen vectors. Characteristc polynomial. Aplications. Invariant subspaces. Diagonalization. To let you know, I own a copy of Apostol's Calculus $\mathrm I $ which has some of those topics, precisely: Linear Spaces Linear Transformations and Matrices. I also have a copy of Apostol's second book of Calc $\mathrm II$which continues with Determinants Eigenvalues and eigenvectors Eigenvalues of operators in Euclidean spaces. I was reccommended Linear Algebra by Armando Rojo and have Linear Algebra by , which seems quite a good text. What do you reccomend? |
I have an information that I would like to encrypt and give it to someone else. I would like to encrypt it using N separate passwords (say 5) and give each password to some other persons. However the tricky part is that I would like to have any M of them (M<=N, say M=4) to be able to get together and decipher the message. Is that possible using some sort of conventional free software? My use case is to write a secret message, give it to one of my friends and then distribute passwords to others. However if one were to lose their part, the entire message would be lost. That is why I would like to have a redundancy. If you have any other idea how to solve this, I am open to it as well. Thank you. | My application requires an AES-256 key K for some secure operation. In order to avoid saving this key in application, I have implemented following scheme: There are 5 individuals who enters their passwords in application. Lets call them PW1..PW5 Using these passwords, I have generated the key as: K = KDF(PW1 || PW2 || PW3 || PW4 || PW5) The problem is that now I need to modify the application such that it works even if only 3 out of 5 passwords are available (but no less than 3). This is required because even if we lose one or two passwords (accident, person refusing to enter password etc.), we are able to recover from that situation. Please can you advise how it can be achieved? |
I am novice in Python and programming. Generators are a bit too complicated to understand for new programmers. Here's my theory on generator functions in Python: Any function contains a yield statement will return a generator object A generator object is a stack contains state Each time I call .next method Python extracts the function's state and when it finds another yield statement it'll bind the state again and deletes the prior state: Example: [ [state1] # Stack contains states and states contain info about the function [state2] # State1 will be deleted when python finds the other yield? ] This is of course might be like the stupidest theory on earth, but forgive me I am just new in the coding word. My Questions: What Python internally makes to store the states ? Does yield statement adds a state to a stack if it exists ? What yield creates internally ? I understand yield creates a generator object, however, I wonder what generator objects contain that makes them work ? are they just a stack/list of states and we you use .next method to extract each state and Python will call the function with the indexed state automatically for instance ? | What is the use of the yield keyword in Python? What does it do? For example, I'm trying to understand this code1: def _get_child_candidates(self, distance, min_dist, max_dist): if self._leftchild and distance - max_dist < self._median: yield self._leftchild if self._rightchild and distance + max_dist >= self._median: yield self._rightchild And this is the caller: result, candidates = [], [self] while candidates: node = candidates.pop() distance = node._get_dist(obj) if distance <= max_dist and distance >= min_dist: result.extend(node._values) candidates.extend(node._get_child_candidates(distance, min_dist, max_dist)) return result What happens when the method _get_child_candidates is called? Is a list returned? A single element? Is it called again? When will subsequent calls stop? 1. This piece of code was written by Jochen Schulz (jrschulz), who made a great Python library for metric spaces. This is the link to the complete source: [Module mspace][1]. |
I see the following picture in Task Manager about my Drive C: As you see, active is 100% most of the time, while disk transfer rate is relatively low and below 10 Mb/s. How to understand this? What is used by 100% if transfer is low? How to know, who is providing this usage? | Looking at Task Manager in Windows, I see my hard drive is pretty maxed out on "Active Time" Empirically that seems to relate to when my hard drive is locked up, apps go grey, etc. (the rest of my resources are pretty low usage on the graph). My questions are: What exactly is "disk active time"? If reducing it would in fact improve my responsiveness, how do I resolve this? What properties in a hard drive should I buy to speed this up? (The disk transfer rate doesn't seem to relate) Are certain apps going to cause a higher active time versus others? |
code: L = [False] * 2 R = [L] * 2 print(R) [[False, False], [False, False]] R[0][0] = True print(R) [[True, False], [True, False]] I am trying to change one element but all elements in first column change. Is this the expected behavior? Thanks | I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3 The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]] Then I changed one of the innermost values: my_list[0][0] = 5 Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]] which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it? |
I have taken the value of $\cos 20^o$ to be $x$. Now, $$\cos 20^o\cos 40^o\cos 60^o\cos 80^o = \dfrac{\cos 20^o}{2}\cos(40^o)\cos(80^o)$$ $$=\dfrac{x}{2}\Bigg( \dfrac{\cos(40^o + 80^o) + \cos(40^o - 80^o)}{2} \Bigg)$$ $$=\dfrac{x}{2}\Bigg( \dfrac{\dfrac{-1}{\text{ }2} + \cos 40^o}{2} \Bigg) = \dfrac{x}{4}\Bigg( \dfrac{-1}{\text{ }2}+2x^2-1 \Bigg)$$ $$=\dfrac{x}{8}(4x^2-3) = \dfrac{4x^3-3x}{8}$$ Can this even be continued (I mean to ask if this method will lead me any further)? If yes, how do I continue it? Thanks! PS : Please don't provide alternatives, I want to try them myself first. This question is only for the sake of asking if this method can be continued and it if can be, then how. | I should prove this trigonometric identity. I think I should get to this point : $\cos(3x) = 4\cos^3 x - 3\cos x $ But I don't have any idea how to do it (I tried solving $\cos(x+60^{\circ})\cos(x-60^{\circ})$ but I got nothing) |
How do I move a label further away from an arrow in XYPic? Example \xymatrix{ g_0 + \beta_1)(n + n') \ar[r]_-{(g_0 + \beta_1)^+(n,n')} & (g_0 + \beta_1)(n) + (g_0 + \beta_1)(n') } I want to move the label further down. | I have a question about my diagram. How can I increase the gap between the arrows and the labels? I would like to have more space between the left arrow and the label (2). Thanks for any suggestions. \documentclass{amsart} \usepackage{graphicx} \usepackage[all]{xypic} \begin{document} \begin{equation*} \begin{gathered} \quad \SelectTips{cm}{} \xymatrix@C=4.5em@R=4.5em{ A \ar@<-1ex>@{=>}[d] _-{(3)}\ar@<1ex>@{=>}[r]^-{(1)} & B \ar@<1ex>@{=>}|{{\object@{/}}}[l]^-{(2)} \\ C \ar@<1ex>@{=>}[r] \ar@<-1ex>@{=>}[u] |{\object@{/}}|{}_-{\;(4)} & D \ar@<1ex>@{=>}[l] \ar@<-1ex>@{=>}[u]_{\;(5)} } \end{gathered} \end{equation*} \end{document} |
I have had my new Nikon for around 2 months and am learning about settings and modes. I have lost the exposure indicator in the information display. What did I do to cause this? Thanks | I can't see that - <---|---> + indicator in my viewfinder (I can see it only in manual mode and it used to be everywhere). I went through the whole menu and didn't find anything that may be causing it. Any ideas? EDIT: when I cover the lens that indicator shows up. But there's no use for this behavior :) |
So, I had to solve this problem: $\left\vert \dfrac{x^2-5x+4}{x^2-4}\right\vert \leq 1$ I factored it in the form: $\left\vert \dfrac{(x-4)(x-1)}{(x-2)(x+2)} \right\vert \leq 1$. After that I found the intervals in which the expression is positive: $x \in(-\infty, -2) \cup [1,2)\cup[4, \infty) $. And when expression is negative: $x \in (-2,1) \cup(2,4) $. So, then I went ahead and solved the equations, when the expression is positive and when it's negative. The answer I got for positive is: $ x \in (-2,8/5] \cup(2, \infty).$ I'm not sure how to proceed from here, I figured that I'd find the intersection of the answer I got (when solved for positive expression) and when x is positive. But that doesn't seem to be the correct way to proceed. Since my answer is way off. I've tried searching how to solve these kinds of problems, but couldn't find anything close to this. So I'd really like to know how to solve this problem and how to approach problems like these in general. I really lack intuition and would like to understand it more. I'd also appreciate any textbook / information about how to solve more complex problems in general. | I am new to absolute-value inequalities, how can I solve this kind of inequation? $$ | \frac{x^2-5x+4}{x^2-4} | \le 1 $$ |
Prove that $X$ is Hausdorff if and only if the diagonal $\Delta$ is closed in $X\times X$. This exercise appeared on a previous exam in my course, and also in Munkres. Here's my attempt: First I want to show the implication starting with assuming that $X$ is Hausdorff. Consider $(X\times X)\backslash \Delta$, then for any tuple $(x_1, x_2) \in (X\times X)\backslash \Delta$ we know $x_1\neq x_2$. Then there are neighbourhoods $U,V$ of $x_1,x_2$ respectively such that $U\cap V = \emptyset$. The set $U\times V$ is a basis element of $X\times X$ so it's in the product topology. So any tuple $(x_1, x_2) \in (X\times X)\backslash \Delta$ lies in an open set of $X\times X$, thus $(X\times X) \backslash\Delta$ is open which makes $\Delta$ closed in $X\times X$. Now I assume that $\Delta$ is closed in $X\times X$. Then $(X\times X)\backslash\Delta$ is open in $X\times X$. Unless I'm mistaken, every open set $A\times B$ in $X\times X$ will be a subset of $(X\times X)\backslash\Delta$. Then $A\cap B = \emptyset$ because otherwise we would have $(x_1,x_1)\in A\times B \subseteq (X\times X)\backslash\Delta$ for some $x_1\in X$, which is a contradiction. Thus $X$ is Hausdorff. I'm simply wondering if my argument is correct. | Let $X$ be a topological space. The diagonal of $X \times X$ is the subset $$D = \{(x,x)\in X\times X\mid x \in X\}.$$ Show that $X$ is Hausdorff if and only if $D$ is closed in $X \times X$. First, I tried to show that $X \times X \setminus D$ is open using the fact that $X \times X$ is Hausdorff (because $X$ is Hausdorff), but I couldn't find an open set that contains a point outside $D$ and is disjoint to it... |
I am having a lot of trouble with a homework assignment. We were given three JPanels: myJPanel, myJPanel1, and myJPanel2. I have to have a JButton in mJPanel1 update the text of a button, b2, in myJPanel2. The problem is I can't make any changes to myJPanel2. Everything I try gives me a NullPointerException. Please help. Here is the code: myJPanel- import java.awt.*; import javax.swing.*; public class MyJPanel extends JPanel { MyJPanel panel; public MyJPanel() { super(); setBackground(Color.gray); setLayout(new BorderLayout()); MyJPanel2 p2 = new MyJPanel2(); add(p2, "Center"); MyJPanel1 p1 = new MyJPanel1(p2); add(p1, "North"); } } myJPanel1- import java.awt.*; import javax.swing.*; import java.awt.event.*; public class MyJPanel1 extends JPanel implements ActionListener { JButton jl1; Student st1 = new Student("Fred", "Fonseca", 44); myJPanel panel; myJPanel2 panel2; public MyJPanel1(JPanel p2) { super(); setBackground(Color.yellow); // the whatsUp of this student has to shown in the other panel jl1 = new JButton(st1.getInfo()); jl1.addActionListener(this); add(jl1); }@ Override public void actionPerformed(ActionEvent event) { Object obj = event.getSource(); if (obj.equals(jl1)) { panel2.b2.setText("test"); //This is where the NullPointerException is... } } } myJPanel2- import java.awt.*; import javax.swing.*; public class myJPanel2 extends JPanel { //================================================== //no changes allowed in myJPanel2 for assignment 05 //================================================== JButton b1, b2, b3, b4; public myJPanel2() { super(); setBackground(Color.pink); //setLayout(new GridLayout(3,1)); b1 = new JButton("When the user clicks on the button in the UPPER panel"); add(b1); b2 = new JButton("Display here whatsUp from the student in UPPER Panel"); add(b2); b3 = new JButton("===>>>>You CANNOT create a student here <======"); add(b3); b4 = new JButton("It has to be the student from the UPPER Panel"); add(b4); } } Any help would be greatly appreciated. I have been stuck on this problem for days. | 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? |
textView.setText(context.getClass().getSimpleName()); Why does this code works and sets the textView "App" , BUT whith if if(context.getClass().getSimpleName() == "App") { holder.textView.setTextColor(Color.RED); } It does not work. Why doesn't it? Sorry for dumbness. I'm new in this | I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug. Is == bad? When should it and should it not be used? What's the difference? |
What's the standard on styling scrollbars? Do you only apply it on panels within your application and leave the window scroll bars to a default? Does messing with scrollbar styles affect user experience and ease of access? | I've noticed that a lot of webapps have started using custom scroll bars. A few examples include Facebook, Trello, Google Docs, and Twitter. I'm sure you can think of some more: How do these types of custom scrollbars affect usability? I often find them harder to click on, and they have a habit of disappearing when I'm not scrolling. Having a smaller area to grab and a disappearing target makes it harder for me to use the web app, but I might be a minority. Is there anything indicating a benefit to the user experience when using these, or is it just done to make things look more fancy and "Web 2.0"? |
I am new to Python and I am stuck in this part of coding. I have a list looks like this: list = [(4, 7, 5), (4, 5, 7), (7, 4, 5), (7, 5, 4), (5, 4, 7), (5, 7, 4)] and I want to change it to something looks like this: new_list = [475,457,745,754,547,574] how do I do that? TIA. | I have a list of integers that I would like to convert to one number like: numList = [1, 2, 3] num = magic(numList) print num, type(num) >>> 123, <type 'int'> What is the best way to implement the magic function? EDIT I did find , but it seems like there has to be a better way. |
If not using virtual-box for 5 min, it goes automatically in standby. How do I increased the time for it to stay a bit longer. Is my VM goes into standby | I run Mythtv on some Ubuntu 11.10 based machines. In the power settings, I can choose from a list of time periods from 5 minutes up to 1 hour for the the machine to suspend when inactive. I would like to set the suspend to occur at a longer interval, like 2 hours or 4. Previously with Gnome, I would think that I could go into the gconf editor and find the key there, I am not sure with Unity where to override a setting like this. Any suggestions? |
I'm seeing a few sites with a sign in form on the far left with a billboard of info on the right (Salesforce, Mailchimp for example). Others like facebook have the sign in on the right. Most are centered. Is there any data on what performs the best? | Why are login forms always centered on the screen? Most horizontally, some vertically also. Sites like Apple/Amazon/Adobe/Microsoft/Google/PayPal/Instagram/Twitter etc. are all centered! Is this an undocumented best practice everyone unanimously decided to use? – Wireframes created with Obviously it's most aesthetically pleasing, but is there any other reasons why? Edit: Many of these sites do not support mobile either, so it wasn't done specifically for that. |
Here's my question: I want to see from javascript if an object is being clicked at the moment, Here is an example: setInterval(function() { if (document.getElementByTagName('button')[0].isBeingClicked) { //I know this isn't right: This is where my question is about. console.log('Button being clicked'); return; }; console.log('Button not being clicked'); }, 1000); With as simplified HTML ofcourse: <html> <head></head> <body> <button>Click me</button> </body> </html> So all together: I want to be able to see whether a button or another object is being clicked at this time. Not if it has been clicked, but is being clicked. | Is there a way to detect if a mouse button is currently down in JavaScript? I know about the "mousedown" event, but that's not what I need. Some time AFTER the mouse button is pressed, I want to be able to detect if it is still pressed down. Is this possible? |
I've initialized HashMap#onCreate method and i want to use HashMap in addLocation method. Everything looks okay but I don't understand why I get this error: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.HashMap.put(java.lang.Object, java.lang.Object)' on a null object reference when I call locationList#put method. Here's my code: public class InitLocationsOnStartup extends Application implements LocationListener { HashMap < String, Double[] > locationList; List < StationViewModel > stations; @Override public void onCreate() { super.onCreate(); stations = new ArrayList < StationViewModel > (); locationList = new HashMap < > (); // } public void getStations(List < StationViewModel > list) { this.stations = list; addLocation(locationList); } public HashMap < String, Double[] > addLocation(HashMap < String, Double[] > locationList) { for (int i = 0; i < stations.size(); i++) { latLong = new Double[] { Double.parseDouble(stations.get(i).getLatitude()), Double.parseDouble(stations.get(i).getLongitude()) }; if (stations.get(i).getStationName() != null && latLong != null) { locationList.put(stations.get(i).getStationName(), latLong); } } return locationList;; } | 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? |
The definition of euclidean ring in my textbook is 1) $N(ab) \geq N(a)$ 2) Euclidean algorithm works. However there is a note that the first condition is not necessary. There is a hint that we can choose a following norm: $N'(a) = \min_{b\sim a} N(b)$. I do not understand why it works. We need to check that euclidean algorithm still works with this norm. I tried to do the following. If $a \sim b$, then $a = bx, x \in K^*$. Let $N'(a)$ be $N(ax)$. Let us divide $ax$ by $bx$ instead of $b$. We get $ax = bxq + rx$, $N(rx) \leq N(bx)$. Here I am stuck and have no idea how to continue. | I recently came across the following definition for a euclidean ring: There exists a function $g:R\to\Bbb N_0$ with the following properties: 1.) $\forall x,y \in R$ with $ y \neq 0$ there exist $q,r \in R$ with $x = qy + r$ where $r=0$ or $g(r) < g(y)$. 2.) $\forall x,y\in R\setminus\{0\}$ we have $g(xy)\ge g(x)$ What I don't understand, is the point of the second requirement. I have seen definitions where this is not a requirement. What does 2.) achieve? Thanks very much |
Lets say I want to do cd home and then ls -lrth. I want these two things combined into a single command. I tried writing an alias, but it didnt work. Can you help me ? | I find that I often do the following: %> cd bla/bla %> ls I would like it that whenever I cd into a directory it automatically does an ls. I fiddled with my .bashrc for a while, but couldn't figure out how to make it happen. |
As it's stated in the title, I need some help on running Ubuntu on my Chromebook 13. I know that there are multiple tutorials, even for the Chromebook 13, however none of them seem to work properly for me. Either Ubuntu kills my ChromeOS, or it simply won't work at all. | I have installed Ubuntu 13.04 on my desktop (runs like a charm). Then I used Crouton to install Ubuntu 12. 04 on my chromebook samsung (ARM). It also works quite well. Here comes my question. Can we have a true Ubuntu (preferably 13.04) on my ARM chromebook? It seems that the Crouton/Ubuntu is not 100% the real thing. The best option would be to have the full Ubuntu 13.04 and remove the Chrome OS. |
Im going to Australia for a year. I dont know exactly when im going back to my country (Chile), so i just want to buy a one way ticket but they cost the same as a round way ticket. Could it be possible to buy a round ticket that is refundable and ask for the money of the return ticket? | I am planning a trip to Asia and then back to Rio. The thing is that I am traveling on flexible dates, so I am thinking of buying a one way ticket to Hong Kong, and I was planning to do the same when I want to come back. But what I noticed is that, for example, a one way ticket from Melbourne to Rio costs no less than $2700 dollars for the month of May. When I do a search for a round-trip from Melbourne to Rio and back, I can find flights for $2200. I know I will not be using that return to Melbourne, but I'd still prefer to save those $500. Can there be any issue with buying a round-trip with a return that I will never use? |
I'm using the following command to set my sections to use roman numerals, and I can set subsections to roman or arabic just fine, but I'd like to remove numerals from subsections altogether. I tried using {} but it leaves a . in front of the subsection. \renewcommand\thesection{\Roman{section}} \renewcommand\thesubsection{} It feels like I need something like this, but I can't find a reference as such. \renewcommand\thesubsection{empty{subsection}} | I found this to remove the numbering from sections, but I also don't need numbering on sub- and subsubsections. I tried to add a second def but then the number on Section is showed again. I am fairly new to Latex and I don't really know what is going on in this code block. Original: \makeatletter \def\@seccntformat#1{% \expandafter\ifx\csname c@#1\endcsname\c@section\else \csname the#1\endcsname\quad \fi} \makeatother Mine: \makeatletter \def\@seccntformat#1{% \expandafter\ifx\csname c@#1\endcsname\c@section\else \csname the#1\endcsname\quad \fi} \def\@seccntformat#1{% \expandafter\ifx\csname c@#1\endcsname\c@subsection\else \csname the#1\endcsname\quad \fi} \makeatother |
If $f(x)= x^3 + 3x + 4$ then the value of $$\int_{-1}^1f(x)dx + \int_{0}^4 f^{-1}(x)dx$$ equals So in this question I got stuck with the part of inverse of the function so I referred the solution and the solution was given as $$\int_{-1}^0f(x)dx + \int_{0}^1f(x)dx + \int_{0}^4 f^{-1}(x)dx = \int_{0}^1f(x)dx $$ What does this step mean , I'm new to Calculus and don't have much experience and so couldn't understand it. Please help :) | $[1]$ If $f(x) = x^3+3x+4\;,$ Then value of $\displaystyle \int_{-1}^{1}f(x)dx+\int_{0}^{4}f^{-1}(x)dx$ $[2]$ Evaluation of definite Integral $\displaystyle \int_{0}^{1}(e-1)\sqrt{\ln\left[1+(e-1)x\right]}dx+\int_{0}^{1}e^{x^2}dx$ $\bf{My\; Try\; for \; (1)::}$ Let $$\displaystyle I = \int_{-1}^{1}f(x)dx+\int_{0}^{4}f^{-1}(x)dx$$ Now Let $f^{-1}(x)=z\;,$ Then $x=f(z)$ and $dx = f'(z)dz$ So Integral Convert into $$\displaystyle I = \int_{-1}^{1}f(x)dx+\int_{f^{-1}(0)}^{f^{-1}(4)}z\cdot f'(z)dz$$ Now Using Integration by parts for Second Integral, We get $$\displaystyle I = \int_{-1}^{1}f(x)dx+\left[z\cdot f(z)\right]_{f^{-1}(0)}^{f^{-1}(4)}-\int_{f^{-1}(0)}^{f^{-1}(4)}f(z)dz$$ Now How can I solve after that, and I have seems second Question is same as $1$ one Help me Thanks |
I'm creating a process to extract the results of ffmpeg running from the command line using the data received function. There is a lot more going on with the process and in the function so I edited it for simplicity so I could focus on the specific question, removing the event handler. Process p = new Process(); p.EnableRaisingEvents = true; p.ErrorDataReceived += new DataReceivedEventHandler ( delegate (object sender, DataReceivedEventArgs e) { output += e.Data + "\n"; } ); I am getting the information I need but when I run it a second time, it terminates prematurely. I tried p.ErrorDataReceived -= null; but that didn't change anything. What I need to know is how to remove the DataReceivedEventHandler when the process completes. I know I could do it by providing a function name and removing that with -= but I want to know how to do it this way. EDIT: I was able to remove the event handler with the code below but it still ended prematurely the second time through so apparently that wasn't my problem. DataReceivedEventHandler myDelegate = null; myDelegate = delegate (object sender, DataReceivedEventArgs e) { output += e.Data + "\n"; }; p.ErrorDataReceived += myDelegate; ... p.ErrorDataReceived -= myDelegate; | Is it possible to unsubscribe an anonymous method from an event? If I subscribe to an event like this: void MyMethod() { Console.WriteLine("I did it!"); } MyEvent += MyMethod; I can un-subscribe like this: MyEvent -= MyMethod; But if I subscribe using an anonymous method: MyEvent += delegate(){Console.WriteLine("I did it!");}; is it possible to unsubscribe this anonymous method? If so, how? |
I need help to answer the following problem: Let $F$ be a field and $n\ge 2$. Define $\phi:GL(n,F)\to GL(n,F)$ by $\phi(g)=(g^{-1})^T$, where $T$ denotes the transpose. Suppose that $F$ has at least four elements. Show that $\phi$ is an outer automorphism of $GL(n,F)$. Thanks in advance for your help. | Consider the transpose inverse automorphism on $GL_n(\mathbb F)$ where $n\geq2$ and $|\mathbb F|>2$. (i.e. $\mathbb F$ is a field, possibly infinite, with three or more elements). I want to show this automorphism is not inner. I was told to consider $\det(BAB^{-1}) = \det(A)$ and $\det(\,^TA^{-1})=\det(A)^{-1}$ and derive a contradiction. However, in some fields (where the result holds) I fail to see the contradiction. What about $\mathbb F_3$? An element of $GL_2(\mathbb F_3)$ either has determinant $1$ or $2$, both of which are their own multiplicative inverses in $\mathbb F_3$. I'm not sure if my knowledge of fields and determinants is flawed or the hint is. |
I've created a virtual chessboard with 64 spaces formed as a nested array. I'm trying to go through each spot and check if the value of the spot is zero. I'm using np.where to get the indexes of the spot, however eventually np.where starts to return multiple values which throws an error. How can I get it to return ONLY the indexes of the spot that I am currently on? while chessboard[result[0], result[1]] != 0: for row in chessboard: for spot in row: if spot == 0: location = np.where(chessboard == spot) print(location) for move in possible_moves: if (location[0] + move[0]) < 0 or (location[1] + move[1]) < 0 or (location[0] + move[0]) > 7 or (location[1] + move[1]) > 7: continue else: chessboard_updated[location[0] + move[0], location[1] + move[1]] = 0 chessboard = chessboard_updated counter += 1 Eventually I get the error ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() because location returns (array([5, 6, 7], dtype=int32), array([1, 2, 0], dtype=int32)) it returns 5,6,7 instead of just 1 value Thank you. | How do I access the index in a for loop like the following? ints = [8, 23, 45, 12, 78] for i in ints: print('item #{} = {}'.format(???, i)) I want to get this output: item #1 = 8 item #2 = 23 item #3 = 45 item #4 = 12 item #5 = 78 When I loop through it using a for loop, how do I access the loop index, from 1 to 5 in this case? |
I'm trying to implement a snippet where we can loop through a dynamic list of objects. using System; using System.Collections.Generic; public class Program { public static void Main() { var l = new List<int>(); l.Add(1); l.Add(2); l.Add(3); l.Add(4); foreach(var i in l){ Console.WriteLine(i); if(i==3){ l.Add(5); } } } } This is throwing below run time error. 1 2 3 Run-time exception (line 15): Collection was modified; enumeration operation may not execute. Stack Trace: [System.InvalidOperationException: Collection was modified; enumeration operation may not execute.] at Program.Main(): line 15 Any help is appreciated. Thanks. | I can't get to the bottom of this error, because when the debugger is attached, it does not seem to occur. Collection was modified; enumeration operation may not execute Below is the code. This is a WCF server in a Windows service. The method NotifySubscribers() is called by the service whenever there is a data event (at random intervals, but not very often - about 800 times per day). When a Windows Forms client subscribes, the subscriber ID is added to the subscribers dictionary, and when the client unsubscribes, it is deleted from the dictionary. The error happens when (or after) a client unsubscribes. It appears that the next time the NotifySubscribers() method is called, the foreach() loop fails with the error in the subject line. The method writes the error into the application log as shown in the code below. When a debugger is attached and a client unsubscribes, the code executes fine. Do you see a problem with this code? Do I need to make the dictionary thread-safe? [ServiceBehavior(InstanceContextMode=InstanceContextMode.Single)] public class SubscriptionServer : ISubscriptionServer { private static IDictionary<Guid, Subscriber> subscribers; public SubscriptionServer() { subscribers = new Dictionary<Guid, Subscriber>(); } public void NotifySubscribers(DataRecord sr) { foreach(Subscriber s in subscribers.Values) { try { s.Callback.SignalData(sr); } catch (Exception e) { DCS.WriteToApplicationLog(e.Message, System.Diagnostics.EventLogEntryType.Error); UnsubscribeEvent(s.ClientId); } } } public Guid SubscribeEvent(string clientDescription) { Subscriber subscriber = new Subscriber(); subscriber.Callback = OperationContext.Current. GetCallbackChannel<IDCSCallback>(); subscribers.Add(subscriber.ClientId, subscriber); return subscriber.ClientId; } public void UnsubscribeEvent(Guid clientId) { try { subscribers.Remove(clientId); } catch(Exception e) { System.Diagnostics.Debug.WriteLine("Unsubscribe Error " + e.Message); } } } |
There's problem with my wifi. I do almost everything that I can. When I lspci -knn | grep Net -A3; rfkill list then it show output like this. I can surf browser through connecting with data cable but wifi is not showing and in setting it said that Wireless adapter is not found. 02:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:d723] Subsystem: Hewlett-Packard Company Device [103c:8319] Kernel modules: wl 0: hci0: Bluetooth Soft blocked: no Hard blocked: no Help me ASAP. | How do I install Wi-Fi drivers for Realtek RTL8723DE device in Ubuntu 16.04? lspci -v | grep -i network 02:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device d723 |
I'm trying to find the width of the terminal window using python (3.8.2), so that I can store it in a variable. By doing this, I can centre text I display in the terminal, no matter the width of it. As a heads up, I'm using an online IDE called 'repl.it'. Is there a way to find the width of the terminal, or even another way to centre text in the terminal without need for finding its width? | Is there a way in python to programmatically determine the width of the console? I mean the number of characters that fits in one line without wrapping, not the pixel width of the window. Edit Looking for a solution that works on Linux |
Can someone remind me of the name of the author, the name of the hero and the name of the series if any? Adventure Sci-Fi books, short by today's epic standards ( = about same length as Heinlein's shorter youth books), probably published late 50s?, early 60s? by Bantam? or Del Rey? I think at least 30, possibly more than 40 books in the series. Not comic books. The author is not a well-known writer. At least, I don't remember seeing the name on any other books, ever. Subject: a man who can move and respond to threats extremely fast learns about a secret potion that allows a person to change bodies with someone else and thus control them. A powerful organization does not want the secret to be known, because they use the potion to control politicians on many planets. The organization's goons are people who had surgeries to remove their emotions, and function like organic computers. They can communicate over interstellar distances and follow and murder anyone who learns the secret. I remember the following detail about the potion: there are two nearly identical molecules that have to be assembled in a certain sequence. Two of the components had to be switched around and that determined who would be dominant and who would be controlled during the mind switch / body swap. Every book finds the hero on another planet with new adventures, and usually taking another deep-sleep-passage to another world, fleeing his pursuers. The background story about the secret potion is dished out little by little in each book. One book in the series starts like this: hero is on very hot planet, diving for valuable marine life, catches a deadly fungus disease and is rescued last moment in exchange for his catch... One of the themes that returns often is that the hero is an excellent knife fighter. Of course he's a womanizer. In the second (or close to 2nd) book in the series, he's involved with a woman who rules a planet. To travel to another world, he usually takes the cheapest dead-sleep passage, and there's always a 10-25% risk you won't wake up from that. | I am trying to remember a SciF series of books I started reading in my early to mid-teens (1980-86) where the main character was searching for humanity's mythical home planet Earth, which I never did finish. These were generally paperbacks I borrowed from the library or picked up in 2nd hand book shops. The main character (male) was a mercenary who made his way from planet to planet financing his space fares by taking various contracts, generally each novel's main plot involved a single contract, but with a larger story arc of searching for humanity's lost home planet. Unique things I remember about the series; The main character tended to wear a one piece combat suit, like chain mail covered in some kind of polymer plastic. He was a skillful knife fighter. Interplanetary travel took time, rich passengers took drugs which slowed down their perception of time and aging. Slow-time? Each planet had a shanty town around the spaceport in which lived unfortunates who could no longer pay for passage off world. There was a religious order who fed these unfortunates at the cost of brainwashing them against violence. Most characters don't believe in the one home world myth, due to the number of races of human. At one point the main character gains the spectrum fingerprint of Earth's sun. Some vague plots I remember from the series; Searching for immortality fungus on a world overrun by fungi. Hunting giant lizards for gems that grew in their brains. |
What is the number of all matrices $n*n$ with entries in $ \{0,1\}$ that in every row and every column has at least one 1? I think maybe it is easier to count those matrices that has some null-row or null-columns. Any ideas? Thanks in advance. | I am looking to calculate the number of $m\times n$ matrices which have no empty rows or columns (at least one $1$ in each row and column). I have looked at the answers to a few similar questions such as and but I am struggling to make these approaches work in this case. |
gave a reason why the OP's code wasn't working, but didn't provide any alternative code; I downvoted it. Then the OP edited it to include some code, but my vote is still locked in: (The last line of code wasn't there when I downvoted). I've edited the answer now, to bypass the lock, but this is a bug that should be fixed. | I downvoted an answer 17 seconds after it was posted, and left. I came back 17 minutes later (what a coincidence) and the post had been edited, but the system didn't let me undo my vote. I believe it was because the edits took place during the grace period and weren't registered. Is that so? I wish I were able to remove my downvote. |
I'm running Ubuntu 15.10 with GNOME shell (not 16.XX because Steam is having a hard time on that release right now) and I'm looking for a way to change my monitors refresh rates. My GPU is an AMD Radeon R9 Fury X, and my monitors are the BenQ XL2730Z 144Hz, BenQ XL2420T, and Seiki SE42UMS. All of my monitors are using Displayport1.2 (in the case of the Seiki SE42UMS, it's using an HDMI2.0->DP1.2 adapter.) Any help would be appreciated and I'll try and port forth any more information that would be useful for helping resolve this issue I'm having. Thanks. | My eyes hurt so I thought I should check the screen refresh rate (monitor frequency), but I couldn't find it. Where is it? (in Ubuntu 12) |
I am working on ASP.NET MVC and I need to create separate dll of all pages in project. Let me explain what should I need. Suppose I have create controller like: home.cs index.cs test1.cs test2.cs and view : home.cshtml index.cshtml test1.cshtml test2.cshtml then I need to create dll like home.dll and index.dll separately of every page because of if i have publish my project after changes in any one controller that time i just need to update the changeable controller dll only. I don't know it is possible or not but if anyone know then please suggest me ? Thanks in advance. | I'm just learning asp.net mvc and I'm trying to figure out how to move my controllers into a separate project. Typically when I have designed asp.net web apps before, I created one project for my models, another for my logic, and then there was the web. Now that I'm learning asp.net mvc I was hoping to follow a similar pattern and put the models and controllers each into their own separate projects, and just leave the views/scripts/css in the web. The models part was easy, but what I don't understand is how to make my controllers in a separate project be "found". Also, I would like to know if this is advisable. Thanks! |
In the docker official doc (), to enable remote/tcp API access you use an override as follows: /etc/systemd/system/docker.service.d/override.conf: [Service] ExecStart= ExecStart=/usr/bin/dockerd -H fd:// -H tcp://0.0.0.0:2376 I followed the above and it works. But why do we need 2 ExecStart? Does the 1st one serve any purpose? | Suppose a package provides whatever.service file so certain events (including whatever.socket) cause a daemon to start with a certain configuration. I want to disable this completely. In particular, I want the old socket and any other unit files that might refer to this service by name to be unable to start the daemon. Instead, I want to create my own unit files for this daemon with a different .socket unit and different environment variables. I also want my override to automatically take account of possible upstream updates to the original unit file (which my current solution of copying whatever.service as whatever-modified.service and editing it unfortunately does not provide). If I create the following symlinks and files: /etc/systemd/system/whatever.service → /dev/null /etc/systemd/system/whatever-modified.service → /usr/lib/systemd/system/whatever.service /etc/systemd/system/whatever-modified.service.d/fix.conf systemd considers the new service to be masked as well and refuses to start it. How to avoid this? |
I have old Ubuntu 10.04. It has been 5 years ago. I want to update it. But I cannot success to upgrade it. Does anyone know about this problem. I have tried a couple days to fix it. Thanks a lot x11proto-core-dev x11proto-input-dev x11proto-randr-dev x11proto-xext-dev xdiagnose xkb-data xorg xserver-common xserver-xorg xserver-xorg-core xserver-xorg-input-all xserver-xorg-input-evdev xserver-xorg-input-synaptics xserver-xorg-input-vmmouse xserver-xorg-input-wacom xserver-xorg-video-all xserver-xorg-video-intel xserver-xorg-video-nouveau xserver-xorg-video-openchrome xserver-xorg-video-qxl xserver-xorg-video-vmware xsettings-kde xsltproc xterm xul-ext-ubufox zeitgeist zeitgeist-core zenity zenity-common Restoring original system state Aborting Reading package lists... Done Building dependency tree Reading state information... Done Building data structures... Done === Command detached from window (Tue Oct 20 09:33:50 2015) === === Command terminated with exit status 1 (Tue Oct 20 09:33:50 2015) === | Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found: $ sudo apt-get install vlc Reading package lists... Done Building dependency tree Reading state information... Done E: Couldn't find package vlc |
Ex: I have 3 Chrome windows (each has multiple open tabs). Pressing on the red button in the upper left corner closes my whole session and I don't want other instances to also die. Only one of them with 4 tabs. Command + W works only for the current tab, not the current window. How do I achieve this with using mouse? How do I achieve it with the keyboard? (Command + Q closes all Chrome windows so, also, not good). I am running Google Chrome Version 75.0.3770.100 (Official Build) on macOS Mojave 10.14.5. | I am looking for a way to close the currently focused window using a keyboard shortcut. Effectively I want to do the same thing as the red "X" button in the top left corner, only using a keyboard. On windows/linux this is done by alt+f4 I know about: ⌘ Cmd+w - in any tabbed application such as google chrome it will close the current tab instead of current window ⌘ Cmd+q - will close the entire app instead of just the current window |
I'm running this .exe Windows called ngrok, but that really doesn't matter. The basics are though, I want to "grab" or store a IP that it displays (Forwarding Https variable on the cmd prompt) Is there an easy way to grab this value and store it in a variable and pass it to another batch script ? | I'm looking to get the result of a command as a variable in a Windows batch script (see for the bash scripting equivalent). A solution that will work in a .bat file is preferred, but other common windows scripting solutions are also welcome. |
Is there a way to have OS X-like behavior in Nautilus? Nautilus elementary is long gone? Basically I'd like to have an option to a tree view (only 2 views, not multiple like in max os x) where the parent will be on the left, and the content on the right. On Mac OS X, it looks like this Possible something similar on Ubuntu? | I found a feature request at but it doesn't seem easy to get a column view with Nautilus while with Mac OS X it's a default feature. Have I missed something or is this not currently possible? |
I want open business bank account in Michigan. I have not SSN. I have EIN. My friend is in Michigan. I don't want to go USA just for open Bank account. Is this possible to open business account online without physical present in USA? | I'm Swedish, but living in Switzerland at the moment. Can I open a US bank account? Either when in the US on vacation or through the internet/phone? There are lots of situations when I find myself in need of an american credit card or just a bank account. When ordering things online (most retailers refuse to accept my orders if I try to pay with my Swedish or Swiss credit card, even if I ship it to an US address... ) etc etc. |
I currently use a bash script in the following format to update local data with remote one: usr=$1 scp -P 4444 -r [email protected]:/some/folder/*Tools /home/localUser/someFolder/ scp -P 4444 -r [email protected]:/some/folder/*.project /home/localUser/someFolder/ i.e., I want to copy each folder (its content and subfolders) that ends with Tools and to copy each file that ends with .project from /some/folder/ (okay, I would not need -r here) at the remote machine into my local folder /home/localUser/someFolder/. (Not sure if this is important, I run this script with bash myScript.sh) Currently, I have to enter the remote user's password two times, once per scp command. Is there a way so that the password has to be entered only one time? | I want to be able to login to a remote via ssh without having to enter the password all the time. How do I set it up? Is a different command required to execute a password-less session? |
$f: D \to C$ is analytic, Denote $f = u+iv$ and if $\exists$ an $\mathbb{R}$ differentiable function $g: R \to R$ where $u = g\circ v$. Show that $f$ is locally constant function. My idea is to partial differentiate $u$ wrt $x$ and $y$ respectively and get $$u_{xx} =g_{xx}(v) \cdot v_{x}^2+g_x(v) \cdot v_{xx}$$ $$u_{yy} = g_{yy}(v) \cdot v_{y}^2+g_{y}(v) \cdot v_{yy}$$ And since $f$ is analytic, we know that $u,v$ are harmonic. I tried adding up both equations and got stuck, any ideas on how to continue? | The problem as stated in R. Remmert's Theory of Complex Functions p. 62., is this: Let $f = u + iv$ be holomorphic in the region $G \subseteq \mathbb{C}$ and satisfy $u = h \circ v$ for some differentiable function $h : \mathbb{R} \to \mathbb{R}$. Show that $f$ is constant. I've attacked this computationally in each way I can think of. I've tried to show that $\frac{\partial f}{\partial z}$ is zero; played with the Laplace equation, knowing that $h \circ v$ and $v$ must be hamonically conjugate, etc. I even considered spinning an argument based on the maximum principle. It seems obvious, but I have not succeeded in a proof yet. Perhaps I am missing a concept? |
I create a list of identical dictionaries and I would like to update only the value of one specific key of one of the dictionaries of the list, but I don't get what I expect. Would you know how to do that? | I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3 The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]] Then I changed one of the innermost values: my_list[0][0] = 5 Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]] which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it? |
The default .bashrc in the standard distribution of Ubuntu 16.04 that comes with AWS has these lines: # don't put duplicate lines or lines starting with space in the history. # See bash(1) for more options HISTCONTROL=ignoreboth However, it doesn't seem to work. I have been running pm2 restart myApp and pm2 list repeatedly using the Up Arrow key, and the command buffer now contains nearly a hundred lines of these. What could be wrong? | The same command is listed in my history again and again. How can I avoid this? I know it's possible via HISTCONTROL but I haven't found the right way. |
I'm kindof a C# noob and I want to create a byte[] from a String[]. Here is an example: string[] macString = new string[]{"AA","11","02","BB","A5","AA"}; And I want the following output: byte[] mac = new byte[] { 0xAA, 0x11, 0x02, 0xBB, 0xA5, 0xAA }; Can somebody help me with this? | Can we convert a hex string to a byte array using a built-in function in C# or do I have to make a custom method for this? |
Prove that $$\lim_{n\to\infty}\frac{(n+1)(n+2)\cdots(2n-1)2n}{n^n}=\infty$$ I saw that $$\frac{(n+1)(n+2)\cdots(2n-1)2n}{n^n}=\prod_{i=1}^n\left(1+\frac in\right)$$ I think I can use squeeze law, but I'm not sure. Can you give me a hint? | I have a sequence $(a_n)$ where for each natural number $n$, $$a_n = (1+\frac{1}{n})(1+\frac{2}{n})\cdots(1+\frac{n}{n})$$ and I want to find its limit as $n\to\infty$. I obviously couldn't prove it and after several futile attempts decided to post it here. Here is a list of a few observations which I got from those attempts: The sequence $(a_n)$ is a strictly increasing sequence. To prove this, I rewrote each element as $$a_n = (1+\frac{1}{n})(1+\frac{2}{n})\cdots(1+\frac{n}{n})= \frac{(n+1)\cdots(n+n)}{n^n}= \frac{(2n)!}{n!n^n}.$$ Then $$\frac{a_{n+1}}{a_n}= \frac{2(n+1)!}{(n+1)!(n+1)^{n+1}}\frac{n!n^n}{(2n)!}=\frac{(2n+1)(2n+2)}{(n+1)^2(1+\frac{1}{n})^n} \to \frac{4}{e}$$ as $n\to\infty$. Since $\frac{4}{e}>1$ we have $a_{n+1}>a_n$ eventually. The limit of this sequence is bounded below by $e$. By replacing $1,2, \ldots, n$ with $1$ in the expression of $a_n$, we get $a_n \geq (1+\frac{1}{n})^n$. And thus $\lim{(a_n)}\geq e$. $\lim{(a_n)}\geq e^2$ and $\lim{(a_n)}\geq e^3$. The first assertion follows from the fact that $$a_n\geq(1+\frac{1}{n})(1+\frac{2}{n})^{n-1}= \frac{(1+\frac{1}{n})(1+\frac{2}{n})^{n}}{(1+\frac{2}{n})} \to e^2.$$ And the last one follows the same way because $$a_n\geq (1+\frac{1}{n})(1+\frac{2}{n})(1+\frac{3}{n})^{n-2}.$$ Now I have a gut feeling that for any natural number $k$, one can show that for all sufficiently large natural number $n$, $$a_n\geq (1+\frac{1}{n})\cdots(1+\frac{k-1}{n})(1+\frac{k}{n})^{n-(k-1)}.$$ And therefore for all $k \in \mathbb{N}$, $\lim{(a_n)}\geq e^k$ making the sequence divergent. But I'm really not sure about this approach and I'll appreciate any help towards this end. Thank you. [Note: As this sequence is quite common, there may be other posts on math.SE asking the same question. I didn't search for them because I just don't know how to search for an expression this big. Though a link related to any previous question concerning this particular sequence will be good enough, I will greatly appreciate if someone takes the trouble to look into my approach/observations and point out where I'm going wrong.] |
Generally, one column form is considered the best practice for form design. However, when the form has too many fields it wouldn't look good to create a super long form that spans 3+ screens either. For business/patient information, breaking down the form down into steps or collapsible parts are not great solutions as well. Shall I just use a multiple-column form instead? | I'm trying to give the best experience to users of a very huge system (like a CRM). It has a lot of forms and much of these have a lot of fields. My doubt is about if I should use a single column form (which raises too much vertical scrolling), or a two columns form (which needs less vertical scrolling and uses more horizontal white space) and a last one with four columns (which has few scrolling and uses almost whole white space to try to keep most of the fields above the fold). It's important to say that our clients hate scrolling, and they always ask why we don't use the horizontal white space when we present a one column form). So I'm little bit confused about it, because a lot of UX studies and good practices recommend to do not use/avoid multicolumn forms but the clients most of times ask multi column forms. Our clients are very used to desktop programs and not everybody is very familiar with web based systems. Below follows some possibilities I would like to share to illustrate an example of a complex form in the system with the three possibilities I mentioned: In the example above I'm using the one column form (most recommended in UX studies), but with a very long vertical scroll. In the second example I tried to reduce vertical space by using two columns. This is the client's favorite one, 4 columns using white space and trying to keep everything above the fold. The lengths of fields are based on the average of characters amount for each field. I would like to know your opinion about the best approach to this case. |
I wanted to know, what’s the quickest way to get diamonds? I want to start a survival world, but I want to be able to get diamonds quickly. Please share the quickest ways you found! | When I'm not exploring fresh caves or lands in minecraft, I'm busy trying to find deposits of diamond, gold and iron deep in the earth. So far I've just been digging around just above bedrock on a whim to look for these rare minerals but I've started thinking that I should be taking a more controlled, efficient approach to mining. What is the optimal mining strategy that yields the most rare minerals while minimizing blocks removed and time spent digging and traveling? Edit: The existing answers are great for mining, but no one has addressed travel time to and from the mine which is usually ~60 blocks downward and incredibly tedious. Solutions? |
I am going from NYC to San Antonio TX- about 28 hours- and have planned several stops. My dog loves to be in the car. I am wondering if it is better to go a short (ie 4 hr) day and then a long one (ie 8-9 hrs) or to balance them out. Some of the stops are good in the short days and the long ones have few places to stop. Any advice very welcome. | I'm planning a move across the United states (literally coast-to-coast) and my large (75 lb) dog needs to come along. According to google maps it's a 36 hour drive, which I figure will take a minimum of 3 days once some slight sight seeing, eating, and sleeping is factored in. Clearly I need to bring dog food, maybe a blanket for him to lay on in the hotel room and probably a travel crate. What else do I need to take into account? |
How safe is stinky tofu since it does smell like feces? Is there risk of bad prep when making it or coming out of places with questionable food safety practice? | What general rules do I need to follow to keep my food safe? How do I know what temperature to cook something to, or whether my food is safe at room temperature? |
Show that $$\lim_{n\to\infty}n\Bigg\{\dfrac{1}{(n+1)^2}+\dfrac{1}{(n+2)^2}+\dfrac{1}{(n+3)^2}+\cdots+\dfrac{1}{(2n)^2}\Bigg\}=\dfrac{1}{2}.$$ Proof: We can rewrite $$\lim_{n\to\infty}n\Bigg\{\dfrac{1}{(n+1)^2}+\dfrac{1}{(n+2)^2}+\dfrac{1}{(n+3)^2}+\cdots+\dfrac{1}{(2n)^2}\Bigg\}=\lim_{n\to\infty}n\Bigg\{\sum_{k=1}^n\dfrac{1}{(n+k)^2}\Bigg\}$$ Which looks astoundingly similar to the form in Corollary 8.3, where $\dfrac{b-a}{n} = n\implies b-a = 2n$. Corollary 8.3: Let $f$ be a continuous function on an interval [a,b]. Then $$\int_a^bf(x)dx=\lim_{n\to\infty}\dfrac{b-a}{n}\sum_{k=0}^{n-1}f\Bigg(a+\dfrac{k}{n}(b-a)\Bigg)$$ That would mean the term in Corollary 8.3 would morph into $$f\left(a+\dfrac{k}{n}(b-a)\right)=f\left((b-2n)+\dfrac{k}{n}(2n)\right)=f(b-2n+2k)$$ We need $f(b-2n+2k)$ to look like $\dfrac{1}{(n+k)^2}$. This would imply that $f$ is ... but then I get stuck. I am unsure how to find $f$ or even if I need to find $f$. | Can you help me with this limit? What do I have to do? I'm lost. $$\lim_{n\to\infty}n\left(\sum_{i=1}^{n}\dfrac{1}{(n+i)^2}\right)$$ The solution given is $\dfrac{1}{2}$. |
I'm making my own Command line like windows command prompt or macs terminal. My plan was to have it take input(works) analysis it(does not work) and display it(works) then repeat. This is the testing file for it import java.util.Scanner; public class addingStrings { public static void main(String[] args) { Scanner scan = new Scanner(System.in); //Init String out = ""; String input = scan.nextLine(); String component[] = input.split(" "); for(int i = 0;i < component.length;i++) { if(component[i] == "echo") { i++; while(component[i] != "\\") { out += component[i]; i++; } } } System.out.println(out); } } what it does is splits up the code into an array then checks each string in the array for a command such as echo or print. Once it finds one it would then print every thing after the echo command. ex: it would read: "echo Hello World \\" split it into component = {"echo", "Hello", "World", "\"} then check and find that component[0] is "echo" then display every thing until it hit \ and would display Hello World Every thing works except for the if statement. for some reason if i use an array like this String[] component = {"echo", "Hello", "World"}; instead of splitting a String; it works fine. Is there any way to make it read the split string array the same way as the normal array or does splitting a string to an Array output a string differently than directly saving values into an array. | I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug. Is == bad? When should it and should it not be used? What's the difference? |
Some tuples in my database need to be erased after a given time. I need my django app to check if the rows have expired. While I can definitely write the function, how do I make Django run at everyday at a fixed time? I have heard about Task Queues like Celery. Are they too much powerful for this? Is their anything simpler? May be something build-in? | I've been working on a web app using Django, and I'm curious if there is a way to schedule a job to run periodically. Basically I just want to run through the database and make some calculations/updates on an automatic, regular basis, but I can't seem to find any documentation on doing this. Does anyone know how to set this up? To clarify: I know I can set up a cron job to do this, but I'm curious if there is some feature in Django that provides this functionality. I'd like people to be able to deploy this app themselves without having to do much config (preferably zero). I've considered triggering these actions "retroactively" by simply checking if a job should have been run since the last time a request was sent to the site, but I'm hoping for something a bit cleaner. |
I was checking my progress in the review queue's and discovered that they're looking at an 8 day windows to report the weekly review total. 160 reviews at 20 reviews/day is 8 days of activity not 7. This is from the Low Quality Review queue on StackOverflow. I get the same for Suggested Edits; the other queues I either don't have enough reviews to see anything obviously wrong with the total or don't have access to at all. | In the review page, it shows stats of recent reviewers. But it is showing wrong stats. Because today (on Monday) it shows week count 53 (on Meta Stack Overflow) which is impossible as there is a limit of 20 reviews per day. PS: This bug and . But the bug has occurred again. |
While using nohup to put a command to run in background some of content appear in terminal. cp: error reading ‘/mnt/tt/file.txt’: Input/output error cp: failed to extend ‘/mnt/tt/file.txt’: Input/output error I want to save that content to a file. | How do I save the output of a command to a file? Is there a way without using any software? I would like to know how. |
I'm getting the following error message: Fatal error: Unsupported operand types in /var/www/public_html/domain.com/includes/form.inc on line 1079 It seems to be because the following code for an admin menu. function MY_MODULE_admin_menu() { $menu_items = db_query("SELECT * FROM my_module")->fetchAll(); $header = array('Template ID', 'Name', 'Type', 'Template'); $rows = array(); if (!empty($menu_items)) { foreach ($menu_items as $menu_item) { $rows[] = array($menu_item->tid, $menu_item->name, $menu_item->type, $menu_item->template); } } return theme_table(array( "header" => $header, "rows" => $rows, "attributes" => array(), "sticky" => true, "caption" => "", "colgroups" => array(), "empty" => t("Table has no rows"), ) ); } What's causing this? As far as I can tell, this is how it is supposed to look for Drupal 7. | I am simply trying to return the rows from a table in my db but i keep getting this error thrown back at me no matter what I do "Fatal error: Unsupported operand types in C:\xampp\htdocs\d7\includes\form.inc on line 1009". Am I missing a argument or something? This is my function Hook menu function auto_form_menu() { $items = array(); $items['admin/config/auto_form'] = array( 'title' => 'My Module', 'description' => 'description', 'page callback' => 'drupal_get_form', 'page arguments' => array('auto_form_records'), 'access arguments' => array('administer site configuration'), 'file' => 'auto_form.admin.inc' ); $items['admin/config/auto_form/manage'] = array( 'title' => 'My Module', 'type' => MENU_DEFAULT_LOCAL_TASK, 'description' => 'description', 'weight' => -10, ); return $items; } 'auto_form.admin.inc' function auto_form_records() { $header = array('First Name', 'Last Name'); $dbresult = db_query("SELECT first, last FROM {auto}"); $rows = array(); foreach ($dbresult as $dbrow) { $rows[] = array( $dbrow->first, $dbrow->last ); } return $output = theme('table', array('header' => $header, 'rows' => $rows)); } Updated Code: Any help is appreciated seeing how I am completely lost on figuring this out. |
I'm running 12.04 and do not have a clue how to set up my wireless card. The strange thing is the box says that it's made by netis. But on a query (lspci) of the device, it says: 01:02.0 Network controller: Ralink corp. Device 5362 I guess Ralink manufactured their chips. I looked on the NETIS site, and they only have a windows driver. I looked on the Ralink site, which has moved, and they do not have a driver for that device or model number. Could someone suggest a driver that might work as far as the ralink ones go or is there a workaround maybe? Hoping someone else has some time and can walk a newb through this task. | I recently upgraded from ubuntu 13.10 to ubuntu 14.04. Wifi (with ralink rt3290 card) was not working in ubuntu 13.10, but after the following the guide here, , it worked fine. But in ubuntu 14.04, no matter how much I try it does not work. Can anyone please figure out what the problem is and how to solve it. |
I'm having trouble finding resources on how the linux kernel actually finds the hardware, that it is running on. For example, what kind of graphics card there is, so it knows which driver to load. Or if there is a graphics card present at all. I picked up somewhere, that it could have something to do with ACPI tables, but I'm at a loss what to search for. | As far as I know, the kernel detects hardware, adds information to sysfs creates a device in /dev and then generates a udev event. My question is, do device drivers do all of this or it is the kernel itself? If drivers do it, then they would know the device major and minor number to create the file in devtmps. I also understand (maybe wrongly) that it is udev who calls modprobe to load the drivers that handle a device. I was told that they do so with the contents of the MODALIAS uevent environment variable, thus loading all modules whose aliases match this string (the correct driver). In short: what are the steps of hardware detection in linux and WHO performs each step: the kernel itself, the driver inside the kernel or udev in userspace. Thanks. |
I recently installed Xubuntu...and it runs great...until I tried to install software using the Terminal window. Specifically...$ sudo apt-get install unrar. I downloaded .rar files and needed something to open them. After pressing enter, it then asked for my password which contains numbers. YES!!! the numlock was on. lol I couldnt type my password. No numbers came up. | When I'm about to install a program in the terminal it wants the password: [sudo] password for xxx: But when I start to type my password nothing happens. What should I do? |
I have been trying to set environment variables that would be saved upon reboot, but without success. When I set variables using the export or setenv command, as root or any other user, it gets saved on the session until reboot. After reboot, the variables are lost. In particular, I need to set $JAVA_HOME. So I do like this but nothing is working as I indicated. What am I doing wrong? | This is irritating me. I seen several suggestions (all using different files and syntax) and none of them worked. How do I set an environment variable for a specific user? I am on debian squeeze. What is the exact syntax I should put in the file to make ABC = "123"? |
when I open up a video on YouTube or play something on Rhythmbox. The YouTube video never loads, and the music on Rhythmbox starts skipping like a minute every second. I tried sudo killall pulseaudio then running pulseaudio logged in as root. I get the below error messages after a little bit: root@aa-ul:~$ pulseaudio W: [pulseaudio] main.c: This program is not intended to be run as root (unless --system is specified). W: [pulseaudio] alsa-mixer.c: Your kernel driver is broken: it reports a volume range from 0 to 0 which makes no sense. W: [pulseaudio] alsa-mixer.c: Your kernel driver is broken: it reports a volume range from 0 to 0 which makes no sense. Here's a link to the that I killed when it took a while. Output of aplay -l: aa@aa-ul:~$ aplay -l **** List of PLAYBACK Hardware Devices **** card 0: MID [HDA Intel MID], device 0: ALC269 Analog [ALC269 Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 2: HDMI [HDA ATI HDMI], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0 How can I get audio to work? I tried apt-get install --reinstall pulseaudio but it didn't work. I'm running Ubuntu 14.04 64-bit over 3.13.0-34-generic, and the system is up-to-date. Here's the output of an ALSA information script that contains the output of some useful commands: | I was trying to fix my audio problems using suggestions from . One of the comments suggested I execute this and only this: killall pulseaudio So I did, and I restarted my computer just in case, but all it did was remove my soundcard and I still couldn't hear anything. Now I don't know how to get my soundcard back. Please note that I am extremely inexperienced when it comes to Ubuntu. |
Determine the limit of: $$\lim_{x \to -\infty} \left(\sqrt{x^2 +2x} - \sqrt{x^2 - 2x}\right) $$ I've tried a few times, most notably the following two versions. I'm looking for a comment on both, since both amount to a wrong answer. First attempt $$L = \lim_{x \to -\infty} \left(\sqrt{x^2 +2x} - \sqrt{x^2 - 2x}\right) $$ I thought it'd be nice to get rid of as much ugliness as possible by moving $x$ out of the roots: $$ \begin{split} L &= \lim_{x \to -\infty} \left(x\left(\sqrt{1 + \frac{2}{x}}\right) - x\left(\sqrt{1 - \frac{2}{x}}\right)\right)\\ &= \lim_{x \to -\infty} \left(x\left(\sqrt{1 + \frac{2}{x}} - \sqrt{1 - \frac{2}{x}}\right)\right) \end{split} $$ Seems simple enough, since $\frac{1}{x}$ should be an (infinitely) small number I thought it could be discarded with regard to $\sqrt1$, yielding: $$L = \lim_{x \to -\infty} \left(x\left(\sqrt{1} - \sqrt{1}\right)\right) = 0$$ Wrong, Second attempt Multply both sides with the conjugate: $$ \begin{split} L &= \lim_{x \to -\infty} \sqrt{x^2 +2x} - \sqrt{x^2 - 2x}) \\ &= \lim_{x \to -\infty} \frac{4x}{(\sqrt{x^2 +2x} + \sqrt{x^2 - 2x})} \\ &= \lim_{x \to -\infty} \frac{4x}{x\sqrt{1 + \frac{2}{x}} + x\sqrt{1 - \frac{2}{x}}} \\ &= \lim_{x \to -\infty} \frac{4}{\sqrt{1 + \frac{2}{x}} + \sqrt{1 - \frac{2}{x}}}\\ &= \frac{4}{\sqrt{1} + \sqrt{1}} = \frac{4}{2} = 2 \end{split} $$ Wrong as well... The answer should be $-2$, but I don't get how to 'get the negative' in... | I am stuck on this. I would like the algebraic explanation or trick(s) that shows that the equation below has limit of $-2$ (per the book). The wmaxima code of the equation below. $$ \lim_{x \to - \infty} \left( \sqrt{x^2 + 2x} - \sqrt{x^2 - 2x} \right) $$ I've tried factoring out an $x$ using the $\sqrt{x^2} = |x|$ trick. That doesn't seem to work. I get $1 - 1 = 0$ for the other factor meaning the limit is zero...but that's obviously not correct way to go about it :( Thanks. |
I had two separate tex files ( theory.tex & molecular_dynamics.tex ) for chapter 2, where i had some written text in these tex files, and are included in a single tex file named main.tex whose working directory is as shown below: On compiling this main.tex file, i get the end page of theory.tex file containing blank spaces(shown in attached screenshot) and the page of molecular_dynamics.tex file starts from new page (shown in attached screenshot) rather being continuous from the same page, not in next page, where the last page of theory.tex file ends. Is there any command that makes continuous text between these two included files? However i want the usual format when it jumps to new chapter. \documentclass[a4paper,12pt,oneside]{book} \include{packages/packages} \begin{document} \include{ch2/theory/theory/theory} \include{ch2/theory/molecular_dynamics/molecular_dynamics} \include{ch3/results1/results1} \include{ch3/results2/results2} \end{document} | There are two different commands to incorporate another file into the source of some document, \input and \include. When should I use one or the other? What are the differences between them? Are there more things like them to be aware of? |
I know this question may be stupid but I've been studying for my test tomorrow and I'm so frustrated, I can't figure this one out. if we have a square root function like this: $y = \sqrt{x}$ wouldn't $y$ be both $+2$ and $-2$ for $x = 4$, so shouldn't the graph look like a quadratic graph? | How $\sqrt{x}$ can be a function when $\sqrt{4}$ is equal to $-2$ and $2$? |
When I went to edit a question here on meta I saw that the box to add Tags was to small (or the tags are just to low), here are some screens from different browsers: Google Chrome version:34.0.1847.116 m Opera version:20.0.1387.91 FireFox version:28.0 Internet Explorer version:11.0.9600.16659 Not running any user scripts, only extensions are Adblock (2.6.29) and FireBug Lite (1.4.0.11967) but those don't seem to effect it when turned off. | When editing a question the tags are feeling a little shy and aren't displaying themselves fully. The inline tag editing does not have the same problem but the tags jump around a little as well. I'm fairly sure that this has happened before but it was fixed and I can't find the bug report. This only appears to be happening on MSE. I'm on Chrome 34.0.1847.116 on Windows 7 if it makes a difference. |
After a form submission I display the user's submitted data, but I struggle with showing an optional note. This is how I display it when it wasn't filled: And this is how I currently display it with given data: This does not only look really bad, it also implies that it's an input which is not exactly userfriendly. It's only suppose is to display the user's data again. I also tried without the outline, but it looks as bad. How can/should I display the user's note to look good and userfriendly? | Should I use labels for read-only information, or should I use read-only text boxes to maintain the look of the fields? It seems to me that if something is in a textbox it implies there is some way to edit it, whereas plain text is explicitly read-only. Update: While my question is similar to , mine is different in that I'm referring to fields that are never editable by anyone. It's not based on the user's rights or role. – Wireframes created with |
Newton's third law states that whenever a force acts on you, you act on it with the same force, just with an opposite direction(except it's stated a little fancier). Now if an apple is falling through the air, it is falling because the gravity is pulling it downwards, what exactly is the reaction that the apple applies to the gravity? (or even more broad examples like satellites that constantly get pulled downwards by gravity but never land due to centripetal force) | When a person is standing still, the action of the Earth on their body is a gravitational force. What is the reaction force? Is it the person's weight acting on the Earth? |
I remember a scene from a movie or TV show where a guy is walking on the train tracks and sees a trapped turtle. He bends to rescue the turtle and gets his foot stuck in the switching mechanism for the tracks as a train approaches. He uses his telekinetic powers (maybe for the first time?) to stop the train and get away. What was that show? | Some 30 years back, I saw a film about the son of an extraterrestrial who gets involved in a gold heist. The main character does not initially know that he is the son of an extraterrestrial and that has special telekinetic powers. The film opens, I think, with him being in some train yard, his foot getting stuck in a switch with a locomotive approaching. He stops it using his powers intuitively, possibly passing out (not realizing what he actually did). I think his mother subsequently reveals his heritage to him. He somehow gets hired as a bodyguard for someone planning a gold heist. I think they know his abilities and use him to steal a million US dollars. Actually, that is just a distraction, covering that they steal 30 million dollars from the same location (through the air, not sure on that part). The last part I remember is some underground tunnels where the thieves set up to melt the gold. The main character is locked in there. Does anyone know the title of this movie? Searching for things like "sci-fi gold heist extraterrestrial etc." did not reveal anything to me. I also had a hard time picking proper tags (sorry). |
I'm having trouble proving that $|A^{B×C}| = |(A^B)^C|$ , where $M^N$ is the set of all the functions $f:N \to M$. My thoughts: to prove this, I need to find a bijection between $|A^{B×C}|$ and $|(A^B)^C|$, so I need a bijection between the set of all functions $g:B×C \to A$ and the set of all functions $h: C \to A^B$. | One of the basic (and frequently used) properties of cardinal exponentiation is that $(a^b)^c=a^{bc}$. What is the proof of this fact? As Arturo pointed out in his comment, in computer science this is called . |
I need to know the real space a directory is using in Windows. By real space I mean the number of bytes that will be freed up if I remove the directory with the Windows explorer. In other words: Directory links cannot be counted Files hardlinked outside the directory () cannot be counted Files hardlinked inside the directory () but not outside must be counted once only This is different to this because there are two different kinds of hardlinks in a directory: files hardlinked to a file outside the directory (or subdirectories) also called unsaturated hardlinks, and files hardlinked to files inside the directory (or subdirectories) also called saturated hardlinks. Tools like or count only one instance of saturated hardlinks and every instance of unsaturated hardlinks. But if I remove the directory every unsaturated hardlinks will still be in the partition and won't free up space. That's the reason for not counting unsaturated hardlinks to know the real space the directory is using. | On a Win7 NTFS volume, I'm using cwrsync which supports --link-dest correctly to create "snapshot" type backups. So I have: z:\backups\2010-11-28\cygdrive\c\Users\... z:\backups\2010-12-02\cygdrive\c\Users\... The content of 2010-12-02 is mostly hardlinks back to files in the 2010-11-28 directory, but there are a few new or changed files only in 2010-12-02. On linux, the 'du' utility will tell me the actual size taken by each incremental snapshot. On Windows, explorer and du under cygwin are both fooled by hardlinks and shows 2010-12-02 taking up a little more space than 2010-11-28. Is there a Windows utility that will show the correct space acutally used? |
I just got a TP-Link Archer T2U Plus. I couldn't get it working on Ubuntu 19.10. with Kernel 5.3.0-24-generic. my lsusb: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 004: ID 0bda:5621 Realtek Semiconductor Corp. HD WebCam Bus 001 Device 003: ID 8087:0aa7 Intel Corp. Bus 001 Device 002: ID 0581:0105 Racal Data Group Bus 001 Device 005: ID 2357:0120 TP-Link 802.11ac WLAN Adapter Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub As you can see it is listed, however I cannot use it to connect to a network. Is there any official or unofficial driver which I can use for Linux (not just Ubuntu but Raspbian as well)? I would really appreciate your input. | On Ubuntu 19.04 I had current rtl8812au (AC1200) and rtl8814au (AC1750) dkms drivers for my USB wireless dongles installed and running fine. They both broke after I upgraded to Ubuntu 19.10. I've been able to find a replacement/newer rtl8812au driver that works with kernel 5.3 on Ubuntu 19.10. I haven't been able to find a replacement/newer rtl8814au driver that works with kernel 5.3 on Ubuntu 19.10. Github.com has a number of rtl8814au drivers available, even some that proport to compile with kernel 5.2. I believe that I've tried about 6 different rtl8814au drivers from github, but none of them work, even though some of them do compile with kernel 5.3. Does anybody know of a working rtl8814au driver that works with kernel 5.3 on Ubuntu 19.10? |
I've recently noticed (within the last few weeks or so) that when I view certain users' network profiles and click on the 'Accounts' tab, some of their accounts are highlighted with a grey background: There doesn't seem to be any pattern behind which accounts are highlighted in this manner, but I'm assuming there must be one. What do these grey backgrounds signify? | Can I hide my accounts that I already participate in, for a specific site? For example, I'm in one where I don't want to make my accounts visible for others: Or is this not possible? |
Can someone let me know whether IJCA () is a valid open access journal to publish our research work? BR, Tharindu from Sri Lanka | A colleague and I recently submitted a paper to a journal with an impressive-sounding name, the "International Journal of Artificial Intelligence and Computational Research". According to , IJAICR is a referred [sic] journal in the field of computer science, artificial intelligence and soft computing methods. It was accepted two days after we submitted it. That's too fast. We were suspicious. Although the journal said that all papers are peer-reviewed, we could not see how that was done in two days. Plus, we received no comments from the reviewers. Also, the submission guidelines didn't ask for a "blind" copy (without our names or any references to who we were). But wait, there's more. The acceptance letter asked us to send them US$300 to publish it. We did not. We've withdrawn our submission and will submit a new version of the paper to a more reputable journal in the coming months. How might we make a better choice of respectable journals before we submit next time? |
I am using a model class Model_userDetails to parse data from the server and save in it . public class Model_userDetails { public String name; public String email; public String mobile; } Now i want yo use this model class to display its data on my fragment . I am using this syntax t_email.setText(model_userDetails.email.toString()); in my fragment but the app crashes and gives null pointer exception What should i do ? I have used log so that i can see whats happening JSONArray message = jsonObject.getJSONArray("data"); boolean success = false; for (int i = 0; i < message.length(); i++) { JSONObject temp = message.getJSONObject(i); if (i == 0) { if (temp.getString("success").equals("1")) { success = true; } } if (i != 0 && success) { Model_userDetails modalIUserDetails = new Model_userDetails(); modalIUserDetails.email = temp.getString("email"); Log.e("ABCdata",temp.getString("email")); Log.e("ABCdata",temp.getString("name")); modalIUserDetails.name = temp.getString("name"); modalIUserDetails.mobile = temp.getString("mobile"); modalIUserDetails.state = temp.getString("state"); modalIUserDetails.district = temp.getString("district"); modalIUserDetails.block = temp.getString("block"); modalIUserDetails.village = temp.getString("village"); modalIUserDetails.designation = temp.getString("designation"); Log.e("ABC1","adding"); arrayList.add(modalIUserDetails); Log.e("ABC1",modalIUserDetails.email); } } Log.e("ABC1","returning"); return ; 02-28 16:18:27.892 20959-20959/katheria.vhp E/ABC1: [email protected] 02-28 16:18:27.892 20959-20959/katheria.vhp E/ABC2: [email protected] 02-28 16:18:27.893 20959-20959/katheria.vhp E/ABC: endpoints 02-28 16:18:27.894 20959-20959/katheria.vhp E/ABClast: [email protected] 02-28 16:18:30.532 20959-20959/katheria.vhp E/ABC1: data parser 02-28 16:18:30.532 20959-20959/katheria.vhp E/ABCdata: [email protected] 02-28 16:18:30.532 20959-20959/katheria.vhp E/ABCdata: Shekhar Singh 02-28 16:18:30.532 20959-20959/katheria.vhp E/ABC1: adding 02-28 16:18:30.532 20959-20959/katheria.vhp E/ABC1: [email protected] 02-28 16:18:30.533 20959-20959/katheria.vhp E/ABC1: returning 02-28 16:18:30.533 20959-20959/katheria.vhp E/ABC1: returned | 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? |
Given the following integral $$ \int_{0}^{1102}\lfloor \sqrt x \rfloor dx $$ What are the ways available to compute this integral? I've tried plugging it into the integral calculator on desmos.com and it gives an answer of 23825 However, when I tried manually expanding this equation, i,e $$ \int_{0}^{1102}\lfloor \sqrt x \rfloor dx =\\= \int_{1^2}^{2^2} 1 \space\ dx + \int_{2^2}^{3^2} 2 \space\ dx + \int_{3^2}^{4^2} 3 \space\ dx \space +...+ \int_{32^2}^{33^2} 32 \space\ dx + \int_{33^2}^{1102} 33 \space\ dx $$ I get a value of $23837$. Is there something extra I'm accounting for in my expansion and calculation? | I want to find a general formula to calculate the integral of such function (x>0) Could someone kindly help me? $$\int_0^{1102} \lfloor{x^{1/2}}\rfloor \mathrm{d}x$$ Thank you! |
I would like to know the difference between: She does love me and She loves me. | This morning I read this sentence (see ): On July 24th and again on July 29th, Egyptian police did shoot dead unarmed African migrants attempting to cross that border. Why "did shoot" and not "shot"? |
I just spent six months in the UK as a student on a passport stamp. Since my parents live in the UK (on a Tier 2 Work visa and a Spouse visa), I would like to return to the UK to see them for a couple of weeks. However, I just left the UK in January. It's March now. How soon can I go back? I really miss them. Is it possible to return since I'll be going back on a different kind of passport stamp? Thanks! | I am a US citizen and have recently visted the UK with simply a passport which allowed me to vist for 6months I have heard rumors that I am obligated to stay in the US for a Equal amount of time that I have visited the UK before I am able to return, but I am struggling tour no any proof of this obligation .. Am I missing somthing or is it simply not true |
I’ve been working as a designer for a while. I work on print and digital assets. I work in-house especially involving materials for events, such as posters, flyers and social media post graphics. My problem is when designing a concept from scratch I am slow. I get caught in the layout phase and go round and round until I come up with something I think works. This can take days sometimes. At the beginning of the project I look for inspiration, make sketches and then start work laying out. Then I get into a cycle of beginning to layout and struggling with getting the layout/colors right. I often abort the idea go back to the drawing board and sketch out something else, only to repeat this several times before I land on something good. Or alternatively I end up spending a whole heap of time on one idea and not getting a finished layout I like. I get frustrated with myself and I know it takes longer than needed. Any thoughts on how I can learn another way to work through this? ETA The kind of work is mainly for events, posters, flyers and social media graphics to advertise events. Typical age range for events is 18-25 year old. Events are either educational or entertainment. My role is to design from scratch. I get under a day to get creative draft done, which is 2-3 concepts to send to approved. They expect finished designs and that’s how the other few designers in my team work. | I've been a designer for 6 months, having previously had a 1st class honours degree in Graphic Communication. My issue is that I am a Very good designer, but I work too slow. It's beginning to drive a rift between myself and the creative director who desperately wants me to work quicker. I've always been a workaholic even in university, I put in 110% all the time, really work my ass off, but I'm still not fast enough to complete projects quickly, my work is good, but it's not efficient. Do you guys have any tips to help me speed up? |
I am going through the process of changing all my passwords using KeePass2, using 256bit encryption, with keyfile held on microSD. In test I cannot seem to get my autotype to work. I created a shortcut in the keyboard manager Name: KeePass Auto-Type path: mono /usr/lib/keepass2/KeePass.exe --auto-type according to installed xdotool as needed. I try to place auto-type password into browser my KeePass2 entry has the title "Google" username now when I hit the key to autotype it types a portion of the 64 characters an estimated 16 then attempts to sign in? Chromium v28.0.1500.71 : Ubuntu 13.04 | I'm trying to integrate KeePass and Chrome/Chromium after installing ChromIPass when I try to connect to KeePass, It gives the following error: ChromeIPass has been disconnected from KeePassHttp. Association was unsuccessful Press the reconnect button to establish a new connection. How can I connect ChromeIPass with KeePass? |
I do not care to gain access to any database data, I simply want to reset the root password for the MySQL server on an ubuntu 14.04 LTS vm that I am using for development and testing. Several places I have read that dpkg-reconfigure will prompt for a new MySQL root password, but it does not. Nor does uninstalling and reinstalling mysql-server. I tried uninstalling and zapping the configuration folder /etc/mysql, and that also had no effect. It must have prompted me when I ran the installer and now I've forgotten what I entered. | In the past there has been sudo /etc/init.d/mysql reset-password, (1) is manually restarting and setting the password with an sql command again required? (2) (1) (2) |
I am trying to play Dota2 and FT2 on my pc when I got this error: "Could not find OpenGL entry point 'GLGetError'! Either your video card is unsupported or it needs to be updated." I have spent the last week reading all of the similar questions and have tried some of them (many solutions were to advanced for me to try so I stayed away from them) and I do not know what else to do. If there is any other information needed just ask. I am using: Ubuntu 14.04 32 bit GLX version is 1.4 OpenGL version string: 1.4 Mesa 10.1.3 00:02.0 VGA compatible controller: Intel Corporation 82G33/G31 Express Integrated Graphics Controller (rev 10) (prog-if 00 [VGA controller]) - libgl1-mesa-glx:<br> Installed: 10.1.3-0ubuntu0.1<br> Candidate: 10.1.3-0ubuntu0.1<br> Version table:<br> *** 10.1.3-0ubuntu0.1 0<br> 500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main i386 Packages<br> 100 /var/lib/dpkg/status<br> 10.1.0-4ubuntu5 0<br> 500 http://us.archive.ubuntu.com/ubuntu/ trusty/main i386 Packages | Just recently upgraded to 13.04 and am having trouble running TF2 via Steam. Whenever I start Steam I get a dialog saying: OpenGL GLX context is not using direct rendering, which may cause performance problems. Every time I go to launch TF2 I get a dialog saying: Could not find required OpenGL entry pint 'glGetError'! Either your video card is unsupported, or your OpenGL driver needs to be updated. I tried updating my Nvidia drivers, hoping that would solve this issue but alas, it did not. I believe this issue is related to a fix I used to get Skype working with 13.04, specifically . Just a heads up I'm using GNOME Shell 3.8. Let me know if you need anymore information about my system. |
I'm not quite sure the benefits of working over a prime modulus in Shamir's secret share- but doesn't limiting the numbers you pull from make the secret easier to guess? Instead of being over the real numbers, with infinite elements, limiting yourself to some prime limits the possibilities-albeit that number can get very large. Isn't this bad? What benefits are there to working over a prime that justify this choice? | I read ampersand's question , where he asked why Shamir's Secret Sharing Scheme uses arithmetic in a finite field of prime order. The answers to that question explain that a prime field is not necessary for Shamir's scheme, but, rather, that any finite field can be used. However, they don't really address the other part of the question, namely why do we need a finite field at all? Couldn't we just use, say, ordinary integer arithmetic instead? Can someone please explain (in the simplest possible manner) the reason that Shamir's Secret Sharing Scheme uses finite field arithmetic? |
I want the div #container to be in the center of the page. Like horizontally and vertically. I tried to make position: absolute; top: 50%; bottom: 50%; left: 50%; right: 50% but it didn't work. And it has to be like in the center of the page no matter the size of the display. Thank you in advance! Heres my code: @import url('https://fonts.googleapis.com/css?family=Catamaran:100,200,300,400,500,600,700,800,900|Droid+Sans:400,700|Josefin+Sans:100,100i,300,300i,400,400i,600,600i,700,700i|Open+Sans:300,300i,400,400i,600,600i,700,700i,800,800i|Oxygen:300,400,700|Roboto:100,100i,300,300i,400,400i,500,500i,700,700i,900,900i|Ubuntu:300,300i,400,400i,500,500i,700,700i'); #container { width: 30em; background-color: #eee; height: 30em; border-radius: 50%; position: absolute; top: 50%; left: 50%; } #wrapper { width: 30rem; height: 30rem; border-radius: 50%; } <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <header> <div id="main-head"> <a href="#"><h2 id="main-heading">sKoolBook</h2></a> </div> </header> <section> <div id="container"> <div id="wrapper"> <script type="text/javascript"> var dataCap = document.getElementById("chooseSchool").value; document.write(dataCap); </script> <form method="POST" id="chooseSchool"> </form> </div> </div> </section> <footer> </footer> <p id="demo"></p> | I want to center a div vertically with CSS. I don't want tables or JavaScript, but only pure CSS. I found some solutions, but all of them are missing Internet Explorer 6 support. <body> <div>Div to be aligned vertically</div> </body> How can I center a div vertically in all major browsers, including Internet Explorer 6? |
i create 2 custom user register form mode : When i go to mysite/user/register Drupal show me the last form mode i create : S'inscrire But when i go in the admin mode, for add a user, it show me the same form. i try to display "Affichage Admin" form mode with more field. So i try to alter the form mode programmatically. Any idea how can i change form mode before it render ? | I created a new_form_mode for a content type in D8 and removed some fields in that form mode from Manage form display tab of the content type by selecting that new_form_mode . But how can i select that form should be displayed for that content type instead of default form mode? |
An example of an internal force is the tension in the spring of a harmonic oscillator. An example of an external force is the gravity on a pendulum. Are there any forces that are both internal and external? Are the fields generated by a force field internal, external, or (if they exist) internal-external? EDIT: My question is different from the "suggested" post because I'm asking for whether there exists a third category, while the suggested post is asking for an explanation of the difference between internal and external forces. | When a person lifts a book while standing on the earth's surface. Why is his force considered external to the book-earth system? Isn't his force internal like the case of the forces that cause the exploson of a bomb. I think the forces the person exerts on both the book and the earth are internal since they are equal but opposite therefore resulting in the position of the centre of mass of the system being maintained and if i'm right is the mechanical energy of the system constant? Am i wrong? Please correct me. |
Which form is correct: My hair grow slowly or My hair grows slowly | My hair is short so I'm growing them for my wedding Is it grammatically correct to use "them" with hair? |
What happens behind the scene when a string in double quotes is passed as an argument to a function? Where is memory allocated for that string? If I do memcpy(ptr, "SINGH", strlen("SINGH")+1);, output is SINGH only. From where is the extra byte copied from? For below program: void func(char *ptr) { memcpy(ptr, "SINGH", strlen("SINGH")); cout << ptr << endl; /* Output is SINGHHELLO */ /* If I do memcpy(ptr, "SINGH", strlen("SINGH")+1); Output is SINGH only. From where does extra byte is copied from? */ } int main() { char str[11] = "HELLOHELLO"; char str2[10] = "ABC"; memcpy(str, "HELLO", strlen("HELLO")); /* Where is memory allocated for string 'HELLO' ? */ cout << str << endl << str2 << endl; func(str); return 0; } | Is a string literal in c++ created in static memory and destroyed only when the program exits? |
My data is 2 point-layers: 1 layer origins and 1 layer destinations. I connected these pairs of origins and destinations: firts with lines. As I know that in qgis, there is still no gradient fill for lines, I did a very small buffer on mi lines. And now, I have polygons, wich represent my flows, and I would like to represent them with a gradient fill wich show the direction of each flow (it means: from the origin point to the destination one). I have an idea but I don't achieve to go further. Do you know how to use options of the gradients filling? I have the idea to use the two Reference Points to represent the orientation of the flow (from origin to destination). I would like to use 4 table: - abscissa of my origin points (as x of reference point 1) - ordinate of my origin points (as y of reference point 1) - abscissa of my destination points (as x of reference point 2) - ordinate of my destination points (as y of reference point 1) But it doesn't work. | I have a series of LineStringM geometries. The measure value represents slope (or stream gradient) at each point in the geometry. I love QGIS's robust styling options, but I can't find a way to render each measure value along my linestrings. Ideally, I would have blue for slow gradients, and red for very steep gradients. To help understand what I'm trying to accomplish, let's suppose we've used Linear Referencing to encode the length of the LinestringM thus far into each point's measure value. At the top, you would have 1.0 and at the bottom, you would have 0.0. I've added an image what what I'm hoping to accomplish below. I made this in Paint.NET, so it's just a mock-up. How would you go about accomplishing this in QGIS? |
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