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I was working on a project which was committed on GitHub. I made some changes and tried to commit it to the repo, But I got the error saying Your branch is ahead of 'origin/main' by 3 commits. So I tried to go back to the branch origin/main and I did git reset --hard origin/master Now I was on the main branch. So I pushed the code on Github. Code got pushed but it was not reflected in the repo. And When I came back to the editor all the changes I made on Local machine were gone it is not there. I need my changes made codes back on my local machine. Please Help! | Is it possible to undo the changes caused by the following command? If so, how? git reset --hard HEAD~1 |
One of the premises of the classic sci-fi show Farscape is that a person could travel through black holes, I'm curious as to what exactly would happen to a person body if you were to enter a black hole and how far out the premise of traveling through black holes really is? | I've heard many scientists, when giving interviews and the like, state that if one were falling into a black hole massive enough that the tidal forces at the event horizon weren't too extreme, that you wouldn't "notice" or "feel" anything, and so forth. Thinking about this for a few minutes, it seems to be quite wrong. If you're falling feet first for example, as your feet cross the horizon, your brain can no longer receive any information from them, as the information would have to travel faster than light. Once you are entirely within the horizon, no part of your body closer to the singularity can send any sort of signal to any part of your body that is further away, for the same reason. Even bloodflow would stop, as blood that is pumped downward towards your feet could never be pumped back up again. In other words, inside the event horizon is a series of even more event horizons, like the layers of an onion, infinitely thin. Am I missing something important? |
#!/bin/bash filename=../deleted/$1 #Testing condition before deletion of file if [ "$1" = "" ] ; then echo "No filename provided" elif [ -f "../deleted/$1" ] ; then echo "File doesnot exist" str=$(fgrep "$1" ../.restore.info | cut -d ":" -f2) path=${str%/*} mv "../deleted/$1" "${path}" newname=$(fgrep "$1" ../.restore.info | cut -d "_" -f1) mv -i "$1" "${newname}" else echo "file does not exist" fi ---------- ( I have written script to move file from the deleted folder to its original path and its working fine. But now i have to check if there is already a file with same name then it should give alert user "do u want to overwrite " if yes then overwrite if no or anything else then do not restore) | I want to pause input in a shell script, and prompt the user for choices. The standard Yes, No, or Cancel type question. How do I accomplish this in a typical bash prompt? |
There is a very cool foam effect rising on the shore in this low poly water asset made in Unity: And here: Is it possible to create a similar effect in Blender? I have the water material down, I just want a cool foam effect! | so I'm trying to recreate this effect and I've gotten as far as having the white area around a rock, but I've been struggling with animating the area where the brush touches the canvas. Eris gives a few notes on how he did it, but I haven't been able to follow them. Does anyone have a more detailed step on how to use noise texture to only affect the Brush area of effect? Thank you |
I just discovered that a python exception can be indexed directly very similarly to a Sequence type object, like so: >>> e = Exception('msg') >>> print e[0] msg >>> e = Exception(1,2,3) >>> x,y,z = e It looks like BaseException contains methods for example __getitem__ and __getslice__ that implement this syntax. However, what surprise me is that I can not find any relevant description about this behavior in the documentations I can think of looking into, e.g., related sections of and . Is this a documented syntax and where is it documented? | I have been bitten by something unexpected recently. I wanted to make something like that: try : thing.merge(iterable) # this is an iterable so I add it to the list except TypeError : thing.append(iterable) # this is not iterable, so I add it Well, It was working fine until I passed an object inheriting from Exception which was supposed to be added. Unfortunetly, an Exception is iterable. The following code does not raise any TypeError: for x in Exception() : print 1 Does anybody know why? |
I know there's a ton of questions about this topic but I'm not being able to find the right answer. I have GNOME Version 3.22.2 running on a Debian GNU/Linux 9 (stretch) 64-bit. The problem: I'm trying to set up a shared folder (say thefolder) such that multiple users of a group (say thegroup) on the same machine can work on it. To do that I changed the ownership of the folder to thegroup and set the setgid bit of the folder. $ ls -l drwxrwsr-x 6 me thegroup 4096 Oct 1 20:29 thefolder The only problem now is that the default umask in Debian is 0022 and this prevents other users to write on any subfolders or files that I create on thefolder. What I've done so far: My first (naive) try was to set the umask in one of the shell configuration files. I added the line umask 0002 in all of the files /etc/profile, /etc/bash.bashrc, ~/.profile and ~/.bashrc (each one at a time obviously) until I realized that this worked only for the shell (GNOME Terminal and TTYs) but not for other applications like Files or Gedit. I then deleted all these lines and tried something else. I added the line session optional pam_umask.so usergroups at the end of the file /etc/pam.d/common-session and restarted the computer. It is worth noting at this point that the options UMASK 022 and USERGROUPS_ENAB yes are both enabled in the /etc/login.defs file. Having done that I noticed that the umask was correctly set as 0002 for TTYs but not for the GNOME session (the GNOME Terminal and all other programs accessed through the graphical interface still worked with a 0022 umask) After that I tried to set the umask in the Xsession script of the GNOME Display Manager. I wrote the line umask 0002 at the begining of the file /etc/gdm3/Xsession but the problem persisted. I made a little experiment and wrote instead the following line echo "umask: $(umask)" > $HOME/Desktop/debug and after log out and log in again the debug file contained the line umask: 0002 which means that at that point the umask was still correct and that it is overwritten somewhere else after the Xsession script. The question Can someone explain to me where is the umask for the GNOME session defined and how can I change it? | Using Gnome 3.18. I share files between other family members, but the default umask on my distro (archlinux) is 0022. So every file/directory created is not writable for our common group. I tried to put umask 0002 in /etc/profile but the gnome session is still using 0022. It's working for a login bash shell, though. I also tried to add this line in /etc/pam.d/system-auth: session required pam_umask.so umask=0002 It has the same effect as the one in /etc/profile. I tried If I change the umask manually in a gnome-terminal shell, then I launch an application from it, say gedit, then the files created by it have the wanted permissions. If I launch gedit from the gnome menus, it doesn't. So my matter is really to set the umask for the gnome session, and I can't find where to do it. EDIT (to answer Gilles' comment): I'm using gdm 3.18 as the DM. I also tried to add the pam_umask line into /etc/pam.d/gdm-launch-environment. All other gdm-* files contains includes of session from the system-auth file, so they should not need more. It doesn't change anything. /etc/login.defs contains UMASK 077 but also USERGROUPS_ENAB yes which should set the umask to either 0077 or 0007 for users whose primary group is the username. The only file that contains 022 for umask in /etc is /etc/profile but that was my first try. As for /etc/Xsession.d, I don't have this directory. Besides, as wayland is now the default display server, I'm not sure the umask should be set as part of X initialisation, even if I'm still using it myself. |
I'm in a class where we are creating a ray tracer from the ground up in C++. I'm at a point where I can't seem to wrap my head around the math that is required to calculate the point at which a ray intersects a polygon. We have some direction for how to do this, but all of the class materials as well as my Googling of the subject have not helped. These are the functions we must complete: bool polygon::Intersect(const ray &R, intersection &inter) { // To Do: If you have implemented the "CalculateNormal" method // below, should already be calculated and placed in the member // "n". // // Now, using n, you need to calculate the intersection of the // ray with the plane containing the polygon. Then, once you // have that point, you need to loop through each edge in the // polygon and make sure the point is to the left of that edge. // // If it is to the left of every edge, then fill the structure // inter with all of the data for the intersection and return // true, if not, return 0. // // Don't forget to check to see if the t you calculate for the // ray is > 0. return false; } void polygon::CalculateNormal(void) { // To Do: Use the edges of the polygon to calculate the normal // of the polygon. You should be careful to take care of the // case where two edges give you a zero normal. Place the // normal into the member "n" so that the intersection method // can use it when called. // } Could someone please explain this in a bit further detail? Note: I am not asking for anyone to write the code or do my homework for me, but instead help me understand what exactly is going on here. Thank you. | I'm developing a picking system that will use rays that intersect volumes and I'm having trouble with ray intersection versus a plane. I was able to figure out spheres fairly easily, but planes are giving me trouble. I've tried to understand various sources and get hung up on some of the variables used within their explanations. Here is a snippet of my code: bool Picking() { D3DXVECTOR3 vec; D3DXVECTOR3 vRayDir; D3DXVECTOR3 vRayOrig; D3DXVECTOR3 vROO, vROD; // vect ray obj orig, vec ray obj dir D3DXMATRIX m; D3DXMATRIX mInverse; D3DXMATRIX worldMat; // Obtain project matrix D3DXMATRIX pMatProj = CDirectXRenderer::GetInstance()->Director()->Proj(); // Obtain mouse position D3DXVECTOR3 pos = CGUIManager::GetInstance()->GUIObjectList.front().pos; // Get window width & height float w = CDirectXRenderer::GetInstance()->GetWidth(); float h = CDirectXRenderer::GetInstance()->GetHeight(); // Transform vector from screen to 3D space vec.x = (((2.0f * pos.x) / w) - 1.0f) / pMatProj._11; vec.y = -(((2.0f * pos.y) / h) - 1.0f) / pMatProj._22; vec.z = 1.0f; // Create a view inverse matrix D3DXMatrixInverse(&m, NULL, &CDirectXRenderer::GetInstance()->Director()->View()); // Determine our ray's direction vRayDir.x = vec.x * m._11 + vec.y * m._21 + vec.z * m._31; vRayDir.y = vec.x * m._12 + vec.y * m._22 + vec.z * m._32; vRayDir.z = vec.x * m._13 + vec.y * m._23 + vec.z * m._33; // Determine our ray's origin vRayOrig.x = m._41; vRayOrig.y = m._42; vRayOrig.z = m._43; D3DXMatrixIdentity(&worldMat); //worldMat = aliveActors[0]->GetTrans(); D3DXMatrixInverse(&mInverse, NULL, &worldMat); D3DXVec3TransformCoord(&vROO, &vRayOrig, &mInverse); D3DXVec3TransformNormal(&vROD, &vRayDir, &mInverse); D3DXVec3Normalize(&vROD, &vROD); When using this code I'm able to detect a ray intersection via a sphere, but I have questions when determining an intersection via a plane. First off should I be using my vRayOrig & vRayDir variables for the plane intersection tests or should I be using the new vectors that are created for use in object space? When looking at a site like this for example: I'm curious as to what D is in the equation AX + BY + CZ + D = 0 and how does it factor in to determining a plane intersection? Any help will be appreciated, thanks. |
I'm stuck on a astriod and there is no oxygen so I die really fast I can't mine fast enough help.I've tried coal but I don't have enough. | I'm stuck on a planet with no wood trees and no resources that are easy to exploit, and I want to get off of it as quickly as possible. What do I need to do to get my spaceship enough fuel to go to another planet? |
Please. I need a new screen recorder so I can record my emulated games. (PS1, SNES) Please suggest me ones that are simple and require no hard to understand sudo code. | How can I record my screen on Ubuntu? The app I'm looking for has ideally all of these features: Can record in a format that can be played back easily on any platform and/or accepted by YouTube or another popular video site Can record just a window (instead of the whole screen), possibly selecting it with a mouse click Can start recording after a configurable delay (e.g., I launch the app and have time to do arrangements to my desktop/window before actual recording starts) |
Just got a new iPAD air 2, iOS 9.1. It says I should update it to iOS 9.3.1. I might be interested to jailbreak it later on, so I'd like to preserve that option for me possible. I hear jailbreak for 9.3.1 is not available yet, and on the other hand, apple stopped signing iOS 9.1 and it is impossible to install or downgrade to iOS 9.1. I want to know how I can back up the current state with iOS 9.1, and later after I updated the iOS, when ever I wanted I could restore to the iOS 9.1. I know that I should backup shsh blobs using Tiny Umbrella. but I cannot find the official download file in their website. Also I don't know how to backup APTicket. Thanks | I'm trying to downgrade my iPhone from the current iOS to an older one, as per . But every time I try, I always receive this error: The iPhone could not be restored. This device isn't eligible for the requested build. I have tried many times with and without DFU mode. Any ideas regarding this? |
What is the best texturing / materials course you've ever seen? (photo realistic, not stylized and of course using nodes, not actual photoscanned textures). I've seen a few but I feel like I'm still missing a good approach when trying to recreate a material from a photo reference. Paid / not paid - doesn't matter as long as the author is able to get actually photoreal results. | Since asking for tutorials, videos, resources, links to other content or downloads is considered off topic here, this is a specifically created Community Wiki which gathers resources for Blender and it has been approved by the . Just write in the appropriate answer/section. If you have concerns, questions, post a question, so we don't clutter the comments, but you can link your meta question from the comments. Questions regarding such resources are not allowed anymore, except for very specific and on topic requests (ask on if you're unsure about your question). Follow the instructions made in the question about how to post, what can be posted, etc. Learning Assets (also see: ) Reference Images/Blueprints (also see: ) Tools (also see: ) Other Special Interest () Also see the . |
I would like to install OpenOffice because I like it better than LibreOffice. However, my dependencies are not satisfied for the writer module. Apparently OpenOffice-EN-US is a dependency of itself. I have provided a screenshot in the hopes that someone can tell me what packages I need to install (Preferably not all of them). | As a new Ubuntu user, I have installed a few apps through the Terminal. I have tried to follow several, albeit outdated, threads that explain how to install OpenOffice, but I cannot get it to work. It would be really helpful if someone would provide me with the necessary commands for it to work. |
I want to know the formula for the below if 40% of A1 is less than 15000 then A2 =15000 else A2 should be equal to 40% of A1. What i want is A2 should not be less than 15000. Thanks much in advance!! | IF(B4-40<0,0,(B4-40)) Above is my formula to show only positive numbers above 40 in the given cell. If my hours are, let's say, 35, I do not want a value of -5; I want the cell value to be 0. Why is this not working? |
If I throw two objects with the exact same shape and size, but one of them is heavier, will they arrive at the same time? We learn in basic Newtonian physics that mass doesn't influence the speed in which an object fall in vacuum. But if there is air is that still true? My hypothesis is that the more massive an object is, the faster it will fall through air because then the mass of the air particles become proportionally irrelevant. Am I correct? | We all know that in an idealised world all objects accelerate at the same rate when dropped regardless of their mass. We also know that in reality (or more accurately, in air) a lead feather falls much faster than a duck's feather with exactly the same dimensions/structure etc. A loose explanation is that the increased mass of the lead feather somehow defeats the air resistance more effectively than the duck's feather. Is there a more formal mathematical explanation for why one falls faster than the other? |
Sometimes you are faced with problems that you can not understand . Now I have a hidden column inside my Issue tracking list, which is used to store a series of string to be read by the list workflow. now i set a defualt value for the column such as "ABC", and i set it as a hidden field, so user will not be able to modify its value or see it. but the problem is that if admin users chnage the defualt value of the hidden field from the "List Option>> List Setting >> Columns >> click on the hidden column", then its type inside the content type will be changed from hidden to optional and the field will appear inside the New and edit forms ,, so can any one adivce on this please? is there a way to prevent the hidden column from being set as optional when its defualt value is changed ? Thanks | Sometimes you are faced with problems that you can not understand. Now I have a hidden column inside my Issue tracking list, which is used to store a series of string to be read by the list workflow. Now I set a default value for the column such as "ABC", and I set it as a hidden field, so user will not be able to modify its value or see it. But the problem is that if admin users change the default value of the hidden field from the "List Option>> List Setting >> Columns >> click on the hidden column", then its type inside the content type will be changed from hidden to optional and the field will appear inside the New and edit forms, so can any one advice on this please? Is there a way to prevent the hidden column from being set as optional when its default value is changed ? I have the following problem inside my team site: I set a site column as hidden from the list content type. then I modify the column at the list level, where I changed its default value. then after that the column will be set as optional instead of hidden at the list content type. So can anyone advice on this ? How can I remove this behavior ? |
I am writing a paper using IEEEbib.bst. I remark that references are changed in lowercase. \documentclass{article} \usepackage{spconf,amsmath,graphicx,array} \usepackage{multicol} \usepackage{xcolor} \usepackage{pgf, tikz} \newcommand{\argmax}{\arg\!\max} \newcommand{\subfigANDtitle}[2][.2\linewidth]{% \begin{tabular}{@{}>{\centering\arraybackslash}p{#1}@{}} #2 \end{tabular}} % % % % % % % % % % % % \usepackage{tikz} \usetikzlibrary{shapes,arrows} % % % % % % % % % % % % % Example definitions. % -------------------- \def\x{{\mathbf x}} \def\L{{\cal L}} % Title. % ------ \title{xxxxyyyyyyyzzzzzzz.} % % Single address. % --------------- \name{xx,yy} \address{xxxxxx,yyyyyy} \begin{document} \maketitle \section{section1} adaafasfaa \cite{4761608} \clearpage \bibliographystyle{IEEEbib} \bibliography{exbib} \end{document} | Titles of articles I'm about to cite contain upper case letters and when using BibTeX it converts them to lower case ones. This happens only in the title and only the first letter conserves its case. For example, when I cite an article about HF, the reader won't know if it is about Hafnium (Hf) or fluorine acid (HF). I know that I can fix it manually in the .bbl file but I would like to avoid it, or fix it automatically. |
Why is the main stackexchange.com site still using the old style top-bar? It seems odd for that particular page not to match everything else at this point. BAD: GOOD: | , and 1 still show the old bar. 1 See |
Let $ \mathbb N _ 0 $ denote the non-negative integers. Find all functions $ f : \mathbb N _ 0 \to \mathbb N _ 0 $ such that $$ x f ( y ) + y f ( x ) = ( x + y ) f \left( x ^ 2 + y ^ 2 \right) \quad \forall \, x, y \in \mathbb N _ 0 $$ I got that $ f ( x ) = f \left( 2 x ^ 2 \right) $ for non zero $ x $ by setting $ x = y $. Does this show $ f $ is always constant, since the constant case does work by plugging in? | The question below is from the 2002 Canada National Olympiad. I have found one family of functions but need help in finding (or proving the non-existence) of others. Suggestions on how to improve the solution method (especially rigour of arguments) would also be appreciated. Let $\mathbb{N} = {0,1,2,\dots}$. Determine all functions $f : \mathbb{N} \rightarrow \mathbb{N}$ such that $xf(y) + yf(x) = (x + y)f(x^2 + y^2) \tag{1}$ for all $x,y \in \mathbb{N}$. Expressing $f$ as a power series: $f(t) = a_0 + \displaystyle{\sum\limits_{k=1}^{\infty}{a_k x^k}} \tag{2}$ Assuming the power series is convergent, the general coefficient, $a_n$, is the same on both sides of equation (1). [I am not sure of this step]. So for $a_0$ $x(a_0) + y(a_0)=(x+y)(a_0)$ which is satisfied for all values of $a_0$. Hence $\boxed{f(t)=a_0,\:a_0\in\mathbb{N}}$ is a solution. For any $n > 0$, we have $\begin{align} x a_n y^n + y a_n x^n &= (x+y)a_n(x^2+y^2)^n \iff \\ a_n(xy^n+yx^n) &= a_n(x+y)(x^2+y^2)^n \end{align}$ and if this is true for fixed $n>0$ and all $x,y\ge0$ then $a_n=0$. So I am unable to find any other functions. |
I have been introduced, in class, to Newton's proof of the gravitational law. I was studying it, and one passage in the way it was presented did not convince me. So, I tried , where I found this picture, which is more or less the same picture I drew with GeoGebra by recomposing all the construction in the lesson notes: The curve is an ellipse (the trajectory of the orbiting body), $P$ is where the body is, $A$ and $B$ are endpoints of the axes, $S,H$ are the foci, $C$ the center, $Qx$ is parallel to the tangent $PR$, $PF$ is orthogonal to $DK$, $DK$ is the diameter parallel to $PR$, $PG$ the one through $P$, $HI$ is parallel to the tangent line, $QT$ is orthogonal to $PS$, and $v$ is unclear to me. Referring to this figure, Wikisource's text states that $I\hat PR=H\hat PZ$. Why is that so? | How to prove geometrically that if we have a tangent of ellipse with focus F and F' in point P, that tangent is bisector of the angle between a line joining focus F to point P and the line F'P outside the ellipse? |
So I'm building a game for an event in about a month or so and I'm having different kits being given by NPCs (I'm new to event/game making so I'm doing the best I can lol if there's a better way to do this let me know), and the /clear command used to ensure inventories are cleared before giving the kit they choose when they right-click on an NPC does not clear their armor slots nor offhand, so I have compensated by doing a lot of different /clear commands for every item in the kits (ex: /npc cmd add -o minecraft:clear @s iron_axe, /npc cmd add -o minecraft:clear @s crossbow, and so on) which seems to be working so far. However, when they first right-click the NPC it spams opped users with about 15 messages of "No items were found on player [ing]." Is there a way to stop these commands from being sent when the clear command is used? When like 10 players are right-clicking these NPCs it is extremely spamm-y and I've tried a million commands and don't know if it's possible. I've also never asked a forum question before so if I messed up somewhere tell me <3 | I want to make a tellraw shop but to activate command blocks I want to use /setblock command when clicked on a text. Is it possible to disable "Block placed" text showing up? |
Sequence of events: Arthur has 7 hit points left. Arthur is hit and receives 12 damage. Arthur is becomes unconscious and is dying (0 HP.) Arthur's turn comes around, he rolls a Death Saving Throw and fails. Eleonore applies his medicine kit and stabilize Arthur. Lancelot casts an Enhance Ability spell and gives Arthur 8 temporary hit points. The Goblin hits Arthur and generate 3 hit points of damage. When the Goblin generates 3 hit points of damage, will Arthur still be stabilized? Since Arthur still has 5 temporary hit points, I would think that he did not go back to the Dying State. That being said, his HP are still 0 and the rules say: Damage at 0 Hit Points. If you take any damage while you have 0 hit points, you suffer a death saving throw failure. And at the same time, the Temporary Hit Points section says: If you have 0 hit points, receiving temporary hit points doesn’t restore you to consciousness or stabilize you. They can still absorb damage directed at you while you’re in that state, but only true healing can save you. I'm wondering whether the temporary hit points means we're not exactly at 0 HP in that specific circumstance... How do you interpret the rule on this one? | I have been thinking that temporary hit points were like virtual health as per: Temporary hit points aren’t actual hit points; they are a buffer against damage, a pool of hit points that protect you from injury. The fact that's virtual makes me think that you don't actually get hit per se. That is, you'd get out without even a scratch if you only lose temporary hit points (i.e. protect you from injury). However, I have not seen anything anywhere saying that if you are bitten by a creature such as a spider and only lose temporary hit points, you don't get poisoned. Yet, if you don't even sustain a scratch, how could you get poisoned or paralyzed or sick? How do you guys understand the rules in such circumstances? |
Disclaimer: Please read complete question before marking duplicate. I am thinking to setup a server on our college's internal network, which can host some very common apt-get packages. As there are many Ubuntu users in my college, it would save us and even other Ubuntu servers some bandwith. What I want is that I setup a server similar to those listed in the "Download From" in the software sources. If a person tries apt-get install , Ubuntu should go to my personal server, if it finds the package there, fetch from there else go to some alternate server. Is it possible? And how can I go about this? Thank You | I have multiple Ubuntu machines at home and a pretty slow internet connection, and sometimes multiple machines need to be updated at once (especially during new Ubuntu releases.) Is there a way where only one of my machines needs to download the packages, and the other machines can use the first machine to get the debs? Does it involve setting up my own local mirror? Or a proxy server? Or can it be made simpler? |
In a comment on , Cort Ammon states I have heard interesting solutions to these issues involving encrypting something with a proper tested algorithm first (not second), and then encrypting it with your home brew solution with an unrelated key. It seems legit, but I can't actually claim I've analyzed that particular configuration to see if it actually works or not. Why does order matter? What makes encrypting with AES and then re-encrypting with the Caesar Cipher better than encrypting with the Caesar Cipher and then re-encrypting with AES? | I have two encryption schemes $\Pi_0, \Pi_1$, at least one of them is IND-CPA secure but I don't know which one. The task is to construct a scheme $\Pi$ that is guaranteed to be CPA secure and to provide a proof for this. Despite reading , I still don't understand the best way to construct the scheme and how to fully prove its security. Any ideas or hints into the right direction are appreciated! |
After updating to iOS 14.2 it’s not possible to open the iPhone app anymore. The app crashes right after the start on an . Stack Exchange didn’t seem too eager updating the app in the past. But this is really more than a convenience feature. | I'm using the official Stack Exchange mobile app for iOS or Android, and My app crashed! It doesn't look good on my new smartphone. It won't run after I updated my device. I noticed another bug. I have an idea for a new feature which is currently not in the app. How do I report bugs with or request features for the iOS and Android apps? Also: I've used the built-in functionality of the app to report a bug or submit a feature request. Did I do the right thing? The app prompted me to post on Meta after an error occurred. Should I post about it here? I'm wondering why the latest version is from 2017. I've heard rumors that the apps are no longer supported; is that true? I can't find the app on my device's app store anymore! Where did it go? We get a lot of bug reports from users about the mobile apps, which are unsupported, and at the moment, there is no centralized Q&A pair for those to be closed as duplicates of (the relevant answers are spread across multiple unrelated questions). This question is an FAQ proposal, to serve as a directly-related duplicate target for those questions. |
Consider the circuit diagram below. What will happen if at some instant the inverter input is zero? | Not-gate, if get a 0(Off) input, it gives an 1 (On) output. And if get a 1 (On) input, gives-back a 0(Off) output. Now, if-I could bring the output back to the input of the not-gate, then what will happen? If the gate is getting a 1 input, it is giving a 0- output, and then if it is getting a 0 input, it is giving an 1 output. The situation sounds-like a physical-model of a "self-contradiction" (self- false) (like when fever-attacked kid-Bertrand Russel waiting to be april-fooled by his brother, taking preparation against all possible tricks, Bertrand Russel's brother made Bertrand an april-fool by doing "no-april-fool" at all; and if Bertrand's brother uses any april-fool trick, Bertrand will Not be april-fooled, and if Bertrand's brother use no april fool that means Bertrand hasbeen april-fooled by-his brother). Now, what will-be happen in case of the real hardware called a NOT gate? I ASSUME the possibilities; the gate will always remain as 0 (off)-output . the gate will always remain as 1(on)-output . The gate will be "PULSATING"; once it will 1 output; at the next-moment, after receiving that 1(on)-signal it will give-out a Zero (off) signal, and the cycle will run on and on. The frequency of this oscillation will depend on physical-characteristics of circuit component. the circuit will be get-damaged ( due to some anomalous current, overheating, etc) and soon permanently stop working. Will something happen within-these assumptions? PS. I'm thinking about this-problem from my schooldays, but since yet I do-not know, how to assemble a not-gate in a circuit, from-where they could be bought, etc; I yet could-not test it experimentally. |
I learnt in Merriam-Webster and other reliable sources that advice differs from advise. Advice is a noun while advise is a verb. Same goes with the words device and devise. However, the word practice does not differ from practise as stated by the Merriam-Webster Dictionary. Is it true? Or the rule is still the same like on the words advice and advise? Here are some examples the Webster Dict. used: You need to practice what you preach.- It is a verb because it entails that you need to apply or carry out what you have been preached. Being a good musician takes a lot of practice- It is used as a noun because it entails a systematic exercise for proficiency in music. | I am having trouble working out whether the following two uses of practice should be the verb (-ise) or the noun (-ice). Can anybody please help clarify? Every single member of our staff practices/practises discipline A practiced/practised workforce I am interested in an answer based on UK English. |
I have a List<string> and I want to take groups of 5 items from it. There are no keys or anything simple to group by...but it WILL always be a multiple of 5. e.g. {"A","16","49","FRED","AD","17","17","17","FRED","8","B","22","22","107","64"} Take groups of: "A","16","49","FRED","AD" "17","17","17","FRED","8" "B","22","22","107","64" but I can't work out a simple way to do it! Pretty sure it can be done with enumeration and Take(5)... | Is there any way I can separate a List<SomeObject> into several separate lists of SomeObject, using the item index as the delimiter of each split? Let me exemplify: I have a List<SomeObject> and I need a List<List<SomeObject>> or List<SomeObject>[], so that each of these resulting lists will contain a group of 3 items of the original list (sequentially). eg.: Original List: [a, g, e, w, p, s, q, f, x, y, i, m, c] Resulting lists: [a, g, e], [w, p, s], [q, f, x], [y, i, m], [c] I'd also need the resulting lists size to be a parameter of this function. |
I am using SQL Server 2005 and would like to delete duplicate records that have the oldest dates. For example, I have a training database that captures an employee number, class name and date. Some folks have taken the class more than once, but we only need to keep the record of the latest class attendance. | What is the best way to remove duplicate rows from a fairly large SQL Server table (i.e. 300,000+ rows)? The rows, of course, will not be perfect duplicates because of the existence of the RowID identity field. MyTable RowID int not null identity(1,1) primary key, Col1 varchar(20) not null, Col2 varchar(2048) not null, Col3 tinyint not null |
I have made a live installation of ubuntu to a usb key using the provided usb universal installer and selected an amount of persistant hard drive space on the key. What I want to know is, will booting from and using the usb key ubuntu OS in anyway way, shape or form touch, affect, write to or modify my internal hard drive with windows 10 sitting on it? Thanks in advance? | My laptop which had Windows 7 on it crashed today. Being unable to access any file kept within, I found about the LiveCD. So I created a LiveUSB with Ubuntu in it, and managed to access my Windows desktop. I'm now backing up files important to me, but I have a question: Now I'm cutting and pasting the files I want to save, using Ubuntu. Are these files being moved in Windows as well, or do the alterations I make through Ubuntu not affect the Windows state? So let's say,if I cut and paste all of the D drive, and then format C and reboot with Windows, would the files in D have been gone (since they were cut and not copied) or still be there? Thanks. |
"Did anybody said something?" is an incorrect sentence grammatically, but I don't get why. This might be an excessively silly question, but I am new to the English Language. | Should I use the past tense with did? For example, I was to say: The important question is: Did they knew what it means or not? Or should I say: The important question is: Did they know what it means or not? In other words: Should I use past tense with did? I looked at this: but it didn't really answer my question. |
I'd like to be able to print the definition code of a lambda function. Example if I define this function through the lambda syntax: >>>myfunction = lambda x: x==2 >>>print_code(myfunction) I'd like to get this output: x==2 | Suppose I have a Python function as defined below: def foo(arg1,arg2): #do something with args a = arg1 + arg2 return a I can get the name of the function using foo.func_name. How can I programmatically get its source code, as I typed above? |
I have an enum defined like that: [Flags] public enum Orientation { North = 1, North_East = 2, East = 4, South_East = 8, South = 16, South_West = 32, West = 64, North_West = 128 } Is there a generic way to tell if exactly one flag is set, multiple or none? I don't care for what the value of the enum is, I just want to know how many flags are set. This is not a duplicate for counting the number of bits. If I initialize the enum like this and count the number of bits I get 10. But the number of set flags would be 8. GeographicOrientation go = (GeographicOrientation) 1023; | 8 bits representing the number 7 look like this: 00000111 Three bits are set. What are algorithms to determine the number of set bits in a 32-bit integer? |
I purchased 3 PCs with identical hardware that have Windows 8.1 installed. I purchased 3 licenses for Windows 8.1 Pro retail/full version. I want them to be configured identically initially, including the administrator account and password. I will be spending considerable effort to configure a PC, and I would rather not have to do it 3 times. I don't do IT for a living, and I would rather not go through that learning curve for a one-time deployment. I saw , but it is for Windows 7 and the answer looks like more learning and effort than what it would take me to manually configure 2 PCs. Referencing , will the following scenarios work? Scenario A Install Windows 8.1 Pro on the 1st PC, with the 1st Product Key Install updates, drivers, common apps, change settings, etc. Open a Command Prompt window as an administrator Move to the %WINDIR%\system32\sysprep directory. Enter command: Sysprep /generalize /shutdown /oobe Use disk backup software to take an image of the drive Restore the image to the 2nd and 3rd PCs At the next boot for all 3 PCs, enter the Product Key as part of the OOBE Activate Windows on all 3 PCs Scenario B Install Windows 8.1 Pro on the 1st PC, with the 1st Product Key Activate 1st PC Install updates, drivers, common apps, change settings, etc. Use disk backup software to take an image of the drive (1st-PC specific) Open a Command Prompt window as an administrator Move to the %WINDIR%\system32\sysprep directory. Enter command: Sysprep /generalize /shutdown /oobe Use disk backup software to take an image of the drive (generalized) Restore the 1st-PC-specific image to the 1st PC Restore the generalized image to the 2nd and 3rd PCs At the next boot for the 2nd and 3rd PCs, enter the Product Key as part of the OOBE Activate Windows on the 2nd and 3rd PCs | We just purchased a bunch of new PC's in bulk and I have one computer setup the way I like with all of our company software. I want to push the System Image I created in Windows 7 onto the remaining pc's. My question is, can I push this image to the other PC's through system recovery without any issues? All PC's have identical internal hardware. I've never done this before and want to make sure we won't have any SID's that are identical (think Norton Ghost. I've had a little bad luck with that in the past). I'm guessing I'll have to put the computers on the domain and the image will take care of the rest if it is, in fact, possible? |
I'm writing the "results" section where I have small descriptions and graphs. I want to have a \section(blabla) followed by a small text and then the graph. Right now I do have a \section(blabla), then a huge space(automatically generated), then the text (approx. in the middle) and on the bottom the graph. How can I have the text right beneath the section title? It looks really weird with such a huge space...Thank you! Code: \section{Comparison of graphs} In figure \ref{fig:gnorm_levels}, \ref{fig:shear_levels} and \ref{fig:compression_levels} Lorem ipsum dolor sit amet, consectetur adipiscing elit. Mauris varius magna ipsum. Curabitur vel tortor nec ipsum pulvinar lobortis ut eu tortor. Phasellus rhoncus dolor nunc, eget pellentesque magna egestas in. Donec convallis finibus molestie. Nulla iaculis orci sit amet vehicula porttitor. Praesent mattis vehicula purus id ultrices. Vestibulum ex orci, imperdiet at fermentum vel, maximus sed diam. \begin{figure}[H] \centering \includegraphics[height=8cm]{graphics/levels.png} \caption{Comparison} \label{fig:gnorm_levels} \end{figure} | Every now and then a question/answer with a float environment with option H appears, and every time someone points out that this option should not be used. However, I haven't found a specific post about this topic. Therefore, once and for all, can someone clearly explain: why H should not be used what are all the possible alternatives (htbp, no float at all, etc.). I know there is , but it's too broad and detailed, this question is more focused upon the H option, and I'm searching for a practical answer for beginners. \documentclass{article} \usepackage{mwe} \usepackage{graphicx} \usepackage{float} \usepackage{caption} \begin{document} \blindtext \begin{table}[H] \centering \caption{A Table} \begin{tabular}{ccc} A & B & C \\ 1 & 2 & 3 \\ \end{tabular} \end{table} \blindtext \begin{figure}[H] \centering \includegraphics{example-image-a} \caption{A Figure} \end{figure} \blindtext \end{document} |
Asus x555u Intel Core i5-6500U 2.30 GHz, x64. Windows 10 NVIDIA GeForce 920M It turns back on with no issues when you plug the power back in. Keyboard and mouse input is processed while the screen is off. When connected to TV via HDMI I can see that the computer is on and everything works on the TV even when unplugged, but the laptop screen is off without the cord. Replaced battery. Changed all the sleep mode settings up and down. Changed windows. Changed the display brightness when on battery up and down. Changed power options. Edited plan settings of the active plan for both battery and plugged in. Updated drivers. Any other options? | Asus x555u Intel Core i5-6500U 2.30 GHz, x64. Windows 10 NVIDIA GeForce 920M It turns back on with no issues when you plug the power back in. Keyboard and mouse input is processed while the screen is off. When connected to TV via HDMI I can see that the computer is on and everything works on the TV even when unplugged, but the laptop screen is off without the cord. Replaced battery. Changed all the sleep mode settings up and down. Changed windows. Changed the display brightness when on battery up and down. Changed power options. Edited plan settings of the active plan for both battery and plugged in. Updated drivers. Any other options? |
The black part is the insulation, brown part is copper. How can I calculate the capacitance between the two small copper cables? There are 3 conductors, 2 of them inside the big conductor | I have a cable as in the drawing. The black parts are insulators and the brown parts are copper, so there is a big copper cable and inside are two smaller copper cables. When the big copper cable is tied to ground I can use a time domain reflectometer (TDR) on the smaller cables to determine the length of the cable. What happens if the big copper cable is in use with a current running through it that is 1000 times bigger than the current running through the two smaller copper cables? Will I still be able to determine the length with a TDR? I think there shouldn't be a capacitance between the two smaller copper cables - but how am I then able to measure with it a TDR? |
Recently I just deleted one of my answer in stackoverflow where there was one comment. After deleting the answer it also show for sometime that we all know but in the comment it still allow us to up to make it useful but as I clicked it it just showed me the message: If we are not allowed to do then what was the meaning? Why don't it just be removed or make it disable if the answer is deleted. Just don't show UI for actions that can't be actioned | Currently, the system makes you think you can upvote/downvote your own question/answer but then you get notified that you can't. Why have the up/down vote buttons there then? In general, if some operation is not allowed, then don't put UI for that up or make it disabled so it is apparently disabled - no post operation error panels please? ps: hope this is not a dupe, but if so, just comment it and I will remove (+a joke: a user notification panel message: I deleted this file. Is this a problem? Yes/No.) |
Im new to sqlserver, we have a sqlserver running on linux and we are encountering performance issues i see sometimes SUSPENDED on the queries / selects etc If i change the max degree of parallelism 0 32767 0 0 would it help? any other comments would be great | I am not able to get the meanings of DB Session status. I searched it for some references, but not getting any help. Can anyone explain these status (runnable, sleeping, suspended, running and background) what actually means, that would be help me a lot. Thanks in advance. |
I am looking for a movie in which a kid fell in a sewer accident/challenge and ends up in a different universe. I remember the kid having a problem with one of his legs some sort of iron staff was surrounding his leg from the knee down. | I have memories of a fantasy movie that I watched as kid, yet I can't remember the title or a single character's name! The protagonist was a boy. I know that it took place in a fantasy realm, possibly starting on Earth and then traveling to that fantasy realm. There was definitely an older mentor in the film, who is murdered by the main villain in combat. The villain was very pale and I remember a shot of the dying mentor with a diagonal slash across his face from the villain's blade. It was definitely live-action, in color, I remember watching it on VHS in English, probably got it from Blockbuster in the US, pretty sure the world had some form of magic in it, at least some of the fighting was martial-arts-esque, pretty sure (but not positive) there were sentient non-humans (maybe like Ewoks but wiser/less ridiculous). I believe the swords were metal, not laser swords or anything, and at least the villain used a large curved sword/scimitar |
I saw this exercise: Prove that the number of group homomorphisms from $\mathbb{Z}_m \to \mathbb{Z}_n$ is $k=\gcd(m,n)$, where $m,n$ are natural numbers. If $m,n$ are prime to each other, then the only homomorphism is the trivial one. I know that a homomorphism $t$ from $\mathbb{Z_n}$ to some other group $H$ matches an element $g\in H$ such that $g^n = e$, $t(1)=g$. How does the $gcd$ here take place and give the number of homomorphisms? | This question coutesy of Allan Clark's "Elements of Abstract Algebra" (60$\zeta$). Find the number of homomorphisms from $\Bbb{Z}_m\to \Bbb{Z}_n$ as a function of $m$ and $n$. This is stumping me, can anyone help? |
I have been using a domain name for the last few years. A larger company is threatening to sue me for using my initials as my company name! So as an answer to this I have created a new domain URL with the addition of my location in the URL. So I now have redirected my old URL to my new URL. But...I want Google to acknowledge this is really then same site and to keep any rankings, or to transfer the rankings from the old URL to the new URL! Is this possible? | We have to shift our web-site to a new domain due to some unavoidable circumstances. The portal has been up and running there since 2009. It has good index in various search engines and we are getting a good number of page hits on daily basis. Losing the search hits and index are our big concern. We are not sure how best we can handle this. What all can be done to preserve as much as possible while shifting to new domain name. |
Let $x,y -$ positive integers, such that $xy|(x^2+y^2+1)$. Prove that $$\frac{x^2+y^2+1}{xy}=3.$$ My work so far: 1) If $x=y=1$ then $\frac{1^2+1^2+1}{1}=3$ 2) Let $x=1$ (or $y=1$) $\frac{1^2+y^2+1}{y}=k \Rightarrow y^2-ky+2=0$ $D=k^2-8=m^2 \Rightarrow (k-m)(k+m)=8 \Rightarrow k=\pm3, m=\pm1 $, but $k\in \mathbb N \Rightarrow k=3$ 3) $x,y>1$ $xy|(x^2+y^2+1) \Rightarrow x^2+y^2+1=kxy, k \in \mathbb N$ $D=k^2y^2-4y^2-4$ Here I need help... | Let $x$ and $y$ be positive integers such that $xy \mid x^2+y^2+1$. Show that $$ \frac{x^2+y^2+1}{xy}= 3 \;.$$ I have been solving this for a week and I do not know how to prove the statement. I saw this in a book and I am greatly challenged. Can anyone give me a hint on how to attack the problem? thanks |
Here is link with the picture of the fan: The fan name is "ZALMAN ZM-F3(SF) 120MM ULTRA QUIET FAN" I looked it up online, but I don't understand, I'm colourblind and it's difficult to distinguish the colors. | I just got this PC fan and it has a 3 pin connector, I know the wire with the white stripe is positive but how can I find out which of the other two wires are negative? If you can't see the photo, here is a link to it: |
Let A be an $n$ x $n$ matrix and let $u$,$v$ $\in$ $\mathbb{F^n}$. Prove that $$Au\cdot v = u\cdot A^Tv$$ when <,> is the standard inner product. how can I prove it ? | Let A be an $n$ x $n$ matrix and let $u$,$v$ $\in$ $\mathbb{R^n}$. Prove that $$Au\cdot v = u\cdot A^Tv$$ I tried using the fact that $A^Tu=A\cdot u$. However, I cannot seem to get to this result. Could anyone please help me out? |
Base case $n=3$ - true Inductive Step Assume that for every $k \geq 3$, $2^k>2k+1$ show that $P(k+1)$ holds, that is show that $2^{k+1} > 2k+3$ $2^{k+1} = 2^k*2 > (I.H) (2k+1)*2 > (k+2)*2 = 2k+4 > 2k+3$ Did I do this right? I am asking because I am not sure about $(2k+1)*2 > (k+2)*2$ step | Prove that $ n < 2^{n} $ for all natural numbers $n$. I tried this with induction: Inequality clearly holds when $n=1$. Supposing that when $n=k$, $k<2^{k}$. Considering $k+1 <2^{k}+1$, but where do I go from here? Any other methods maybe? |
I'm using Windows 7. All of a sudden from nowhere, my D: Drive is showing a red bar for space, and it says there are only 620 MB free out of 28.9 GB. Yet when I browse into D:, select all files and folders, right click, and choose "Properties", the total space taken by the contents of D is a mere 2 GB. I've already enabled viewing hidden files, but the hidden files are really small. What on earth is taking up the rest of the space? Or is the My Computer's browser falsely saying I'm almost out of space? Edit I tried the solution here: But I got this error: Error: The shadow copy provider had an unexpected error while trying to process the specified command. | My Vista 64 installation has drive C, a 150 GB hard drive. I also has a 1.5 TB drive D. My C drive has 12.3 GB free. I don't know what's using up all the space. There's almost 83 GB unaccounted for!!! As per question and question, I downloaded and . WinDirStat, once I found the right options, tells me there's 82.9 GB of . SpaceMonger, which has a particularly nice display of the data, tells me there's 82.3 GB "Unscanned", with 2 unscannable folders. Where do I turn now? Both tools roughly agree there's a large amount of data on my drive, but neither seem to be able to tell me what. I've tried the standard approach; disk cleanup, remove hibernation file, set the virtual memory to the D drive instead of the C drive. |
I prepared a program written in GAP's envirounment. I'd like to put them all in one of my beamer pages exactly as follows: gap> z:=CyclicGroup(IsPermGroup,10);; n:=CyclicGroup(IsPermGroup,15);; s:=DirectProduct( z, n );; e:=Elements(s);; r:=Filtered(e,t->Order(t)=10);; Size(r);; What can I do? I used \text{} to get the result as it is shown above but it's useless. Thanks for any help. | Possible Duplicate: I'm relatively new to LaTeX, and am starting to use it for academic paper writing. I'm doing a lot of computer programming as part of my academic work, so need to be able to include code extracts easily. I know I can easily make them appear in a monospaced font, but what would you suggest for getting automatic syntax highlighting? |
My name is shiva and I am 31 and single. I live in Iran and recently I got my refusal letter for a visitor visa from Canada. I work in a company which represents an international brand. I have a high position and I provided 6 payslips with high payments. I have recently had a promotion which is shown in my payslip. I had a letter that said I have 2 weeks off from my company to visit Canada and I must come back after these days. My bank account is good enough but I do not own any house or property and I live with my parents. All my family (parents and siblings) live in Iran and I said this in my cover letter. My travel history was good enough and two years ago I had a Schengen Visa. My invitation letter was from my cousin who is married to a Canadian. They said in that letter that they will be my host for 2 weeks and they have been advised and verily believe that my financial status is such that I am comfortably able to pay my expenses without any assistance and verily believe that I will not overstay. My rejection reasons are: Family ties in Canada and in Iran Purpose of visit My question is why I got rejected and what can I do about it? | Hi I'm a citizen of Mauritius. I applied to Canada for a temporary visa to see a friend who would give me accommodation for 1 month. To my surprise my visa was refused, for the following reasons: Travel history: I don't understand this statement as I have been to Japan, Malaysia, Australia, Switzerland, France, England, Germany, Italy and Spain. Family ties in Canada and Mauritius: True for Canada as I'm visiting a friend; incorrect for Mauritius, as mentioned in my application that my dad and I live in the same house. Reason for my visit: I said that it was for tourism. Finance: I said that I would bring $2000 for the month, and I would have free accommodation. However, the bank statement which I provided showed more than that amount. Job: I provided a letter from my employer, a international company, in which I'm a senior software engineer. With all this, I don't understand the refusal. Can I do anything about it? |
I'm working on stats problems and am a bit rusty with calculus as I haven't worked with it in 3 years. My prof gave us an equation $\int_{-\infty}^\infty ke^{\frac{-x^2}{2}} ~dx =1$ where XER and f(x) is a PDF to solve for k. Could someone please explain to me how he arrived at $k = \frac{1}{\sqrt{2\pi}}$ | How to prove $$\int_{0}^{\infty} \mathrm{e}^{-x^2}\, dx = \frac{\sqrt \pi}{2}$$ |
When we add images to posts, they're often shrunk to fit the web page (reduction of the width and height). I suspect this is done automatically by the HTML. However, some times, we need to see the bigger picture (literally). I often edit posts such as and add the option to view the large image by simply adding the image as a link. Can/should this feature be enabled as standard? To have a link (some how) which shows the full version when ever we add a graphic (or at least, where applicable)? Already asked here (not sure if cross posting in meta is OK or not, if not I will delete the SU one) | The current image handling is minimal, there is no rescaling a all and the full image is simply scaled to the width of the post. This works well until you have images that are wider than the 640px available for posts. There are two important categories of images that pretty much always break this limit: Pictures taken with a digital camera and screenshots. Sites that would benefit from an improvement here would be especially Photo.SE, Arqade, DIY and other image-heavy sites. The current result of this for inexperienced users is that they put the full-sized image in the post. This means a waste of bandwith for everyone looking at it, and also makes the full-sized image not accessible to non-technical users. An experienced user will rescale the image before uploading. This takes more time and also makes the full-sized version of the image unavailable for everyone. A very experienced SE user can work around the whole thing and use the automatically created thumbnails from imgur to create a preview image linked to the full-sized one. This is only known to very few users, it is not discoverable and quite a lot of work. I'll use a project from a developer that is rather well-known around here as an example how the image handling could be done better: . When uploading an image it should be rescaled automatically to the width of the post the image should be linked automatically to a lightbox (or to a new tab) that will show the image in the maximum possible size on the screen. There should be no need for a user to do any manual work, this should just work automatically. |
so I'm learning programming and I understand variables, if else statements, cin and cout. So for a starter project I'm just creating a console application that asks the user questions, such as age, location etc. One of them I would like just a simple yes or no answer. I've managed to do this, but what the user inputs must be the same case as the word in the if statement. i.e. if statement contains "Yes" with a capital 'Y'. If the user inputs "yes" without a capital 'Y' then the program fails. The if statement sees if it is a "Yes", if it is, provides positive feedback. If "No", then it provides negative feedback. How can I make it no matter whether the answer is "YES", "yes" or even "YeS"? | I want to convert a std::string to lowercase. I am aware of the function tolower(). However, in the past I have had issues with this function and it is hardly ideal anyway as using it with a std::string would require iterating over each character. Is there an alternative which works 100% of the time? |
A classmate and I have been looking over some stats regarding a study looking at the (lets call it) survival rate of an item of food. He ran his analysis using coxph to generate a model to compare the survival of a piece of food on camouflaged vs non-camouflaged backgrounds. Reviewing the summary of this analysis he saw that the R squared returned a value of 0. Both of us are biology students with a very limited background in statistics, but it struck us as odd that the R squared could be 0, as surely there must be some marginal level of variance explained by the model. Reading up on this, I saw that R squared for coxph is not functionally equivalent to the R sq. returned by linear models etc. So I guess my questions are: How should we interpret this information? Is there an equivalent measure for data variation? I understand this is similar to a previous question asked about , but mine is more focused on a comparison of (or inability to compare) this value to one that might be returned in a linear model. Many thanks. | What is the $R^2$ value given in the summary of a coxph model in R? For example, Rsquare= 0.186 (max possible= 0.991 ) I foolishly included it a manuscript as an $R^2$ value and the reviewer jumped on it saying he wasn't aware of an analogue of the $R^2$ statistic from the classic linear regression being developed for the Cox model and if there was one please provide a reference. Any help would be great! |
For example, if your champion has 200 magic resistance / armor and your enemy has some crazy AP/AD damage that can be dealt with one single spell/attack, say 800 damage at once... Considering the enemy doesn't have any magic/armor penetration (not even MPen/APen runes), how much damage would your champion receive? | The formula for calculating damage reduction from armor in League of Legends is Damage Reduction = Total Armor / (100 + Total Armor) It seems clear to me that this formula dictates that adding more armor has diminishing returns. For example, let's say my champion has 50 armor, which gives damage reduction of 33.33% and I buy an item that gives 25 more armor; then my champion's total armor would be 75 and damage reduction would be 42.86%. That means I saw a 28.6% increase in damage reduction (damage reduction was increased by 9.53%). Now let's say I buy another of these items with 25 armor. Now my champion's armor will be at 100 which gives damage reduction of 50%. That means I saw a 16.66% increase in damage reduction (damage reduction was increased by 7.14%). Therefore, from the first 25 armor item I bought got me 9.53% damage reduction, while the second time I bought the item it only got me 7.14% damage reduction. It looks to me like it was 25.08% less effective the second time I bought it. That screams diminishing returns to me. Why would someone say otherwise? Would they say anything different about Magic Resistance? Note: This question was inspired by a comment thread which started off of this question: . I have heard similar insinuations made before, though, implying that magic resist and armor are somehow different in the department of diminishing returns (although I am not sure if that was implied in the comments on the related question). |
In november i posted this question: The question was how to modify the bibliography to how i wanted it to look. I wanted the webpage reference to look like this: [#] Author (year). Title. Available: I got a good answer, but now I see that I get a dot after the URL, and I am not supposed to have that. Do you know how to "get rid of" the dot after the URL? My MWE: \documentclass[12pt]{report} \usepackage[a4paper,width=150mm,top=25mm,bottom=25mm]{geometry} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{fourier} \usepackage{filecontents} \begin{filecontents}{referanser.bib} @online{Ibsen90, author = {Henrik Ibsen}, title = {Hedda {G}abler}, year = {1890}, url = {http://www.uia.no/no/portaler/bibliotek/finn_fagstoff}} \end{filecontents} \usepackage[norsk]{babel} \usepackage[ backend=biber, style=ieee, sorting=none ]{biblatex} \addbibresource{referanser.bib} \DeclareFieldFormat[online]{title}{\mkbibemph{#1}\isdot} \DefineBibliographyStrings{norsk} { bibliography = {Litteraturliste}, url = {Tilgjengelig}, } \usepackage{xpatch} \xpatchbibdriver{online}{% \setunit{\adddot\addspace}% \printtext[parens]{\usebibmacro{date}}% }{% \setunit{\addspace}% \printtext[parens]{\usebibmacro{date}}% }{}{} \xpatchbibdriver{online}{% \newunit\newblock% \usebibmacro{url+urldate}% }{% \setunit{\adddot\space}\newblock% \usebibmacro{url+urldate}% }{}{} \begin{document} \nocite{*} \printbibliography \addcontentsline{toc}{chapter}{Bibliographie} \end{document} | In my thesis, I need to have the webpage reference in the bibliography to look like this: [#] Author (year). Title. Available: I need the title to be italics and the "Available to say "Tilgjengelig"(norwegian) Now it says "side" which means page. When I use @online, the reference is how I want it, exept the title is not italics, and it says "side"(page) instead of tilgjengelig(available) I do not know how to upload files. I paste everything here: \documentclass[12pt]{report} \usepackage[a4paper,width=150mm,top=25mm,bottom=25mm]{geometry} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[norsk]{babel} \usepackage[ backend=biber, style=ieee, sorting=none ]{biblatex} \addbibresource{referanser.bib} \begin{document} \chapter{Test} Blablabla \nocite{*} \renewcommand{\bibname}{Litteraturliste} \printbibliography \end{document} This is my references: My references: @book{barbero2013, address = {Boca raton, Florida}, author = {Barbero, Ever J}, booktitle = {Composite materials: Analysis and design}, keywords = {elementmetoden,komposittmaterialer,matematiske,modeller}, publisher = {CRC Press}, title = {{Finite element analysis of composite materials using Abaqus}}, year = {2013} } @book{bunsell2005, address = {Bristol}, author = {Bunsell, A R and Renard, J}, keywords = {Fiberforsterkede komposittmaterialer,fiber,forsterkninger,kompositter,komposittmaterialer,materialer}, publisher = {Institute of Physics Publishing}, title = {{Fundamentals of fibre reinforced composite materials}}, year = {2005} } @misc{hovland2011, author = {Hovland, G}, title = {{Mekatronikk Labfasiliteter}}, url = {http://old.uia.no/no/portaler/om\_universitetet/teknologi\_og\_realfag/-\_ingenioervitenskap/-\_-\_mekatronikk/lab}, year = {2011} } @online{byg402, author = {{Universitetet i Agder}}, title = {{BYG402-G Elementmetoden i konstruksjoner}}, url = {http://old.uia.no/portaler/student/studierelatert/studiehaandbok/14-15/emner/byg402}, year = {2014} } @book{zenkert1996, address = {Stockholm}, author = {Zenkert, D and Battley, M}, publisher = {Kungliga Tekniska h\"{o}gskolan}, title = {{Foundations of fibre composites}}, year = {1996} } @misc{iso3451, title = {Plastics : Determination of ash. Part 1: General methods}, howpublished = {ISO3451-1}, year = {2008} } @misc{iso527, title = {{Plastics - Determination of tensile properties - Part 5: Test conditions for unidirectional fibrereinforced plastic composites}}, howpublished = {ISO-527}, year = {2009} } |
It seems to me that proving this requires invoking the axiom of choice, but I'm not entirely sure. Prove: If there is an injection $\mathit{p :D_1 \hookrightarrow D_2}$, then $\exists$ a surjection $\mathit{q : D_2 \twoheadrightarrow D_1}$, where $\mathit{q \cdot p = id_{D_1}}$ | Theorem. Let $X$ and $Y$ be sets with $X$ nonempty. Then (P) there exists an injection $f:X\rightarrow Y$ if and only if (Q) there exists a surjection $g:Y\rightarrow X$. For the P $\implies$ Q part, I know you can get a surjection $Y\to X$ by mapping $y$ to $x$ if $y=f(x)$ for some $x\in X$ and mapping $y$ to some arbitrary $\alpha\in X$ if $y\in Y\setminus f(X)$. But I don't know about the Q $\implies$ P part. Could someone give an elementary proof of the theorem? |
From this calculation (), two protons seperated by the distance of one atom feel the electromagnetic force repelling them 1.239*10^36 stronger than the gravitational force attracting them. This means that for gravity to be able to bring hydrogen atoms together to make stars, their overall charge must have to be PERFECTLY neutral. Is this level of symmetry surprising? Does it show protons and electrons were cut from the same cloth? | What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of photon field, but is this explanation enough? Do we have some experimental evidence that quarks have 2/3 and -1/3 charges? By the way I think about bare charge of electron and proton. And I am also wondering if this can be explained by Standard Model. |
I have a urgent question which almost make me crazy now. I used the following command for MATLAB installation: sudo mount -o loop /home/study/MATLAB/R2017b/iso/iso2.iso /home/caihongzhu Under /home/study directory, I have all my useful files. After using this command, I lost all files under the /home/study directory (for user caihongzhu). Thanks a lot for your help! | I wanted to mount my flashdrive, and made the mistake of setting the mount path as /home/my_name. Now all of my documents, downloads, pictures, etc. are unavailable since my flashdrive has replaced my previous home folder. When I go to terminal and type sudo umount /home/my_name I get the error message: umount: /home/my_name: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) Is there a way to fix this, where I can restore my old /home/my_name folder and then mount the flashdrive to a proper location? |
Let $G$ finite group, and suppose $G$ has unique subgroup of each order (which divides $G$'s order) - Show that $G$ is cyclic. I reduced the problem to sylow subgroups of $G$ (they are all normal), so I need to prove the statement only for $p$-groups, and really have no idea.. | Problem Suppose G is a finite group of order $n$ which has a unique subgroup of order $d$ for each $d\mid n$. Prove that $G$ must be a cyclic group. My idea: I try to prove it by induction. Let $p|n$ be a prime. Then by condition, there exists a unique subgroup $H$ of order $n/p$. Since $|gHg^{-1}|=|H|$, we must have $gHg^{-1}=H$ by the uniqueness part of the condition. So, H is a normal subgroup. Now, $|G/H|=p$ and thus $G/H=\langle x\rangle$ where $x^p \in H$. However, I cannot continue. My another idea is that first consider the case when $|G|$ is a power of some prime $p$. But, it still doesn't work. |
If $f:[a,b]\to R$ is a continuous function, prove that there exists $c \in [a,b]$ such that $\int_{c-a}^{b-c}f(x)dx=0$. | If $f,g : [a,b] \to (0,\infty)$ are continuous functions, prove that there exists $c \in (a,b)$ such that: $$\int_{a}^{c} f(x) \ \mathrm dx = \int_{c}^{b} g(x) \ \mathrm dx$$ |
Well, for some reason that I will try to find out later, my TeX Live under Linux doesn't work anymore and I had to go through windows emulated system. The file I work with include a \graphicspath command, but it seems that the "\" specific to windows path makes problem. The only I had to solve the error messages was to put all files in the same directory without spaces in the path. Does anyone had experienced such kind of problems and solved it? Thanks for help | I want to import graphics into my main input file using the macro \includegraphics. It does not work if the filename contains spaces. also discusses this subject, but there is no solution there. My compilation routine is latex->dvips->ps2pdf (because of PSTricks). |
Late 2015 iMac is rebooting on its own. Only Finder running, OSX 10.11.6. (2) 8GB RAM sticks. Got to catch it in the act today. After reboot I find kernel: Previous shutdown cause: -128 That doesn't appear to correspond to anything useful in the old MacOS error codes documentation from 1998: -128 userCanceledErr User canceled an operation The is a refurb unit, hoping it doesn't need to go back for another refurbishment. thanks | My MacBook Pro 11,2 (Retina 2014) shuts down suddenly from time to time. When I run macbook again, I inspect the log file I see the following message: Previous shutdown cause: -128 Sometime, when I close a laptop, fans begin to hard work. It happens with/without power adapter. I launched Diagnostic and I got 'NO ISSUE'. When I run macbook in SafeBoot, all work correctly, but very slowly. I tried: Reset SMC, PRAM. ERASE Disk and install macOS from scratch. Also, I tried to remove battery and use the power adapter only. In this case it work correctly, but sometime I get another error (It happens rarely). Macbook pro 11,2 Retina 2014 (15 Display) Intel Core i7 2,2 GHz RAM 16 GB SSD 256 GB |
I'm new to Linux. Is there a way to find out the name of my greeter (where you sign in) or whether I have many installed (a way to find apps by function: greeters, text editors, terminals, etc...)? | For those who don't know, greeter is basically the login screen. In case of Lightdm specifically, there are several versions of it: unity-greeter kylin-greeter lightdm-gtk-greeter lightdm-kde-greeter lightdm-webkit-greeter razorqt-lightdm-greeter The goal: I need to know how to obtain the greeter version currently in use. Scripting solutions are most welcome ( preferably python, shell scripts, perl ) but also open to C code. Ideally , the solution would work like so: $ ./get_greeter kylin-greeter Issues and failed approaches: Checking process listing doesn't work. I have kylin-greeter in use right now, but pgrep -f lightdm | xargs -L 1 ps -o args --no-header -p or pgrep -f kylin | xargs -L 1 ps -o args --no-header -p return nothing that points to /usr/sbin/kylin-greeter lsof -p <LIGHTDM_PID> also provides no insights - no /usr/sbin/kylin-greeter among the listing. Parsing /etc/lightdm/lightdm.conf is a potential, but not ideal solution, since some flavors of Ubuntu ( such as Kylin ) won't explicitly state greeter session in that file. I would prefer something more reliable. gsettings doesn't provide a reliable means of determining greeter in use either - presence of schemas for unity-greeter doesn't mean I am currently using that. examining paths and methods on org.freedesktop.DisplayManager service for system bus provided no insights into what greeter is in use either. |
Extensions like no longer work with the Thunderbird version 60+ . How can I run thunderbird version 60+ minimised to tray? I run awesome-wm v4.2. | After update, my Thunderbird stopped getting minimized with the "MinimizeToTray revived" add-on. Is there any way to minimize my Thunderbird? Any other add-on that works with the new version? |
My question: Define the distance on $C[0,1]$ by $$d(f,g)=\max_{x\in [0,1]}|f(x)-g(x)|.$$ Prove that the set $S \subset C[0,1]$ is not compact, where $S=\{f \in C[0,1]|d(f,0)=1\}$. My idea: For this, I assume that if I choose a sequence $\{f_n\}$ in $S$, that is Cauchy, but the limit of $\{f_n\}$ is not continuous. This implies $S$ is not compact. I chose $f_n(x)=(-1)^{n}$. The limit points of $f_n(x)$ are $f(x)=1,$ and $-1$. I observed that this sequence is not Cauchy, so I cannot use my idea. I choose another example, $f_n(x)=x^n$, but this is also not Cauchy. Can anyone suggest an example of this case that works? | I know that this question has been asked to death, and multiple solutions are given, but I still don't understand why the "standard" proof works Following Let $C_o([0,1])$ be the space of continuous functions on $[0,1]$. Define $\|f\| = \sup\{|f(x)| x \in [0,1]]\}$ Let $B[0,1] = \{f \in C_o|\|f\|\leq 1\}$, show that this Closed, Unit ball in $C_o$ is not compact. Proof Sketch: Let $\{f_n\} \subset C_o, f_n = x^n, x \in [0,1]$, then $f_n \in C_o, \|f_n\| = 1 \thinspace \forall n$, so $f_n \in B([0,1]) \thinspace \forall n$ But $f_n \to f \notin C_o$. So $B([0,1])$ is not compact. Three questions: if $f_n \to f \notin C_o$, wouldn't that mean $B([0,1])$ is not closed in the first place (contradicts with assumption)? How does the above implies that no subsequence converges in $B([0,1])$ Is the proof sketch essentially correct? |
I need to know what page a user made the request FROM ... $_SERVER["REQUEST_URI"] tells me what file the request is made to, however I want to know what file / page the user was on when the request was made. | What is the most reliable and secure way to determine what page either sent, or called (via AJAX), the current page. I don't want to use the $_SERVER['HTTP_REFERER'], because of the (lack of) reliability, and I need the page being called to only come from requests originating on my site. Edit: I am looking to verify that a script that preforms a series of actions is being called from a page on my website. |
I'm trying to match alphanumeric with the regex below, but still matched the result that I don't need. ([0-9a-z_]+|[0-9a-z]+) What I really want to match are Example: abc123 abc_123 What I don't want to match are Example: abc 123 123_123 abc_abc | I need to find a reg ex that only allows alphanumeric. So far, everyone I try only works if the string is alphanumeric, meaning contains both a letter and a number. I just want one what would allow either and not require both. |
The error appears when running the code (line 10). This is it: Exception in thread "main" java.lang.NullPointerException at classification.GetExtensionOfFileMain.main(GetExtensionOfFileMain.java:10) Line 10 is: File txtFile = new File(classLoader.getResource("loginDao.txt").getFile()); Since it is a classLoader and automatically has to "do its job", I don't know what's wrong. Please help! import java.io.File; public class GetExtensionOfFileMain { public static void main(String[] args) { ClassLoader classLoader = GetExtensionOfFileMain.class.getClassLoader(); File txtFile = new File(classLoader.getResource("loginDao.txt").getFile()); String fileExtension = getExtensionOfFile(txtFile); System.out.println("File extension for loginDao.txt is " + fileExtension); File folder = new File("C://src//files"); String fileExtensionFolder = getExtensionOfFile(folder); System.out.println("File extension for C://src//files is " + fileExtensionFolder); } public static String getExtensionOfFile(File file) { String fileExtension = ""; // Get file Name first String fileName = file.getName(); // If fileName do not contain "." or starts with "." then it is not a valid file if (fileName.contains(".") && fileName.lastIndexOf(".") != 0) { fileExtension = fileName.substring(fileName.lastIndexOf(".") + 1); } return fileExtension; } } | 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? |
Unfortunately the hard disk of my system is damaged. I am trying to recover my database, but it cannot be attached again to SQL management studio 2005. The error is myfile.mdf is not a primary database file. (SQL server , error 5171) | Unfortunately hard disk of my system is damaged, now I recovered my database. But it cannot be attached again to SQL management studio 2005. The error is: myfile.mdf is not a primary database file. (SQL server , error 5171) |
I have two positive semidefinite matrices, $A$ and $B$, of size $((N-1) \times (N-1))$. I know that for all $i$ and $j$ in $\{1,...N-1\}$, $|A_{i,j}-B_{i,j}|<k$ for some positive real constant $k$ and $|A_{i,j}|<l$ and $|B_{i,j}|<l$ for some positive real constant $l$. How can I place on the below expression an upper bound in terms of $k$, $l$ and $N$? $$|\det(A)-\det(B)|$$ I.e. I'm looking for an expression in terms of $N$ and $k$, $C_{n,k,l}$, such that: $$|\det(A)-\det(B)|\leq C_{n,k,l}$$ I believe such an expression exists as I am working through a proof which does something similar but gives no explanation as to how it achieved it. Going by what is in the proof, it seems as though the answer should come to something similar to: $C_{n,k,l}=k2^{N}N(N!)(l+1)^{N-1}/2$ The proof I am working through says this result should be obvious but I am unsure why. | Let $A$ and $B$ be two real, $n\times n$ matrices. Using Hadamard's inequality, it is not hard to show that $$ \left|\det A - \det B \right| \leq \|A-B\|_{2} \frac{\|A\|_{2}^n -\|B\|_{2}^n}{\|A\|_2 -\|B\|_2}. $$ Where $\|A\|_2=\sqrt{\sum_{i,j}a_{ij}^2}$. From this, I can derive a sup bound, for example $$ \left|\det A - \det B \right| \leq n^{n+1} \|A-B\|_{\infty} \max (\|A\|_{\infty}^{n-1},\|B\|_{\infty}^{n-1}). $$ Where $\|A\|_\infty=\sup_{i,j}|a_{ij}|$. The constant $n^{n+1}$ is not the best bound possible : any reference (or proof) for a better (or the best) one? I show below that one can obtain $n^2(n-1)^{n-1}$, but that isn't much better. I just tried $10^5$ random matrices on Maple and obtained a maximal constant (much) smaller than one : this is not a proof, but it looks like there is room for improvement nevertheless. Just for completeness (and in case someone sees a factor I missed), to get the first bound, writing $A=[A_1,\ldots,A_n]$ in terms of its column vectors, an expansion shows \begin{eqnarray*} \det A &=& \det (A_1 -B_1,A_2,\ldots,A_n) + \det (B_1,A_2,\ldots,A_n) \\ &=& \sum_{j=1}^n \det (B_1,\ldots, B_{j-1}, A_j -B_j,A_{j+1},\ldots,A_n) \\ && + \det B, \end{eqnarray*} Thus by Hadamard's inequality, \begin{eqnarray*} \det A -\det B &\leq& \sum_{j=1}^n \prod_{i=1}^{j-1} \|B_i\|_{2}\prod_{i=j+1}^{n} \|A_i\|_{2} \|A_j-B_j\|_{2} \\ &\leq& \|A-B\|_{2} \sum_{j=1}^n \|B\|^{j-1}_{2}\|A\|^{n-j}_{2} \\ &=& \|A-B\|_{2} \frac{\|A\|_{2}^n -\|B\|_{2}^n}{\|A\|_2 -\|B\|_2}. \end{eqnarray*} The second bound is just that $x^n -y^n\leq n \max(|x|^{n-1},|y|^{n-1}) |x-y|$ and $\|A\|_2 \leq n\|A\|_\infty$. Another approach is calculus, namely, to write that $\det B - \det A = f(1)-f(0)$, with $f(t)=\det(A + t(B-A))$. By the mean value theorem $f(1)-f(0)\leq \max |f^\prime (t)|$. We can compute that $$f^\prime(t) = {\rm trace}\left({\rm Cofm}(A +t(B-A))(B-A)\right)$$ (if I did not mess up, using the formula for the differential of a determinant, where Cofm means the matrix of Cofactors). Then, it should deliver something better, if there is a nice way to bound it. The simplest thing is to use Cauchy-Schwarz, namely $$ \left|{\rm trace}\left({\rm Cofm}(A +t(B-A))(B-A)\right)\right|\leq \|B-A\|_{2} \|{\rm Cofm}(A +t(B-A))\|_{2} $$ and then, by lack of a better idea, $$ \|{\rm Cofm}(A +t(B-A))\|_{2}\leq n \max_{ij} |{\rm Cof}_{i,j}(A +t(B-A))|, $$ and brutally, $|{\rm Cof}_{i,j}(A +t(B-A))|\leq ((n-1) \max(\|A\|_\infty,\|B\|_\infty))^{n-1}$ gives a slightly better constant, namely $$ n^2(n-1)^{n-1} <n^{n+1} $$ but that still seems a very rough way to bound a determinant, as it is never sharp, since to attain this bound all coefficients should be equal, and therefore the cofactor would be zero. They are of the same order in $n$, and I suspect this order is wrong. |
Two boxes, one is gold and the other silver. The sign on the gold box reads, "The portrait is not here." The sign on the silver one reads, "Exactly one of the two statements is true." Guess where the portrait is. What I want to see is how you reason the problem. | Gold casket: the portrait isn't in the silver casket. Silver: the portrait isn't in this casket. Lead: the portrait is in this casket. At least one of the statements was true and at least one of them was false. Which casket contains the portrait. If you say any one of the three statements is true, you will end up with all of them being true. |
I try add object to ArrayList and got error: Error: Exception in thread "main" java.lang.NullPointerException at Voiting.addCandidate2(Voiting.java:29) at Main.main(Main.java:11) public ArrayList<Candidate> candidates; public void addCandidate2(String CandidateName){ Candidate candidate=new Candidate(CandidateName); candidates.add(candidate); //нужен конструктор списка кандидатов } Constructor Voiting: public void Voiting(){ candidates=new ArrayList<Candidate>(); } In main class: Voiting voiting=new Voiting(); voiting.setTitle("Vibor 2018"); voiting.addCandidate2("Candidate1"); | 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? |
Consider this dict1={} dict2={} dict2["first_d2"]="Yes" dict1["first_d1"]=dict2 print dict1 print dict2 dict2={} print dict1 ===>Here's the doubt print dict2 The Output: {'first_d1': {'first_d2': 'Yes'}} {'first_d2': 'Yes'} {'first_d1': {'first_d2': 'Yes'}} ===>Why is this not resetting?Its referencing to dict2 {} Now python dictionaries are mutable.So dict1 is referencing to dict2.Now after first operation dict2 is reset,why is the value of dict1 not resetting? As per my understanding mutable object change the contents in memory and do not return a new object.So why is this not happening here?What am i missing? I am confused from the point of view of mutable and immutable! | In python, is there a difference between calling clear() and assigning {} to a dictionary? If yes, what is it? Example:d = {"stuff":"things"} d.clear() #this way d = {} #vs this way |
I am writing a press release, and I am stumped as to what punctuation I use for listing numerous names. The following is a sample. Montana authors include:; John Brown, Mary Lamb, Susie Sunshine, Tom Foolery, Bud Wiser, etc. What punctuation is correct after the word include? | What is the correct punctuation in English: There are two types of insectsXX a) white b) black Should the punctuation at XX be “;” or “:”? |
I'm trying to derive Ward-Takahashi identity $$k_\mu V^\mu(p,q,k)=Z_1 Z_2^{-1}e(S^{-1}(q)-S^{-1}(p))\tag{68.12}$$ using Schwinger-Dyson equation and Ward identity. In renormalized spinor QED, the Lagrangian is: $$\mathcal{L}=\bar{\Psi}(iZ_2\gamma^\mu\partial_\mu-Z_m m)\Psi-\frac{1}{4}Z_3F^{\mu\nu}F_{\mu\nu}+Z_1 q\bar{\Psi}\gamma^\mu\Psi A_\mu.$$ Under a global gauge transformation $\Psi\rightarrow e^{-ie\alpha}\Psi,\ \bar{\Psi}\rightarrow\bar{\Psi}e^{ie\alpha}$, the conserved current is: $$J^\mu = \frac{\partial \mathcal{L}}{\partial(\partial_\mu \phi)}\delta \phi=Z_2 q\bar{\Psi}\gamma^\mu\Psi\alpha\equiv Z_2 j^\mu \alpha$$ Where $j^\mu$ is defined to be $q\bar{\Psi}\gamma^\mu\Psi$. Plugging that into Ward identity (eq. (22.26) of Srednicki), we can obtain: $$\begin{aligned} iZ_2 k_\mu & \langle \Omega|\mathrm{T}\{\tilde{j}^\mu(k)\tilde{\Psi}(q_1)...\tilde{\Psi}(q_n)\tilde{\bar{\Psi}}(p_1)...\tilde{\bar{\Psi}}(p_n)\}|\Omega\rangle \\&=e\sum_{i}\langle \Omega|\mathrm{T}\{\tilde{\Psi}(q_1)...\tilde{\Psi}(q_i-k)...\tilde{\Psi}(q_n)\tilde{\bar{\Psi}}(p_1)...\tilde{\bar{\Psi}}(p_n)\}|\Omega\rangle \\&-e\sum_{j}\langle \Omega|\mathrm{T}\{\tilde{\Psi}(q_1)...\tilde{\Psi}(q_n)\tilde{\bar{\Psi}}(p_1)...\tilde{\bar{\Psi}}(p_i+k)...\tilde{\bar{\Psi}}(p_n)\}|\Omega\rangle \end{aligned}$$ Where the Fourier-transformed correlation function was defined to be: $$\begin{aligned} \langle \Omega&|\mathrm{T}\{\tilde{j}^\mu(k)\tilde{\Psi}(p_1)...\tilde{\Psi}(p_n)\tilde{\bar{\Psi}}(q_1)...\tilde{\bar{\Psi}}(q_n)\}|\Omega\rangle\equiv \\& e\int d^4x\int d^4x_1...\int d^4y_1... e^{ikx}e^{-iq_1x_1}...e^{ip_1y_1}...\langle \Omega|\mathrm{T}\{\bar{\Psi}(x)\gamma^\mu\Psi(x)\Psi(x_1)...\Psi(x_n)\bar{\Psi}(y_1)...\bar{\Psi}(y_n)\}|\Omega\rangle. \end{aligned}$$ Using Schwinger-Dyson equation of $\langle\Omega|\mathrm{T}\{A_\mu\Psi\bar{\Psi}\}|\Omega\rangle$, we have (working in Feynman gauge): $$-Z_3 \partial^2\langle \Omega|\mathrm{T}\{A_\mu(x)\Psi(y)\bar{\Psi}(z)\}|\Omega\rangle=Z_1 \langle \Omega|\mathrm{T}\{j_\mu(x)\Psi(y)\bar{\Psi}(z)\}|\Omega\rangle.$$ After Fourier transform, that became: $$Z_3 k^2\langle \Omega|\mathrm{T}\{\tilde{A}_\mu(k)\tilde{\Psi}(q)\tilde{\bar{\Psi}}(p)\}|\Omega\rangle=Z_1 \langle \Omega|\mathrm{T}\{\tilde{j}_\mu(k)\tilde{\Psi}(q)\tilde{\bar{\Psi}}(p)\}|\Omega\rangle.$$ Using Feynman diagrams to evaluate the LHS, we can get: $$\langle \Omega|\mathrm{T}\{\tilde{j}_\mu(k)\tilde{\Psi}(q)\tilde{\bar{\Psi}}(p)\}|\Omega\rangle=Z_1^{-1}Z_3(2\pi)^4\delta^4(k+p-q)(\delta_{\mu\nu}+\Pi_{\mu\rho}(k)\Delta^{\rho}_{\ \nu}(k)+\cdots)(\frac{1}{i}S(q))(iV^\nu(p,q,k))(\frac{1}{i}S(p))$$ Where $V^\mu$ is the 1PI vertex, and $S(p)$ is the exact fermion propagator. From local gauge invariance, we know that $k_\mu \Pi^{\mu\nu}(k)=0$. So contracting the equation above with $k_\mu$ yields: $$ik_\mu \langle \Omega|\mathrm{T}\{\tilde{J}^\mu(k)\tilde{\Psi}(q)\tilde{\bar{\Psi}}(p)\}|\Omega\rangle=Z_1^{-1}Z_3(2\pi)^4\delta^4(k+p-q)k_\mu S(q)V^\mu(p,q,k)S(p).$$ Combining that with Ward identity: $$Z_2 Z_1^{-1}Z_3(2\pi)^4\delta^4(k+p-q)k_\mu S(q)V^\mu(p,q,k)S(p)=(2\pi)^4\delta^4(k+p-q)e [S(p)-S(q)].$$ And we can finally get: $$Z_3 k_\mu V^\mu(p,q,k)=Z_1 Z_2^{-1} e[S^{-1}(q)-S^{-1}(p)].$$ It turns out that there's an extra factor $Z_3$ in my result, compared to the correct Ward-Takahashi identity $$k_\mu V^\mu(p,q,k)=Z_1 Z_2^{-1}e(S^{-1}(q)-S^{-1}(p)).\tag{68.12}$$ I know that the result I've got must be wrong since LHS is infinite but RHS is finite. But I can't figure out where's wrong in the derivation. Where's my mistake? | In QED, according to Schwinger-Dyson equation $^{[1]}$, $$\left(\eta^{\mu\nu}(\partial ^2)-(1-\frac{1}{\xi})\partial^{\mu}\partial^{\nu}\right)\langle 0|\mathcal{T}A_{\nu}(x)...|0\rangle = e\,\langle 0|\mathcal{T}j^{\mu}(x)...|0\rangle + \text{contact terms}.$$ And the term $\left(\eta^{\mu\nu}(\partial ^2)-(1-\frac{1}{\xi})\partial^{\mu}\partial^{\nu}\right)$ is just the inverse bare photon propagator$^{[5]}$, so if we put the photon on shell, then the l.h.s will yield the complete $n$-point Green function with the complete photon propagator removed and also multiplied by a factor $Z_3$, the vector field renormalization constant. But the r.h.s gives, according to the Ward Identity associated with global symmetry of the Lagrangian, $$\partial_{\mu}\, \langle 0|\mathcal{T}j^{\mu}(x)...|0\rangle = \text{contact terms}^{[2]}$$ which is the sum of complete $(n-1)$-point complete Green functions each multiplied by a certain $\delta$ function. So if we truncate all the $n-1$ external complete propagators, then we are left with the proper vertex Ward identity. The problem is, now the constant $Z_3$ appeared. For, example, if we apply this to $j^\mu=\bar\psi\gamma^\mu\psi$, $$\partial_{\mu}\, \langle 0|\mathcal{T}j^{\mu}(x)\psi(x_1)\bar\psi(x_2)|0\rangle = -ie[\delta(x-x_1)\langle 0|\psi(x_1)\bar\psi(x_2)|0\rangle-\delta(x-x_2)\langle 0|\psi(x_1)\bar\psi(x_2)|0\rangle]^{[3]},$$ we will get an identity containing $Z_3$ RATHER THAN the well known proper vertex Ward identity (which is derived from the gauge or local symmetry of the Lagrangian), e.g. $$q_\mu\Gamma^\mu_P(p,q,p+q)=S^{-1}(p+q)-S^{-1}(p)^{[4]}$$ which doesn't contain $Z_3$. Where went wrong? Please help. [1]. Peskin&Schroeder, An Introduction to Quantum Field Theory, page308, eq.(9.88) [2]. Peskin&Schroeder, An Introduction to Quantum Field Theory, page310, eq.(9.97) [3]. Peskin&Schroeder, An Introduction to Quantum Field Theory, page311, eq.(9.103) [4]. Lewis H.Ryder, Quantum Field Theory, page 263-266, eq.(7.112) [5]. Peskin&Schroeder, An Introduction to Quantum Field Theory, page297, eq.(9.58) |
In every picture we see that galaxies are spiral, why so? are there any other shapes possible? | Question: As we know, (1) the macroscopic spatial dimension of our universe is 3 dimension, and (2) gravity attracts massive objects together and the gravitational force is isotropic without directional preferences. Why do we have the spiral 2D plane-like Galaxy(galaxies), instead of spherical or elliptic-like galaxies? Input: Gravity is (at least, seems to be) isotropic from its force law (Newtonian gravity). It should show no directional preferences from the form of force vector $\vec{F}=\frac{GM(r_1)m(r_2)}{(\vec{r_1}-\vec{r_2})^2} \hat{r_{12}}$. The Einstein gravity also does not show directional dependence at least microscopically. If the gravity attracts massive objects together isotropically, and the macroscopic space dimension is 3-dimensional, it seems to be natural to have a spherical shape of massive objects gather together. Such as the globular clusters, or GC, are roughly spherical groupings , as shown in the Wiki picture: However, my impression is that, even if we have observed some more spherical or more-ball-like , it is more common to find more-planar such as our ? (Is this statement correct? Let me know if I am wrong.) Also, such have a look at this more-planar Spiral "galaxy" as this NGC 4414 galaxy: Is there some physics or math theory explains why the turns out to be planar-like (or spiral-like) instead of spherical-like? See also a p.s. Other than the classical stability of a 2D plane perpendicular to a classical angular momentum, is there an interpretation in terms of the quantum theory of vortices in a macroscopic manner (just my personal speculation)? Thank you for your comments/answers! |
Whenever i run the app, enter the name and press the submit button the app crashes.Here's the code public class MainActivity extends AppCompatActivity { int x, sum=0; String str,str2; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Toolbar toolbar = findViewById(R.id.toolbar); setSupportActionBar(toolbar); final Button chk = findViewById(R.id.check); final Button sub = findViewById(R.id.submit); final EditText name = findViewById(R.id.name); chk.setEnabled(false); sub.setOnClickListener( new View.OnClickListener() { public void onClick(View view) { x = str.length(); str = name.getText().toString(); if (x >= 4 && x <= 10) chk.setEnabled(true); } }); And here's the xml code for the submit button <Button android:id="@+id/submit" style="@style/Widget.AppCompat.Button.Colored" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:text="@string/submit" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> I'm a beginner and it's my first app so please excuse me if you find it a naïve question. The following is the logcat message: 12-11 22:55:20.678 4277-4277/com.example.shantanu.namerank D/AndroidRuntime: Shutting down VM 12-11 22:55:20.702 4277-4277/com.example.shantanu.namerank E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.shanu.namerank, PID: 4277 java.lang.NullPointerException: Attempt to invoke virtual method 'int'java.lang.String.length()' on a null object reference at com.example.shanu.namerank.MainActivity$1.onClick(MainActivity.java:32) at android.view.View.performClick(View.java:5610) at android.view.View$PerformClick.run(View.java:22265) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) | 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? |
I've recently started working on a custom D8 module. I've used $this->t() (or t()) wherever I had to output a text so that this text would then be translatable. My module works correctly, but when I visit Drupal's "User interface translation" (admin/config/regional/translate) page, those strings are nowhere to be found. Two examples: _1. in the mymodule.module file, I have implemented the hook_help() function to display a help page in the admin: <?php /** * Implements hook_help(). */ function mymodule_help($route_name, RouteMatchInterface $route_match) { switch ($route_name) { case 'help.page.mymodule': return t('<p>Here is the (much longer) help text.</p>'); } } ?> The help page is visible in the admin and shows the text; however this text cannot be found in the "User interface translation" page. _2. the module has a configuration page in the admin, with several fields and a description for each field. This configuration form is defined in src/Form/mymoduleForm.php: <?php namespace Drupal\mymodule\Form; use Drupal\Core\Form\ConfigFormBase; use Drupal\Core\Form\FormStateInterface; class mymoduleForm extends ConfigFormBase { /** * {@inheritdoc} */ public function buildForm(array $form, FormStateInterface $form_state) { // Form constructor. $form = parent::buildForm($form, $form_state); $config = $this->config('mymodule.settings'); $form['field1'] = array( '#type' => 'textfield', '#title' => $this->t('The first field:'), '#default_value' => $config->get('mymodule.field1'), '#description' => $this->t('<p>Description for this field.</p>'), '#required' => TRUE, ); // and so on } // other code } ?> Here again, the configuration page works, all the fields are visible, but none of the strings in the code above appear on the "User interface translation" page (neither the title of the string, nor the description). The same goes for strings declared in the *.yml files: they're supposed to be picked up automatically by Drupal, but I don't seen any of them in the interface... (e.g. the module description in the *.info.yml file.) What am I missing? | In my module I have some custom strings. I use these in the t() function. When I go to admin/config/regional/translate/translate and filter the untranslated strings my custom strings do not show here. What could be going wrong? |
Although, the question is displayed correctly with MathJax when opened. App Version: 1.0.85 Device Manufacturer: Spreadtrum Device Model: Celkon A35K OS Version: 4.4.2 (eng.root.20140613.225402) | See this screenshot: MathJax is now enabled for the Android app (yay!). However, it doesn't work in titles. Could this be fixified? |
I am trying to upgrade to Drupal 9, but I have two modules that aren't compatible. I patched both the modules to make them compatible. However, I can't upgrade to Drupal 9. When I do, it tells me those modules don't meet the requirements, which of course is true, since they need to be patched. How can I upgrade to Drupal 9 if those modules initially don't meet the requirements? | Given I have Drupal 9 composer installation with composer-patches plugin and given a contrib module with a stable v8 release, but no v9 release (not even dev branch) and given that contrib module has a working v9 patch in the issue queue is there any method to install that module + patch in composer? Even if I manually add both, the package and patch, to my composer.json, I still can't require or update this module with composer due conflicting versions. I really want to avoid duplicating /contrib code into my project's /custom codebase. My current workaround is: forking that module to my own, private git repo applying patch there creating a new composer.json in my private git, and changing the package vendor to my custom_private_vendor adding my private git as VCS repo in the D9 project's composer.json and then composer require custom_private_vendor/contrib_module This fulfills my goal of not duplicating the contrib module in my project's custom codebase, but every time I do this I feel the urge to wash my dirty hands. Is there something more elegant like composer require drupal/contrib_module --apply-patch-first or can I somehow target drupal.org's git with a specific patch included? |
Thanks to , I know it is possible to float and wrap text around a listing. I would like to setup an environment for mini-code snippets that always floats and wraps the same way. I can achieve the effect manually, but every attempt I have made at combining the environments falls flat. Here is a MWE that shows what I'm after and what doesn't work: \documentclass{scrartcl} \usepackage{listings} \usepackage{blindtext} \usepackage{wrapfig} \lstnewenvironment{mysnippets}[1][]{% \lstset{aboveskip=-12pt,belowskip=-12pt,caption=#1,captionpos=b} \ttfamily }{% } \lstnewenvironment{yoursnippets}[1][]{% \lstset{aboveskip=-12pt,belowskip=-12pt,caption=#1,captionpos=b} \wrapfigure{R}{.5\textwidth} \ttfamily }{% \endwrapfigure } %% This sort of arrangement doesn't work %\newenvironment{oursnippets}{% % \wrapfigure{R}{.5\textwidth} % \mysnippets[test] %}{% % \endmysnippets % \endwrapfigure %} \begin{document} \subsection*{This works if you do it by hand} \begin{wrapfigure}{R}{.5\textwidth} \begin{mysnippets}[ac karni cozumu] if (aciktim) { manti yeyeyim } \end{mysnippets} \end{wrapfigure} \blindtext \subsection*{This arrangement floats but not to anywhere useful} \begin{yoursnippets}[ac karni cozumu] if (aciktin) { manti yeyin } \end{yoursnippets} \blindtext %\subsection*{This and all my other attempts don't even compile} % %\begin{oursnippets}[ac karni cozumu] %if (aciktik) { % manti yeyelim %} %\end{oursnippets} %\blindtext \end{document} Which currently only produces something like: I am not attached to wrapfig, but would really prefer to stick with listings as possible since I use it extensively for larger blocks of code samples already. Is there a way to combine these environments so I have a snippets environment that always floats here and wraps, but is typeset by listings? | For some teaching I've been doing, I'd like to have code from two different languages side-by-side. To do so, I hacked together a newcommand which uses a tabular environment to arrange two verb environments, but the problems are myriad: Indentation can only be accomplished by changing spaces to ~'s Any math symbols have to be escaped with \, which requires knowing which ones to escape and which ones not to (can't escape the <'s for instance, otherwise it complains) The <- assignment operator gets changed into an upside down !- when compiled. The listings environment doesn't work either. Error message is: Runaway argument? ! Forbidden control sequence found while scanning use of \lst@next. <inserted text> \par l.23 \codeListing{x <- y}{f(g(x))} Here's some code to reproduce the problem: \documentclass[english]{article} \usepackage[latin9]{inputenc} \usepackage{geometry} \begin{document} \newcommand{\codeListing}[2]{ \begin{tabular}{p{8cm} p{8cm}} \begin{lstlisting} #1 \end{lstlisting} & #2\tabularnewline \end{tabular} } \section{verbatim test} \begin{verbatim} logLik <- function(x) { y <<- x^2+2 return(sum(sqrt(y+7))) } \end{verbatim} \section{codeListing test} \codeListing{}{ logLik <- function(x) \{ ~~y <<- x\^2+2 ~~return(sum(sqrt(y+7))) \} } \end{document} Is there any way to make a newcommand wrap parameter-passed code? It doesn't have to be keyword-highlighted or do any of the other tricks that the fancier packages do; it just has to preserve whitespace and no interpret code as latex commands. |
My son cannot break blocks anywhere, in any mode. ALso he cannot attack anything. He tried using the Wiki; but no success. He tried breaking dirt with a shovel, he tried breaking stone with a pickax, he tried to attack slimes with a sword, nothing works. help! | I'm playing on a Survival world with cheats on, "easy" difficulty, and at night in-game. I didn't have a sword or anything to make a sword with, and I was starving, so I switched to Creative to give myself a stack of food and a bed to set my spawn point. When I switched back to Survival, I couldn't destroy or place blocks. I'm on single player, and my Internet is fine, and I can destroy blocks still if I switch to creative. I've tried resetting the button one, and reloading the map, and it still doesn't work. I've even tried deleting everything I gave myself in Creative. This happened before on a different world and I ended up deleting it. This only happens on this world. How do I fix it? If I know I'm in the correct game mode, what else can cause this? Are there different causes in multiplayer? |
I was told that to achieve the same font that appears on the following screenshot, I had to use \usepackage{lmodern}. But IMHO it does not look the same: DESIRED: MINE: \documentclass{article} \usepackage{lipsum} \usepackage{xstring} \usepackage{lmodern} \usepackage{amsmath} \newcommand{\mystring}{Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis. Curabitur dictum gravida mauris. Nam arcu libero, nonummy eget, consectetuer id, vulputate a, magna. Donec vehicula augue eu neque. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Mauris ut leo. Cras viverra metus rhoncus sem. Nulla et lectus vestibulum urna fringilla ultrices. Phasellus eu tellus sit amet tortor gravida placerat. Integer sapien est, iaculis in, pretium quis, viverra ac, nunc. Praesent eget sem vel leo ultrices bibendum. Aenean faucibus. Morbi dolor nulla, malesuada eu, pulvinar at, mollis ac, nulla. Curabitur auctor semper nulla. Donec varius orci eget risus. Duis nibh mi, congue eu, accumsan eleifend, sagittis quis, diam. Duis eget orci sit amet orci dignissim rutrum.} \begin{document} \StrBefore[90]{\mystring}{ } \begin{equation} \dfrac{\partial C_{ui}}{\partial b_{u}} = - \text{err}_{ui} + \lambda b_{u} \end{equation} \end{document} Last but not least, how can I get this T? | Is it possible to identify the font used in a specific document/picture? Answers to this question should identify: Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y"). This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's tag. |
I'm looking for an old sci-fi story about large alien creatures that are immobile, building layers of hard shell around them. They use the planets mobile apex creatures (ape-like creatures) for fertilisation, bringing them inside their bodies and pressing them up against a surface that they bite and scratch at, which causes fertilisation, before the Mother creature digests them. I larremember part of the story being this creatures description of the layers she built around herself, using metals and minerals from the surrounding rocks. She also repositioned her stomach and other internal organs for better use, and there was a large canid type creature that managed to gouge it's way through her early shell, only to fall into and cook in her repositioned stomach. The first part of the story is told by the female, about her beginning and devolment (from memory) and then later a male and female human explorer come to the planet and are captured by these creatures. The male is kept within the mother for some time till he fertilises her and then she intended to digest him, but somehow they end up communicating and she keeps him around for company. He is there long enough to witness the birth of her babies and plays with and interacts with them inside her big spongy cavity where he lives. He tries to make her understand that the other human he was with was female, a mother herself, but the alien creature is greatly disturbed by this concept as the only "mothers" on the planet are the immobiles like herself. That's as far as I got through the story and would like to finish it, if only I could remember what it was. I keep thinking the term "mother" is relevant but can't find anything online about sci-fi stories with that title. Think it was originally something from my dad's collection that I read back in the 80's but he doesn't remember either. | In the story, the man (a marooned astronaut on an alien planet, perhaps) is living inside a sealed cave. The cave is sentient, and speaks to the man, and even provides food and water. There's a weird scene where the cave wants to "become pregnant", and the only way for that to happen is for the man to use a knife to rip into a membrane in the cave... but there's danger involved, because the process (as with a black widow spider) involves the death of the one doing the membrane-shredding. The sentient cave somehow overcomes the instinct to kill the man, who has become her friend. It was a bizarre story, probably from one of those Best Of ...." Books from the old Science Fiction Book Club. |
When I upgrade my Ubuntu 14.04 to 16.04 and download new packages, I saw the following error message: Failed to fetch http://in.archive.ubuntu.com/ubuntu/pool/main/f/fonts-noto-cjk/fonts-noto-cjk_1.004+repack2-1~ubuntu1_all.deb Size mismatch | After installing Ubuntu 12.04 (clean install) I fetch a bunch of program via synaptic (installed specially), all programs worked except Gimp 2.8. So I tried purging Gimp, install again (no luck). Checked broken packages and reinstalled them. When using the Software center I get this MSG: Failed to fetch http://is.archive.ubuntu.com/ubuntu/pool/main/o/openexr/libopenexr6_1.6.1-4.1_amd64.deb Size mismatch Tried also this: sudo apt-get purge gimp* sudo add-apt-repository ppa:otto-kesselgulasch/gimp sudo apt-get update sudo apt-get install gimp And get this MSG: Failed to fetch http://is.archive.ubuntu.com/ubuntu/pool/main/o/openexr/libopenexr6_1.6.1-4.1_amd64.deb Size mismatch E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? I am wondering if the Icelandic Archive has an outdated version or something? would really like to install Gimp 2.8 but Gimp 2.6 is OK to. I am also wondering if I am doing something wrong? |
"My patient has been under my care from January 1st to Jan. 19th." "My patient has been under my care from Jany 1st through Jan. 19th." Do both of these windows of time include the 19th as part of the span of time that the patient was under the doctor's care? thanks! | The study was carried out up to visit 11 under the name of X1, whereas all later visits were carried out under a different name, X2. In the above sentence, does V11 belong to X1 or X2? I want the sentence to mean that V11 was included in X1, how should the sentence be then? |
For a one-man company which is planning to hire a small staff, I'm considering transforming a former small form factor desktop into a server to deliver files through SFTP. As a basis for evaluation, let us estimate that the staff will gradually increase to 5 people. I have several possible candidate machines, which all have quad-core Intel vPro i5 or i7, Gen2 processors. I wonder if i5 is enough to ensure a smooth user experience in this context ( — I assume so because better than most processors we can see in small NAS —), or if an i7 is recommended. Details of the upgraded desktop: SFF computer with Intel i5/i7 (Gen2) quad-core processor professional SATA SSD with MLC NAND (e.g. Intel DC S3500, Samsung 860 PRO, SanDisk Extreme PRO) 8 GB RAM DDR3 10600U CentOS in console mode (or with a lightweight desktop) Processors of candidates machines: i5-2500 3.3 GHz (max. 3.7 GHz Turbo), 6 MB cache, 4 cores, 4 threads i7-2600 3.4 GHz (max. 3.8 GHz Turbo), 8 MB cache, 4 cores, 8 threads Detail of requirements: The purpose is to allow a small staff (max. 5 people) to access to CAD drawings and excel files remotely. I plan using an SFTP mapping software on the client laptops, so that each user can see the files like if they were on his own computer. The files are transfered through SFTP, behind the scenes. So basically, the server will act like a NAS, but offer the comfort of a true computer, making easy to connect a screen, keyboard or backup drive. There is no need for remote desktop. All ressource-hungry things (e.g. viewing a CAD drawing) are client-side. In the past, for a larger team, I have used a true server (e.g. Dell PowerEdge T310 with Xeon X3400, 8GB RAM DDR3 ECC, SAS HDD in mirror, CentOS). But this time, the team is smaller, 1-3 people (max. 5). We want to save space, limit noise, power consumption, and save some money as well. N.B. I'm aware of VPS servers, but running own server offers more comfort, especially for backups, privacy and additional "local" security in case of a network outage at the ISP. So, running own server is a deliberate choice. | This is a about Related: I have a question regarding capacity planning. Can the Server Fault community please help with the following: What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application? |
Plase explain with an example the form correct of: $ \displaystyle {\limsup_{n\to \infty} s_n = s^* }$ with Rudin definition, because $s^* =\sup E $ and $ E $ is all point of subsequential limits. Because iam confused. | Here are two equivalent definitions of $\limsup_{n\rightarrow\infty} a_n$: Let $u_n=\sup\{a_n, a_{n+1}, a_{n+2},\ldots\}$. Then $$\limsup_{n\rightarrow\infty} a_n = \lim_{n\rightarrow\infty} u_n = \lim_{n\rightarrow\infty}\left(\sup\{a_n,a_{n+1},\ldots\}\right)$$ Let $E$ be the set of all subsequential limits of $\{a_n\}$. Then $$\limsup_{n\rightarrow\infty} a_n = \sup E$$ I'm curious as to which one people usually learn first, or which one people find more intuitive. Baby Rudin only has the second definition, but doesn't mention the first as far as I know. As far as intuition, I think of the second definition as "the biggest limit point." I'm not sure how to think of the first definition though. I can see that $u_n \ge u_{n+1}$ for all $n$, but I'm not sure how to interpret the limit of those $u_n$ conceptually. Are there any other ways to conceptualize $\limsup$? |
If I am travelling in a train and the train accelerates forward then I experience a pseudo force backward. But if someone is free falling under gravity where does he experience pseudo-force because pseudo is experienced in an accelerated frame. | Note: For the purposes of my question, when I refer to free fall assume it takes place in a vacuum. From my (admittedly weak) understanding of the equivalence principle, falling in a gravitational field is physically indistinguishable from floating in interstellar space. This would make sense to me if gravity simply caused an object to move at a constant velocity. Moving at a constant speed, or floating in space, are just two different ways of describing an inertial frame, and are fundamentally no different. But free falling in a gravitational field means accelerating continuously, and doesn't an accelerating body experience a force? Then isn't free falling fundamentally different from floating in space? |
Let $\mathbb{Q}(\sqrt{d}) = \{a + b \sqrt{d}: a,b \in \mathbb{Q} \}.$ Show that $\mathbb{Q}(\sqrt{d})$ is a field. Everything seems obvious except for existence of inverses in the multiplicative group of $\mathbb{Q}(\sqrt{d}).$ Suppose $\alpha \in \mathbb{Q}(\sqrt{d}) \Longrightarrow \alpha = a + b \sqrt{d}.$ To prove that $\mathbb{Q}(\sqrt{d})$ contains multiplicative inverses, observe that for a non-square $d$ and $a - b\sqrt{d} \ne 0$ one has $$\frac{1}{\alpha} = \frac{1}{a+b\sqrt{d}} \cdot \frac{a - b \sqrt{d}}{a - b \sqrt{d}} = \frac{a}{a^2-b^2d}- \frac{b}{a^2-b^2d} \sqrt{d}.$$ If $a,b \in \mathbb{Q} \Longrightarrow a^2,b^2 \in \mathbb{Q} \Longrightarrow b^2 d \in \mathbb{Q}$ (since $d \in \mathbb{Z}$) $\Longrightarrow a^2-b^2d \in \mathbb{Q} \Longrightarrow \frac{a}{a^2-b^2d}, \frac{b}{a^2-b^2d} \in \mathbb{Q}.$ Hence $\frac{1}{\alpha} \in \mathbb{Q}(\sqrt{d}).$ Is this correct? | For which $c$ will the set $K(c) = \{a + b\sqrt{c} : a, b \in \mathbb{Q}\}$ be a field? I know for example, that $K(\frac{2}{3})$ will be one, I am just wondering what the most general result of this type is. |
How exactly does k-means clustering for categorical data work? I have a dataset which has several categorical features that can have 2,3,4,..,n values. I could one hot encode them, but I'm not sure if it even makes sense because k-means uses a distance metric. I looked into k-prototype clustering, but tried it on my dataset, but plotting it does not make sense when the y-axis and y-axis are just integer values that are small. | My data set contains a number of numeric attributes and one categorical. Say, NumericAttr1, NumericAttr2, ..., NumericAttrN, CategoricalAttr, where CategoricalAttr takes one of three possible values: CategoricalAttrValue1, CategoricalAttrValue2 or CategoricalAttrValue3. I'm using default . It works with numeric data only. So my question: is it correct to split the categorical attribute CategoricalAttr into three numeric (binary) variables, like IsCategoricalAttrValue1, IsCategoricalAttrValue2, IsCategoricalAttrValue3 ? |
Say a wizard has a major bloodline. Is their maximum level wizard-17/bloodline-3(in which case they only have 17 HDs), or wizard-20/bloodline-3 (in which case their total caster level is 23)? This isn't so much about if bloodline increases ECL for the purpose of XP requirements (that's been answered) as it is if bloodline-granted ECL results in fewer class levels. | , in all their weird but flavorful glory. For those who don't know, bloodlines are kind of like a racial template that gives you more abilities as you level up. Instead of having a level adjustment, you have to take pseudo-levels (1-3 of them) in the bloodline by certain points in your career. I'd always assumed those increased your ECL (effective character level, important for things like XP) like a regular level, but a guidebook I just read claimed otherwise. Sure enough: Class levels of "bloodline" do not increase a character's character level the way a normal class level does, but they do provide certain benefits (see below). So, do bloodlines not increase your ECL? |
Sorry as this is a rather soft question, but I'm really struggling to get to grips with some packages for this (espcially since I really don't care about learning all the in's and out's). I literally just want the Petersen graph, $C_3$ and $C_6$. The problem with finding the pictures online is that the graphs will look inconsistent (different sizes of nodes etc from different webpages). | I need to draw simple graph (for example ) in LaTeX. I am using Kile in Ubuntu. I exactly don't know that which package should I use. Any suggestion with example is highly expected. |
list1 = [1, 2, 3, 4] element = list1[1:][1] print(element) Why does it print 3? How is this evaluated? Does it first take the elements of list1 that are from index 1: then it takes the 1 index of that? | I need a good explanation (references are a plus) on Python's slice notation. To me, this notation needs a bit of picking up. It looks extremely powerful, but I haven't quite got my head around it. |
How can I put my name in the lower corner of my pictures using Photoshop? Specifically, how can I put my name in mass numbers of my pictures using Photoshop? I have 1500 photos from a recent biology trip that need my name in them so people know that the works are mine. I can do it one by one, but is there a faster way to do it? | I have around 15,000 JPG files that need to be watermarked. Is there any way to process these images en masse and add a watermark? The images may be different sizes, I want the watermark placed in the center of the images. |
I am trying to install a vagrant instance while I am sitting in a group on a congress. Since we don't have such a big bandwidth here, I would like to limit the bandwidth of the initial download of the vagrant box. Is there a simple way how to limit the throughput of my wireless card right now? | I am getting complaints that I consume lots of internet bandwidth. Is there any software that can limit internet bandwidth on my computer from my own computer? I use Firefox as browser and use bittorrent and download software from software center. (Is there also a way to monitor it?) |
I'm trying to connect to a FTP to upload a file from a cent os box. I can access to the server, but the connection times out whenever I try to upload with 'put' command. I can upload a file without a single problem on my local machine. It sounds like a port issue. I've already opened outbound port 21. Are there any other ports that I need to open for uploading? logs ftp> put localFile remote 227 Entering Passive Mode. ftp: connect: Connection timed out | Whenever I install vsftpd on centos, I only setup the jail environment for the users and rest is default configuration of vsftpd. I create user and try to connect with filezila ftp client, but I could not connect with passive mode. I always change the transfer settings to active mode to successfully connect to the ftp server otherwise I get Error: Failed to retrieve directory listing So is there a way to change any directive in vsftp.conf file and we can connect with passive mode to the server? |
I have some bibliography entries with points in the title field like "org.apache.lucene.analysis" or "java.util.Date". As there is no linebreak after ".", the text runs over the page margin in some cases. Is there a way to change this behaviour? | I have an BibLaTeX entry which causes in \printbibliography command a overful hbox. How can I tell BibLaTex that a line break is allowed without a minus symbol? In my case I have a text like ABC.learning. I want to allow BibLaTex to break the line after the dot. |
I watched a documentary on monkey flying into black hole and what it would perceive. Entire history of the universe redshifted in all directions, but without any way of knowing it's passed event horizon. Isn't it what we are seeing? In addition, universe is accelerating towards all directions, which would be perfectly explicable if we were inside the black hole which, as I understand, would be in all directions, because our entire future cone would be pointing there. EDIT: is NOT a duplicate as I am discussing a perceived differences, not only plausibility of this actually being true. | I was surprised to only recently notice that An object of any density can be large enough to fall within its own Schwarzschild radius. Of course! It turns out that supermassive black holes at galactic centers can have an average density of less than water's. Somehow I always operated under the assumption that black holes of any size had to be superdense objects by everyday standards. Compare the Earth to collapsing into a mere 9mm marble retaining the same mass, in order for the escape velocity at the surface to finally reach that of light. Or Mt. Everest packed into one nanometer. Reading on about this , it increases proportionally with total mass. Assuming matter is accumulated at a steady density into a spherical volume, the volume's radius will only "grow" at a cube root of the total volume and be quickly outpaced by its own gravitational radius. Question: For an object the , what would have to be its diameter for it to qualify as a black hole (from an external point of view)? Would this not imply by definition that: The Earth, Solar system and Milky Way are conceivably inside this black hole? Black holes can be nested/be contained within larger ones? Whether something is a black hole or not is actually a matter of perspective/where the observer is, inside or outside? |
This is a question about biasing 0V-referenced AC input signals to a positive single-ended signal. Even if the best solution for my question would be something else (and I'd like to hear about that, too,) I'd still mainly like to learn about the biasing question. I have searched all the "biasing analog video signal" posts in here, as well as googled datasheets, and I haven't actually found one that answers the questions I ask here. Just searching the titles of other posts is misleading, because they have other requirements (using other devices, different power supplies, etc.) The suggested duplicate question "AC-Coupling on Composite video" talks about re-processing the signal, which I explicitly do NOT want to do. Question Background I have a remote operated robot with a video camera generating a composite video signal going into a transmitter. I'd now like to switch the transmitter between two separate cameras. I don't need genlock (synchronized pictures); I'm OK with the "glitch" that happens when switching between unsynchronized signals. Weight is important, and sticking to the current design of the control systems of the robot is important. I have looked at dedicated "video switching" ICs. The older ones, like MAX4566 and NJM2595, are generally bipolar, and require dual power supplies (+/- 3-12V.) I only have a single end power supply (5V) and ground easily available. (The video signal, generated by the camera(s), is referenced the the ground I have available.) The newer "video switching" ICs (like the TS3V330) are all for digital video differential signals (HDMI etc.) They do not work with input signals less than 0V. A simple SPDT switching IC like the SN74LVC1G3157 is readily available, but it has protection diodes from input signal to ground and to VCC. This means that the negative half of the input signal swing will be clamped by the diode to ground. (once the diode voltage drop of 0.3V or so has been overcome) Actual Question The AC signal centered around 0V is generated by an output stage in the camera (or other video equipment) like this: The input to the transmitter, and other video processing devices, looks something like this: (Illustrations shamelessly "borrowed" from the MinimOSD open source project schematics.) I would like to take two of these video signals in, and switch between them (without any specific sync requirements) into one output signal, which is forwarded to the transmitter input. I would like to not re-buffer and re-amplify the video signal. I could do that with an opamp with sufficient bandwidth, but that adds more parts and complexity. Call me lazy if you want! So, my question is: Can I switch this signal by biasing it using a simple resistor ladder, then switching it, then adding an output capacitor? If so, what should the values for that ladder be? What will happen to the 75 Ohm output impedance seen by the original transmitter, and the eventual receiver? Example: (If the output from the camera doesn't actually use an isolating capacitor, I'm in trouble, though.) Am I missing something else here, or would this "work" with reasonable signal quality? | Many sources say that composite video input should be AC-coupled. Voltage levels for blank, black and white signal are also specified. How is it possible to detect these voltage levels after AC coupling (aka dc-blocking capacitor)? Doesn't the DC-component (average) of the signal vary wildly depending if the content is all black (0V-0.3V) or all white (0V-1V)? |
I’m traveling from India to USA in which i got a 15 hour layover at London airport. My flight will land at London at 6 p.m. and other flight will take off at 9 a.m. next day. So an overnight stay. So will I be needing a transit visa? I don't want to get out of the airport. | Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have. |
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