I already have Windows 10 and ubuntu dual booted in my laptop and I would like to triple boot it with El Capitan.   Is it safe? And will it affect other OSes?


I can't connect a wireless network wifi network in Ubuntu 18.04 LTS I followed some tutorials on the internet and not working! Can anyone help me? I'm a really noob 😑 and new to this os! Please help me! As described in Ubuntu Desktop Guide>>Networking,web & email>>Wireless Networking>>Connect to a wireless network there is no thing as Wifi Not Connected in right side of top bar! What to do? Help me!! Here is the screenshot:  Here is the result when i run sudo lshw -c network in terminal, *-network description: Ethernet interface product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:01:00.0 logical name: eno1 version: 15 serial: f4:39:09:74:75:46 capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 firmware=rtl8168h-2_0.0.2 02/26/15 latency=0 link=no multicast=yes port=MII resources: irq:16 ioport:4000(size=256) memory:b1104000-b1104fff memory:b1100000-b1103fff *-network UNCLAIMED description: Network controller product: RTL8821CE 802.11ac PCIe Wireless Network Adapter vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:02:00.0 version: 00 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress cap_list configuration: latency=0 resources: ioport:3000(size=256) memory:b1000000-b100ffff


How should I add a realistic shadow to this?

I'm working on a mockup of a jQuery slider which can be found .   Now, I'm not the best graphic designer by any stretch of the imagination, and I can't seem to be able to get a realistic looking shadow. What I want is for the phone to appear as if it's standing on its side, but all of my attempts in Photoshop usually result in the phone looking like it's floating at a weird angle.  What I've tried so far (and failed at):   Added an elipse near the bottom of the phone and blurred it. This sorta worked but just doesn't look right. Added a rectangle and did the same as the previous bullet, but this looked worse. Tried using a drop shadow layer effect. This looked horrible.   Can anyone give me some suggestions?


During review, I found a superior solution. What now?

I received a journal paper for a review. The paper suggests a solution to an important problem, but the solution is very complicated and has mediocre performance. While reading the paper, I thought of a different solution, which is much simpler and has better performance (to give some scale: their solution is 1 page to write and 5 pages to prove; my solution is 5 lines to write and half a page to prove).  What should I do now?  A. Write my solution in the review, hoping the authors will remember to "thank the anonymous reviewer"?  B. Recommend that the paper published as is, then write a paper of my own with my improved solution?  C. Something else?  EDIT: Before I found the superior solution, I thought of recommending "resubmit with major revision", with the reasons that I mentioned above: your solution is too complicated and its performance is too weak.  However, now I am not sure it is the good course of action. A major revision may take a long time. The authors might even decide to delay or stop working on the paper without telling the editor (or me). Meanwhile, I will have to postpone the publishing of the superior solution for an indefinite amount of time. What do you think?


I'm trying to install i3 desktop environment and I just can't figure out how. I'm following tutorial . and I'm stuck on the line:  echo "deb http://debian.sur5r.net/i3/ $(grep '^DISTRIB_CODENAME=' /etc/lsb-release | cut -f2 -d=) universe" >> /etc/apt/sources.list.d/sur5r-i3.list   My terminal says Permission denied


Add title uniqueness to the heuristics for detecting low-quality questions

This feature request is a response to  Two days ago,  suggested that we . However, given that  (hat tip ) as well as ...  262  103   ... I suggest that we take it a step further. Let's extend the heuristics for detecting—and blocking—low-quality questions to enforce unique titles, or at least flag new questions with duplicate titles automatically. We can leave the precise heuristics of detecting a duplicate title up to the Stack Overflow development team. I have no delusions about the fact that a few questions will "slip through the cracks." The goal here is to be proactive about minimizing the number of duplicates, and I think that the best place to start is the existing heuristics for detecting low-quality questions. After all, duplicate question titles are bad for a number of reasons: They often indicate a question that is itself a duplicate, but perhaps just as importantly, they decrease the signal-to-noise ratio when searching for questions. I honestly can't think of any reason that duplicate question titles are helpful, unless you are asking for a solution to the same problem in a different programming language. Even then, I think that it would be acceptable to rephrase the question to say "How do I do X in (insert programming language here)?"  makes a good point about the potential problems with this solution:  I have a hunch that if we do that, people will find ways to circumvent it (changing case or punctuation, adding random spam), and we'll end up stuck in a an arms race.  We may get stuck in an arms race with some users, but I honestly think that many people new to Stack Overflow just don't understand the etiquette of asking questions here. If we could even convince people to rephrase their question more clearly 20% of the time, I think that it would be a tremendous boon to the community. Furthermore, remember that heuristics for low-quality questions already exist, arms race or no.


I'm reading this chapter   from a forecasting book.  The author has explained a linear regression model. Now this linear regression model will definitely have some errors in fit. For these errors, the author has listen certain characteristics, which should be taken into account. He assumes that these errors:   Have mean zero; otherwise the forecasts will be systematically biased. Are not autocorrelated; otherwise the forecasts will be inefficient as there is more information to be exploited in the data. Are unrelated to the predictor variable; otherwise there would be more information that should be included in the systematic part of the model.   The problem is that I'm not able to comprehend these and come up with an example to get a hang of these points. Could somebody point out some examples / situations from daily life so as to understand these points. For example the author wrote in point 2.] ..."there is more information to be exploited  in the data"...   What is this information? How does it come into being? If I don't even know how this information comes into existence, then how will I be able to understand its existence or effects for that matter?  Is  there a simple explanation with example for my question? I have been trying to understand this since quite some time, please help.


Can I view the Markdown-source of an unedited question/answer?

Once a post has been edited, you can go into the revision list, and click "View Source".  If a post has not been edited (and I don't have the edit privilege) is there any way to see the raw Markdown?  The reason I ask I because of  - it's impossible to see the source markdown, and how it's different from the rendered Markdown.  Not exactly a huge issue, just curious!


text inside an align without being aligned or influence the align

I have this code     \arg(z-z_1)=&\theta\\     \arg((x-x_1)+i(y-y_1))=&\theta\\     \frac{y-y_1}{x-x_1}=&\tan\theta \\     (\theta \mbox{ is a fixed angle so } \tan\theta \mbox{ is a constant.)}\\     y-y_1=&\tan\theta(x-x_1)\\ \mbox{( This is the equation of a straight line with gradient }\tan\theta      \mbox{ passing through the point )}(x_1,y_1).) \end{aligned}\)  And what I get is this  I would like that my text is aligned to the left without interfering my alignment


Remove duplicate array on the base of key in multidimendional array PHP

From following array key with ID 16 is comming twice. Hown can we remove this this duplicate ID. (REMOVE IF ID IS DUPLICATE OTHER FIELDS IGNORE)   Array    (      [1] => Array             (                 [ID] => 16                 [username] => dudda                 [message-time] => 2016-08-25 12:12:53             )     [2] => Array             (                 [ID] => 16                 [username] => dudda                 [message-time] => 2016-08-25 12:01:54             )    [3] => Array             (                 [ID] => 3                 [username] => himanshu                 [message-time] => 2016-08-15 12:53:38             )    [4] => Array             (                 [ID] => 15                 [username] => dawinder                 [message-time] => 2016-08-10 11:40:33             )     )


How do I join a Windows Active Directory?

We have a "mix-mode" Lab. and we want to migrate to Ubuntu, from Windows.  In this process, how do we add Ubuntu workstations to a Windows Domain / Active Directory ('AD') setup?


Damaged Indian passport UK visa application

Hi All  My wife has applied for UK tier 2 general visa and travelling to India to submit application. While we were checking documents for her we observed a small line near back cover page near binding (as shown in picture). Could you please let us know if this can cause any issue in application?  Thanks for your help.   The passport is absolutely fine and doesn’t have any other issue and binding is also perfectly fine.... it’s just this one line   This is related to visa application and also the threading hasn’t come out hence a separate question as other questions on this portal are related to threading coming off and people trying to travel with such passport and not applying visa.


How to resolve surprise and "instant actioning" initiating combat

DMed for the first time yesterday and one of the things I feel I need to sort out, among other comments, improvements, and similar, is how combat itself is actually initiated. The main example I want to use involves  attempting to generate surprise conditions by players. Here the characters have entered a ruined city and generally been noisy about the whole thing - using a spell to make their voice louder and literally ask if there is anyone about. Any enemies around probably know what something is about to kick off but arguably don't know precisely what. After resting the PCs head up a long flight of steps to a temple on the edge of the city. At the top only one crests and finds 3 bandits lounging around, chatting, and doing whatever bandits do in their spare time. After a brief exchange of pleasantries a combat starts:  DM "The bandit spits in your direction 'we're not done looting the temple, so you can clear off', and starts raising his crossbow as his mates emerge from their cover behind the pillars... PC "I cast Firebolt at Bandit Keith" DM "Hang on, I hadn't finished, everyone rolls for initiative...  Which sparked a debate about whether or not the PC could preemptively cast/attack before the combat starts by "instant actioning" (as above) as I was describing the start of the combat. As far as the bandits are concerned a lone half-elf who is pretty heavily armed has popped up in front of them, not even tried to be diplomatic, and ended up saying something rather suggestive about their mothers. The PC then asked about it being "surprise" because the bandits wouldn't necessarily expect an attack, but my view of "surprise" is closer to an ambush where one party is unaware of the other's existence. (This precise example is close to how  works, however this specific PC was always the first of the party to go into rooms (only one with darkvision) and consistently felt they should get free rounds at the start of combat based on declaring attacks before I could "start" the combat.) The second example the party came to more bandits, who were not alert immediately, in an underground room. They used magic to yell something obscene at the bandits and shut off all the torches so the bandits were effectively blinded. At this point they wanted to burst into the room casting spells, swinging maces, and playing some "meaty chords" (the bard's words, not mine). Again they wanted surprise arguing that, despite the fact that the bandits were yelling and cursing in confusion, they couldn't be sure they were actually being attacked as such. In the end a character with darkvision wanted to sneak in to a corner and again wanted surprise based on passing stealth rolls, so they would start the "combat" by firing a crossbow. At that point I think I relented because it was clear that they would do anything to try and win combats in a single round. In a nutshell, my question is: "how liberally can the concept of surprise be applied to combat - is it only when one party is literally unaware of a threat (as I read the rules), or just when they are caught slightly off guard by the exact situation?" NB I already plan to address the attempts at interrupting descriptions with actions next session, because it happened at other times and actually threw me off quite a bit.


Intuitive explanation of the half in the $\frac{1}{2}at^2$ distance equation?

The full equation  $$ Xf = X_o + V_o t + \frac{at^2}{2} $$  is integrated from the velocity function (which was integrated from constant acceleration function), right?  The problem is, I can't seem to put my mind around why the acceleration part needs to be halved.  Doesn't $at$ already measure the change in velocity over time? Why not just add that to the velocity then use the new V to measure Xf?


Why doesn't chmod work in my bash script? Error is something about the directory...?

Script is this: #!bin/bash echo "setpriv start" chmod u=rwx ./ * echo "setpriv end"  Output in bash window is this: robertk@HP_2013:~$ bash -x setpriv ' echo 'setpriv start setpriv start ' chmod u=rwx ./ '* chmod: cannot access '*'$'\r': No such file or directory ' echo 'setpriv end setpriv end robertk@HP_2013:~$ ^C  ????? Thanks -- something dumb / simple, I'm sure, but what???


How to assign an app to specific workspace with XFCE?

I would like to assign apps to workspaces, so every time an app is launched, it starts in specific workspace that it's assigned to. I'm using XFCE4 on Arch Linux.


What is swap and how large a swap partition should I create?

I have a system with 4gb of RAM and Intel i5 processor. I want to know how much memory I should allocate to SWAP. Will allocating more memory help increase the system performance.  In the past i have always allocated 4gb for SWAP.


Where can I ask about oauth plugins for PHP?

What is the appropriate SE site for asking about oauth plugins for PHP?


How to change keyboard layout in Lubuntu 15.10?

I have recently upgraded my PC from Lubuntu 14.10 to 15.10. Before the upgrade my keyboard layout matched my Danish keyboard. But after the upgrade I probably have a standard English/US layout.   Preferences/Language Support, doesn't let me configure the keyboard layout. Preferences/Keyboard and Mouse, only let me configure stroking delay and similar.    I don't know about iBus and fcitx, as far as the tooltip infomation tells me, its for more complex languages such as Chinese.  I don't have a US icon in the taskbar, no keyboard and/or language icon at all.  Things I have tried:   Running the following in a terminal works, but only until the next reboot:  setxkbmap -layout dk  I got the following parameter in the file /etc/default/keyboard:  XKBLAYOUT="dk"  Installing and running the app Lxkeymap changes the keyboard to Danish when I run it, but rebooting will change the layout back to US.   I don't want anything fancy, I just want to set my keyboard layout to Danish. How can I do that?


How does predicate logic handle contradictory statements about something that does not exist?

Let    p denote ringing telephone s denote someone   A denote answered   ¬∃x(Px) ∀x∃y((Px⋀Sy) →Ayx) ∀x¬∃y((Px⋀Sy) →Ayx)    So,    There are no ringing telephones.  Every ringing telephone was answered by someone. Every ringing telephone was not answered by someone.    Those three statements could all be true. (I believe 'vacuously true' is the term.) How does propositional logic treat them? How would one prove they are not contradictory?


Sampling with replacement or without replacement

I'm writing a program in R that simulates bank losses on car loans.  Here is the questions I'm trying to solve:  You run a bank that has a history of identifying potential homeowners that can be trusted to make payments. In fact, historically, in a given year, only 2% of your customers default. You want to use stochastic models to get an idea of what interest rates you should charge to guarantee a profit this upcoming year.  A. Your bank gives out 1,000 loans this year. Create a sampling model and use the function sample() to simulate the number of foreclosure in a year with the information that 2% of customers default. Also suppose your bank loses $120,000 on each foreclosure. Run the simulation for one year and report your loss.  B. Note that the loss you will incur is a random variable. Use Monte Carlo simulation to estimate the distribution of this random variable. Use summaries and visualization to describe your potential losses to your board of trustees.   C. The 1,000 loans you gave out were for 180,000. The way your bank can give out loans and not lose money is by charging an interest rate. If you charge an interest rate of, say, 2% you would earn 3,600 for each loan that doesn't foreclose. At what percentage should you set the interest rate so that your expected profit totals 100,000. Hint: Create a sampling model with expected value 100 so that when multiplied by the 1,000 loans you get an expectation of 100,000. Corroborate your answer with a Monte Carlo simulation.  I'm confused about how to set up this simulation up from a high level point of view and have the following questions: 1. For part A, Should I create a pool of 1000 customers or should I create a larger pool of customers? 2. For part A, when sampling, do I sample with or without replacement? 3. For part B, I'm confused about how to set up the monte carlo simulation.  Am I varying the size of the customer pool? 4. For part C, I'm not sure how to set up a sampling model that involves the interest rate.  Any advice or guidance would be appreciated.  I'm also thinking that if I fully understood the high level concepts for parts A and B, part C might not be such a mystery.


A man with a wife is a husband, a man with a concubine is what?

As concubines are rare these days (and bastardry ignored), I a wondering if there is symmetry in names of male roles in relationships involving concubines or mistresses as there is with wives, or if it is like the classic Miss/Mrs. vs. Mr.


How are visits, pageviews, and bounce rate related in Alexa's stats reporting?

My site has 40,000 visits with 76,000 pageviews.  If there is a bounce rate of 44%, then does it mean that only 15,000 users generated the 67,000 page views or that 50,000 visits generated the 78,000 page views.  My site's Alexa ranking is still getting worse day by day. When I started to do SEO for my site, it was at 13,000 but it is now at 23,000. I am highly disappointment about my Alexa Ranking. It's keep on increasing day by day.  I drove 10K+ traffic everyday to my website from different sources such as Search Engines, Social Media and other quality referral's. Can any one suggest how to control that?


I've never seen a capacitor that looks like this, and I known blown ones are either in pieces or typically bulging. This looks like compound I've seen on CRT rings and pots, put there by the factory to show something has been calibrated and not moved since, but why would they put it on a cap like this? Just to show it's original?    I'm assuming of course that I'm not way off base and this cap is blown. This is a 100V power board that I'm reasonably sure has been connected to a 220V source at some point, the fuse to the left is clearly blown.


Let $\sum a_n$ be a convergent series of positive numbers and set $r_n=\sum_{k=n}^\infty a_n$. Prove that the series $\sum \frac{a_n}{r_n}$ diverges.   Solution I have tried  By definition, $r_n=a_n+r_{n+1}$. Hence,  $\frac{r_{n+1}}{r_n}=1-\frac{a_n}{r_n}$,  $\frac{r_{n+2}}{r_n}=\big(1-\frac{a_n}{r_n}\big)\big(1-\frac{a_{n+1}}{r_{n+1}}\big)>1-\frac{a_n}{r_n}-\frac{a_{n+1}}{r_{n+1}}$.  By induction we have  $\frac{r_{n+p}}{r_n}>1-\frac{a_n}{r_n}-\frac{a_{n+1}}{r_{n+1}}- \dots \frac{a_{n+p}}{r_{n+p}}$.  As the series $\sum a_n$ is conv, we have that $r_{n+p} \to 0$ as $p \to \infty$.  Now what? I am stuck here.


Integral $\int_0^{\infty} \frac{\sin^2(x)}{x^2(x^2+1)} dx$ using Feynman method.

$$\int_0^{\infty} \frac{\sin^2(x)}{x^2(x^2+1)} dx$$  The integral is equals with $\frac{\pi}{4}+\frac{\pi}{4e^2}$, but i can't prove it.


8GB usb become 1GB after installing ubuntu?

I've just installed and booted to Ubuntu from my bootable USB, which is originally 8 GB USB.    Now when I'm looking at the USB size I can only find 1.1 GB partition?    Is Ubuntu really taking up 7 GB from my USB or am I missing something?


C# Windows Service not able to launch an exe

I have a c# Windows Service that is required to call an exe periodically.  That exe need to interact with desktop. When I installed the service, I clicked "Allow service to interact with desktop" option.     Service Starts fine but it is not running the exe as expected.           var myProcess = new Process         {             StartInfo = new ProcessStartInfo(@"C:\windows\TestApplication\TestApplication.exe"),             //StartInfo = new ProcessStartInfo(@"C:\temp\Projects\TestConsoleApp\TestConsoleApp\bin\Debug\TestConsoleApp.exe"),         };         myProcess.StartInfo.Domain = "MyDomain";         myProcess.StartInfo.UserName = "Testuser";         myProcess.StartInfo.Password = pwd;         myProcess.StartInfo.CreateNoWindow = true;         myProcess.StartInfo.UseShellExecute = false;         myProcess.StartInfo.CreateNoWindow = true;         myProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;         myProcess.Start();         myProcess.WaitForExit();   Any ideas as to what could be the issue? Is Local System Account does not have access to the System ? How do I find the Local System Account?   Any pointers?


How to get the wavelength values of bands from hyperspectral image?

I am trying to open and read a hyperspectral image using GDAL like below.  So after reading the data like this :  data = gdal.Open( filename )   then I can see the x, y, dim information of the dataset :  x = data.RasterXSize y = data.RasterYSize dim = data.RasterCount   Now the question is that if there is any way to find out that each band wavelength from image.? I have the following data image: sub_66 Type:File sub_66 Type:hdr sub_66 Type:aux(xml) This data file is of AVIRIS(Hyperspectral Data) sensor.


Are there any differences between URLs with and without "www" and "http://"

Are there any differences among these addresses?     www.example.com http://www.example.com example.com


Let $p\colon X \to Y$ be a quotient map then if each set $p^{-1}({y})$ is connected, and if $Y$ is connected, then $X$ is connected.

Let $p\colon X \to Y$ be a quotient map. Show that if each set $p^{-1}({y})$ is connected, and if $Y$ is connected, then $X$ is connected.     I am totally stuck on this problem. Can I get some help how to tackle this problem


Are theoretical questions about programming acceptable that aren't as deep as cstheory?

Last night there was a question on Stack Overflow:  It was subsequently put on hold for being too broad of a question.   To me, this is a very simple question with a simple answer: yes it is possible, but it would  not be a trivial task. The OP did not ask specifics about how to implement it, so it's probably not appropriate for Stack Overflow.   The CS Theory site might be a little overboard for this question because if he wanted to know whether PHP was Turing complete, he could ask (or get migrated) there. Would the Programmers SE be appropriate for this sort of question? Or is there any other Stack Exchange site where this sort of question would be applicable?


I have error: "Sorry, this version of Skype is not supported anymore."  How i can upgrade skype 5.x to 8.x?


How can I synchronize on my computer two different dropbox accounts?  I share one privately and one with my office.


How can I install Ubuntu on Acer Nitro 5?

I have a new Acer Nitro 5 and I'm trying to install Ubuntu 18.10 on it. I disabled secure boot, tried nomodeset and it still didn't work. I got it to install adding acpi=0, but then it didn't recognize my wi-fi adapter... The laptop has a nvidia graphics card, and I heard it might be the issue with it, but I couldn't install it even with nomodeset active. The main issue seems to be that the mouse freezes completely. I have the same problems on 18.04.  I can access the terminal on the new install, but nothing else. I don't know what to do to solve it, I'm fairly new to Linux and I can't find this exact problem (or the solutions don't work). Thanks in advance!


How can I zoom into only a portion of a PNG for interpretation

Hello guys I have a PNG picture. and i would like to zoom into a portion of it for the reader to see the changes made by my algorithm. How can i do this. I have MWE below: \documentclass[margin=0.1cm] {standalone} \usepackage[left=1in,right=1in,top=1in,bottom=1in]{geometry}  \usepackage{graphicx} \usepackage[version=0.96]{pgf} \begin{document}  \insertimage{example-image-a}  \end{document}


Why is the unbiasedness condition in hypothesis testing called "unbiasedness"?

I already know the definition of an "unbiased" hypothesis test: $$\max\{\pi(\theta) : \theta \in \Omega_0\} \leq \min\{\pi(\theta) : \theta \in \Omega - \Omega_0\},$$ where $\pi(\theta)$ is a power function for the test.  However, unlike an unbiased estimator, which is quite intuitive, I can't understand the actual meaning of an "unbiased" test.  I found this related question (), but I still need some help.  Why do we call a test "unbiased" if it satisfies the above condition?


Semisimple Lie subalgebra closed under JC decomposion

I have a question about the tagged argument in : Let $g$ be a semisimple Lie subalgebra of $gl(V )$.  For any $x \in g$ we have J-C decomposion $ x= x_s +x_n$ but that's not clear to me why $ x_s ,x_n  \in n_{gl(V)}(g) $ where $  n_{gl(V)}(g) = \{y \in gl(V) | [y,x] \in g $ for every $ x \in g \} $.  By the way: it would be enough to prove $ad(x_s)(g) ⊆ g, ad(x_n)(g) ⊆ g$, but I don't now how...


How do I request a question be re-answered?

Say I have the question "How do I solve A". I do a search, and I find that Bob has already posted this exact question. He has also posted an answer, in which he says "I figured out I could avoid the issue by doing X", and marked correct.  However, I can't work around the problem. I need an actual solution to A. I can't post a new question, because then it will be immediately closed as a duplicate. But the old question is not going to get any more answers, because it already has an accepted one.  What am I supposed to do?


Asking in the dark. A better reputation scoring or tag needed for Novice users

Although this question has been marked duplicate. This question:  is more the question I was asking. I'm not asking to be ignored.  I just don't want to bother the higher ups with my dumb questions.  Answers may very do to each individual SE policy.   I had a positive reputation when I posted this question and still got suspended. When I wrote this I thought I was OK to post as many questions I wanted and the worst would happen is a question suspension, but I got fully suspended. I easily got longer suspensions for very minor mistakes.   When I revise my poor quality questions it just get more down votes furthering other kinds of bans like the 6 month/indefinite question ban.   The rules are defined, but the most important rules not stated like how many votes can one person give to another? How many "questions received poorly" can be asked before a full suspension is applied? and others limits would have really helped me from stumbling into full year suspensions.   It would have been nice if I got something saying 1 more bad question or anything and your suspended.    Why can't up grades be made to this system for one user to block/ingore another user if they are bored and/or annoyed by the questioner thus allowing lower lever users to answer it for them and giving everyone a chance to answer?


How to make the workspace toggle indicator disappear in Ubuntu 18.04?

Every time I switch between workspaces in Ubuntu 18.04, I get this thing on the screen (picture below). Is there any way to completely hide it? I want to be able to switch between workspaces instantly without that indicator lingering for a second on my screen.


Can't open questions in the browser from the Android app

Since the most recent update (I think), I can no longer open questions in the browser, which is one of the "more" options. This option is useful when you need to do something not supported by the mobile app, like viewing the revision history, but can be done in the mobile website.  Attempting to use this option will crash the app every time, without fail. This is definitely a regression, as in past versions (1.0.71) I have been able to use this option.  App version: 1.0.77 OS version: 6.0.1


Object appears in 3D view, but partially disappears in camera view and rendering

I'm trying to make a world background by enclosing the whole area in a big sphere, and projecting a spherical map onto that sphere, as per a tutorial on youtube that I can't post because it won't let me post more than 2 links, but it's called "Blender Game Tutorial (2.6): Building a 3D Game - Part 1".  The sphere looks normal in the 3d viewport. Here it is with 3d display mode set to Solid, and inset in that image is with 3d display mode set to Material, showing that my image successfully mapped onto the sphere to make a space background to the world.    But when I go into active camera view (numpad 0), part of the sphere disappears!    The same thing happens when I render with F12 (I can't post more than two images though).  It does not seem to be an issue clipping/camera distance. I varied the max camera distance to quite a wide range of values, and it didn't affect this phenomenon at all.  I'm fairly new at Blender, thanks for any help you can give.


I am getting the message "Too many of your edits were rejected." while trying to add a tag wiki. Am I banned from such edits? Is the ban temporary or permanent?


Attach atom to center of ring in chemfig

Sometimes chemists want to signify that something is attached to a C-ring without specifying the exact position to which it is bound, for example because it's random. Instead they to something like  (see the R^1). This could also be attached to the center of the ring or the "aromatic circle" in the bottom left. Can this be done in chemfig?


Check if Internet Connection Exists with jQuery?

How do you check if there is an internet connection using jQuery?  That way I could have some conditionals saying "use the google cached version of JQuery during production, use either that or a local version during development, depending on the internet connection".


Proving that E (set of even integers) is equal to F (sum of two odd integers)

Define E to be the set of even integers; E = {$x$ $\in$ $\mathbb{Z}$ :  $x$ = 2$k$, where $k$ $\in$ $\mathbb{Z}$}.   Define F to be the set of integers that can be expressed as the sum of two odd integers such that   $F   =  \{y  $$\in$  $\mathbb{Z}$ : y  = a  +  b,  where  $a$ = $2k_1$ +  1 and $b$ = $2k_2 +1\}$.  Prove E = F.  My attempt: If $x$ = 2$k$ is even $a$ and $b$ can be written as a = $2k_1$, b = $2k_2$. so $a + b$ = $2k_1 + 2k_2 + 2$ = 2($k_1 + k_2$ + 1) which is even.


past simple vs present perfect in following examples

I am trying to understand differences in using past simple and present perfect. Let consider following examples.     I have put onion in the soup.   I am cooking the soup now, onion is floating in water, we use perfect because we can see result now.     I put onion in the soup and I closed the pan with a lid.   There is story about actions, we use past simple. The words below are from one song:     I have climbed the highest mountains   I have run through the fields   Only to be with you.   This is report on the actions, and actions do not bound with each other. We use perfect.  Let consider next sentences.     I have made the soup. I have cleaned up my home.   It looks like report on actions, we use perfect.  But if we want to say that I first made the soup, and then did the house cleaning?     I made the soup, then I cleaned up my home (???)   How to distinguish fine line between reporting on unrelated actions and actions in the story?  EDITED ##########################################################  Thanks for reply. When I used first example, I wanted to say something in following context:   - What have you done this morning? - I have made soup. (You can eat it now)       Present perfect, I want to point to result by now. We can use past simple, but perfect can be used too.   But if I made a sequence of actions, I can say:     I bought vegetables, washed it, sliced it, cook it. Thus I made soup.   This is story about sequence of actions, I cannot use present perfect.  Let consider another song   Oh, where have you been, my darling young one? I’ve stumbled on the side of twelve misty mountains I’ve walked and I’ve crawled on six crooked highways I’ve stepped in the middle of seven sad forests I’ve been out in front of a dozen dead oceans  Read more: http://www.bobdylan.com/us/songs/hard-rains-gonna-fall    We have report of performed action by reporting period (sorry for tautology). My book tells me that present perfect is good for this context, because this is not story about sequence of actions, and we can use present perfect.    As I understand now, difference between story (past simple) and report (present perfect) may depends on context and what I want underscore it sentences. We can say      "I have lost my key and painted door to red colour this   morning".   (= you can see red door and that I cannot ride car now.)  But I can rephrase it to      "I lost my key, tried to find it, but failed. Then I remembered about   pale door and paited it to red colour."   It looks like story about sequense of actions, and we cannot use present perfect.  Correct me if I'm wrong.


How do I append an object (such as a string or number) to an array in JavaScript?


Isn't time consuming questioning in sites of SE?

Experts suggest that before you ask a question follow the following faithfully : READ how to ask  READ FAQs for stack exchange  Then Search for the site, lookup it's domain..   Search then Research then search..   To Avoid duplicates..   Actually no keywords of the same question would match perfectly  It could be a long fruitless search.. Then wait for down votes only until then it's closed.   And then you have major job to be done FORMATTING YOUR QUESTION Making it attractive place to attract experts  Attaching link,  pictures of your code or etc..,  highlighting major points using bold, italics..  Ah!   IT CONSUMES 75% OF THE TIME WE DEVOTE TO QUESTION IN SE..  15% for reading the answer and researching on that question further.  IS THIS USER FRIENDLY.. IF YES, STILL TIME IS PRECIOUS.. AND FOR A PARTICULAR ANSWER WE COULD RATHER DEVOTE READIND MORE BOOKS RELATED TO IT AND GOOGLE IT and we have many more options..   I know SE have attracted many users over years but this may be a possible reason why new users (by it l mean those who want to learn and they're premature to share knowledge,  so questioning is a only option for them) devote lesser and lesser time..  All i mean things are becoming more complicated by reading and research on the rules of SE.. Reading the pages with n no. of answers.. AND researching on the fact how to write a question in SE rather the question itself. P. S: No offense to any users of SE.


Why do columns of Markov matrix approach the steady state vector?

If $A$ is a Markov matrix, all the columns of $A^k$ approaches the steady state vector $x_\textrm{ss}$. How can you prove this?   So far I was trying to understand with the decomposition.  $A^k = S \Lambda^k S^{-1} = c[x_1, 0 , ..., 0]S^{-1} = c[x_1, x_1, ..., x_1] $ where $x_1$ is the first column of $S$ or an eigenvector of $A^k$ associated with $\lambda = 1$, which is the steady state vector, $x_\textrm{ss}$. Here $c$ is just a constant so that the components of $cx_1$ sum to 1.  I can't figure out the last equality.   Although the suggested question is very similar to my question, I think my question focuses more on why other columns of $A^k$ which does not have to do with "probability vector" mentioned in the other question. So I don't think this is an exact duplicate.


I am trying to type the word Łojasiewicz. What is the proper command to code the polish character Ł?   Thank you for your help.


How to check if a string ends with only a specific value using REGEX

I am trying to find if a particular string ends with only a specific word and no words are after that  strings i subjecting to searching:  1.) https://beta-qa.pearson.com/iie-api/courses/5daa3022e4b0ef7dce37acec/assignments  2.) https://beta-qa.pearson.com/iie-api/courses/5daa3022e4b0ef7dce37acec/assignments/984fa00d-d002-4826-80f4-76d1267e3aaa  What I want is to only get the string that ends with assignment (i.e. the first string from the above two examples)  This is the regexes I was using: *\[assignments]$, \assignments/$  This is not working this gives both results. How can I only filter the string that ends with assignments?  Can someone please help me?


Reclassifying multiple rasters using ModelBuilder of ArcMap

I am using ArcMap 10.1 or 10.2. I have a folder with more than 500 raster (DEM) and i want to reclassify (equal interval method) each of them but number of classes in each case is determined by the number of 100m elevation bands. i.e number of classes =(max elevation- minimum elevation)/100. I have obtained max and minimum elevation of each raster from GetRasterProerties tool. How do I put this custom number of classes for each raster using ModelBuilder?


Is any particular punctuation necessary when a quotation is the subject of a sentence? For example, in the sentence below, should there be a comma after export? Or anything else?     "Laughter is America's most important export" is a well-known quote of Walt Disney's.


How to share an encrypted storage on Windows, Mac OS X and Linux in a secure way

I got a 2 TB drive that I have to use with both Windows 8.1 / Windows 10 and Yosemite to OS X / OS X El Capitan and maybe even on Linux.  I need to encrypt the volume. Or rather, I want to create two partitions: a 1.7 TB encrypted and unencrypted the remaining space.  Now I use Windows BitLocker to 512bit. On Mac and Linux nothing, obviously.  What do you recommend?  I saw TrueCrypt (and I read about all the confusion created after May 2014), of VeraCrypt, of GNUPG, Disklocker to read BitLocker on Unix.  But I feel lost and without a good idea.  And if I use TrueCrypt 7.1a waiting for new solutions such as precautions to prevent memory dumps and other potential crack?  And then how should I use TrueCrypt to format the drive? In GPT? MBR? Journaled? FAT?


Suppose $f: \mathbb{R} \to \mathbb{R}$ is function such that $f^3$ is continuous on $\mathbb{R}$. Prove that $f$ is continuous on $\mathbb{R}$

Suppose $\epsilon > 0$ and that $c \in \mathbb{R}$. Since $f^3$ is continuous, we can choose $\delta > 0$ such that whenever $\lvert x - c \rvert < \delta$ we have that $\rvert f^3(x) - f^3(c) \lvert < \epsilon$.   To show that $f$ is continuous, I know I need some number $\delta_1 > 0$ such that $\lvert x - c \rvert < \delta_1$ implies that $\lvert f(x) - f(c) \rvert < \epsilon$.   I've tried manipulating the expression $\lvert f(x) - f(c) \rvert < \epsilon$ by using the fact that $a^3 - b^3 = (a - b)(a^2 + ab + b^2)$. I get  $$   \lvert f(x) - f(c) \rvert < \frac{\lvert f^3(x) - f^3(c)\rvert}{\lvert f^2(x) + f(x)f(c) + f^2(c) \rvert} < \frac{\lvert f^3(x) - f^3(c)\rvert}{\lvert f^2(x) + f(x)f(c) \rvert}. $$ However, I am not sure how to continue and I am also not confident that this is a good way to approach the exercise.


A second isomorphism theorem for action on cosets II

Let $G$ be a finite group, and $K$, $L$ subgroups of $G$ and $H=K \cap L$ such that:     $G = \langle K,L \rangle$.   $\forall g \in G$ : $HgK=KgH$ and $HgL=LgH$   Remark: These assumptions imply that $G=KL=LK$, but the converse is false,  because the example of Jack Schmidt  doesn't check the second assumption.  Let $\Omega = G/K$ and $\pi: G \to S_{\Omega}$ the canonical action on cosets.       Question: Is it true that $\forall g \in G$ $\exists l \in L $ such that $\pi(g)=\pi(l)$ ?      If yes, then $\forall k \in K$ $\exists s \in K \cap L $ such that $\pi(k)=\pi(s)$, because $ker(\pi) \subset K$.


At Stack Exchange, one's reputation can never decrease below 1. Is negative reputation that is not counted in case of insufficient reputation deducted later on, i.e. when reputation is earned?  EDIT: SOLVED. The point of my question was that it is ambiguous from /other Q&A whether, in the case of insufficient reputation mentioned above, the reputation is not decreased to below 1 just for the time being or the negative reputation is permanently ignored. The doubt was considering the fact that every user's reputation change is recorded, and there are reversions in reputation change in case of deletion of posts.


This is not a contradiction and I know it is impossible but still consider a thought experiment by me and point out if something is wrong. See the following picture and then the explanation follows.    Rest frames are easy to understand. They are just for clarification. Lets move on to the moving frames. The velocity of the box is $0.1\ c$. Now a photon is emitted (I am not taking a light ray to avoid complication in discussion). After emission the box also moves a certain distance ahead. So the photon takes more than one second to reach the wall. But even the source moves that much distance ahead. When the light is reflected back, the source and the wall again move forward as the box is moving. But after reflection the wall has no role to play. We are concerned about the source. The source moves a certain distance ahead and therefore light takes less than one second to reach back. But the difference of the first case and the second case is not the same. To explain, I will give some equations.  Moving frame 1:  Velocity of the box: $0.1\ c = 30,000km/s$  Time taken by light to reach the wall $=\frac{330,000\ \text{km}}{300,000\ \text{kms}^{-1}}= 1.1s$  Distance moved ahead by the box from original position: $30,000\ \text{km}$  Moving frame 2:  distance moved ahead by the box from original position  $>30,000\ \text{km}$ as the box also moves ahead after reflection.  let $d$ be the distance moved ahead by the box after reflection.  Time taken by light to reach the source: $\frac{270,000\ \text{km}\ -\ d}{300,000\ \text{kms}^{-1}} <0.9s$  Therefore we see that this could possibly determine the absolute motion.  So in total we see that the light will take lesser time to reach the source. Please correct me if I am wrong and give your opinion why is it so.  EDIT 2 for clarification  The box is the compartment in space in which you are moving and I am calculating the time the light takes to reach back the source. I am not even adding velocities. Please correct me and tell me where did I add velocities. For clarification just let me give a simple example. Suppose person A is standing still and B is running towards a light source. Obviously he will see the light before person A even though the speed would be the same. So, what I am doing over here is not increasing the speed of light, but instead decreasing the distance to be covered by it.


Prove that if $p$ is prime greater than $3$ ,then: $p^2+2015$ is multiple of $24$?

Prove that if $ p $ is prime number $(p >3)$, then the number $p^2+2015$ is    multiple of $24 $?  Thank you for any help


The US secretary of state says America is working with Arab nations to cut the private pipeline of funds to Islamic State. (Aussie  news;  of it)   I listened to and wrote the above audio down, and I couldn’t catch there was ‘d’ in ‘funds.’ Is there no pronunciation difference between ‘funs’ and ‘funds’? If there is, how to pronounce differently?


example for algebraic but not finite dimensional vector space

there is a theorem on Galois theory that  if F is a finite dimensional extension field of K (say [F:K]=n) then F is algebraic over K  I'm thinking about the converse of this statement. is the converse false? can anyone give me an example that contradict the converse


How to evaluate this determinant by just using row and column operations ? I'm stuck.Help please!  \begin{vmatrix} -2a & a+b & a+c \\ b+a & -2b & b+c \\ c+a & c+b & -2c \end{vmatrix}  BTW is there any general method to simplify symmetric determinants like this?


In the last arc in Naruto Shippuden, Madara once used Susanoo without eyes. It's explained that one can use Susanoo even without possessing Sharingan if one has already obtained Susanoo before.    In the battle against Kaguya, Obito's spirit somehow gave Kakashi 2 Sharingan and then Kakashi obtained Susanoo. After that, Kakashi lost those 2 Sharingan.    So now in Boruto era, can Kakashi use Susanoo without possessing Sharingan?    Edit: The possible duplicate question didn't mention about one can use Susanoo even without possessing Sharingan if one has already obtained Susanoo before


Blender crashes when selecting object and I can't leave object mode

Alright, so I have no clue what's going on here... The project was perfectly fine, I saved, closed Blender, reopened the project in Blender, and now I'm having all these problems with it. The file is important to my problem because I'm not having this problem with any other objects I make, in either the same file or a different one.  So here's a link to the file:  .  And here's a screenshot:    So the first problem is, if I right click on the anvil to select it (or left click in my case, because I switched the left and right click assignments), Blender crashes. I've tried running Blender from the command line and when it closes out after trying to select the anvil it says: error: EXCEPTION_ACCESS_VIOLATION.  The second weird thing is that I can't leave Object Mode. If I make another object and select it I can enter Edit Mode just fine, which is normal, but if I press a when looking at the anvil in Object Mode, it gets this orange outline around it, instead of the usual yellow, and I still can't leave Object Mode, and Blender is acting as if the object isn't selected because I can't edit it in the right hand pane by clicking on the Object section because it isn't there and if I click on the menu on the bottom to try to leave Object Mode, it doesn't give me any other choices and pressing tab does nothing. If I press n I get shown grease pencil stuff rather than the usual object properties when something is selected.  Hopefully someone knows what's going on here.  Some other info:   There's a half made anvil on the last layer that I can select/edit just fine The main (finished) anvil has a subsurf modifier on it with a very high tri/quad count The main anvil has a mirror modifier on it I know the screenshot shows I have two layers selected, I've deselected the second layer and it does nothing I'm on Windows 7 with an Intel CPU and no GPU :(   If there's anything else I can add to help anyone figure out what's going on, please let me know.


Inverse of $5$ under multiplication modulo $11$ on $Z_{11}$

Find the inverse of $5$ under multiplication modulo $11$ on $Z_{11}$  Please help me with problem. Can't show any work because I don't know how to proceed.


Calling a space a set - abuse of terminology?

I am kind of confused on the terminology of "space". From  I am getting that  In mathematics, a space is a set (sometimes called a universe) with some added structure.  And from topological and metric spaces, I know that we a space is a a tuple of a set and a structure, e.g. $(X, \tau)$, $(X, d)$, where $\tau$ and $d$ are a topology and a metric respectively. On the other hand, in machine learning the term "features space" is used a lot for sets like $\mathbb R^n$, e.g.  and although it often refers to the set underlaying set itself, not the tuple of set plus the added structure. In fact, I have done the same in a previous publication (which the peer-reviewers accepted), but I would like to be both correct and precise in what I research, write, and submit. Is it just that machine learning researchers are imprecise in their terminology? Is it just an ? I think, what some people are doing, might be they consider a space to be a set, which is somewhat structured, instead considering the set with the structure (so, the tuple), to be the space.  I am not sure how to think about this. How do I deal with this in my writing? Especially since, what happens a lot is that I need subsets and element out of the underlying sets of all kinds of spaces.  Of course it would greatly help if there was a general name for a set that is the underlying set of a space, , but it seems that there is no dedicated name for such a set. Let's say there was a features space $(X, \cdot)$, (where I am not even sure, what structure we would add). Then it would be great to have a name for the set, let's call it an asdf. So we could say the feature asdf.  Afterthoughts: What makes it worse for me is that it seems ( and ) I am not even using the word "structure", right, since it is about operations, so we are talking about an "algebraic structure", while "geometric space" is... something else...? So apparently a "vector space" is actually not a "geometric space", but an "algebraic structure". I can understand that point, but the language gets even more confusing.


Is there a black 'dot' symbol that I can use?

I want something like this:    gh $\blackdot$ On  I am aware of cdot but this needs to be much bolder.


Where should I put my script so that I can run it by a direct command?

Where can (should) I put my (bash) script so that it can be used (forever) by terminal or by a direct command: Alt+F2?  I know there is /usr/bin and /sbin & /bindirectories but when should I use between them?  Where should I put my script?


Originally travelled as a tourist on B1/B2 visa. Can I use it for business purposes?

Earlier this year I applied for B2-TOURISM visa to travel to USA with my husband who was on a business trip. I got the visa stamped as B1/B2. However in DS 160 I specifically requested for tourism and medical purposes visa.  I travelled to USA on Feb 2015 and spent 16 days there. At the port of entry the officer marked B2 on top of the ink stamping.  Now that there is a business opportunity to travel to USA from my office in India. Since it's stamped as B1/B2 my visa cell executive suggests that I use my old visa. Also the visa is valid for 10 years and allows multiple entries. The entry is purely for gaining knowledge in a tool and attending knowledge sharing sessions.  My concerns are:   Visa officer marked B2 on the passport page on my first entry. I requested B2-Tourism and medical treatment visa in my DS 160 The US consulate interviewer has not seen my itinerary and the POE personnel marked B2 with pen on the passport.


Verb form of "drive" after "see" in a sentence

I saw him .... off.  A.drive B.to drive C.driving D.driven  I chose C but the key is A. I don't know why. Can you help me explain the reason?


The phrase "We've got ~" spoken by British people

I sometimes hear British people say "We've got ~" just like "We've got an apple", instead of " We have an apple." And I wonder if British people use "We have ~" or not. Is this phrase used in conversations in daily life?


How to determine original location of file that is currently in the Trash?

Suppose some file "Any File.pdf" is in the Trash (aka ~/.Trash).  How can I determine its original location?  By "original location" I mean the folder where that file would be moved to if one were to apply the "Put Back" command to it (but without actually doing so)?  (See figure below.)  (I had hoped that this information would be available through running "Get Info" on the file, but I did not find it there.)


Extract arbitrary XML from a text file using sed

I have a log file with multiple request XML snippets in it.  I am using this sed command to extract and print the request XML:  sed -n '/<GetCompensableProductIdentification*/,/<\/GetCompensableProductIdentification>/p' ProductIdentifierService.log   I want to use variables for the request start and end tags so that I can filter out any request I want.  How can I do that?


An Integrable function which is not essentially bounded on any subinterval of $[0,1]$

I am looking for an Integrable function $f : [0,1] \to \mathbb{R}$ which is not essentially bounded on any subinterval of $[0,1]$.  Thank you in advance.


How do we use the words 'electric' and 'electrical' correctly?

These two words are used differently as shown below: Electric engineering (incorrect✖) Electrical engineering (correct✓) Electrical lamp (incorrect✖) Electric lamp (correct✓) And sometimes, they're used interchangeably as shown below: Electric appliance (correct✓) Electrical appliance (correct✓) I am curious to know how these words are used correctly, how to know which one to use, for instance, with 'substation'.


Everyone calls the centrifugal force a pseudo force and claims that it is not really present, even though there are so many machines listed as taking advantage of it (e.g. centrifuge, washing machine, drier). It also has the same magnitude as the centripetal force, so that they cancel each other out but I can definitely feel it every time I take a sharp turn in a car.  So can you explain whether the centrifugal force is real?


How to solve the "Error Mounting..." error dialog in LXDE / PCManFM

I'm getting the following dialog from time to time when playing music from my external HD (Seagate Expansion+ 2TB):  Whenever that happens, my music player (cmus) skips to the next track.  This happens with any music player I use, it doesn't happen all the time though. If not solving the issue, I'd like to no longer get these dialog popups, as they come in groups of 3-4, and often cannot be closed at all. Update I'd like to also note that my Seagate Hard Drive is connected through an i-tec USB 3.0 Docking Station, in case it's relevant.


Not able to read variable within if statement but can read it everywhere else

I'm using android studio and my app has 3 pages with 2 spinners, one on each of the first two pages. I'm able to get the value of the selected item from both of those using String moodPicked = getIntent().getStringExtra("moodSelect"); String genrePicked = getIntent().getStringExtra("genreSelected");  and I'm able to set the text of my title with both of those variables using playlistTitle.setText("Here is a " + moodPicked +" playlist for " + genrePicked + " lovers");  Which if the user selects happy / pop from the two spinners it will return Here is a Happy playlist for Pop lovers I also have another textview field where I'm playing to display text based off what choices the user picked and im using the code  public void selectPlaylist(){                   String moodPicked = getIntent().getStringExtra("moodSelect");         String genrePicked = getIntent().getStringExtra("genreSelected");          if (moodPicked == "Happy" && genrepicked == "Pop"){               playlistText.setText("happy / pop playlist") }  }  But when I call the function after choosing "happy" and "pop" it only shows up in the playlistTitle, not the playlistText. I've double checked everything was spelled correctly, and took the variables out of the if statements and it's able to read the string. I'm not sure how I can get it to properly read the variables within the if statement and al help would be appreciated. Thanks!


Why a smaller covariance matrix is valid when calculating Eigenfaces?

I am reading  to understand the Eigenface approach but I can't follow the derivation of the PCA as presented on the paper.  In the algorithm it is necessary to do a PCA using a covariance matrix $AA^T$. However, $A$ is of size $N^2\times M$ where $N$ is the dimension of the image and $M$ is the number of images. This means $N^2$ is a very large number and finding the eigenvectors of $AA^T$ is therefore computationally intensive.  Then it is said that for PCA it's enough to find the eigenvectors of $A^TA$ instead of $AA^T$, and it turns out this is a lot easier because $M \ll N^2$ . The reasoning is the following:   Eigenvectors of $A^TA$ are the vectors $\vec{v}_i$ that for some number $\lambda_i$ it holds that   \begin{equation} A^TA\vec{v}_i = \lambda_i\vec{v}_i \end{equation}  and once we left multiply with $A$ we get  \begin{equation} AA^TA\vec{v}_i = \lambda_iA\vec{v}_i \end{equation} from which we see that $A\vec{v}_i$ are the eigenvectors of $AA^T$.  The authors then proceed to use these eigenvectors in the algorithm, but why can we use those? These are not the original eigenvectors $\vec{v}_i$ we were looking for, but $A\vec{v}_i$, different vectors of a different matrix.  So the question is: why can we use eigenvectors of $A^TA$ instead of $AA^T$? Is this something specific to the Eigenfaces algorithm?


Cannot get regular expression work correctly with new line

I am using regular expression for preventing any html tags to be entered in text box on client side. It is:  [RegularExpression("^(?!.*<[^>]+>).*"   But when I want to have new line by enter key, it also triggers notification. Any idea how to make it accept multi line input?


Which books or content should I prefer to understand particle physics operator and representations

I am just a intermediate passout and I want to know which books should I prefer for learning the mathematics of particle physics level like the different representation, operation like Hamiltonian,  Hamiltonian Mechanics, Lagrangian and every concept related to particle physics.  I must tell you that I know little bit physics theorem and almost no mathematics background.


A line of 100 airline passengers are waiting to board a plane. Everyone has an assigned seat. Assume we know that the first, drunk passenger did not choose his own seat. All other passengers will go to their proper seats unless it is already occupied. In that case, they will randomly choose a free seat. You are person 100. What is now the probability that you end up in your own seat?


I have an MFC app which I have been working on for a few weeks now, I want to manually set the dimensions of the main frame when it is loaded, can someone give me a hand with this, specifically where to put the code as well?  Thanks!


Have a client who's Sql Server instance serving SP2010 databases has MAXDOP=0. What are immediate/postponed cost in terms of resource usage (CPU/mem/IO) when MAXDOP is set to 1?  Should then I apply it ASAP or wait for minimum farm usage hours?  UPDATE This is NOT a dublicate Q: I've marked the important part


I am working on a data set that has 930 rows and 5 columns. I'm implementing KNN Regression with bootstrapping and my RMSE is almost 400 (depending on different cross validated outputs). I read  and one of the answers mentioned that if the training and test RMSE are similar, then the model is good; any my training error is close to 400 too. I've tried searching online for reliable sources to know if this high an error rate is acceptable, but I've mainly read articles and posts that say the closer the RMSE is to 0, the better, which definitely is not the case here.   Any advice is appreciated!


Errors installing php extensions on Centos 7

I'm pretty sure I know what the problem is i just dont know how to fix it.  Im trying to install mcrypt "yum install php-mcrypt" and i get the following error  Error: Package: php-mcrypt-5.3.3-3.el6.x86_64 (epel)   I can see that el6 is the error. I have php el7 installed already. How can i get the el7 version instead of el6?  I checked the current repolist and i dont see any el6 repos there. The current active repos are   CentOS-7 - Base  Extra Packages for Enterprise Linux 7 - x86_64      CentOS-7 - Extras     MySQL Connectors Community     MySQL Tools Community - Source   MySQL 5.6 Community Server   CentOS-7 - Updates    Yum error when running yum install php-mcrypt  --> Finished Dependency Resolution Error: Package: php-mcrypt-5.3.3-3.el6.x86_64 (epel)    Requires: php(api) = 20090626    Installed: php-common-5.4.16-23.el7_0.3.x86_64 (@base)        php(api) = 20100412-64 Error: Package: php-mcrypt-5.3.3-3.el6.x86_64 (epel)    Requires: php(zend-abi) = 20090626    Installed: php-common-5.4.16-23.el7_0.3.x86_64 (@base)    php(zend-abi) = 20100525-64


Prove a matrix $B$ is the result of matrix $A$ undergoing $n$ row and column exchanges

I have a square matrix $A$ which is $m\times m$ large, for example: $$ A=\begin{pmatrix} a & b & c\\ d & e & f\\ g & h & i \end{pmatrix} $$ and a shuffled version of it, for example: $$ B=\begin{pmatrix} a & e & b\\ d & c & i\\ h & g & f \end{pmatrix} $$ Is it possible to prove that $B$ is a product of $A$ undergoing an unknown number of row and column exchanges? (for example, swap row 1 with row 2, then, swap column 2 with column 3, ...)  As far as I know, I can disprove it if they have different values for the absolute value of their determinant, but say they have the same determinant or one has the negative determinant of the other?  How about if the matrix is not square?


There are 17 mathematicians and 3 official languages. Every pair of mathematicians communicate in one of the official languages. Prove that there are 3 mathematicians communicating in the same language, pairwise. I guess pigeonhole principle must be applied but I cannot see how to move forward with it. So, let us consider the three languages (say, A, B and C) as pigeonholes. By pigeonhole principle, at least one of A, B and C must contain at least ceil(17/3) = 6 pigeons. So, 6 mathematicians must be there and all of them know the same language. I can only see this.


what is the recommended RAID level for applications by MegaRAID 9261-8i

I wanna to know which RAID level is good to set for database usage, webservers and so on when I use MegaRAID SAS 9261-8i or 9263-8i..  I will glad if help me.


Show that:   $\binom{n+1}{2} = \binom{n}{2} + n$  I think I am supposed to use the number of Combinations formula:   $ \binom{n}{k} = \frac{n(n-1)(n-2)(n-k+1))}{k(k-1)(k-2)..1)} = \frac{n!}{k!(n-k)!}$  I tried to use the formula on the LHS and got this:  $\frac{(n+1)!}{2(n-1)}$


Convergence of sequence of real numbers and (sub)subsequence

Let $(x_n)_{n\in \mathbb{N}}$ be a sequence of real numbers. A well known result is:     The sequence $(x_n)_{n\in \mathbb{N}}$ converges to $a\in \mathbb{R}$ if and only if every subsequence $(x_{n_k})_{k\in \mathbb{N}}$ converges to $a\in \mathbb{R}$.   Now, I'm working on an exercise which essentialy asks to prove the following:     The sequence $(x_n)_{n\in \mathbb{N}}$ converges to $a\in \mathbb{R}$ if and only if for every subsequence $(x_{n_k})_{k\in \mathbb{N}}$ there is a (sub)subsequence $(x_{n_{k_j}})_{j\in \mathbb{N}}$ which converges to $a$.   Now, one direction is trivial. If in fact $(x_n)_{n\in \mathbb{N}}$ converges to $a$, then by the result I've mentioned, every subsequence of $(x_{n})_{n\in \mathbb{N}}$ converges to $a$. Let then $(x_{n_k})_{k\in \mathbb{N}}$ be an arbitrary subsequence. In that case, we know that it is a subsequence of itself, and hence we've found a (sub)subsequence which converges to $a$.  The other way around seems quite complicated for me. The reason is as follows: I must assume that every subsequence $(x_{n_k})_{k\in \mathbb{N}}$ has a (sub)subsequence which converges to $a$ and the proof that the original one converges to $a$.  My problem is exactly that "a". If it had all (sub)subsequences converging to $a$, then by the result i've mentionted, the subsequence $(x_{n_k})_{k\in \mathbb{N}}$ would converge to $a$. In that case, we would have every subsequence converging to $a$ and the result would follow.  My idea to prove the claim was then:  First remember that a subsequence is the restriction of the original one $x: \mathbb{N}\to \mathbb{R}$ to an infinite subset $\mathbb{N}'\subset \mathbb{N}$. In that case a (sub)subsequence is the restriction of $\tilde{x} = x|\mathbb{N}'$ to an infinite subset $\mathbb{N}''\subset \mathbb{N}$. But since $\tilde{x}$ is the restriction of $x$ to $\mathbb{N}'$ and since $\mathbb{N}''\subset \mathbb{N}'$, the restriction of $\tilde{x}$ to $\mathbb{N}''$ is itself the restriction of $x$ to $\mathbb{N}''$.  In other words, every (sub)subsequence can be viewed as a subsequence of the original one. Considering this, by hypothesis every subsequence has a (sub)subsequence which converges to $a$. But by this argument, this means that we can replace every subsequence with a convergent one. And then we can use the result I stated.  Is my idea correct? Is this really the way to prove the claim? My only doubt is that I need every subsequence converging to $a$ to use the result. In this case I can't see how I can argue that this implies every subsequence converges to $a$.  How can I finish this proof?


How can i make my python discord bot caps non sensitive. if message.content.startswith('$doge'):         price('dogecoin')          await dembed('Dogecoin', 'https://www.shareicon.net/data/2015/09/14/101012_doge_512x512.png', message.id)          print('Dogecoin:', rprice)


Dissolving polygons based on attributes with Python (shapely, fiona)?

I have been trying to create a function that does basically the same thing that the QGIS "dissolve" function. I thought it would be super easy but well apparently not. So from what I have gathered around, the use of fiona with shapely should be the best option here. I just began to mess around with vector files so this world is pretty new to me and python as well.  For these example, I am working with a county shapefile founded here  So here are some piece of code I gathered but can't find a way to make them work together  For now my best method is the following based on : . It works fine and I get a list of the 52 states as Shapely geometry. Please feel free to comment if there is a more straight forward way to do this part.  from osgeo import ogr from shapely.wkb import loads from numpy import asarray from shapely.ops import cascaded_union  ds = ogr.Open('counties.shp') layer = ds.GetLayer(0)  #create a list of unique states identifier to be able #to loop through them later STATEFP_list = [] for i in range(0 , layer.GetFeatureCount()) :     feature = layer.GetFeature(i)     statefp = feature.GetField('STATEFP')     STATEFP_list.append(statefp)  STATEFP_list = set(STATEFP_list)  #Create a list of merged polygons = states  #to be written to file polygons = []  #do the actual dissolving based on STATEFP #and append polygons for i in STATEFP_list :      county_to_merge = []     layer.SetAttributeFilter("STATEFP = '%s'" %i )      #I am not too sure why "while 1" but it works      while 1:         f = layer.GetNextFeature()         if f is None: break         g = f.geometry()         county_to_merge.append(loads(g.ExportToWkb()))      u = cascaded_union(county_to_merge)     polygons.append(u)  #And now I am totally stuck, I have no idea how to write  #this list of shapely geometry into a shapefile using the #same properties that my source.   So the writing is really not straight forward from what I have seen, I really just want the same shapefile only with the country dissolve into states, I don't even need much of the attribute table but I am curious to see how you can pass it on from the source to the new created shapefile.  I found many pieces of code for writing with fiona but I am never able to make it work with my data. Example from  :  from shapely.geometry import mapping, Polygon import fiona  # Here's an example Shapely geometry poly = Polygon([(0, 0), (0, 1), (1, 1), (0, 0)])  # Define a polygon feature geometry with one attribute schema = {     'geometry': 'Polygon',     'properties': {'id': 'int'}, }  # Write a new Shapefile with fiona.open('my_shp2.shp', 'w', 'ESRI Shapefile', schema) as c:     ## If there are multiple geometries, put the "for" loop here     c.write({         'geometry': mapping(poly),         'properties': {'id': 123},     })   The problem here is how to do the same with a list of geometry and how to recreate the same properties than the source.


Previous post     As hopefully most moderators are aware, we've been working over the last few months to revamp the moderator flag dashboard.  After running a small and then wide alpha, collecting and addressing plenty of feedback along the way, we're officially launching the new design mostly. Mostly? We like the new design, we think it makes more sense, will be easier to build on, and is just more pleasant.  That said, today might not be the day for you to try a new moderating tool.  You may be under a spam attack or cleaning up a bunch of nasty comments from someone's unfriendly bot and a sudden change could mess everything up.  For the next few weeks, you will be able to use the old UI by deselecting the "Admin Dashboard Refresh" checkbox on your site's /users/preferences/current. But please don't unless you have to, and please switch back when you have the bandwidth.  The new dashboard is the shipped product, and the old one won't stick around forever - if something's blocking you from using it, we need to address that not ignore it! What's new?  Old UI  New UI   As described in the alpha phase announcement post:  Beyond appearances, there have been some thoughtful reworks:  More / clearer context for flags (e.g., edited-after-flag indicator, post owner indicator). Consistent location and ordering for actions on posts, flags, and comments (making muscle memory matter!) Comment editing, move comments to chat works the same in the dashboard and on the question page. The flag "waffle bar" stays better in sync with changes happening the page and vice versa. Same with actions taken inside embedded posts. Responsive design for phones and tablets. Previously undiscoverable UI components are now actual buttons. "No further action" has been brought inline with the page. Smaller quality-of-life improvements along the way.   There are some additional improvements over what shipped last month:  Less content shifting to minimize mouse movement when handling comment flags. Less information overload. Flagged answers are treated as the primary UI element rather than their parent question.  (Less question information, links go to answer.) Auto-flags don't have the long unneeded dismiss UI. Previously viewed posts are less faded and should be easier to read without hovering over them. Various bug fixes and design tweaks.  A special note for international site mods I've reached out to the international team with the (mostly accurate) list of recently introduced strings that need to be translated for this feature.  The strings and hashes are available in . Next steps At the end of July 2019, we will review feedback we receive and run additional rounds of interviews. After this, we expect to share an updated timeline on when the legacy UI will be decommissioned. If everything is relatively minor, we would aim to turn it off as early as early August. Bugs and Feature Requests Since we are officially out of alpha, all bugs and feature requests should be done in the form of questions tagged  on MSE, not answers on this post.  Feel free to post an answer here if you have specific concerns about the release process.


Assigning strings to arrays of characters

I am a little surprised by the following.  Example 1:  char s[100] = "abcd"; // declare and initialize - WORKS   Example 2:  char s[100]; // declare s = "hello"; // initalize - DOESN'T WORK ('lvalue required' error)   I'm wondering why the second approach doesn't work. It seems natural that it should (it works with other data types)? Could someone explain me the logic behind this?


Temporary concreate derived object passed where a reference to abstract base needed doesn't work?

I guess there is something about temporary objects that I don't understand. Given the relationships:  class C {};  class F { public:     C getC() { return C(); }; };  class N { public:     N( C & base ){}; };   This works:  N n(C());   This doesn't work:  F f; N n(f.getC()); //compile error   Why?


Can users without the required reputation suggest new tags?

On the Stack Exchange boardgames' domain I sadly was not able to submit my response, as the game I was posting about is not so popular (). So I just went on and put any random tag on it. I am really thinking something should be done to the reputation system, as it clearly benefits 'veterans' and removes all the 'simple' rights of newcomers (me :D). I think those people should be able (1) to create tags, which won't be created at first, only displayed and awaited for approval, (2) be able to upvote thankful answers in their topics (as it's obvious that new people will reply a 'thank you', while they shouldn't, as it seems like).  Also, I would strongly recommend (3) on any forum the special 'undefined' tag, which will be a ping for experienced people: They can later on help adding correct tags, and show which tags could be used. I mean, if you don't find the correct tag, most of you either create the one they need or use any tag randomly, since one is the minimum, right?  Well, personally, that's how I'd fix a problem. Believe me, no-one reads the terms, every accepts them. Same with new users: I think stack overflow should have something similar to an 'explanation modus', where every button may have a question mark, explaining what it does, how to avoid, etc. For example this meta site here. I only heard 'discussing the site itself here': I am completely sure that this topic gets bumped with off-topic marks, without anyone explaining me, where else? Right? Basically, where do you suggest things to the sites if not here (I made a topic about the site on the meta, it was off-topic, I mean, I just couldn't search/find for what to do in this hopeless situation)?  The last thing I'd suggest is basically not to display the amount of downvotes. Imagine the following scenario: Someone joins stack overflow, and maybe he has searched wrong and couldn't find anything, and maybe even had some spelling mistakes: 31 downvotes, 10 people mark the topic as off-topic, 5 as duplicate.. I clearly know how he would feel because I was in a similar situation: I asked for help and someone just hid my topic. I felt like in dictatorship, where there is no right for opinions. If stack overflow is such a dictatorship, then please redirect me to a nicer forum. Well, I hope it's not, so, no matter who is down there trying to prevent me from asking for help, please don't and remember when you just joined stack overflow. The way reputation currently works is ill for new users: being stuck in the endless circle of 'bad' questions, not becoming better, not having any ability to raise up.


How to shutdown my laptop automatically if I'm away for 30 minutes

I'm using a Dell Inspiron N5110 running Windows 7. Please tell me how to shutdown my laptop automatically if I'm away from it for 30 minutes or more.


How can I update ubuntu from 32bit to 64bit?

I am a android developer, I recently installed ubuntu in my another desktop that is 32 bit.  I installed ubuntu 14.04 LTS  When I am going to make a virtual android device through eclipse+android sdk, it's not running. It's saying me to update into 64bit.  Can anyone please give me a solution, how can I run it or update to 64bit from 32bit.  Thanks in Advance.


Can't connect ad hoc network to Windows 8.1 Pro

I'm trying to connect to my ad hoc network through the command prompt with the the following command:  netsh wlan show network   ... I get the following output:  SSID 3 : Range  Network Type : Adhoc Authentication : WPA2-Personal Encryption : CCMP   I am trying to connect using this:  netsh wlan connect Range   But I'm getting this error message:  The network specified by Profile "Range" is not available to connect   How can I connect to my network using netsh wlan connect?


Today I visited the sign up page of Interpersonal Skills from a browser which I didn't signed in to Stack Exchange and saw a message,     Warning: this site is currently in **private beta** for at least 1 more day.   I assume the double ** is used to indicate the private beta in bold text.  But it actually renders as    The same also happens in the Login message.


In general, EFL students are taught the two main ways of pronouncing the determiner "either" are the British [ˈaɪðə] and the American [ˈiːðər] varieties. However, I've repeatedly heard from specific North American individuals (face-to-face and on TV) another pronunciation: [ˈaɪðər]. My specific question here is: does that phenomenon take place because of some dialectical/idiolectical/sociolectical background? Thanks!


What happens often at my D&D 5e tables (both as a DM and a player) is that somebody finds a better weapon and just drops the previous one. For instance, one might have a Longsword, +1 and then finds a Flame Tongue Longsword. The character would simply drop the Longsword, +1 to use the Flame Tongue Longsword. But I don't find that very good story telling: it's their sword that they're dropping, the one they killed their first goblin with, the one they saved the town with, and they just drop it for some random sword because it's "more powerful". What would be better is that the player takes their old Longsword, +1 and extracts the power of the other sword and imbue it on their own sword. If I take the Flame Tongue example, the sword might still be a +1, but the extra damage from their Flame Tongue/+1 would be a d6 instead of 2d6. Are there rules that allow one to improve their gear as they adventure (so really as a progression), rather than drop/take another piece of gear? If any I'd prefer D&D 5e official rules, then possibly Unearthed Arcana, then only any other official D&D source. I might go homebrew, but then it'd be my take based on existing UA or previous editions, so please don't link to existing homebrew.


A clever way to defragment a FAT filesystem?

What is the best way to defragment a FAT filesystem when running Linux/Unix (on usb stick for instance)?   Copy all content elsewhere, format, copy back again? Use , in a KVM command? Boot with ? other?


Privilege banner buggy? Or am I just confused?

On the main Stack Overflow site, I arrived and had a banner: "Congrats, you've gained the privilege – create wiki posts and 3 other privileges" This confuses me, because I only see two privileges listed at 100%. Is the banner just buggy?  Or is there a better place to see my privileges that the page linked to by that banner?


This maybe a silly question, but how do I type this first symbol? I can't seem to find it in any lists. Is it a small delta?


For PHP what is the best email validation using preg, NOT ereg because it's deprecated/removed.  I don't need to check if the website exists (it's not like maximum security).  I've found many ways with ereg but they (obviously) aren't good practice.


What is true meaning of the White Walkers' terrifying Spiral Symbol in GOT

In the season 8 episode, we saw the following symbol  His victims in this episode were the residents of Last Hearth—the seat of House Umber, a Northern ally of House Stark. None of them were left in the Northern fortress except for the young Lord Ned Umber, dead and nailed to the wall amidst a slew of severed limbs in a spiral pattern. Tormund and their crew find the haunting symbol when they arrive at Last Hearth. "It's a message from the Night King," Beric notes of the bloody formation. But what is the Night King saying? We have seen the same kind of symbol in Season 1, Episode 1. So what is the meaning behind those symbols?


I want to run a trial in D&D 3.5, but how can I avoid invalidation by magic?

The Background  I'm a pretty new DM, and I'm running a casual game of D&D 3.5 (with some rulings from Pathfinder added to the mix, for practical reasons) and I like doing special things for my players, who are very close friends.  One of my PCs seeks justice, to clear his name from a heinous crime he didn't commit. So, I'm trying to set up an investigation and trial arc, with some rewards on his head to spice things up.  But, I'm thinking about setting up something mechanically special for this arc. By the climax, after investigations and ready to prove innocent, I want a trial to take place, but as a game itself, similar to what the Ace Attorney videogame series, loved both by me and the player in question, does. And seeing how the series implemented itself on a medieval setting already (), I thought I could do something similar.   This way, I can get more of a "game" out of this situation, and reward logical thinking in a more structured manner. Witnesses, cross examinations and evidence analysis would be added as mechanics by me, so they aren't the problem. Neither will be the setting, not being based on the "Kings do Divine Justice".  Also, I'll be creating or finding some class to serve as the "Truth People" or something like that, to carry on with this idea, so I don't have to twist the whole setting to fit this thing in.  But...  ...then I got slapped in the face by the fact that magic, even though not so strong in our setting, still exists and will probably destroy everything I can think for this system, from illusion and transformation spells to Zone Of Truth, for starters.   They would make everything so obvious, or so fabricated it wouldn't need a trial. Shove people on Zone Of Truth and there you go. Modify an item with magic, perfect piece of evidence.  I don't want to cherry-pick spells to rule them out just for this scenario. So, is there a way to set this up without being so "Ok magic here works different because I want to"? Am I overestimating the use of magic in D&D? Should I give up this silly idea before it ruins the game?


Proving a set of functions is uncountable

I am trying to prove that $D(\mathbb{N}$)={ $f\in \mathbb{N}^\mathbb{N}$ | f is a bijection such that $f(n)\neq n$ for all $n\in\mathbb{N}$} is uncountable. So, I was thinking of showing $D(\mathbb{N})$ ~ $P(\mathbb{N})$ using Cantor Bernstein Theorem.   For the one direction, is it found to say since $D(\mathbb{N})\subset \mathbb{N}^\mathbb{N}$ ~$P(\mathbb{N})$ then there is an injection from $D(\mathbb{N})$ to $P(\mathbb{N})$?   I am not too sure how to go about the other direction. Should I show equinumerous to functions from $\mathbb{N}^\mathbb{N}$ instead of using the power set?


installing ubuntu on windows 8 ubuntu doesn't load

I installed Ubuntu 12.4 on computer with previously installed windows 8. When I reboot the system I have two options to choose from when I select Ubuntu it give me a black page that says that windows is damaged and I have to repair it. It says that there are missing files in Ubuntu directory.Did I downloaded the correct Ubuntu?  I selected for the option Other when asked what kind of operational system I am running - there was no option window8.


How to get a part of string with regular expression

I am working with Alteryx and I really have troubles writing regular expressions.  My data sample:  /abc/04. bcc/cc /ab bn/uat/ab /abnm ag/adgr gada/rfd/dfd/cv   I need two regular expression sentences to get the part of string in the first / / and the other in the second / / in two separate columns.  Desired result:  First column:  abc ab bn abnm   Second column:  04. bcc uat adgr gada


What does Stack Overflow do about posts that have been deleted years ago or months ago?

I want to know if my question was deleted 4 months ago.  I don't want it, but whenever I go to my questions, I can see my questions in the recently deleted questions.


I proposed an edit on , and my edit was rejected.  I'm not contesting the rejection, but something appears screwy.  When I first saw the question, there was no code formatting.  So I clicked "Edit", added the code formatting and clicked "Save Edits".  I got a message saying that my edit was less than six characters, so I made another slight change (added the second "I" in "I realize I can totally").  Hit "Save Edits" again and got the Thank You message.  Now, when I click on the "suggested edit" link for the question (in my Activity list), what appears for both the original text and my edited text are very different from what I saw when I made the the edit.  The original text has the code formatted, and my edited text includes a number of spelling and grammar changes that I did not make.  Also, the "original" text matches what the question currently looks like.  Only thing I can think of is that the OP edited his own question at the same time I was doing the same, and that his edit and mine were swapped, with my change being applied as if it was his.    Bug?  Or did I do something wrong?


How can I change the Data Source of Membership?

I'm setting up Membership on my ASP.Net website. I'm using a remote database. I have created membership tables on this database by using aspnet_regsql.exe.  When I click security, I get this error on ASP.Net Web Application   I clicked Choose Data Source, but there is not an option to be able to set my remote database. What I'm missing ?  How I can fix this error ? Thanks in advance


Are both is equal to and equals similar in meaning? Which is the more natural?  For example, one plus one equals two or one plus one is equal to two.


Total of attribute field of point layer per polygon layer

I have a polygon shapefile of many lakes, I also have a point shapefile of locations on those lakes where fish were caught.  The point shapefile contains the attributes: Fisherman_iD, Fish_Caught, Lat, Long.  The polygon shapefile contains the attributes Lake_name, Points_per_polygon(PNTCNT)  Each point obviously has differing entries under the fish_caught field.   What I want to get is the average fish caught per lake (polygon).  So I need to have a total number of fish caught, per individual polygon, and then I can divide that by the PNTCNT file I create using the Points in a Polygon tool.  Ideas? I am relatively new to QGIS.


"Photos of Someone" vs "Someone's Photos"

In facebook, in the photos page, you will see:    I know the difference in facebook, the first tag "Photos of Someone" will show photos you are tagged in, the other tag "Someone's Photos" will show the photos you uploaded.   Is there a difference in English between "Someone's Photos" and "Photos of Someone"? or was facebook out of words so they just used this?


Are there english words for a person who sincerely thinks of himself as an expert but in reality (by common standards) is not?

Are there english words for a person who sincerely thinks of him as an expert but in reality (by common standards) is not?  Source: Recently, in my native place, a very popular movie actor (let us say his name is extrem) started a music band and held a live show during a government sponsored program which was widely criticized and made fun of. Nowadays, if someone claims to be something he is not, the media refers to it as extremism jokingly.


Compact topological space with closed graph implies continuity

Let $X,Y$ be topological spaces and $f:X \rightarrow Y$  If $Y$ is compact and $G(f)$ (graph of $f$) is closed, show that $f$ is continuous.   I consider an open set in $X$, and as $G(f)$ is closed, $(X \times Y)-G(f)$ is open. And I guess I need to do something here. Then I can get some open sets. Also, I notice that compact is something relate to "finite". I guess I can use the compactness to do finite intersection or union and get the result finally.  But what should I do in the middle or I am not even on a right track.


Use Find-command to filter out files with specific pattern to terminal

I want to show all files with the name "index.php" in a specific area of my machine. For this I wrote this code-line:  -find /iu/cuve/u3 -name "index.php"   I want it to only show the lines witch include "index.php" in it, but this command shows a bunch of other lines witch does not include "index.php". Many of them ends with "Permission denied", maybe thats why I can't see the "index.php" part of the line.  I tried to add a -exec grep command to it, but didn't get the results I'm looking for.


When is $(\Bbb Z/n\Bbb Z)^\times$ cyclic?

Is the group of units $(\Bbb Z/n\Bbb Z)^\times$ always cyclic? Do we need that $n$ is a prime or something?


If the red curve is an ellipse, is the green curve also an ellipse?

See the figure below:    The red curve is an ellipse; the blue curve is a unit circle.  Green curve is the locus of the circle center.  Is the green curve an ellipse?


why does texstudio internal PDF viewer shows streak white lines on image?

issue also opened at     When I compile this MWE latex file in texstudio, on windows, using MikTex, then view the result using texstudio internal PDF viewer, it shows white streak lines going over the image. These lines are not in the original image.  Also these lines do not show up when I view the compiled PDF file using external PDF reader such as adobe.   Why is that?  The image is also a PDF file. Is it possible to resolve it? It is not a big issue really, since this seems to be just an artifact of texstudio pdf viewer itself, but thought to ask if there is an option to fix this.  Here is MWE  \documentclass{article} \usepackage{graphicx} \begin{document} This is my image, as PDF file, imported using includegraphics  \includegraphics[width=\textwidth]{image}     \end{document}   I put the file image.pdf is on my web page   This is how the compiled PDF looks like inside texstudio PDF viewer    This is how the PDF looks like inside adobe PRO pdf reader    Notice the white lines that show up in texstudio. This is pdfinfo on the image file  pdfinfo image.pdf   Creator:        Wolfram Mathematica 11.2.0.0 for Microsoft Windows (64-bit) (September 10, 2017) Student Edition - Personal Use Only Producer:        CreationDate:   Sat Mar  3 16:13:39 2018 ModDate:        Sat Mar  3 16:13:39 2018 Tagged:         no UserProperties: no Suspects:       no Form:           none JavaScript:     no Pages:          1 Encrypted:      no Page size:      470 x 367 pts Page rot:       0 File size:      99049 bytes Optimized:      no PDF version:    1.5   I am using   TeXstudio 2.12.6 (hg 6632:7777b2b8a906) Using Qt Version 5.9.1, compiled with Qt 5.9.1 R   Windows 7.


What is the inverse of X modulo $1 + X + X^2 + X^3 + X^4$? Is there any open softwares to calculate such things easily?


I did MD5 Password hash but since it is that MD5 password Hash is crackable is there any other built in password hash function in PHP?  Which is easy to implement and no need for other libraries.  Big thanks in advance


How to not install recommended and suggested packages?

I use Ubuntu 12.04 64-bit, I did the following: sudo gedit /etc/apt/apt.conf and added  APT::Install-Recommends "false"; APT::Install-Suggests "false";    But it did not work. When I try to install a package, it still wants to install the suggested and recommended packages. How can I solve this?


Need to create an SQL result suitable for data mining

I have a database of supermarket transactions that I wish to use for associative data mining purposes. Below is an image of my current SQL query however I am not sure if what I require is possible with SQL (Explained below image).  I need my results to be in the following format - Each unique ProductName needs to have its own column with a binary 0/1 representation of whether the CustomerID purchased the product.  Is this possible? If so where exactly would I start?


On fresh Ubuntu 13.10 installation, on boot it shows black screen with error message.  How can I fix this?  Gave up waiting for root device. Common problems:  - Boot args (cat /proc/cmdline)    - Check rootdelay= (did the system wait long enough?)    - Check root= (did the system wait for the right device?)  - Missing modules (cat /proc/modules; ls /dev) ALERT! /dev/disk/by-uuid/f8d8eb7d-2423-4cc5-b0e6-72d47678121e does not exist. Dropping to a shell!


How does this table have too many unprocessed floats


Hello I'm somewhat new to the world of programming. So I tried creating an interface for a test object. As soon as I create the object I get a StackOverflowException.  Program.cs       class Program {      static void Main (string[] args) {         TestObject test = new TestObject("test");     }  }   TestObject.cs  public class TestObject : IObject {      public string Name {get{return Name;}set{Name = value;}}      public TestObject (string name) {         Name = name;     }  }  interface IObject {     string Name {get;set;} }


Problem Installing Ubuntu Using Windows Installer

I am trying to install Ubuntu using the Windows installer (my first time trying to use Linux!), and when I try to download the installer, I get the screen asking for donations, but can't go any further. There is a "pay with paypal" button, and no way to continue. Any help appreciated! I am using XP.


No tests in the legacy project - what to start with as tester?

I've just joined a project which is developed for internal use for over 10 years now. There are no unit tests nor any other manual/automated tests designed. I'm going to be the only tester. What should I start with when it comes to testing in general? There is no detailed specification or documentation. I was thinking of going through the past bugs/tickets/stories developed and prepare test cases based on that. Also to start preparing test cases for regression tests for key functionalities. In the future, I will consider automating the regression suite with Selenium most likely (especially that my exp is very little in this topic). The project is developed in .net and .net core technologies. Please share your thoughts and experience. Thanks!


I'm submitting an mathematics article concerning research that was done entirely while I was an undergraduate at University A.  This August I will be a graduate student at University B.  The only funding I received came from NSF through a ten week program at University C at the very beginning of the project, after which I finished the research on my own while attending University A.  On the other hand, while University B has nothing to do with the publication, it is the most up to date institution as far as contact information goes.  Should I put University A or University B as my affiliation (or both)?


Add a list of questions selected for HNQ to the 10k tools

Now that questions selected for Hot Network Questions have a record attached to them, those can be queried for in the Data Explorer. However, the Data Explorer is only updated once a week. It would be nice to also have a full list of questions that are selected for Hot Network Questions and the times they were selected added to the 10k tools. In my opinion, it adds to the "bird's eye view" of the site that is afforded to them, and is in line with other similar lists (e.g. migrated questions, protected questions, etc.). Also, a list of questions that were removed from Hot Network Questions by a moderator would be very nice as well.


MariaDB - "ERROR 1205 ... Lock wait timeout exceeded; ..." when doing multiple parallel UPDATEs affecting different rows

We are using MariaDB 10.1.19 hosting a legacy database. We have an lpr table (on InnoDB) where we want to move from a text column gate to a normalized foreign key gate_id. Our code is doing the UPDATE in parallel, like this:  UPDATE lpr SET gate_id=1 WHERE gate_id IS null AND gate LIKE '%[1]%' UPDATE lpr SET gate_id=2 WHERE gate_id IS null AND gate LIKE '%[2]%' UPDATE lpr SET gate_id=3 WHERE gate_id IS null AND gate LIKE '%[3]%' UPDATE lpr SET gate_id=4 WHERE gate_id IS null AND gate LIKE '%[4]%' ...   since the rows affected by all the UPDATEs are disjoint, and the table is on InnoDB, we wouldn't expect lock contention, but we get the error:     ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction   for all the UPDATEs. Increasing innodb_lock_wait_timeout to ~100 doesn't change anything, as well as setting FOREIGN_KEY_CHECKS to 0.  The gate column never contains more than one [VALUE] string.  If we do a single UPDATE by hand, no such error occurs.  Doing a SHOW FULL PROCESSLIST doesn't show any lock during the UPDATEs.  What are we doing wrong? Is there a table-level lock even if using InnoDB? Or do the UPDATEs lock more rows than those strictly selected by the WHERE clause?


Suggested edit. Only one tag added or removed

Is there any rule or discussion where I can read the information - how to review the suggested edit with only one tag added or removed?  For example some question that has already C# tag, become also C# 4.0 one.  Is it minor one?  Sure I dont mean the situation where the C# code question has not C# tag at all.  One more example - question has Entity Framework 4.0 tag and become also Entity Framework. Minor?


Let $X$ and $Y$ be square integrable random variables s.t. $E[X|Y]=Y$ and $E[Y|X]=X$. Prove $P(X=Y)=1$.  Furthermore, when the condition changes to $X$ and $Y$ are integrable, show that the conclusion is still true.  So far, I only know $E[X]=E[Y]$, which means $E[X-Y]=0$. So, that means I need to show $var(X-Y)=0$, right? Any hints would be appreciated.


Cropping the exact same part of several pictures

I have several pictures that are exactly the same except for some small variations. It was one picture that was photoshopped in several different ways. Now, I need to crop them all (13 in total) but I need to crop exactly the same part of it. It needs to be pixel perfect.  How do I do that with Pixelmator?


Code open-ended, opinionated, code discussions are discouraged on the regular SO. Is there a SO community for that?