I am facing a DDOS attack from a few hundred IP addresses, all of them coming from various cities in India and have the same organization: "................ for GPRS Service". (I'm not mentioning the whole name).  The attack started around 5 hours ago and it consists on hundreds of IP addresses that open 1 to 5 connections (as opposed to one or a few IPs making thousands of connections). The IP addresses are coming from a wide range of subnets.  Is there a way to tell the firewall to block the internet provider of the remote IPs, at least until the problem is solved?

This is a  about DoS and DDoS mitigation.   I found a massive traffic spike on a website that I host today; I am getting thousands of connections a second and I see I'm using all 100Mbps of my available bandwidth.  Nobody can access my site because all the requests time out, and I can't even log into the server because SSH times out too!  This has happened a couple times before, and each time it's lasted a couple hours and gone away on its own.  Occasionally, my website has another distinct but related problem: my server's load average (which is usually around .25) rockets up to 20 or more and nobody can access my site just the same as the other case.  It also goes away after a few hours.  Restarting my server doesn't help; what can I do to make my site accessible again, and what is happening?  Relatedly, I found once that for a day or two, every time I started my service, it got a connection from a particular IP address and then crashed.  As soon as I started it up again, this happened again and it crashed again.  How is that similar, and what can I do about it?


I am using a java program called Processing (3.2.3), and I am getting a nullpointer when attempting to draw. This has been tested, and is definitely in the rect() call.  Here is my main class:  square[][] squares;  void setup(){   frameRate(30);   size(600, 600, P2D);   background(0);   stroke(255);    int row = 20, col = 20;   squares = new square[row][col];    for (int i = 0; i < row; i = i + 30) {     for (int j = 0; j < col; j = j + 30) {       squares[i][j] = new square(i, j, i+30, j+30, 1);     }   } }  void draw() {   frameRate(30);   for (int i = 0; i < squares.length; i++) {     for (int j = 0; j < squares[0].length; j++) {       squares[i][j].display();     }   } }   Here is the square object:  class square { float x1, y1; float x2, y2; int age;  square (float x1, float y1, float x2, float y2, int age) {   this.x1 = x1;   this.y1 = y1;   this.x2 = x2;   this.y2 = y2;   this.age = age; }  void display() {   stroke(255);   if (age == 0) {     fill(0);   } else {     fill(255);   }   rectMode(CORNERS);   rect(x1, y1, x2, y2); }  }   On the call to rect(), it gives me a null pointer.  Full error:  java.lang.NullPointerException     at sketch_161212a.draw(sketch_161212a.java:38)     at processing.core.PApplet.handleDraw(PApplet.java:2418)     at processing.opengl.PSurfaceJOGL$DrawListener.display(PSurfaceJOGL.java:884)     at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:692)     at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:674)     at jogamp.opengl.GLAutoDrawableBase$2.run(GLAutoDrawableBase.java:443)     at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1293)     at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:1147)     at com.jogamp.newt.opengl.GLWindow.display(GLWindow.java:759)     at com.jogamp.opengl.util.AWTAnimatorImpl.display(AWTAnimatorImpl.java:81)     at com.jogamp.opengl.util.AnimatorBase.display(AnimatorBase.java:452)     at com.jogamp.opengl.util.FPSAnimator$MainTask.run(FPSAnimator.java:178)     at java.util.TimerThread.mainLoop(Timer.java:555)     at java.util.TimerThread.run(Timer.java:505)

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Say we have a double value of 12345.6789 (should be dynamic)  Now the requirement is split the number and get the decimal digits and fractional digits, which would be:  double number = 12345.6789; int decimal = 12345; int fractional = 6789;   I get the decimal part work out but could you please give a hint on the fractional part? Thanks a lot.

How do I get whole and fractional parts from double in JSP/Java ? If the value is 3.25 then I want to get fractional =.25, whole = 3  How can we do this in Java?


I have never used this visa before. But I want to use it for my first time to visit Belgium for a about 10 days.   I want to know if it's ok or my first visit has to be Germany before going to any other Schengen country.

In case, if I get a multiple-entry Schengen visa in one of the embassies in Ukraine, Kyiv - should my first trip be to the country which issued the visa?  Any there any requirements of this sort? Does this condition vary depending on embassy which issued the visa?  What are the possible consequences on not visiting that country first? Does it somehow depend on country where the embassy is (i.e. non-Schengen and not EU members)?


I wish to modify an existing Configuration Profile installed on an iPhone, but I do not have a disk copy of it, nor can I download it again from the source (no longer available).  Using Apple Configurator 2 there appears to be no way to export to disk, or modify, the full contents of an already existing and installed Configuration Profile.  Nor indeed to inspect its contents (which would provide a tedious but manual way to re-create a new profile by inspecting the contents of an existing one)  Is there a way of extracting an installed Configuration Profile from an iDevice to disk so that I can then open it and modify it using Configurator?  Thanks.

I've been looking for hours now on how to edit a profile on Apple Configurator but to no luck. There are some similar responses, but none of them were of too much help. I am trying to edit a profile that exists on a iPad Air, but not the mac. Can anyone help me?


Recently I got nine downvotes for one of my questions which I think is OK to be asked in Stack Overflow:    The question is on hold, and it got downvoted even after being on hold.  Is there a way that I can delete that question or should it be removed from Stack Overflow?  Note:   It's quite embarrassing for ones` profile to have a question with 9 downvotes. :( I learnt the lesson. I'll improve my future questions. :/   Update:  One of the  of a similar question states:     Once you get eight downvotes, you pretty much disappear (edits won't bounce you to the front page).   I'm not sure how true this statement is. But if it is true, even if I edit my question, it won't show up to the front page so no one will see the edit and no one will upvote and the question will always have downvotes.

I wrote a question about blocking certain characters in passwords. It became tremendously unpopular, and it seemed like everyone wanted to rain on my parade every day.  Eventually, I "got it," agreed completely with what people were saying to me, and just wanted to withdraw my question so that my reputation didn't slide even further downhill.  Unfortunately, the system is designed such that I can't withdraw my question or redeem myself. Instead, I just get daily reputation attacks. That's a terrible system, and it needs to be changed.


I typed firefox -v in my console. The output was  firefox -v  (process:5516): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed Mozilla Firefox 33.0   What is that failed assertion? Something serious?

After upgrading to Fedora 18, I am seeing the following critical messages on /var/log/messages whenever I log on to the computer:  CRITICAL: gsm_manager_set_phase: assertion \`GSM_IS_MANAGER<br> Gtk-CRITICAL: gtk_main_quit: assertion `main_loops != NULL' failed   Based on my limited knowledge, critical messages and above can affect the usage of my computer if I don't deal with these urgently. Not that they are affecting the current usage of my computer, but I would like to find out more about them (seems to deal with mobile technology and GIMP toolkit?) and how to turn them off if I do not need these services.


I've been trying to fix this for a while, but I haven't been able to find a solution.  Some notes about my setup:   I am not using VirtualBox I am running Nginx 1.4.6 Ubuntu   The CSS's cache will not clear even when using the "expires: off;" flag in my site configuration. Here's my site config:  server {   # Replace this port with the right one for your requirements   listen 80;  #could also be 1.2.3.4:80    # Multiple hostnames separated by spaces.  Replace these as well.   server_name www.example.com; # Alternately: _    root /var/www/;    error_page 404 /404.html;    location = /404.html {       root  /etc/nginx/errors;     }     #access_log logs/star.example.com.access.log;    index index.php index.html index.htm;    location ~* \.(jpg|jpeg|gif|css|png|js|ico|html)$ {     access_log off;     expires off;   }    location / {     root /var/www;     try_files $uri $uri/ @extensionless-php;     index index.php index.html;   }    location ~ \.php$ {     include fastcgi_params;     fastcgi_intercept_errors on;     # By all means use a different server for the fcgi processes if you need to     fastcgi_pass unix:/var/run/php5-fpm.sock;   }    location ~ /\.ht {     deny  all;   }    location @extensionless-php {     rewrite ^(.*)$ $1.php last;   }  }   My nginx.conf is as follows:  user www-data; worker_processes 4; pid /run/nginx.pid;  events {     worker_connections 768;     # multi_accept on; }  http {      ##     # Basic Settings     ##      client_max_body_size 150m;      sendfile off;     tcp_nopush on;     tcp_nodelay on;     keepalive_timeout 2;     types_hash_max_size 2048;     # server_tokens off;      # server_names_hash_bucket_size 64;     # server_name_in_redirect off;      include /etc/nginx/mime.types;     default_type application/octet-stream;      ##     # Logging Settings     ##      access_log /var/log/nginx/access.log;     error_log /var/log/nginx/error.log;      ##     # Gzip Settings     ##      gzip on;     gzip_disable "msie6";      # gzip_vary on;     # gzip_proxied any;     # gzip_comp_level 6;     # gzip_buffers 16 8k;     # gzip_http_version 1.1;     # gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;      ##     # nginx-naxsi config     ##     # Uncomment it if you installed nginx-naxsi     ##      #include /etc/nginx/naxsi_core.rules;      ##     # nginx-passenger config     ##     # Uncomment it if you installed nginx-passenger     ##      #passenger_root /usr;     #passenger_ruby /usr/bin/ruby;      ##     # Virtual Host Configs     ##      include /etc/nginx/conf.d/*.conf;     include /etc/nginx/sites-enabled/*; }   Thank you :)

We are using Nginx to serve static files on a development platform. As it is a development platform, we'd like to disable caching so that each change is propagated to the server. The configuration of the VHost is quite simple:  server {   server_name  static.server.local;   root /var/www/static;    ## Default location   location / {     access_log        off;     expires           0;     add_header        Cache-Control private;   }  }   When we access an HTML file (http://static.server.local/test.html), we have no issue: the server returns a code 304 Not Modified as long as the file is not changed, and a 200 OK response with the modified file when the file is changed. However, it seems to behave differently with a Javascript or a CSS file. Once the file is changed, we get a 200 OK response as expected, but with the old text. Is there an internal cache mechanism in Nginx that could explain this behaviour? Or some configuration that we should add?    As a side note, here is the header returned by Nginx when the file has been modified (it seems correct):  Accept-Ranges:bytes Cache-Control:max-age=0 private Connection:keep-alive Content-Length:309 Content-Type:text/css Date:Fri, 13 May 2011 14:13:13 GMT Expires:Fri, 13 May 2011 14:13:13 GMT Last-Modified:Fri, 13 May 2011 14:13:05 GMT Server:nginx/0.8.54   Edit After trying different settings with the expires directive and Cache-Controlheader, I made some further investigations. In fact, the server is installed on a VirtualBox guest Ubuntu, and data are read from a shared folder that is on the Mac OSX host. If the file is edited from an IDE (NetBeans) on the host, it seems that changes do not appear whereas if I edit it directly on the guest (using VIM), it is refreshed. The strange thing is it does not behave similarly with HTML files. Quite puzzling.  Edit 2 (ANSWER) Indeed, the origin of the issue was more on the VirtualBox side. Or rather a conflict between VirtualBox and the "sendfile" option of the server. This link  gave me the solution: switch the sendfile flag in the server configuration to off:  sendfile  off;   Hope this could also help other person using VirtualBox for development. :) There are some additional information on the .


Any ideas how to start.   I am having trouble figuring out the region itself   All ideas are appreciated  thanks

The question is: There is a square dart board with a side length of $2$m, and a dart has equal probability to land anywhere on the board. What is the probability that the dart will land closer to the center than to the edges? So I know that if I center the square at the origin, I have to find $f(x)$ such that every point on $f(x)$ is equidistant between the origin and the line $x=1$ or $y=1$ (I'm only working with the first quadrant since by symmetry the probability should be the same). Another reasonable assumption that I made is that $f(x)$ is reflected over $y=x$, so I only have to work with the first $45$ degrees of the first quadrant. So to find $f(x)$ I did the following: $\sqrt{x^2+[f(x)]^2}=1-x$, so $f(x)=\sqrt{1-2x}$. Now I know that I just find the area under this curve and divide it by $1/8$ the area of the square to find the probability. I just wanted to know if my $f(x)$ was okay? Thanks!


I followed the instructions in  in order to reproduce a table from an earlier chapter with the original caption number and it works to call the page number of the original table and hide the new figure from the contents list but the caption number is still wrong. (i.e. it continues to say 6.2 and I want it to say 3.2.)  The only difference between egreg's answer and what I'm doing is that my original table and the place where I want to reproduce it are in separate tex files and are pulled together in a master file. On advice I changed my master file to use \input to call up all the individual chapters (previously was using \include) but this has not fixed the problem. Any ideas, please?  EDIT: Identified that the \thefigure needed to be changed to \thetable in order to apply to table. Sorted.

I have a figure that relates to two different issues discussed at very different point in a long document. Rather then send the reader back 50 pages to look up a figure, I would like to include the figure again at the later point.  However, I don't want it to appear twice in the list of figures or receive a new label number.  In this example, I would like it to appear in chapter 2 as figure 2.5 and again in chapter 4 as figure 2.5.  Is there a simple way to accomplish this? I am using Xelatex Version 3.1415926-2.5-0.9999.3 from the Texlive 2013 Arch Linux package.


Let $(f_n)_{n \in \mathbb{N}} \subset L^1$ and $f \in L^1$ such $f_n \longrightarrow f \ a.e. $ and $ ||f_n||_1 \longrightarrow ||f||_1 $; then $ ||f_n - f||_1 \longrightarrow 0$. Why?

Let $1\leq p < \infty$. Suppose that    $\{f_k\} \subset L^p$ (the domain here does not necessarily have to be finite),  $f_k \to f$ almost everywhere, and  $\|f_k\|_{L^p} \to \|f\|_{L^p}$.    Why is it the case that $$\|f_k - f\|_{L^p} \to 0?$$   A statement in the other direction (i.e. $\|f_k - f\|_{L^p} \to 0 \Rightarrow \|f_k\|_{L^p} \to \|f\|_{L^p}$ ) follows pretty easily and is the one that I've seen most of the time. I'm not how to show the result above though.


I enabled virtualization in the bios yesterday and the virtual machine worked yesterday. Today, I double checked in the bios and virtualization is still enabled. But the virtual machine is giving me this error when I tried to start it up:  Failed to open a session for the virtual machine Ubuntu 15.04.  AMD-V is not available (VERR_SVM_NO_SVM).  Result Code: E_FAIL (0x80004005) Component: ConsoleWrap Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}   What's causing this, and what do I do?  My motherboard is a Gigabyte GA-78LMT-USB3  My CPU is an AMD FX-6300 3.5GHz 6-Core Processor Black Edition  Update: After installing a 32-bit version of Ubuntu on the virtual machine, it worked fine. However, that still doesn't explain why VirtualBox doesn't detect that I have AMD-V, I tried running ubuntu on vmware and that tells me that I have to turn Hyper-V off, so my virtualization is definitely on, it's just that virtualbox does not detect it.  Update 2: Ubuntu launches, but it keeps flickering non-stop; this means that VirtualBox is not detecting my Hyper-V.  Update 3: Hyper-V was installed on the system, Hyper-V apparently causes a conflict between other virtual machines, I'm turning this off now and letting windows restart.  Update 4: IT WORKS!

Recently I started having an issue with VT-x on my Windows 10 running on HP EliteBook. I was using Oracle VirtualBox to run some VMs on it before and VT-x was enabled in BIOS and was working fine.  I started getting VT-x is not available error every time I was trying to start any of my VMs. That started happening after I installed Docker on my machine, so I tried uninstalling it and rebooting. Didn't help.  I checked BIOS settings and it says VT-x is enabled but checking with Intel(R) Processor Identification Utility shows that VT-x is not supported and Oracle VirtualBox also doesn't see it.  There were no hardware changes and the only software change was installing/uninstalling Docker.  How can this issue be fixed?


I have built a simple console application, and I need to give a specific time for user to input a keychar.  Should I use this?  System.Threading.Thread.Sleep(1000);   For those who didn't understand, I need the program to skip the Console.ReadKey().KeyChar; after x seconds.  Is this possible?

I have a console app in which I want to give the user x seconds to respond to the prompt.  If no input is made after a certain period of time, program logic should continue.  We assume a timeout means empty response.  What is the most straightforward way of approaching this?


So, I was working on Python for making List of arrays for my project work.   Sample code:  var0 = 0 var1 = 0 car = [0,0] listitem = [car[:] for i in range(10)] for i in range(10):     car[0] = var0 + i + 1     car[1] = var1 + i     listitem[i] = car print listitem   As the logic would suggest we would be expecting an output like:  [[1,0],[2,1],[3,2],[4,3],[5,4],[6,5],[7,6],[8,7],[9,8],[10,9]]   But the output comes as:  [[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9],[10,9]]   I have come with a theory where the car array uses some pointers to the variable space.  Does anyone has a probable explanation for the same? Thank you

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I have a strongly trended series where the trend appears to be exponential and I believe the errors tend to be proportional to the current value. In order to convert it to a stationary series for purposes of forecasting, I expected to do the usual difference in logs transformation. However, it seems that changes have to be really tiny, or else you get a consistent bias strictly from the numerical approximation when it is transformed back into levels. For example, if you have a three percent change from a base of, say, 100, log(103) - log(100) = 0.0295588  (approximately. All calculations done with R.) So 0.029558 would be my dependent variable in this case. To reconstruct the value of the change, take the base, 100, times one plus the estimated change, and subtract the base from the result. 100 * (1 + 0.0295588) = 102.9559 (3 – 2.9559)/3 = 0.0147  Which is to say, a consistent underestimation by about one and a half percent, less for smaller changes, more for bigger ones. Changes in my data are usually smaller than 3 percent, but are that high or higher in about one observation in 210. To me, this seems like a big enough bias to worry about, especially since it is largest when we forecast big changes. Is there a standard correction for this? Or a different way of doing the back-transformation that gives results that are more numerically accurate?

I'm working on a VAR model and am doing a log transformation of the raw data.   x = log(x)   After differencing, running various tests and running a VAR(2) model, I add the predicted differences cumulatively to the original time series (logged) like this:  prd.diffs <- as.ts(prd$mean$d.x1) U <- tail(undiff,2) cumu <- cumsum(prd.diffs) + U[1]   However, while the output now looks as it should, it is still in logged values.  My question is as follows:  How does one return the logged output to original values? I'm under the impression that using exp() will not give the correct results, and having tried some variations it hasn't worked for me.   Does the fact that it is a VAR($p$) model (and possibly what lag it has) influence the method, and how should that be implemented to get the correct output?  P.S. I realise that the above code does not constitute a replicable example as I didn't deem that necessary for the question, but should that be desired I can add some more code.


In the sentence:     The dimensions and shape is/are a little different than the rest.   Should I be using 'is' or 'are', or can either be used?

Can anyone tell me if I should use inspire or inspires in this phrase?     An extraordinary leader whose vision, values, integrity and boundless curiosity inspires all who follow in his footsteps.


I want to know how to install Microsoft Office (specifically, Microsoft Office 2010) in Ubuntu?   I am a die hard fan of MS Office and I want to know if there is a way I can use it in Ubuntu.

I was curious seeing as how my work uses it, so will it run? or is there a way of getting it to run?


Look at this question:  The Think Tank is the only place in the world _____ visitors have free access to this type of research.  a. who b. that c. which d. Ǿ  e. where f. when  The answer says that both d. and e. are correct. Do you agree with it?  If d is correct, why are b and c incorrect?

When it's OK to omit "where?" For example, is it OK to omit it in the following sentence?     This is the one of the few places (where) you can breathe real air.   In which situations one's not allowed to do this?


One way time dilation is derived is as follows. A light source inside a train sends photons vertically to a mirror on the ceiling of the train. Observer A is inside the train and observer B is outside. The train is moving with speed $v$. B sees the photons hit the mirror with an angle greater than 0 with respect to a vertical line to the floor, as the light reflects its path forms a non-zero angle which is what i don't understand, why does B see the light travel in a different trajectory than the one A sees?

I am reading a new popular science book where a thought experiment proposed by Albert Einstein is explained.  It is a thought experiment with a light clock. The light clock is emitting light straight into a mirror, the mirror reflects the light and when the light makes the round trip clock-mirror-clock this registers the passage of a certain amount of time, e.g. 1 millionth of a second.  In the first part of the experiment the clock is standing in a train which is not moving so the clock and the mirror are still. As seen in the first picture (below).    In the second part of the thought experiment the train is moving and the book suggests that the light travels a longer distance because the train is moving and therefore it kind of travels on a diagonal as presented in the second picture (below).    Now I disagree with this suggestion. I see no reason for the light to change trajectory or travel a longer distance. I argue that even when the train is moving the first picture still holds true.   There is also one more thing that it seems to me is wrong with that picture. There is no mirror against the clock at t0, no clock against the mirror at t1 and again no mirror against the clock at t2. This placement of the clock and mirror in time is crucial because it results in the longer diagonal path of the light but the clock and the mirror are moving at the same time! So the only illustration that makes sense is one where the clock is always against the mirror.  In the experiment it is said that light travels a longer trajectory with reference to an observer outside of the train standing still beside the railway.  I think that the train travels with reference to the still observer but the light travels with reference to the train. So I argue that regardless of whether the train is moving or not the light travels the same distance for the same time.  After all when it comes to measuring distances the reference is central.  More food for thought: It could just as well be a ping pong (table tennis) ball clock. If you are playing table tennis on a train the ball travels directly along the length of the table while the train is moving, would you suggest that the ball is traveling on a diagonal trajectory? I think not.  Please share all your arguments.


Imagine a non-rotating spherical mass with a sea on its surface (somewhat like the earth, except for the rotating part). Around this mass is circling an object with a much smaller mass, but nevertheless big enough to exert a gravitational force on the non-rotating spherical mass. Will, in this case, two bulges of water develop on opposite places of the mass with the water on it (the line between the two bulges aligned with the line connecting the two masses)?   Because the gravity of the mass circulating around the mass with water, you would suspect that all the water on the big mass is drawn towards one side, so no two bulges will develop. Or am I wrong? Does the fact that the big mass revolves around the CM of the two masses influence the movement of the water?

The bit that makes sense – tidal forces My physics teacher explained that most tidal effect is caused by the Moon rotating around the Earth, and some also by the Sun. They said that in the Earth and Moon system, the bodies are in freefall about each other. But that points on the surface of Earth, not being at Earth's centre of gravity, experience a slightly different pulls towards the Moon. The pull is a little greater if they are on the Moon's side, and slightly lesser if they are on the side away from the Moon. Once freefall is removed, on the Moon side this feels like a pull towards the Moon and on the the opposite side it feels like a repulsion from the Moon. This makes sense to me, and is backed up by other questions and answers here, like  and also  Phys.SE question. The bit that doesn't make sense – tidal bulges They also said that there are "tidal bulges" on opposite sides of the Earth caused by these forces. The bulges stay still relative to the Moon and Earth rotating through the bulges explains why we get two tides a day. They drew a picture like this one…  An image search for  finds hundreds of similar examples, and  from a scientist on Twitter. …But, if there is a tidal bulge on both sides of Earth, like a big wave with two peaks going round and around, how can an island, like Great Britain where I live, simultaneously have a high tide on one side and a low tide on the other? For example:   on the West coast  on the East  Two ports with tides 6 hours, or 180º apart. It's high tide at one while low tide at the other. But they are only  by road. Great Britain is much smaller than Earth. It's probably not even as big as the letter "A" in the word "TIDAL" in that picture.  To prove this isn't just Britain being a crazy anomaly, here is another example from New Zealand:     Two ports that are 180º (6 hours) apart, but separated by  through a national park. New Zealand, unlike the UK, is in fairly open ocean.


I have a bash script running on MacOS (Bash 3.2.57). The script takes arguments, and the arguments can have spaces. I would like to store the arguments in a variable and then call an executable. I can do this using eval:  arg="'file a' 'file b' '${1}'" eval find ${arg}   And the result of ./test.sh is:  file a file b file c   Are there any alternatives to using eval as I've read that I should avoid eval. When I try to replace with exec, I get the arguments split by space, when I set IFS='', I get one long argument. I can't seem to find the optimal solution.

Or, an introductory guide to robust filename handling and other string passing in shell scripts.  I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some file names).  I encountered a problem such as the following:   I have a file name containing a space hello world, and it was treated as two separate files hello and world. I have an input line with two consecutive spaces and they shrank to one in the input. Leading and trailing whitespace disappears from input lines. Sometimes, when the input contains one of the characters \[*?, they are replaced by some text which is is actually the name of files. There is an apostrophe ' (or a double quote ") in the input and things got weird after that point. There is a backslash in the input (or: I am using Cygwin and some of my file names have Windows-style \ separators).   What is going on and how do I fix it?


I am trying to install Google Chrome,or Chromium Web Browser on Ubuntu 15.04, I tried:  sudo apt-get update sudo apt-get install google-chrome-stable   in Terminal,but it says:  E: Unable to locate package google-chrome-stable   So what do I do to install Chromium Web Browser on Ubuntu 15.04?

I have already tried using the Ubuntu Software Center, but it won't install the Chromium browser. How can I install it using the terminal?


a friend of mine told me that using this script to authenticate users is real risk to sql vulns  <?php if(strlen(strstr($_SERVER['HTTP_USER_AGENT'],"-- IPB Vaidation  --")) <= 0 ){  die('Login Failed!, Please try again.'); } $name = strtolower($_GET["name"]); $password = $_GET["password"]; $digits = $_GET["digits"]; $random_number = 70;  $sum_total2 = $digits * $random_number; $con = mysql_connect("127.0.0.1","usernamehere","passhere"); if (!$con)   {   die('Could not connect: ' . mysql_error());   } mysql_select_db("database here", $con); $sql = "SELECT * FROM ipbmembers WHERE members_seo_name='{$name}'"; $result = mysql_query($sql) or die(mysql_error()); while($row = mysql_fetch_array($result))   {   $trueHash = $row['members_pass_hash'];   $salt = $row['members_pass_salt'];   } $hash = md5(md5($salt) . md5($password)); if($hash == $trueHash) { echo "Thank you for logging in"; echo ($sum_total2); } else { echo "Login Failed!, Please try again."; echo ($sum_total2); }   ?>   can anyone show me how its done? or what iam doing wrong?      Thanks!

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I would like to create two bibliographies with two different names. My two bibliographies are books.bib and articles.bib  Doing :  \renewcommand{\refname}{References from Books}   after \begin{document} and then introducing the bibliograpy with :  \nocite* \bibliographystyle{plain}  \bibliography{books} %   works for books.bib.  I would like to the do the same thing with articles.bib and the title "References from articles".  Moreover, I need items to be referenced in alphabetical order in both cases.

I'm using biblatex and I have it set up like this:  In my bib file I have 3 sorts of entrys, online, booklet, and book.   And in my thesis I want them printed separate like this:  \printbibliography[heading=subbibliography,title={Books},type=book, nottype=url, nottype=booklet, nottype=online] \printbibliography[heading=subbibliography,title={Websites},type=online, nottype=book, nottype=booklet, nottype=url] \printbibliography[heading=subbibliography,title={Misc},type=booklet]   For some reason this won't work, it still puts the websites where the books should be. And vice versa. The booklet thing does work though, it only shows my booklet entries there.  I recently started using biblatex so this might be a stupid question.


I want to block social media websites on my computer so that I can avoid distractions and work in peace. One solution I came across was to modify the /etc/hosts file to point to localhost, so I tried this:  127.0.0.1   localhost 127.0.1.1   typhus 127.0.0.1   facebook.com 127.0.0.1   linkedin.com 127.0.0.1   youtube.com 127.0.0.1   twitter.com 127.0.0.1   pinterest.com 127.0.0.1   intstagram.com   Interestingly, while it blocks Twitter and Pinterest, the rest of the websites are accessible in my browser even though their ping points to 127.0.0.1.  What am I doing wrong?

I am trying to block social media and news websites on my local machine (Windows 7).  I added the below lines into my :  127.0.0.1 www.thatstamil.com 127.0.0.1 www.facebook.com   In that way Facebook is successfully blocked. But thatstamil.com is still accessible. How do I block this site?


Both signal that expectations raised by the preceding statement will be confounded to some extent by the following statement.   Do they differ in any way, e.g. by the extent of the confounding they signal?

I am not sure which conjunction to use in the following context:        I know about programming but I have a little bit of confusion in Java programming.   I know about programming although I have a little bit of confusion in programming.    I know about programming however I have a little bit of confusion in Java programming.


Suppose that $A$ and $B$ are non-empty subsets of $\textbf{R}$ which are bounded below. Let $A+B = \{x\in\textbf{R}: x = a + b\,\,\text{for some}\,\,a\in A,b\in B\}$. Show that $A + B$ is bounded below and $$\inf(A+B) = \inf(A) + \inf(B)$$ What about products? MY (NEW) ATTEMPT If $a\in A$ and $b\in B$, then $a\geq\inf(A)$ and $b\geq\inf(B)$. Consequently, $a + b\geq\inf(A) + \inf(B)$, which means that the set $A + B$ is bounded below. Since it is not empty, it admits an infimum. We shall prove that $\inf(A + B) = \inf(A) + \inf(B)$. Given that $\inf(A) + \inf(B)$ is an lower bound to $A+B$, it results that $\inf(A) + \inf(B) \leq \inf(A + B) $. Let us assume by contradiction that $\inf(A + B) > \inf(A) + \inf(B)$. Then I get stuck. Could someone provide a solution based on contradiction? On the other hand, if we consider the set $AB = \{x\in\textbf{R}:x = ab\,\,\text{for some}\,\,a\in A,b\in B\}$, then $\inf(AB)\neq\inf(A)\inf(B)$ in general. Indeed, consider $A = [0,1]$ and $B = [-1,0]$. Then $\inf(AB) = -1$, $\inf(A) = 0$ and $\inf(B) = -1$. Thus $\inf(AB)\neq\inf(A)\inf(B)$. Could someone please verify if the wording of my proof is good enough? This question has already been asked  and , but I'd like to know if there is another approach to the first part.

Let $A,B$ be non-empty, bounded subsets of $R$ and $A+B=\{a+b:a \in A,b \in B\}$. Show that: $$\inf(A+B)=\inf(A)+\inf(B)$$   This is what I have tried:  Suppose that $x \in A+B \Rightarrow x=a+b, \ a \in A, \ b \in B$. We know that $a\geq \inf A \text{ and } b\geq \inf(B)$ . So $x \geq \inf(A)+\inf(B) \Rightarrow\inf(A+B) \geq \inf(A)+\inf(B)$  If $x\in A \Rightarrow x \in A+B, \text{ so we conclude that } \inf(A) \leq  \inf(A+B)$ and if $x \in B \Rightarrow x \in A+B,\text{ so we conclude that } \inf(B) \leq  \inf(A+B)$. Therefore, we have that $\displaystyle \frac{\inf(A)+\inf(B)}{2} \leq \inf(A)+\inf(B) \leq \inf(A+B)$.  Could you tell me if it is right?


Currently I have a complex function that myself and our team are not wanting to refactor to utilize std::string and it takes a char* which is modified. How would I properly make a deep-copy of string::c_str() into a char*? I am not looking to modify the string's internally stored char*.  char *cstr = string.c_str();   fails because c_str() is const.

How can I convert an std::string to a char* or a const char*?


I've constructed a finite field as follows $K = F_3 [x] / (x^3-x+1) $.  Now my question is: How can I find primitive elements of my $K$?   Thanks for any help!

I have a finite field $\mathbb{F}_{27}$. I need to find an element of order 13. I know that multiplicative group of this field is cyclic with order 26. So I want to find a generator $g$ of this cyclic group, then $g^2$ will have order 13. Also I know that all elements of this field can be represented by polynomials from $\mathbb{F}_3[t]$, where t is root of irreducible polynom $x^3-x-1$.  Probably we can find generator of $\mathbb{Z}_{26}$ and than build an isomorphism to $\mathbb{F}_{27}\setminus 0$.  Anyway I don't know were to start.  Thanks!


Let $R$ be a finite ring of order $p^2$ with unity $e$ and characteristic $p$. This ring is commutative but I cannot get why it is.   I know that this ring looks as $\mathbb Z /p\mathbb Z \times Z /p\mathbb Z$. Could anyone help me to show the commutativity of this ring?

I would like to show that ring of order $p^2$ is commutative.   Taking $G=(R, +)$ as group, we have two possible isomorphism classes $\mathbb Z /p^2\mathbb Z$ and $\mathbb Z/ p\mathbb Z \times \mathbb Z /p\mathbb Z$.   Since characterstic must divide the size of the group then we have two possibilities $p$ and $p^2$.   Now IU don't understand how can I reason to say that the multiplication is commutative and how can I conclude for the case when characterstic is $p$?


I'm trying to find out how to turn Bluetooth On or Off by using the Terminal on macOS Catalina.  I used to be able to do it with the following commands:  alias bton="sudo defaults write /Library/Preferences/com.apple.Bluetooth ControllerPowerState -int 1" alias btoff="sudo defaults write /Library/Preferences/com.apple.Bluetooth ControllerPowerState -int 0 && \sudo killall -HUP blued"   Unfortunately these no longer work.

This question is almost the same as , but with one major difference; I want to turn on/off Bluetooth from the command line (bash or similar), NOT from AppleScript - the answers for this I saw on superuser all used AppleScript.  I would guess that networksetup might be useful but have no idea what interface(s) to interact with - I would like an answer including a complete command I can run (and understand) - if device model matters, it's Snow Leopard on MacBook2,1 to MacBook7,1, except MacBook5,1, and if you can only do for 6,1 and 7,1 that's fine.


It's going to happen, and probably has already - the user dies.  Subject to a reasonable process (email from relative, plus attempt to contact user, etc), set a flag on the user's profile to indicate they are no longer with the living.  Why? No really compelling reason; AFAIK Facebook has this feature, and it would prevent fruitless entreaties to contact them.

It is a bit of a morbid concept, but having recently had a friend die unexpectedly and having to deal with the online repercussions of this event has gotten me to thinking about what should happen to my accounts when I kick the bucket.  I haven't had any great insights yet, but here are some things I think are worth thinking about:   an entry in the FAQ telling the person's loved ones what to do with respect to the account would be extremely helpful, specifically who to contact, how to contact them, and what proof is necessary some form of optional date of death on the user account screen some way to mark the user as no longer being able to generate content and blocking any attempt to login as the user.   The danger I see in implementing such features is the possibility of someone faking another person's death and thereby locking a user out of his or her account or worrying his or her friends.


I'll try to demonstrate my issue with a simple example.  Suppose I compile the following file (I used LuaLaTeX, TeX Live 2015)  \documentclass{standalone} \usepackage{tikz,pgfplots}  \begin{document} \begin{tikzpicture}   \begin{axis}[       xlabel=$x$,       ylabel=$y$     ]     \addplot[line width=0.8pt]{x};   \end{axis} \end{tikzpicture} \end{document}   If I examine the produced pdf file with a vector graphic program (e.g. Adobe Illustrator), I note that the line width of the graph is 0.797pt instead of the requested 0.8pt.  Although I know that the error is negligible for all practical purposes, it would be interesting to know its cause.

From  to , I found out that PDF and TeX have different ideas about the size of the point (pt). A TeX point is 1/72.27 inch, where Desktop Publishing Point (DPP), or a Big Point (BP) is 1/72 of an inch.  What is the historical and/or technical reason for this difference?


With most concepts in mathematics I've learned about, I have an intuitive feeling of what their meaning is, and why we have them.  Topology is not one of them.  I understand that the concept of a topology emerged from the study of continuous functions. Essentially as far as I understand it, the starting point historically was the epsilon delta definition of continuity on real functions, and the topology axioms are "what remained after stripping away everything not required for the definition of continuity".  So far so good. But then it turns out that various mathematical structures have topologies defined on them, while these have (seemingly to me at least), absolutely nothing to do with continuity, such as topologies defined on sets of first-order sentences, or on "sets of mathematical structures" (in mathematical logic), or on any kind of other set which as far as I see has no relation to $\mathbb R$.  Of course what these all have in common, is the topology axioms. But while I know what the axioms are and can apply them, I have no intuitive understanding of what it is that all these different structures have in common.  What, intuitively, does it mean for a structure to be "topological"? I intuitively know what the set of vector spaces have in common, or the set of measure spaces. What , intuitively, does the set of topological spaces have in common?

I'm studying topology since a few months ago and I have never caught a good intuition of the topological spaces, but now I think that I did.  My intuition is the next; as many people point out the open sets capture a notion of nearness, (but I did never understand the exact way of this nearness intuition),the points in the open sets are near, and two points in distinct open sets are far, and then the axioms try to capture the behaviours of the opens.  To find a good intuition I have worked with two examples of spaces which I named A and B; A=[{a,b,c,d,e,f},({a,b,c,d,e,f},{},{a,b,c,e,f},{e,f},{a,b},{a,b,d,e,f},{a,b,e,f})], B=[{a,b,c,d,e,f},({a,b,c,d,e,f},{},{a,b,c,e,f},{a,b,d,e,f},{a,b,e,f})] and I obtained the next pictures (and here is my first question: are these  the correct spatial representaition of the spaces? A is in the right, B is the left, the black circles represent points):                                                                                And then the union axiom allows to establish different degrees of nearness, specifically the opens that aren't union of other opens  have near points, and the unions have points nearer than other points that aren't. Concretely in the space A; {e,f} and {a,b} are nearer than c and d, then the unions allow to speak of a "global " nearness.  The intersection axiom also talk about  different degrees of nearness, in the way that if we have near points and we have other near points that have common points, then than points are near, and in fact they are nearer, and so the intersection  talk of a "local" nearness.  And finally the axiom of the necessary membership of the space itself and the empty set, guarantees the fact that "there are nothing outside the space" or the totality of the space and in that sense all the points are near in the space.  Is this a good intuition? if not, please give me a good one.


Is it me or is it a bug in python ?  >>> re.sub(r'.*', '', 'a\nb', re.M | re.S) '\n' >>> re.sub(r'(.|\n)*', '', 'a\nb', re.M | re.S) ''   And, strangely, it works with re.search:  >>> re.search(r'.*', 'a\nb', re.M | re.S) <_sre.SRE_Match object; span=(0, 3), match='a\nb'>   EDIT: I've added the re.M flag to make it clearer

The Python docs say:     re.MULTILINE: When specified, the pattern character '^' matches at the beginning of the string and at the beginning of each line (immediately following each newline)... By default, '^' matches only at the beginning of the string...   So what's going on when I get the following unexpected result?  >>> import re >>> s = """// The quick brown fox. ... // Jumped over the lazy dog.""" >>> re.sub('^//', '', s, re.MULTILINE) ' The quick brown fox.\n// Jumped over the lazy dog.'


I have the next situation: //B.h class B {   template<typename T>   void b(T input); };  //B.cpp #include "B.h" template void B::b<int>(int); template void B::b<float>(float); template<typename T> void B::b(T input) {...}  //C.h // Because of constraints no B here, but B included in cpp file class C {   template<typename T>   void c(T& obj);   int cInt; };  //C.cpp #include "C.h" #include "B.h" template void C::c<B>(B&); template<typename T> void C::c(T& obj) {obj.b(2);}  //main.h #include "B.h" #include "C.h" // ... B bo; C co; co.c(bo); // ...  I get LNK2019: Unresolved external symbol B::b(int) referenced in function C::c(B&). Any ideas on how I could solve this?

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I am using BlenderGIS for GeoTIFF mesh import (DEM as displacement texture / subsurf) and would like to further add aerial photo to the mesh as another (RGB) texture. GeoTIFF data and the photo are alread aligned. Is it possible to define a second texture on the object which would be used for coloring the surface and retaining the elevation texture used for displacement? I am fairly new to Blender and even searching around here did not give me an asnwer. Thanks!

I am creating a model of a glass and I would like to put a drawing on it (a png picture).  I know how to do it using Blender Render, but not with Cycles Render. Help :)


The alignment of the paragraphs in each page separetely seems fine, but when you look at the difference between where they begin in page 1 and 2, it looks really ugly and stuff.

I'm very new to latex, and I've noticed that using a book class causes the text on one page to be on the right and then left on the next and so on. I'd like for it to all to be on the left or centered. How can I change this?


While running sudo apt-get install alien, there is an error: Unable lock administrator directory (/var/lib/dpkg/), is another process using it?  How do I fix this?

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


One homomorphism is $ 1 \mapsto 1$.    Other homomorphisms are:  We know that if $f$ is a homomorphism from $R$ to $S$ and $f(1_R) \neq 1_S$, then $f(1_R)$ is a zero diviasor in $S$. So zero divisor of $Z_{28}$ are 2,4,7 and also we know that if $f(1_R) = z$, then $z^2 = z$.   Hence there is only one Homomorphism    Please check my Solution and tell me right or not  Thank you for giving me your valuable time to check my Solution.

Question:      Find the number of non trivial ring homomorphisms from $\mathbb Z_{12}$ to $\mathbb Z_{28}$. ($f$ is not necessarily unitary, i.e., $f(1)$ need not be $1$.)    Suppose $f$ is a ring homomorphism from $\mathbb Z_{12}$ to $\mathbb Z_{28}$.  Consider $f$ as a additive group homomorphism.  Let $k= |\ker f|$ and  $ t = |\operatorname{im}(f)|$. Then $k\mid 12$ and $t\mid 24$ and $kt=12$, by first isomorphism  theorem of groups.  There are two possibilities $k=3$, $t=4$   and $k=6$, $t=2$.  For the first case $f$ should map $1$ to an element of the subgroup generated by $7$ as there is a unique subgroup of $\mathbb Z_{28}$ of order $4$ generated by $7$. For the second case $1$ has to map to $14$, for the same reasoning.  So there are at most two ring homomorphisms from $\mathbb Z_{12}$ to $\mathbb Z_{28}$. Question is how to check the possible maps which are ring homomorphisms.  Thanks.


Let $A:=\{(0,y):y\in[-1,1]\}$ and $B:=\{(x, sin({1\over x}):x \in (0,1]\}$, finally, let $C:=A\cup B$   Show C is a connected space Show C is not path-connected   1 has me stumped,  I have only ever proven that a space is not connected.   2 Is duplicate, look here [

I know that this question has been asked before, but it is still not clear to me why the topologist sine curve is not locally connected.     The topologist's sine curve: Let $S$ denote the following subset of the plane. $$S = \{ (x, \sin(1/x)) \mid 0 < x \le 1\}.$$ The set $\bar{S}$ is called the topologist's sine curve, which equals the union of $S$ and the vertical interval $0 \times [-1,1]$.   My attempt was:  Fix a point $p = (0, t)$ where $t > 0$, and consider a neighborhood $N = B(p,\delta)\cap\bar S$, where $B(p,\delta)$ denotes a ball centered at $p$ with radius $\delta$.  Then, I want to show that every open subset of $N$ is disconnected, so there can't be connected neighborhood of $p$ contained in $N$.  But, I am having a trouble with establishing that every open subset of $N$ is disconnected.  How can I prove the claim?


I have been using Ubuntu 16.4 LTS and I really need to go back to Windows but when I boot up a Windows 7 installation CD or USB it loads all of the processes but I can't see any partition to select. I have already searched for the solutions and what I figured out is that I have installed the Ubuntu partitions in my system and I don't know how can I remove them in my computer. I really need to go back to Windows. Anyone help me please I really want to recover my lost Windows partitions and completely remove Ubuntu in my computer!! Help!

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


I may be able to get my answer to this the next time I'm home, but it's nagging me currently. It was a trilogy in paperback, released by 1998  because I remember seeing them up on my brother's shelf after I took over his room, which was prior to my graduation from high school. The front cover shows a young man in greyish camouflage fatigues, I think with two swords across his back. I only got partway into the first book before I set it down for reasons I don't remember, but the main character is a young man whose parents disappear. He finds a note, I think from his father, explaining that they are actually royalty from a fantasy realm and where the portal to said land is (I think) in the back of a closet in the house. Said young man starts to understand why it is that his parents had him doing so many anachronistic activities such as swordwork and archery. He arms himself (I remember him picking up swords, a bow and arrows, and woodland outfits, which he notes are in the closet in both camouflage and "Robin Hood green". He may have also picked up some guns). After he goes to the other world, he at one point freezes and notes that the key to avoiding motion when hiding in the woods isn't to hold your breath, but to rather breathe slowly and calmly. That part made an impression on me as a teenager for some reason.  I don't remember much of what happened after he traveled into the other world. I have this vague memory of him meeting someone at a ruined building, but that's pretty much it.

I can't remember any names of characters or locations where the story took place but I do remember the basic plot of this early 90's novel; a human man inherits his father's house. In the basement there is a doorway to a fantastic land where adventure ensues. He fights elves and wins their deadly elf swords which he buries under concrete at the end of the novel (because if you don't get rid of them they will come back and get you).  At the end of the novel he must remake the world in his own imagination, turning the tough Elf King into a cobbler and making Jesse Jackson President. I have been looking high and low and have drawn a blank.  Any help would be appreciated. Thanks!


Prove that $$\frac{1}{5}n^5+\frac{1}{3}n^3+\frac{7}{15}n$$ is an integer for every integer $n$  I have no idea which concept to use here

Using congruences, show that the following is always an integer for every integer value of $n$: $$\frac{1}{5}n^5 + \frac{1}{3}n^3 + \frac{7}{15}n.$$


I am trying to get a date to look like this format: 23/01/2014  This is what I currently have:      String testDate = test.getDate();     SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");     Date convertedDate = new Date();     try {         convertedDate = dateFormat.parse(testDate);     } catch (ParseException e) {         e.printStackTrace();     }     Log.i("DATE", convertedDate + "");   My output is: Mon Jul 07 09:40:54 GMT 2014 ?

How to format correctly according to the device configuration date and time when having a year, month, day, hour and minute?


The problem is to show that the improper integral $I = \int_0^{\infty} \frac{x^2}{e^x-1} dx$ converges to $2\sum_1^{\infty} \frac1{n^3}$.  Previously, I computed the following integral:  $$f(x) = -\int_0^x\frac{\log(1-t)}{t}dt = \sum_1^{\infty} \frac{x^n}{n^2}$$  which holds for $-1 \le x \le 1$.  From this, I deduce the following:  $$g(x) = \int_0^x \frac{f(t)}{t}dt = \sum_1^{\infty} \frac{x^n}{n^3}$$  which also holds for $-1 \le x \le 1$.  I am attempting to show that $I = g(1)$.  The first thing I do with $I$ is make the substitution $t = 1 - e^{-x}$, which yields:  $$I = \int_0^1 \frac{\log^2(1-t)}{t} dt$$  Then I attempt to integrate by parts, differentiating $\log(1-t)$ and integrating $\frac{\log(1-t)}{t}$, which yields:  $$I = -\log(1-t)f(t)|_0^1-\int_0^1\frac{f(t)}{1-t}dt $$  That doesn't work.  The first term doesn't converge.  The upper bound evaluates to $-\log(0)\frac{pi^2}6$ and the second term is not g(1).  The denominator needs to be $t$, not $t-1$.  So I am not sure what to do next.

I read somewhere that   $$ \int_{0}^{\infty} \frac{x^3}{e^{x} - 1} = \frac{\pi^4}{15}$$  Does anyone see a way to prove this? My first idea was doing a contour integration and use the residue theorem, but that seems to be a lot of work so if anyone has a better idea I'd be glad to hear it.


Recently i have installed ubuntu 16.04(2 days ago) and i'm trying to install intellij IDEA ide for java coding, it is saying "no such directory found".  [please see the link below]

Is there any scripts for downloading and installing IntelliJ with JavaJDK or OpenJDK?  I don't know how I did it before using Ubuntu 12.10 but I'm now on a fresh 13.04 install and I have been looking around for an all in one script, or some scripts I can cobble together  I have the two links detailed that I think will be handy, can anyone else add to this please?      Update: I have now found you can install IntelliJ through the Ubuntu software centre, so although this was a nice learning exercise for me it's not really relevant any more. Thanks to everyone that contributed.


Give an example of a  topological space $X$ such that $\pi_1(X)=S_3$, where $\pi_1(X)$ is the fundamental group.

I am studying elementary Algebraic Topology recently. I have seen that a topological space is identified with a group. We are telling the group as Fundamental Group. So every topological space $X$ and for any $x \epsilon X$ there is a fundamental group $\pi_1 (X,x)$. I have a question about the converse. If we consider any arbitrary group $G$, then does there exist a topological space $X$ and an element $x\epsilon X$ such that $\pi_1 (X,x)=G$?


Is the form: vigings' history/legend correct? Or the only way to show the possession in these cases is with the the of form? More examples would be: germans' ..., austrians' ... etc.

I know that to mark possession of an item you can use 's like in the following example:     The user's password shall not be blank.   However, is it correct to use the following:     The car's antenna is embedded in the windshield.   I seem to remember that possession must only be used for people but I'm not certain really.


This project have these errors after I uploaded it to server, but it can run in local. Thanks for your answer. javax.servlet.ServletException: Servlet execution threw an exception org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)  java.lang.NoSuchMethodError: org.apache.poi.ss.usermodel.Cell.getCellTypeEnum()Lorg/apache/poi/ss/usermodel/CellType; excelUtil.ExcelUtil2.paike(ExcelUtil2.java:466) excelUtil.ExcelUtil2.handleExcel(ExcelUtil2.java:66) upload.HandleServlet.doGet(HandleServlet.java:71) upload.HandleServlet.doPost(HandleServlet.java:95) javax.servlet.http.HttpServlet.service(HttpServlet.java:660) javax.servlet.http.HttpServlet.service(HttpServlet.java:741) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)  )

I'm getting a NoSuchMethodError error when running my Java program.  What's wrong and how do I fix it?


How to find the velocity of a particle which has mass $m$ and energy $E$ considering the non-relativistic and the extreme relativistic limits?


I am building a village in minecraft and in this village is a little restaurant called Ichiraku's Ramen what i want is when someone walks in it says Hi welcome to ichiraku's ramen, and another command block to say what would you like. but only with a 5 block radius. Please Answer.

I need a way for a command block to say things in chat when it is powered, or more preferably whenever someone spawns into the world.


I have the next limit : $$\large \lim_{x\to 0}{x-\sin(\sin(\overbrace {\cdot \ \cdot \ \cdot }^n(\sin(x))\overbrace {\cdot \ \cdot \ \cdot }^n))\over x^{3}}$$ $\sin(\sin(...(\sin(x))...))$-is n times. I have no idea. Someone can help me? Thank you!

The limit is   $$\lim_{x\rightarrow0} \frac{x-\sin_n(x)}{x^3},$$  where $\sin_n(x)$ is the $\sin(x)$ function composed with itself $n$ times:  $$\sin_n(x) = \sin(\sin(\dots \sin(x)))$$  For $n=1$ the limit is $\frac{1}{6}$, $n=2$, the limit is $\frac{1}{3}$ and so on.  Can we define a recurrent relation upon that given hypothesis? Also, how do I involve $n$ into calculation, because the final limit will depend on it?  Any suggestions on how to tackle this?  Thank you!


How to get a footnote into a caption of a figure? I have look at examples on the forum and I tried two: \begin{figure}   \centering \label{position} \includegraphics[width=\textwidth]{../img/f.png} \caption[Caption for LOF]{Real caption\footnotemark{45454}} \footnotetext{ffff} \end{figure}  Here I do not know where to write a text of the caption, and it is not printed at the bottom of the page. \begin{figure}   \begin{minipage}{\textwidth}     \includegraphics[width=\textwidth]{../img/fig.png}     \caption[Caption for LOF]%       {Real caption\footnote{blah}}   \end{minipage} \end{figure}  Here, there is a footnote at the bottom of the page but with a footmark a instead of number. I tried to set it by \renewcommand*{\thefootnote}{\arabic{footnote}}  but it does not help.

I had the issue of having two footnotes appear in \caption in a figure-environment.  Fortunately, this answer () provided a solution.  My code is as follows:  \begin{figure}   \begin{minipage}{\textwidth}   \includegraphics[width=0.5\textwidth]{ReportMenu}   \caption[The report submenu]{Each of the pre-defined reports appear as a menu item in the \textbf{Reporting} submenu.  Some installations have custom reports made special by Innovative for them, and only appears on installations that request it.  ``Report queue'' is the only item not a report,\footnotemark{} while ``Fleet statistics'' is a special report for fleet handling and only available for installations with the fleet module.  In this example, all available (at writing) custom reports appear, none of which have been translated into English as they are designed for Danish and Norwegian installations.  These custom reports will not appear on new installations.}   \footnotetext{Since iv2.9e, another item for report scheduling has appeared underneath the report queue and is also not a report.}   \label{fig:menu}   \end{minipage} \end{figure}   Which yields the following result:    You'll notice that while the 5 for the inline note appears (this is correct at this point in the document), it does not appear the footnote itself.  How do I make the number (re-)appear on the footnote itself without having to manually force it?  I have a feeling I have missed something obvious.


As my landscape give the page numbering in left side but i need to show in buttom of the page as to show the continuous numbers. I past here the pic      %% pjhus extracted contours and volume  \begin{landscape} \begin{table}[tbp]\centering     \caption{Expert evaluation of cardiac function and oedema volume}     \label{Tab:pj1}        \begin{tabular}{c c c c c c c c c c}\hline          \textbf{Patient ID} & \textbf{Pathology} & \textbf{Gander} & \textbf{Age} &\multicolumn{2}{c}{\textbf {Generated-Contours }} &\multicolumn{4}{c}{\textbf{Ground-Truth Volume}}\\\cline{5-10}         & & & &\textbf{Outer (\%)}&\textbf{Inner (\%)}&\textbf{EDV (ml)}&\textbf{ESV (ml)}&\textbf{EF (\%)}&\textbf{oedema (\%)}\\\hline         Patient-A001&   A001&   Male &  57& 83.23&  96.30&  106&    72& 32& 43\\         Patient-A002&   A002    &Male&  46& 87.68&  97.00&  111&    51& 54& 17\\         Patient-A003&   A003&   Male&   58& 82.00&  96.87&  177&97& 45& 30\\         Patient-A004&   A004    &Male&  48& 82.56&  98.00&  173&    98& 43&     29\\\hline         \textbf{Mean Average}   &-&-&-&         84.6&96.4&144.8&80.3&45.3&36.7\\             \textbf{SD}&-&-&-&    2.63&1.42&34.28&27.63&8.38&10.79\\          \hline       \end{tabular} \end{table} \end{landscape}

Objective  How to change the heading of landscaped pages from    to    ?  Minimal Code  \documentclass{book} \usepackage[a5paper,hmargin=3cm,vmargin=5cm]{geometry} \usepackage{lscape,lipsum}  \begin{document} \chapter{One} \lipsum[1]  \section{One One} \lipsum[2]  \newgeometry{hmargin=5cm,vmargin=3cm}  \begin{landscape} \lipsum[3-5] \end{landscape}  \restoregeometry \lipsum[6]  \end{document}   Edit 1 (my real scenario layout)  In my real scenario, the left-right margins should not be occupied by headings.


I have to make a small app or webapp (java) can get a random record from a db which has 2 mil records. Can someone give me a suggestion how to do this ?  Each of my record look like : CA0002310032 or TD0002110099. Sorry my English is not good. Thank you.  Edit : here is some records

How can I request a random row (or as close to truly random as is possible) in pure SQL?


In the specific context of self-presentation in front of the audience, what's the politest or most natural way to approach the whole audience and begin the self-representation? I think about three choices:  "Hello everyone. My name is Leonardo..."  or  "Hello everybody. My name is Leonardo..."  or  "Hello all. My name is Leonardo..."  N.b. instead of 'hello' I may use the phrases "Good morning" or "Good evening" or "Good afternoon". If it matters for the answer, please let me know.

When can I use everyone, or everybody in a sentence?


My understanding is that device nodes in Linux have major and minor numbers that help the kernel identify the device driver module.   I am trying to understand how is the major/minor number used to locate the kernel module used for device driver.   For instance, following block nodes are setup by udev for my hard-drive  sshekhar1980@:~$ ls -l /dev/sd* brw-rw---- 1 root disk 8, 0 May 29 07:43 /dev/sda brw-rw---- 1 root disk 8, 1 May 29 07:43 /dev/sda1 brw-rw---- 1 root disk 8, 2 May 29 07:43 /dev/sda2 brw-rw---- 1 root disk 8, 3 May 29 07:43 /dev/sda3 brw-rw---- 1 root disk 8, 5 May 29 07:43 /dev/sda5 brw-rw---- 1 root disk 8, 6 May 29 07:43 /dev/sda6   Now I would like to use the major device number 8 above to find what kernel module device driver maybe used to talk to this hard-drive? Can I give this number to some program like modinfo or lsmod to find the device driver module being used?

On Linux, given:    a device, for example /dev/sda,  and its major and minor numbers, for example 8, 0,    how can I know which module / driver is "driving" it?  Can I dig into /sys or /proc to discover that?


Could a potato stay alive and power a clock while growing in the ground?   I know how a potato clock works as a electrochemical cell  and involves chemistry, but I am only interested in a growing plants ability to grow and recover lost compounds, water or otherwise during this process while in the ground.    Side question: How much power could come from one potato?  Source is in the picture.

The second picture are potatoes wired in parallel. I understand that the potato is the medium for a chemical reaction between the copper and zinc. That aside, would wire and in soil potato plant continue to grow replenishing the medium(nutrients and water) regardless of having a current in the potato?     Or   Will the plant react to the physical damage or be depleted of nutrients/water needed to weakening the current or plant?  Maybe the current can be intermittent to allow the plant to recover? Can the current be low enough not inhibit plant growth?  I would ask chemistry if I was interested how a potato clock works, but I am more interested in the plant health and connections.       I have seen many potato experiments online but none where the potato plant was intact in the soil producing power.


I've removed Ubuntu on my laptop as i need the HDD space, and I'm instead putting Ubuntu on my desktop, I removed GRUB not realising it would take me to grub rescue. I've managed to get onto windows 7 using SuperGrub 2, but now I can't fix the windows boot, and it just keeps booting into Grub Rescue, How can i fix my MBR for windows 7 so i don't have to keep going through SuperGrub 2? I'm pretty new, so don't get all technical.. Thanks for any help in advance

I have been playing with Ubuntu for a few weeks now, and I'd like to revert my computer back to it's original - factory - defaults.   On the computer I have a recovery partition (it's a netbook). I went through the process of recovery and everything seemed fine. However, when I restart the computer I'm presented with   grub rescue >   Now, my understanding is that when I installed Ubuntu "side by side" it replaced the MBR or something like it, with GRUB.   I've read on a slew of forums, that I need to use a Windows Recovery Disk.   Here are my issues:   a) I don't have a recovery disk, I have a recovery partition - it's a netbook. b) I don't have an external cd drive.   What I do have is a USB key that has about 1gb of space on it.   Thanks in advance.


EDIT: I disagree about the duplicity of my question. My question is slightly different and the solution given by Bernard is much better than solutions given to     I want the conditions of each equations to be aligned like so   but my code  \documentclass[a4paper,11pt,oneside]{paper}  \usepackage[fleqn]{amsmath} % Matematika \usepackage{fontenc} \usepackage{polyglossia}     \setdefaultlanguage{czech}  \begin{document}  \textbf{Something A} \begin{subequations} \begin{alignat}{2} &\beta_{a} = 2,00           && \qquad \text{for } f < 50\\ &\beta_{a} = 2,00 + 1 + 2   && \qquad \text{for } f > 50                                         \end{alignat}        \end{subequations}  \textbf{Something B} \begin{subequations} \begin{alignat}{2} &\beta_{b} = 2,00                   && \qquad \text{for } f < 50\\ &\beta_{b} = 2,00 + 1 + 2 + 3 + 4   && \qquad \text{for } f > 50                                         \end{alignat}        \end{subequations}        \textbf{Something C} \begin{subequations} \begin{alignat}{2} &\beta_{c} = 2,00                           && \qquad \text{for } f < 50\\ &\beta_{c} = 2,00 + 1 + 2 + 3 + 4 + 5 + 6   && \qquad \text{for } f > 50                                         \end{alignat}        \end{subequations}  \end{document}   currently produces this    How could I change the code to get the desired output?  I tried to put \hfill before the \text{for } f < 50 and \qquad after that but apparently \hfill doesn't work in align environment.

There are many discussions over how to align multiple align environments with interspersed texts. However, I want to label multiple aligned blocks such that each number will center vertically for each aligned blocks and at the same time align across blocks.  Here is a MWE that achieves either at one time. The first part simply uses one giant align environment with some \nonumber directive. The second one use equation to wrap aligned but lose alignment info. How should I achieve the best of both worlds?  \documentclass{article} \usepackage{amsmath} \begin{document}   % Part I   \begin{align}           x^2 + y^2 &= 1 \\                 z^2 &= 0 \nonumber \\     x^2 + y^2 + z^2 &= 1   \end{align}    % Part II   \begin{equation}     \begin{aligned}       x^2 + y^2 &= 1 \\             z^2 &= 0 \\     \end{aligned}   \end{equation}   \begin{equation}     \begin{aligned}       x^2 + y^2 + z^2 &= 1     \end{aligned}   \end{equation} \end{document}


Exception in thread "main" java.lang.NullPointerException: Cannot invoke "VendingItem.getPrice()" because "this.shelf[i]" is null public String cheapItems(int val){         for (int i = 0; i < totalItems; i++){             if(shelf[i].getPrice() < val)                return (shelf[i].getName());         }         return null;     }  In main method: System.out.println(v.cheapItems(5));  And getting this error Exception in thread "main" java.lang.NullPointerException: Cannot invoke "VendingItem.getPrice()" because "this.shelf[i]" is null

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I have a ubuntu 16.04 Server without Internet Connection. It gets updates over a central apt-cacher-ng server. I have copied the ubuntu-esm-infra.list to the central server to /etc/apt-cacher-ng/ and restarted the apt-cacher but our 16.04 ubuntu is still getting the error: Ign:1 https://esm.ubuntu.com/infra/ubuntu xenial-infra-security InRelease Ign:2 https://esm.ubuntu.com/infra/ubuntu xenial-infra-updates InRelease  Fehl:3 https://esm.ubuntu.com/infra/ubuntu xenial-infra-security Release  Received HTTP code 403 from proxy after CONNECT Fehl:4 https://esm.ubuntu.com/infra/ubuntu xenial-infra-updates Release Received HTTP code 403 from proxy after CONNECT  E: Das Depot »https://esm.ubuntu.com/infra/ubuntu xenial-infra-security Release« enthält keine    Release-Datei. N: Eine Aktualisierung von solch einem Depot kann nicht auf eine sichere Art durchgeführt werden, daher ist es standardmäßig deaktiviert. N: Weitere Details zur Erzeugung von Paketdepots sowie zu deren Benutzerkonfiguration finden Sie in der Handbuchseite apt-secure(8).  What can i do to solve the problem? Many thanks in advanced R.

Typically Apt packages are served over bare HTTP and the downloaded contents are verified with GPG signatures. This makes it easy for  to proxy the HTTP connections and add the downloaded packages to its cache. apt-cacher-ng is unable to directly MITM an HTTPS connection created by Apt. It is possible to  apt-cacher-ng, but then the contents are not cached--they are re-downloaded from the remote server every time. This quickly gets annoying when rebuilding Docker containers that install many packages from Apt repositories served over HTTPS. Is there a way to get apt-cacher-ng to cache packages downloaded from HTTPS repositories?


The answer to this is given, but vaguely and the finishing details are left to be done. I unfortunately am at a loss of an idea as to how to finish it, so was wondering how one would do this last step, given in the instructions.  I am told to for every  $$\{n_1,n_2,...,n_k\}\subseteq \mathbb N (n_1<n_2....<n_k) $$   assign   $$0.00..10001...10...1$$  where $1$ is are on places $n_1,....,n_k$  or fraction $$\frac{1}{2^{n_1}}+...\frac{1}{2^{n_k}}$$ and then to map this set to $\mathbb N$. My question is how do I map this set to $\mathbb N$ ??

Show that the set of all finite subsets of $\mathbb{N}$ is countable.   I'm not sure how to do this problem. I keep trying to think of an explicit formula for 1-1 correspondence like adding all the elements in each subset and sending that sum to itself in the natural numbers, but that wouldn't be 1-1 because, for example, the set {1,2,3} would send to 6 and so would the set {2,4}.  Multiplying all the elements in each subset and sending that product to itself in the natural numbers wouldn't work either since, for example, {2,3} would send to 5 and so would the set {1,5}. Any ideas?


I did a simulation and the outcome's size was almost 30k. The other sample I want to compare them has only 50. Can I still do the test or should I radnomly pick 50 from the first and do it?

I want to compare two distributions, to see if they are significantly different. They represent task time completions (so they range from 1 to around 1000 seconds) in two different months. They are not normally distributed. I want to see if their central tendencies are significantly different (at a first glance the mode, mean and median between the two months seem very close, just 3-4 seconds difference), but also to see if their shapes are similar (again, at a first glance, they look similar). I am currently carrying this analysis with SPSS 20. I have the Mann-Whitney test for testing central tendencies and the Kolmogorov-Smirnov test for the shape of the distribution, (although I have read that the K-S test is an overall comparison test for the distributions).  Also, in the first month I have 300,000 observations and in the second month 122,000 observations. So, a lot of data ... but disproportionate. Is this an impediment to running these tests, the fact that the sample sizes are not equal? I ran both Mann-Whitney and K-S and they both seem to reject the null. How much should I trust the results given my sample sizes? Do you suggest any alternative tests? Thanks


I trying to calculate  $$ \lim_{n\to\infty}\big(\frac{n^2+2}{2n^2+1}\big)^{n^2}.\tag{1}$$  Of course I cannot use theorem that if $a_n\to\infty$ then $\lim_{n\to\infty}(1+\frac{1}{a_n})^{a_n}=e,$ because in this particular situation we have $$\lim_{n\to\infty}\big(\frac{n^2+2}{2n^2+1}\big)^{n^2}=\lim_{n\to\infty}\big(1+\frac{1-n^2}{2n^2+1}\big)^{n^2}=\lim_{n\to\infty}\big(1+\frac{1}{\frac{(2n^2+1)}{(1-n^2)}}\big)^{n^2},$$ and $\lim_{n\to\infty}\frac{(2n^2+1)}{(1-n^2)}=-2.$  I would be grateful of any hints and comments.

The limit to solve is $$\lim_{n\to\infty}\left(\frac{n^2+2}{2n^2+1}\right)^{n^2}$$ I tried to use L'Hôpital's rule but the derivatives are quite complex.


Let $m_1, m_2, \ldots , m_r$, $r \geq 2$, be non zero integers which do not have a common prime divisor. Show that there exists $a_1, \ldots , a_r \in \Bbb Z$, such that  $$\sum_{i=1}^r a_i \cdot m_i = 1$$  I am new in this area, any help would be appreciate!

Given $a_1, a_2, a_3, \ldots , a_n$ not all zero, show $\gcd(a_1, a_2, a_3, \ldots , a_n)$ is the least positive integer that can be expressed in the form $a_1x_1+a_2x_2+ \ldots +a_nx_n$. Also deduce $a_1x_1+a_2x_2+ \ldots +a_nx_n = b$ has solutions $\iff \gcd(a_1, a_2, a_3, \ldots , a_n)|b$.   I know that $ax+by=n$ has integer solutions $\iff \gcd(a,b)|n$. I'll need to use induction to show $a_1x_1+a_2x_2+ \ldots +a_nx_n = \gcd(a_1, a_2, a_3, \ldots , a_n)$ has solutions, and then I will be able to say that as $\gcd(a_1, a_2, a_3, \ldots , a_n) | a_1x_1+a_2x_2+ \ldots +a_nx_n $ for any $x_1,x_2, x_3 \ldots x_n$ then $c \leq \gcd(a_1, a_2, a_3, \ldots , a_n)$ and $c \geq \gcd(a_1, a_2, a_3, \ldots , a_n)$, and thus $c=\gcd(a_1, a_2, a_3, \ldots , a_n)$.


I have a cleric player. Every time the party has an NPC dialog, he announces something like "I looked at him carefully, trying to understand if he is telling the truth", implying using Insight.  Normally I ask him to roll the Insight check. Sometimes I try to give a hint, make it sound vague, but on clear success he just gets more information.  That doesn't feel right to me. Every roll has to have some kind of negative consequences, but in this case the character takes no risks. He either gets information (and draw his conclusions) or not (and continues the dialog normally). Repetitive announces feels unneeded and too straightforward.  On the other hand, I want to keep his ability to use his character's social skills. The cleric is proficient in Insight and is supposed to "read" people.  How can I improve this situation as a GM? Giving advice to the player is an option.  Before you mark this as a duplicate  I've seen  prior to my asking. It has an answer, very broad, about how to make Insight checks as a DM. It doesn't cover two points though:   aside from misleading hints, what negative consequences a failed check should have how can a DM handle the described "problem player" situation

I've recently begun DMing a 5th edition D&D campaign after a long time of quiescence as Dungeon Master. I really like this new take on D&D, but still, soon a problem has resurfaced, that is: the (paranoid) use of the Insight (or, as of 3rd edition, Sense Motive) skill, and I'm struggling to keep it in check.  I'm curious to hear how you handle this aspect of social interaction. When I'm interpreting an NPC, players often ask me if they can roll for Insight, and soon everyone at the table starts rolling. I'm thinking of outright disallowing such rolls, as (in my opinion) a player should only make a check when the DM calls for it. However, PCs should get to put their skills and proficiencies to use from time to time. So, this is what I've come up with:  1) Let them roll at most once per social interaction. Actually, I should be rolling for them behind my screen, so that they can't do metagame reasoning on a 1 or a 20.  2) Simply do not allow them to roll if they don't know the person they're interacting with to some minimal extent, or in cases where it is objectively not possible to draw a conclusion (for example, asking a guard if he has seen someone they're chasing, and the guard plainly replying "no").  3) Substituting most of the active Insight checks with passive ones. This would mean that the most empathic or intuitive PCs would sometimes sense something is amiss or tension coming from the NPC, or the like.   4) Only allow Insight checks if a PC clearly starts an interaction being suspicious of an NPC, otherwise not let it happen.  But still, I'm really not satisfied. What do you say to a player who failed or succeeded at the roll? To me, Insight should not be some kind of lie detector, but it often becomes one. Have you ever had this problem, too? What do you do?


I have been editing posts since yesterday, and I haven't yet got any reputation points (+2).  And I even checked in my reputation points action tab, and all my edits are showing as approved as shown below:    When it says approved edit, then why am I not getting the +2 reputation points?

When clicking "edit" I see:  Your edit will be placed in a queue until it is peer reviewed. We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.  Like:     Likewise, when I am not logged in, clicking "improve this question" or "improve this answer" shows:  You are not . Your edit will be placed in a queue until it is .  And when I click 'Save', I get:  Thanks for submitting an edit. It is only visible to you until it's been approved by trusted community members  Like:     Who can suggest an edit? Where do suggested edits go? Who can vote on a suggested edit? How do suggested edits get reviewed? Can I earn reputation? What about abuse or bad edits? Sometimes the Community user approves or rejects my edit. Why is that? When can I not suggest an edit? Is there a minimum change requirement for a suggested edit? How do I check my suggested edit history? I disagree with the reasons why my suggested edit was rejected. What can I do? How do I know whether there are edits waiting for review? Someone suggested an edit to my own post, and the reviewers took the wrong action. What can I do? Are tag wikis included in this scheme? What do the "Improve Edit" and "Reject and Edit" buttons do? Why are apparently valid links to rejected edits resulting in 404 errors?   For more information about editing, see "" in the .


I've got a problem with the settings of lighting in my unity scene.  The objects have got "dark sides" and it doesn't look natural.  You can see the screenshots and my light settings here:  The screenshot that shows the problem

Look at my scene:     Sun is rising and as you can see the scene is realistic; I mean, that what is in shadow is almost completely dark. This is correct, but i would like something less "dark", like an HDR.  These are some parameters i'm using:     This is my unique Light in scene (Sun):     I'm using also a Post-Processing profile with "Eye Adaption" unflagged.  Can you suggest me what i've to change to make my object affected by shadow less.. dark ?   Thanks


I am working on polygon shapefile and I want to display all the labels in the map. But, I am unable to see the labels of few polygons. I checked my geometry, I almost tried every single permutation and combination mentioned in Layer->Labeling.   Please tell me how to resolve this problem?

I am trying to create a simple map of Mexico showing the state polygons and their label.  The state shapefile is from , and the specific file is the first one from the top (Áreas Geoestadísticas Estatales (7.43 Mb)).  I edited the attribute table to create a new column with shorter state names called NOM_SHORT.  To add labels I used the "ABC" dialog as below:     However not all states were labelled, including Oaxaca and San Luis Potosí, as shown below (painted in light grey).  Why?   Here is attribute table:


I have enabled network location to use features of google now on my phone- here's what happens, once or twice a week: instead of my location, which is Milan, Italy, I see myself (and get advice for restaurants, museums, currency exchange) in Belgrade, Serbia.  If I turn on my GPS, then I "get back" home. If, with only network location active, I try to find my phone, it is always at the same address, over 2000 miles away, in a different country.  How does this happen? Should I worry about this? I find no possible way to ask Google if it is their problem- any advice?  Thank you!   Simona

I have a major problem that I hope someone can help with. On my Google Maps feature under my Location History it shows a location that I was never at at any point, but when my wife happened to see that location she doesn't believe me that the GPS could be wrong and pinpoint that location if I was never there.  I was first wondering myself how could that could be possible if I was never there or my phone was never at that location that was 35 miles away from me and second is there any way I could prove the GPS being wrong? Can I contact Google Maps and can they give an official printout of that certain day and every location I was? I really need to prove my honesty to her and hope there is a way.


I'm typing a document which quite heavily relies on script math fonts and a double-stroke 1 for the identity operator, however, text is in Spanish, so I'm using LuaLaTeX for maximum versatility, however, when using it and with the following commands  \includepackage{unicode-math}  \mathbb{1} \mathcal{O} \hbar     I get the above, however, when using PDFLaTeX with  \usepackage[utf8]{inputenc} \usepackage{bbold}  \mathbb{1} \mathcal{O} \hbar   This is the result   And I much prefer this style of calligraphic O and h-bar with horizontal bar. So my question is: Is there a way to use LuaLateX and unicode math but still get what I'd get if I used PDFLaTex?

I am happy with the great majority of what unicode-math does. But at times I find that I prefer a symbol the way it was before. With \varnothing and \complement, for example. In those cases I was able to save them under a different name before loading unicode-math, but this doesn't always work.  Right now I'm trying to access the \mathcal alphabet from plain LaTeX. How might I accomplish this?    Additional Question  I've been looking through unicode-math, trying to figure out where exactly the original \mathcal alphabet gets discarded, but I eventually gave up.  It would be interesting if someone could explain:   how/where the original \mathcal font is defined anyway, and what kind of 'switch' is thrown by unicode-math that makes it unavailable.


I am developing a windows service in C# which will likely write several times per second to a log. I am currently using System.IO.File.AppendAllText(time + message) for each operation and I am concerned so many writes may wear out the disk quickly.   Could this be a problem? Should I use a stream and flush every few seconds? Does the windows disk buffer protect against this?

I understand that .NET FileStream's Flush method only writes the current buffer to disk, but dependent on Windows' disk driver and the hard disk firmware this is no guarantee that the data is actually physically written to disk.  Is there a .NET or Win32 method that can give me this guarantee? So if there is power loss one nanosecond after the call to this method comes back, I can still be sure that everything is OK?


I have a Canon 500D, with the original lens EF-S 18-55mm f/3.5-5.6 IS II. I would like to try a prime lens, but I don't know whether I should choose a 35mm or 50mm lens.  I read that the 50mm was great even for portrait, so I'd like to try it. However, as the crop factor of the 500D is 1.6, does that mean that I should by the 35mm ? (35 * 1.6 = 55).  I may have missed something, and perhaps my question makes no sense. I apologize in that happens to be the case. Either way, I'll learn something.

It's said that 50mm is close to what the human eye sees and is a very versatile focal length in general, especially good for street photography which is what I'm most interested in. That being the case, if I have a cropped sensor (1.6) would I better off with a 35mm prime since it would give me a field of view similar to a 50mm lens (35 X 1.6 = 56) as opposed to a 50mm prime which would give me a field of view similar to an 80mm  lens (50 X 1.6 = 80)?


I am trying to convert an excel nested IF statement into code language, but I am not sure if I am doing it correctly and was hoping I could get some help  Here is the excel statement :  =IF(D3="Feather",IF(OR(I3>1000,R3="n/a"),"",IF(W3="F","F",IF(AND(I3<=1000,R3>8),"F","P"))),"")   My code :  if( D3 == "Feature"){    if (I3>1000 || R3 =="n/a") {     } else if (W3=="F"){        "F"      } else if( I3<=1000 && R3>8){        "F"    } else {        "P"    } }   Thank you

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I have proved that for $k\ge 4$ the sum $$\sum_{i=1}^k i!$$ can never be a perfect square i.e., of the form $n^2\, (m=2).$ But am struggling with the generalisation i.e., with the form $n^m$. Is the statement valid? I found this question on quora and no one has answered it.. Please suggest something... Thanks in advance.

Let $n$, $p$ and  $r$ be three positive integers. Prove that for $n \geqslant 3, r>1$, $$\sum_{k = 0}^{n} k! \neq p^\text{r}$$   SOURCE: BANGLADESH MATH OLYMPIAD (Preaparatory Question)  I am not so familiar with such a this kind of problem. Seeing that problem, I became little bit curious about what the text states and what will be its conception?   I couldn't solve the problem. Moreover, I don't know about the formula of $\sum k!$. Is there any? And I couldn't realize the essence of $p^\text{r}$ and what the reason is behind the fact the summation can't be equal to $p^r$ for some integer $p$.  Any kind of reference or conception will massively help me start with some approach to solve the above problem. Thanks for your support and effort in advance.


I did this once, but I can't find instructions how to do that again. It was probably kernel option that make live cd save in ram.  I have old Xubuntu but want to install nested version of Xubuntu, I've downloaded the iso on my old laptop but it have broken DVD, so how can I run live CD, of old Xubuntu, put it in RAM so I can put empty DVD and then burn new Xubuntu?

I have a live USB made with the standard Ubuntu disk image creator for 16.04 LTS. In the current state, I can boot to this disk, but it still requires the original USB to run properly at all times.  Attempting to pull the drive and use the system generates a large amount of I/O errors, further suggesting that the USB drive is actually needed for things not already loaded into RAM (For example, Firefox worked without the USB, but I used it once before already. apt, on the other hand, did not.)  Is there a way to copy the entire Ubuntu live disk to RAM, so I can remove the drive and free up a USB slot for other things?


Since $3 \times 3$ matrix $A$ has $0$ as one of its eigenvalues, we know that $A$ is singular. From this we can conclude that $\det(A) = 0$ also $\mbox{tr} (A) = 0$. Further, $\det(A^{50}) = 0$. Now I think that $\mbox{tr} (I + A^{50}) = 3$ but how can I get the determinant from here?

I have a matrix $A \in M_3(R)$ and it is known that $\sigma (A)=\{-1, 0, 1\}$, where $\sigma (A)$ is a set of eigenvalues of matrix $A$. I am now supposed to calculate $\det(I + A^{100})$.  I know that $A^{100}$ could be calculated using a diagonal matrix which has the eigenvalues of $A$ on it's diagonal and using matrices which are formed using the eigenvectors of $A$, but I am not sure how to get there. Or it might not even be the right approach.  I know there is a similar question, but I don't really understand the answer given there. It's not fully explained. So if anyone could help, that would be great. Thanks


I am trying to fetch record into listarray as follows:  List<Car> lst = new List<Car>();  string str = "select * from Inventory";   using(SqlCommand cmd = new SqlCommand(str,this.sqlcon)) {     SqlDataReader rdr = cmd.ExecuteReader();      while (rdr.Read())     {         lst.Add(new Car                      {                         CarId = (int)rdr["CarId"],                         Make = (string)(rdr["Make"] ?? ""),                         Color= (string)(rdr["Color"] ?? ""),                         PetName = (string)(rdr["PetName"] ?? "")                      });     }      rdr.Close(); }   Make,color and petname may have null values and thus I used the ?? operator. I get the following error      Unable to cast object of type system.dbnull' to 'system.string'.    What is the correct way of checking for null in this scenario?

Ran across this line of code:  FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();   What do the two question marks mean, is it some kind of ternary operator? It's hard to look up in Google.


I am using following method to display superscript and subscript at the same time but due to the length of for e.g., superscript, the text and the superscript is being overlapped.   \documentclass[aspectratio=169]{beamer} \usepackage{fixltx2e}  \def\SPSB#1#2{\rlap{\textsuperscript{\textcolor{red}{\small #1}}}\SB{\small #2}} \def\SP#1{\textsuperscript{\textcolor{red}{#1}}} \def\SB#1{\textsubscript{\textcolor{blue}{#1}}}   \begin{document}  \begin{frame}   \frametitle{XYZ}   {\fontsize{18pt}{20}\selectfont     R\SPSB{k}{ij} = R\SPSB{k-1}{ij} + R\SPSB{k-1}{ik}(R\SPSB{k-1}{kk})* R\SPSB{k-1}{kj}.} \end{frame} \end{document}   Do I need to space the subexpressions manually or is there any elegant way to do it?

I want to use sub- and superscript together in text mode. I've found this macro to solve the problem  \def\textsubsuperscript#1#2{\rlap{\textsubscript{#1}}\textsuperscript{#2}}  But it doesn't works well when the subscript is long. In that case the subscript overlaps with the following character.  What could be the macro to  enable sub- and superscripting in all cases?


I have Created a Material and Added Some Nodes using Python Script. Now I wan't To Add Some Nodes To Compositor using Python How to do that ? Can anyone tell that directly or Should I share the Code Which I wrote Earlier to create a Material and adding some diffuse and glossy nodes.

I've been looking at the python code loging of Blender. But in there things get loged as mouse clicks.  What i like to do is combine a few images into a larger one using compositor, but i need control over compositor by python script. The problem seams to me that it is a bit hard to "spawn" a few nodes, set their values and connect them.  I need an micture of:  image, scale, source image location, mix nodes, output nodes  I have no Code samples other then the log of blender python which in this case is of no big help.


, I'm getting the syntax coloring properly on the first section but not on the second one. I suspect that it's got to do with it being within an enumerated list. What can I do about it?  I've tried to explicitly set the language as follows but that didn't help.  <!-- language: lang-csharp -->   The tags are set correctly, of course.

Consider the following piece of Markdown code:  This is some regular text.      >>> def factorial(n):     ...     return 1 if n < 2 else n * factorial(n - 1)     ...   * This is a list item.      >>> def factorial(n):     ...     return 1 if n < 2 else n * factorial(n - 1)     ...    Notice that the second code block is preceded by a list item.   Why is the factorial code not properly formatted under these circumstances? To demonstrate the problem, I'll insert the Markdown code show above:    This is some regular text.  >>> def factorial(n): ...     return 1 if n < 2 else n * factorial(n - 1) ...     This is a list item                 def factorial(n):       ...     return 1 if n < 2 else n * factorial(n - 1)       ...               This applies to numbered as well as unnumbered lists.


I am not aware of any way to see all mods a site has had.   and the  lists only the current mods. There should be a page that displays all the moderators a site has had. On my  we are having an election now and three of our four mods are not running. In the not too distant future users will forget, and new users will never know that these users served as moderators. We have already replaced a mod, and many users do not know who he was. SE need a place to recognize the service of all mods, not just during their term. I propose adding a link to the  that goes to a new  moderator page. Where all moderators that have served that site will be listed along with the time of their service.

I am aware that is was asked to have  and , however I couldn't find anywhere any indication of past moderators e.g. someone who was moderator year or two ago but no longer act as one. My incentive for asking for such a thing:  (10K+ rep needed to see it) was deleted by a  who is not a moderator now. I can only guess he was moderator back in March 30th 2011 when he deleted it, but it's only an assumption. So, to the  I suggest to add another link like "Archive" or "Past moderators".


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?

Given an ellipses, enlarge it along normal direction a fixed length say 1cm. Do we get another ellipses? If so, how to prove ?