I Have a problem at the installation of Ubuntu 17.00 with windows 10 .  What is the problem please !!

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


In a table how can you disable the padding between tr's and td's? I have tried setting padding to 0.

In an HTML table, the cellpadding and cellspacing can be set like this:  <table cellspacing="1" cellpadding="1">   How can the same be accomplished using CSS?


Even tho I am new to Blender, I have tried many techniques posted on stack. However, I can't find a way to make this shape with a solid element (with faces).

How can I deform one edge or multiple edges of a plane or cube so they are tapered in and rounded equally?


I have a problem with Nautilus that Nautilus window border is disappearing.    As you can see, there's no window border. What can i do to get it back ?  Using: Nautilus 3.10.1       and Gnome Shell 3.10.4

I seem to live my life in the terminal - many terminals in-fact.  I also love the Ambiance theme - but the new borderless windows does not provide the visual differentiation I'm used to (the same black windows appear to blend into each other).    Thus to my question - how do I add back the single pixel border for windows that is found in earlier Ubuntu versions?  I want to keep the Ambiance overall theme since this looks good and I dont want to swap to another theme.      Now I know that I can modify the Ubuntu Ambiance theme as follows:  mkdir ~/.themes cp -r /usr/share/themes/Ambiance .themes   Then flipping between the theme options in the Settings - Appearance picks up changes in the theme in now in the .themes folder.  I presume I need to alter one of the .css files but I dont know which one.  I was also looking at  but the solutions there doesnt work for 14.04.  I also looked at the  but got rather lost trying to figure out which one applies to my situation.


I have a ton of things building in my file, but I need to be able to retime them. So say I have on part starting to build at 200frames and it builds for 100frames. I need to be able to change the start time from 200 to say 320 in a fast and easy way. Preferable from the dopesheet or graph editor. Because I have over 100 animating objects  Is there a way to add the build modifier timing to the dopesheet so build animations can be retimed?

I was wondering if there was a method to alter object settings at a set point in an animation in blender.  For example, I want to make the color of an object blue for the first 20 frames, but after 20 frames I want its color to change to green. Is there any known method of doing this? I could not find anything when I searched.


Let $a$ and $b$ be nonnegative integers. prove that $\gcd(2^a-1,2^b-1)=2^{\gcd(a,b)}-1.$  So far I have tried using Linear Diophantine Equations, the GCD With Remainder theorem (replacing one input into the gcd with the remainder of the bigger term divided by the smaller term), and writing $d=gcd(a,b)$, let $a=ds, b=dr$, but I am still stuck.  Thanks.

Somewhere on Stack Exchange I saw the equation     $$\gcd(2^m-1,2^n-1)=2^{\gcd(m,n)}-1.$$   I had never seen this before, so I started trying to prove it. Without success...  Can anyone explain me (so actually prove) why this equation is true?  And can we say the same when replacing the '$2$' by any integer number '$a$'?


For now I see only the sites I already have some rep on, in the sidebar favorite section. But I want to add more site to it so that I can visit them easily without going to All sites > search.   On desktop I can just type a url and jump sites, it's not that easy on mobile. On mobile devices there should be an option where one can favorite sites. or else I'd have to search for the site every single time. It's not a browser so there is no tab either for quick access. Even a "last visited sites" section would do it.  TBH, that "favorite sites" section has different meaning for users with high and low reps. For users with higher reps, that section is more usable because they have already matured enough in a site to call it favorite. For users like me with lowers reps, it's hard to call them favorite. And the app is for everyone. Hence my suggestion.  Anything planned for this?

So I finally got my invitation (yay! It's awesome! Thanks!) and I'd like this first feature request to be typed from here.   I propose the ability to change the "favorite" sites, and also include meta sites in there.   Right now, I presume it's reading the list of sites ordered by reputation.  I propose the following:    If I am a moderator on any site, those sites and their metas should come first. After that, ordered by reputation.  The above is only the default order, and can be altered freely by the user.


I cannot not use a shell variable in sed in the $NUMBER form. I have this line in my shell script:  cat shared.txt sed 's/whatever1/$2 ... whatever2/' > shared2.txt   The result in shared2.txt looks like:  ...$2....   What did I do wrong?

I want to do:  cat update_via_sed.sh | sed 's/old_name/new_name/' > new_update_via_sed.sh   in my program.  But I want to use variables, e.g.  old_run='old_name_952' new_run='old_name_953'   I have tried using them but the substitution doesn't happen (no error). I have tried:  cat update_via_sed.sh | sed 's/old_run/new_run/' cat update_via_sed.sh | sed 's/$old_run/$new_run/' cat update_via_sed.sh | sed 's/${old_run}/${new_run}/'


I'm addicted to certain websites to the point where it's interfering with my life regularly and sick of it. I want to install website blockers that aren't easy to circumvent.  In Chrome, incognito mode is easily accessible with a ctrl-shift-n. That is ridiculous. Whenever I feel an urge to go on an addictive website, it doesn't matter what blockers and regulators I've got installed; three keys can get round them in a second.  Simply uninstalling chrome isn't an option either, as it's way too easy to sudo apt-get install it right back.  So yes, I want to disable incognito mode completely (and if possible making it totally impossible to get it back). I note that some guy has figured out how to do it on windows with a registry entry:   If it can be done on windows it can be done on ubuntu!

I use this extension called Website Blocker to discourage me from checking Gmail/Reddit. However, it is easy and tempting to open a New Incognito Window; since extensions are disabled in Incognito Mode, I'm still able to browse Gmail/Reddit while in Incognito.  Is there any way to disable Chrome's Incognito Mode in Ubuntu? Ideally, this would encourage me to use my smartphone as a dedicated Gmail/Reddit checker.


I know the fact that not every $C^{\infty}$ function is analytic, for which there is the famous example:  $$f(x):= \begin{cases}        e^{-1/x} & x>0 \\       0 & x\leq 0    \end{cases} $$  In that case, $f$ is $C^{\infty}$ but its Taylor series is identically zero, which is clearly different from $f$ itself.  But how can I prove a function is actually analytic? Take $\sin(x)$ or $\cos(x)$, for example. We can easily calculate each Taylor series $T_{\sin}(x):=\sum_{k=0}^{\infty}\frac{(-1)^{k}x^{2k+1}}{(2k+1)!}$ and $T_{\cos}(x):=\sum_{k=0}^{\infty}\frac{(-1)^{k}x^{2k}}{(2k)!}$ and check the convergence of both. But how do we prove that $T_{\sin}(x)=\sin(x)$ and $T_{\cos}(x)=\cos(x)$ for all $x\in\mathbb{R}$?   What about other examples ($\tan(x)$, $e^x$ etc)? Do we really have to treat each case separately? Is there any theorem that makes this task easier?  Thanks!

I recently learnt Taylor series in my class. I would like to know how is to possible to distinguish whether a function is real-analytic or not. First thing to check is if it is smooth. But how can I know whether the taylor series converges to the function?   For example: $f(x)=\frac{1}{1-x}, x\in(0,1)$ has $n^{th}$ degree taylor polynomial $\sum_{k=0}^n x^k$. In this case, I understand that $f$ is analytic in its domain since the geometric series $\sum_{k=0}^\infty x^k$ for $x\in(0,1)$ converges to $\frac{1}{1-x}$.   In general, what is the trick? For example, how to know if $\sin(x),\cos(x)$ are analytic?


Consider a system, $A$, of homogeneous linear equations given by a $3\times3$ matrix where the columns of the matrix are some given vectors in $\mathbb{R}^3$. s.t. $Ax = 0$. The claim is that if $\det(A) = 0$, then the given vectors are linearly dependent. Why is this the case?

If $\alpha_1,\alpha_2,\alpha_3$ are linearly independent, and $(\beta_1,\beta_2,\beta_3) = (\alpha_1,\alpha_2,\alpha_3)C$. Prove that if $\mid C\mid \neq 0$, then $\beta_1,\beta_2,\beta_3$ are linearly independent.   This statement seems to be trivial, if $\alpha_1,\alpha_2,\alpha_3$ are linearly independent, then $\det{(\alpha_1,\alpha_2,\alpha_3)} \neq0$, and $\det{(\alpha_1,\alpha_2,\alpha_3) C} = \det{(\alpha_1,\alpha_2,\alpha_3)}*\det{}C\neq 0$, which implies $\det(\beta_1,\beta_2,\beta_3) \neq0$, and hence the columns are linearly independent.  I'm not sure how to prove it rigorously, or if I'm missing any steps here. Would really appreciate any help! Thank you!


When using Android app, if app weren't killed but was suspended on a page with answers and someone posted another answer, answer counter still shows the number of answers from before suspension.

In the Stack Exchange Android App v1.0.7 1.0.33 (with a HTC One running Android 4.4.2), the answer count for a question you're viewing is displayed in two places:   In the label of the answer tab:   At the bottom of the question tab:    I've noticed that these counts don't reliably update when new answers arrive.   If you refresh the question tab, neither count updates. If you refresh the answer tab, the second count will be updated, but the answer tab's count will not, leaving the two out of sync.   Refreshing either tab should probably update both counts!    Screenshots of the bug in action:    I waited for it to be answered. A while later, the question now has an answer.    The tab still says 0 answers though. Switching back to the question tab, , but the tab count still doesn't.


Am using a laptop so need efficient use of battery, so that i can get long backup. i have seen some videos that shows we can use jupiter applet and save our battery but when i try for my laptop there is no result please help me with this.  Regards, Rajesh Jana

I'm trying to install the Jupiter power settings app but, I read it is no longer compatible with the new kernel. Is there a similar program or a way to manage the power settings on 13.04?


Let $a_j$ be a sequence of real numbers.  Define $$m_j=\frac{a_1+a_2+\dots +a_j}{j}$$.  Prove that, if $\lim_{j\rightarrow\infty}a_j= \ell$, then $\lim_{j\rightarrow\infty}m_j= \ell$.  Give an example to show that the converse is not true.  I have been thinking about this question a lot. I know I could rewrite this as  $$m_j=\frac{\sum_{j=1}^\infty a_j}{j}$$ But I am having a really hard time after that. Thanks for any help you can give.

I'm wondering if I have a sufficient proof of the following:   If $(a_n)$ is a sequence such that $\lim_{n \rightarrow \infty}a_n=A$, then $\lim_{n \rightarrow \infty}\frac{a_1+...+a_n}{n}=A$.   My approach:  For all $\varepsilon > 0$, there exists $N$ such that for all $k>N$, $|a_k -A|<\varepsilon$. So we can break the limit up as follows $$\lim_{n\rightarrow \infty} \frac{a_1+...+a_k}{n} + \lim_{n \rightarrow \infty}\frac{a_{k+1}+...+a_n}{n} \overset{\epsilon \rightarrow 0}{=} 0 + \lim_{n \rightarrow \infty}\frac{nA}{n}=A$$  Is this on the right track, or am I missing something about breaking up the limit in the way I have?


I am wanting the ability to vertically align any cell within a table. This appears possible but only on a per column or row basis. At the moment I can horizontally align the contents of individual cells with the help of the \raggedleft and \centering commands. However, \multicolumn applies vertical alignment for the whole row and the longtabu environment can only specify the alignment type per column.  The following is an example of the table I want to create where both horizontal and vertical alignments need to be set for each cell instead of per row or column:  \documentclass[11pt,a4paper]{article} \usepackage{longtable}       \usepackage{tabu} \usepackage{lipsum} \usepackage{multirow}  \newcolumntype{M}{m{\dimexpr 1\tabucolX+1\tabcolsep+\arrayrulewidth\relax}} \newcolumntype{P}{p{\dimexpr 1\tabucolX+1\tabcolsep+\arrayrulewidth\relax}} \newcolumntype{B}{b{\dimexpr 1\tabucolX+1\tabcolsep+\arrayrulewidth\relax}}  \newcolumntype{H}{>{\begin{minipage}[b]{\hsize}}B<{\end{minipage}}}  \begin{document}  \begin{longtabu} to 150mm [l] {|X[l]|X[l]|X[l]|} \hline  \multicolumn{1}{|P|}{ \lipsum[1]} & \multicolumn{1}{H|}{\centering H: Center, V:Center} & \multicolumn{1}{B|}{\raggedleft \multirow{1}{*}[-2\baselineskip]{H:Right, V:Bottom}} \tabularnewline \hline \multicolumn{1}{|P|}{\lipsum[1]} & \multicolumn{1}{P|}{H: Left, V:Top} & \multicolumn{1}{M|}{\centering H:Center, V:Center} \tabularnewline \hline \multicolumn{1}{|P|}{\lipsum[1]} & \multicolumn{1}{M|}{\raggedleft H: Right, V:Center} & \multicolumn{1}{B|}{H:Left, V:Bottom} \tabularnewline \hline  \tabuphantomline  \end{longtabu}  \end{document}   Update:  Attempting the solutions presented in "" won't work.  The first solution I believe simply adjusts the entire column by creating a new column type:  \newcolumntype{B}{>{\begin{minipage}[b]{\hsize}}X<{\end{minipage}}}   This doesn't help my problem where I need the vertical alignment applied to individual cells, not a whole column. Applying this column type to \multicolumn doesn't appear to work.  The second solution places a \baselineskip into the optional parameter of \multirow which works initially but seems to become vertically centred as soon as the cell becomes a certain height.  I have updated my example above to show how it breaks.  Thanks

How do I get the last column text to be at the bottom of the row?  That is I want the XXX to be aligned with the line containing the arrow. I tried playing around with \multirow{3}{-3ex}{XXX}, but obviously I don't understand \multirow. Code: \documentclass{article} \usepackage{tabularx} \usepackage{booktabs} \usepackage{multirow}  \begin{document}     \begin{tabularx}{\linewidth}[t]{l X p{1.3cm}}         & Header & Title \\\cmidrule(lr){2-2}\cmidrule(lr){3-3}         a. & Some text text text text text text text text text text text text text text              text text text text text text text text text text              Want XXX on this line $\rightarrow$%          & XXX\\     \end{tabularx} \end{document}


In my method, I'm saving data from file to an output stream.  For now, it looks like this  public void readFileToOutputStream(Path path, OutputStream os) {     byte[] barr = Files.readAllBytes(path)      os.write(barr);     os.flush(); }   But in this solution, all bytes are loaded into memory, and I want to use buffer to release some of it.   What can I use to supply my reading with buffer?

I was surprised to find today that I couldn't track down any simple way to write the contents of an InputStream to an OutputStream in Java. Obviously, the byte buffer code isn't difficult to write, but I suspect I'm just missing something which would make my life easier (and the code clearer).  So, given an InputStream in and an OutputStream out, is there a simpler way to write the following?  byte[] buffer = new byte[1024]; int len = in.read(buffer); while (len != -1) {     out.write(buffer, 0, len);     len = in.read(buffer); }


I would like to generate a comma separated string for the distinct occurrences for an aggregated column in a group by statement. So I have:  Select Column1, ???statement involving Column2??? from MyTable group by Column1   I can't figure out what to put between the questions marks.

How do I get:  id       Name       Value 1          A          4 1          B          8 2          C          9   to  id          Column 1          A:4, B:8 2          C:9


The question is:  Let T be a tree with sub-trees $T_1,T_2,..,T_n$ such that all trees $T_i,T_j$ have a vertex in common which each set has a vertex in common - show that T has a vertex in all $T_i$.  The difficulty I am having is that if every subtree of T has a vertex in common say $T_4 \cap T_5 \neq \emptyset$ then $T_4 \subset T_5$ or the other way around.  Now if this is the case for all subtrees then they are just subsets of larger subtrees that are subsets of T, but since all subtrees have to have a vertex in common they would all have the root of T in common and hence T would have a vertex in all of its subtrees.    This doesn't seem right as we could form subtrees of T not containing the root node if there is more than one level to the tree.  Any thoughts?  Thanks,  Brian

Can someone please verify my proof or offer suggestions for improvement? I am aware that there is a similar question elsewhere, but I want help with my proof in particular.     Let $T_1, \ldots, T_k$ be subtrees of a tree $T$ such that for all $1 \leq i < j \leq k$, the trees $T_i$ and $T_j$ have a vertex in common. Show that $T$ has a vertex which is in all of the $T_i$.   Suppose, for the sake of contradiction, that for every vertex $v \in V(T)$, there is a subtree $T'$ in the list $T_1, T_2, \ldots, T_k$ such that $v \notin V(T')$.  Pick $v_1 \in T_1$. There is a subtree $T^{(1)}$ such that $v_1 \notin T^{(1)}$. $T_1$ and $T^{(1)}$ have a vertex $y_1$ in common. Now, there exists a tree $T^{(2)}$ such that $y_1 \notin T^{(2)}$. But now, $T^{(2)}$ and $T^{(1)}$ have a vertex $y_2$ in common. Also, $T_1$ and $T^{(2)}$ have a vertex $y_3$ in common.  There exists a path $p_1$ in $T_1$ from $y_3$ to $y_1$. Also, there is a path $p_2$ in $T^{(1)}$ from $y_1$ to $y_2$ and a path $p_3$ in $T^{(2)}$ from $y_2$ to $y_3$. Note that the path formed by the union of $p_1$ and $p_2$ passes through $y_1$, while $p_3$ does not, since $y_1 \notin T^{(2)}$. Therefore, the union of $p_1, p_2$, and $p_3$ forms a cycle, contradicting the fact that $T$ is a tree. Therefore, it must be the case that there is a vertex $x$ in all of the $T_i$.


I've been trying to implement a Machine-Learning based version of the "Smoke Detector" system by Charcoal, which uses human-crafted regular expressions to currently detect spam. It's already a great and highly accurate system, but using Machine Learning may reduce the number of False Negatives & Positives.  The great team at Charcoal was kind enough to provide a Data Dump of all the spam Charcoal has collected. However, this doesn't seem to be enough data for my deep learning systems. I'm trying to train an extremely deep learning model which combines CNNs, GRUs, and parallel models.  While I'm getting reasonably good accuracy, I need more data. Is there a way I can access deleted spam posts from the Stack Exchange network (not just SO in specific)? Of course, all to improve the quality of the content on the SE network :)  Also, this post isn't a duplicate of  (or any other related posts) because I'm not asking for all deleted posts or spam posts in the data dump, I'm asking for a dataset for myself to work with in Machine Learning tasks.  In fact, I've got a Keynote at the Watson Summit in New Zealand in a few days, and I plan to talk about this technology there as well:  (I'm Tanmay Bakshi)  NOTE: I'm currently working with 60,000 rows of data, but I'm thinking 100,000 (or as many as possible) would be much better to work with.

Is there any way for normal people to grab a list of all posts on a site deleted as spam/offensive (presuming I have privileges to view them)? All routes I've explored are dead ends:  Archive.org data dump: Does not include deleted posts. SEDE: Drops body text from deleted spam/offensive posts. API: Does not appear to include deleted posts. Scraping results from  () by including authorization cookies in the requests: Even with 5 second request intervals (giving a 38 hour ETA on Stack Overflow, for example), logs me out after a few dozen requests (presumably either heavy rate limiting or some sort of automated request protection, or the tokens in the acct cookie are periodically invalidated). I had tried with 3 second intervals, then 5, then gave up as I didn't want to press my luck with this one. The developers of various spam detection bots were kind enough to share their existing databases with me but we ran into staleness, completeness, and Unicode-related issues.  Is there a polite, acceptable way to do this? I'd like to build a database of spam/offensive posts for some pattern analysis.


We are running a mailing list by OpenEMM for our customers. However, email addresses in the @qq.com are not delivered.  It seems to us qq.com does not accept any email from our domain.  How can this be fixed?  p.s. SPF record is already set up for our domain.  Typical maillog entries:  Sep  9 00:06:02 MAILER sendmail[982]: 0000DB00000001922: to=<MASKED@qq.com>, delay=00:03:11, xdelay=00:00:09, mailer=esmtp, pri=0, relay=mx3.qq.com. [103.7.29.244], dsn=5.0.0, stat=Service unavailable Sep  9 00:14:51 MAILER sendmail[1067]: 0000DB00000001B8A: to=<MASKED@qq.com>, delay=00:12:00, xdelay=00:00:04, mailer=esmtp, pri=0, relay=mx3.qq.com. [103.7.29.244], dsn=5.0.0, stat=Service unavailable

This is a  about how to handle email sent from your server being misclassified as spam.  For additional information you may find these similar questions helpful:                    Sometimes I want to send newsletters to my customers. The problem is, that some of the emails get caught as spam messages. Mostly by Outlook at the client (even in my own Outlook 2007).  Now I want to know what should be done to create "good" emails. I know about reverse lookup etc., but (for example), what about a unsubscribe link with an unique ID?  Does that increase a spam rating?


Original title: Не могу обновить или установить пакеты Ubuntu server 18.04 Can't update or install packages on Ubuntu server 18.04. Internet provider Rostelecom, we sit behind their proxy server and content filtering. And so that we could work normally with Ubuntu server 18.04, they ask us to provide update ports. sources.list is not enough for them. Where can I see the list of ports??? Thank you in advance! Regards, Oleg.

There are now errors when updating and I cannot install most software due to a corrupted  /etc/apt/sources.list   file. Is there a copy I can download to replace it?  The file would be for Ubuntu 12.04 (Final Beta) in the United States.


I was trying out string concatenation and the '+' operator on a string and encountered the following-   String xyz = "Hello" + null; System.out.println("xyz= " +xyz); String abc= "Hello".concat(null); System.out.println("abc= " +abc);    The output for the first one was : Hellonull  The output for the second one was a Null Pointer exception  I don't understand why there were two different outputs.

Assuming String a and b:  a += b a = a.concat(b)   Under the hood, are they the same thing?  Here is concat decompiled as reference. I'd like to be able to decompile the + operator as well to see what that does.  public String concat(String s) {      int i = s.length();     if (i == 0) {         return this;     }     else {         char ac[] = new char[count + i];         getChars(0, count, ac, 0);         s.getChars(0, i, ac, count);         return new String(0, count + i, ac);     } }


I want to get the changes between commit A and B. Basically what changes have been committed since commit A. Should I use a triple dot when running git log or a double dot?

Some Git commands take commit ranges and one valid syntax is to separate two commit names with two dots .., and another syntax uses three dots ....  What are the differences between the two?


I need to hide content of .sh script and only show echo "messajes". The equivalent of windows batch: @echo off  Examples:  echo "Download..." wget http://mypage.com/files/file.zip echo "Ending..." sed -e '/^#/d' file2.tar.gz | sed 's/^/./' | sort -u > out echo "Done"   I need this result in console:  Download.. Ending.. Done

Just looking for the difference between   2>&- 2>/dev/null |& &>/dev/null >/dev/null 2>&1   and their portability with non-Bourne shells like tcsh, mksh, etc.


private lateinit var  main: MainActivity  override fun onCreate(savedInstanceState: Bundle?) {         super.onCreate(savedInstanceState)          setContentView(R.layout.activity_regions)  main = MainActivity() }      On create method  override fun onActivityResult(         requestCode: Int,         resultCode: Int,         data: Intent?     ) {         super.onActivityResult(requestCode, resultCode, data)         if (requestCode == MainActivity2.SCREEN_RECORD_REQUEST_CODE) {             if (resultCode == Activity.RESULT_OK) {                 //Set file path or Uri depending on SDK version                 main.setOutputPath()                 //Start screen recording                 hbRecorder.startScreenRecording(data, resultCode, this)             }         }     }  here is my  Kotlin method, main is my Java Classes object and I am trying to call the setOutPath Method but when I run the program it gives 'android.content.ContentResolver android.content.Context.getContentResolver()' on a null object reference error ContentResolver resolver; ContentValues contentValues; Uri mUri; @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) public void setOutputPath() {     String filename = generateFileName();     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {         resolver = getContentResolver();         contentValues = new ContentValues();         contentValues.put(MediaStore.Video.Media.RELATIVE_PATH, "Movies/" + "HBRecorder");         contentValues.put(MediaStore.Video.Media.TITLE, filename);         contentValues.put(MediaStore.MediaColumns.DISPLAY_NAME, filename);         contentValues.put(MediaStore.MediaColumns.MIME_TYPE, "video/mp4");         mUri = resolver.insert(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, contentValues);         //FILE NAME SHOULD BE THE SAME         hbRecorder.setFileName(filename);         hbRecorder.setOutputUri(mUri);     }else{         createFolder();         hbRecorder.setOutputPath(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES) +"/HBRecorder");     }     }  here is my java method. It gives me an error on this line. resolver = getContentResolver();

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?


Can my PC run games like GTA 5, Mass Effect Andromeda, Witcher 3?  My question is specific to RAM requirements for the game.  My system specs are:   CPU: i3 7100 Kaby Lake RAM: 4 GB Adata GPU: Nvidia Zotac 1050 Ti 4 GB   If yes, at what settings I can play them? Or should I go for increasing my RAM to 8 GB or 16 GB?

Is there a service that I can use to check if my machine will be able to run a certain game?


The title is obviously the State Alchemist name of Edward Elric, but what does the word "Fullmetal" mean? I watched both series with dub in my mother language, and in that, Ed was referred as "Steel Alchemist". (translated to English)

Why is Edward Elric known as the 'Fullmetal Alchemist' not simply as 'Metal Alchemist'? Is there any reason besides the names sounding better?  I've only watched the 2nd episode of FMA brotherhood.


Can I use the latest LTS version of ubuntu with a celeron processor and 512 MB ram? If the answer is positive then how? I'm now using 12.04 LTS version of ubuntu..

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I Installed Ubuntu 18.04(LTS)  alongside Windows 10 (Dual Boot), and now I want to uninstall (Delete) Windows 10 from my laptop. I have seen many ways to delete Ubuntu , but none to Delete Windows 10.  Any Help would be most appreciated.  Zuli

I want to keep Ubuntu but remove Windows.


If time travelling backward were possible,(by a wormhole, one opening of which has been kept near a massive body, for instance) wouldn't it contradict the law of conservation of energy, since a previously nonexistent packet of energy (the mass of the traveller) has appeared, a point of time in the past?

I just watched the movie  and started pondering time travel.  While pontificating and stretching my limited remembrance of AP Physics, science documentaries, and YouTube videos I remembered the laws of Conservation of Energy and Mass.  Would that not make time travel impossible?  You can't send something elsewhere in time as you would be destroying energy and/or mass, by removing it from the current time.  And it would be impossible to arrive elsewhere in time, as you would be creating energy and/or mass.  I know this is theoretical and a real answer can't be found till someone invents a time machine.  I'm just curious as to what people think of that.


I have a paired sample data with n=21. The two values V1 and V2 are from two different time points for the same group. I want to see if there is any improvement/reduction in values at time 2(V2). Of course, the first thing that comes to my mind is the paired t-test for which differences (D=V2-V1) have to be normally distributed. These are ,  and  of the differences data. The data looks slightly skewed but I'm not sure if I should go with t-test as the sample size is small (n=21). From Shaipro Wilk test, I'm getting p value as 0.025 and W=0.89 which rejects the null hypothesis that the data is normal. I'm thinking of an alternative to t-test such as Wilcoxon- signed rank sum test. Not sure which method is more appropriate. Also, how important is it for the data to be symmetrical for Wilcoxon test? From the box plot, it doesn't look so symmetrical. I'm kinda confused as to how to proceed and would really appreciate any help.    This is how the data looks like:               V1          V2      D(V2-V1) 1          2.5         2.0     -0.5 2          3.5         1.5     -2.0 3          2.0         2.0      0.0 4          1.5         4.0      2.5 5          4.0         3.5     -0.5 6          3.5         4.0      0.5 7          3.0         3.0      0.0 8          2.5         2.0     -0.5 9          4.0         3.5     -0.5 10         3.5         2.5     -1.0 11         3.5         3.5      0.0 12         2.5         1.5     -1.0 13         2.0         2.0      0.0 14         3.0         3.0      0.0 15         1.5         2.5      1.0 16         1.5         1.5      0.0 17         1.5         1.5      0.0 18         2.0         2.5      0.5 19         3.5         2.5     -1.0 20         1.5         1.5      0.0 21         3.0         2.0     -1.0

I have a paired data with a small sample size of 21 and I'd like to conduct Wilcoxon signed rank test using R. wilcox.test from the base stat package gives results with a warning message that says that exact p-value cannot be computed with ties and zeroes. Since my data is small, I cannot afford to discard the ties. I'm also aware of coin package that has wilcoxsign_test function. I'm not sure if it gives the exact p-value.     This is how the data looks like:       Q1.response   Q2.response  avg_diff 1          2.5         2.0     -0.5 2          3.5         1.5     -2.0 3          2.0         2.0      0.0 4          1.5         4.0      2.5 5          4.0         3.5     -0.5 6          3.5         4.0      0.5 7          3.0         3.0      0.0 8          2.5         2.0     -0.5 9          4.0         3.5     -0.5 10         3.5         2.5     -1.0 11         3.5         3.5      0.0 12         2.5         1.5     -1.0 13         2.0         2.0      0.0 14         3.0         3.0      0.0 15         1.5         2.5      1.0 16         1.5         1.5      0.0 17         1.5         1.5      0.0 18         2.0         2.5      0.5 19         3.5         2.5     -1.0 20         1.5         1.5      0.0 21         3.0         2.0     -1.0  As you can see, there are several ties. Any suggestions on how to proceed would be greatly appreciated.    Thanks!


Consider the following figure. A man sits in a pan and tries to raise himself by pulling the rope downwards. Will he be able to raise himself up? Explain.   I understand that it is not possible as like sitting on chair, one can't pull the chair up. But would anyone give a proper justification with necessary mathematical support. Please.

A man sits on a platform attached to a pulley and pulls himself up as shown (ignore the angle of the rope - it should be vertical). Apparently, the man/platform object has a force of 2T pulling it up. Why is it not just T?  Much appreciated!


In  I link to   This would normally auto-parse to the Question title, but it is not. Unlike here, where both the M&TV.se and the Anime.se links auto-parsed. On my question, it does not. But a url to another question on M&TV did.  Is this a bug or is it not implemented for these two sites?

On this  there are more than 50 links to Stack Overflow questions. However, the last 6 links aren't converted to titles (http://facebook.stackoverflow.com/questions/6530420/control-the-image-that-facebook-shows-when-i-like-a-url should be converted to ).   However:  all http://facebook.stackoverflow.com/... into http://stackoverflow.com/... fixes this, both in the preview and the final result. Also, the preview won't show any title for http://facebook.stackoverflow.com/... links.  My question is, what limitations does this converting have? How are these question titles retreived? Via API? Through database?  I'm not sure about title, feel free to edit that


Firstly, how do you gain the score exactly? I know it shows in the bar on the side of the map, but I remember a match where I was lone-wolfing and still got a pretty high score in that bar. I suppose my other squad members were together, but do I also gain for their work?  Also, does the score reset when I start a new game? I mean, I play support with the Offensive perk and it took me a long game of conquest to just unlock lvl-3 extra grenade. In the next match, that 'nade is gone. Don't I keep it forever?

When playing in a squad, you can get "Field Upgrades". However, sometimes when I die, it tells me that I have lost the "Field Upgrade Score".   Where can I see this score and what are the events that make me lose it?


In the following code    why "Node head" is kept outside the inner class node?   Since Node class is defined after writing "Node head", does it create any problem?   why is the inner class defined as static?  class LinkedList{     Node head;  // head of list  /* Linked list Node.  This inner class is made static so that    main() can access it */ static class Node {     int data;     Node next;     Node(int d)  { data = d;  next=null; } // Constructor }

What is the main difference between an inner class and a static nested class in Java? Does design / implementation play a role in choosing one of these?


I have windows 10 pro 64bit on my HP pavilion15 laptop. recently some minutes after system boots up, windows defender user interface 32bit starts working and takes more than 30% of CPU and does not stop. when I open file location it is at C:\Users\myName\AppData\Roaming\Adobe\Windows Defender\MSASCui.exe. I can kill the task but mainly I want to know why does this happen and how to fix this? I have not installed any Adobe product last month this issue occurs last 2 days.

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


How to hide one Chrome tab, not all, and not pin it of course as it won't hide it ? Or how create chrome addon (in javascript) to hide one tab ?

A google search gives number of methods to hide ALL tabs in chrome , but I want to hide 1 particular tab / change the display name of that tab.   Reason: I have an online music playing website open, which keeps showing tracks in the tab name and I just want to remove it from view of my work.


The image above is from Crash Course and I saw the equation the velocity is Delta.  What does the line above acceleration represent?

I've been asked to complete this chart and have never come across this symbol before, nor can I find anything about it on google:    What does the $\bar{y}$ with the line over it represent? And also, does the the t^2 column just mean square all of the time values for each row?


I just joined research gate (finished PhD in December - published 3 papers early this year) and as soon as I made an account, it shows that someone requested full text of one of my papers 20 weeks ago.  Am I allowed to just upload the .pdf? What are the rules there and how will I know if/when it is appropriate?

I recently created a profile on . And to add your publications list it requires you to upload the paper. Is it legal to upload published journal articles on public servers, where everyone can download it for free?


I have been encountering an issue where the camera zoom slows down then completely stops moving before I reach an object which I'm trying to zoom into. I'm not too sure how to fix the issue and I've searched the web but still struggling to fix the problem. Thanks in advanced

I often find that I can zoom in to a point, but then cannot zoom any more, even when there is a lot of room to zoom to the meshes on the scene.   This is particularly annoying in the following scenario:  I often land up left clicking on the scene and the 3D cursor shifts there. I use Shift+C to shift the 3D cursor back to the origin. However, this also centers the view on the cursor and shifts the view to show all objects, and sometimes this zooms things way out – at this point, if I try to zoom in, I can zoom in to a point (using the pinch/zoom on trackpad), but then it stops zooming in.   How do I zoom in after that? Is there anything else I am doing wrong in this case?


I have my code here: import java.util.Scanner; public class Calculator { public static void main(String[] args) {  Scanner x = new Scanner(System.in);  System.out.println("List of operations: add subtract multiply divide alphabetize");  String boy = "Enter an operation:";  String operation = x.next();  String need = operation.toLowerCase();  if (need != "add" && need != "subtract" && need != "multiply" && need != "divide" && need != "alphabetize") {    System.out.println("Invalid input entered. Terminating...");    return;  }  switch (need) {    case "1": need = "add";      String jog = "Enter two integers:";      int huh = x.nextInt();      int buh = x.nextInt();      int duh = huh + buh;      System.out.println("Answer:" + duh);      break;    case "2": need = "subtract";      String hog = "Enter two integers:";      int guh = x.nextInt();      int cuh = x.nextInt();      int zuh = guh + cuh;      System.out.println("Answer:" + zuh);      break;    case "3": need = "multiply";      break;    case "4": need = "divide";      break;    case "5": need = "alphabetize";      break;  } } }  Now I'm just stuck attempting to fix one thing, and that is the if statement right at the beginning. I need that to only do the print code if the above need string is not any of those words. And even when I put in "add" (without quotes) as my input it doesn't work, it goes straight to the print code. And also after that, I want to cut the code so it stops but I'm not sure how. I don't want to use System.exit(), however... I'm stuck.

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'm sitting on my seat in a train and the train is moving at a very high speed, let's say 600 mph. If I throw a ball vertically up in the air (while still sitting on my seat), will the ball fall back in my hands or will it fall in the seat behind me since my position would have changed from the time I threw the ball, but the balls vertical trajectory will remain the same?

Why is it that if I'm sitting on a seat on a bus or train and its moving quite fast, I am able to throw something in the air and easily catch it? Why is it that I haven't moved 'past' the thing during the time its travelling up and down?


As I run programs in wine-1.6.2 my screen speakers will be used as default. The default, as changed via alsamixer, is to disable the screen speakers and allow all other sound to flow freely (auto mute: disabled). I have no idea why this happens.  I run Ubuntu 14.04 64-bit. I have no special sound drivers installed. I don't really know how to troubleshoot this issue so I don't have any further information.

Ubuntu's desktop gui is great for changing audio settings (System->Preferences->Sound), like the default input/output device and setting the volume.  However, I would like to be able to do these things from the command-line. What tool is the gui using behind the scenes?


I am keen to know the source code for .toString(16) in javascript Because I would like to check logic of how the dec code converted to hex code?

How do you convert decimal values to their hexadecimal equivalent in JavaScript?


I usually put manual sqli parameter checks in place (i.e to check if input is a valid email).  Although in this case, I need to put a user message into my DB  How would this work?  I tried this code, but the whole input gets erased somehow.  <?php  $text = "Hello World";  echo "$text is now ";  $text = stripslashes($text); $text = mysqli_real_escape_string($text);  echo $text;  ?>   Thannk you!

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?


"let's make a robot ___ creates a copy of itself" What would be the right word to use here? That or which?

When is it appropriate to use that as opposed to which with relative clauses?


I'm trying to install 14.04.3 onto a former Vista PC, downloading from U's website, using Unetbootin 613.exe with 8GB USB2.0 flash drive. PC is Advent, 2GB RAM, 250 GB hard disc, Nvidia Geforce 7300LE. After installing, it shows error "ACPI PCC probe failed" and either 0:663712 or 4.991714. After the initial splash screen, the screen goes blank. The screen is fine, as it works OK on another PC.

ACPI PCC Probe Failed is the error that pops up instead of the default GRUB loader after I updated my kernel to 3.19.  I searched around and couldn't find much information except that it is a known error and it is registered in kernel.org's launchpad . My question is, is anyone else facing it?, what are the impacts of this? And if only an update in the future can fix it, any suggestions or safety tips till then?


Is the phrase "We have not got apples." correct, or we must use  We have not got any apples. instead?

Is it grammatically necessary to use any in the following sentence? Can I omit any in exams and formal writings in similar sentences and contexts?     Yesterday was mothers' day but I did not post (any) photos with my mother on social media. I think importance of my mother to my life cannot be described by just clicking pictures or posting them on social sites on mother's day.


I have the following system: BIOS:   American Megatrends Inc. F6, 30/05/2014 Motherboard: Gigabyte Z97X-Gaming 7 CPU: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz, 4001 Mhz GPU: NVIDIA GeForce GTX 970 RAM: Ballistix Tactical 16GB Kit (8GBx2) DDR3 1600 MT/s (PC3-12800) UDIMM 240-Pin - BLT2CP8G3D1608DT1TX0CEU  And when I try to install ubuntu-17.04-desktop-amd64 or ubuntu-16.04.3-desktop-amd64 into my system I get this screen:  I have connect my screen using HDMI to the graphics card. Sorry, but I don't have a DVI screen. And I don't know if it is related to this but my system clock get delayed two hours. I have installed successfully CentOS 7.0 on my system without any problem. Is there any problem with my graphics card? What can I do? I have also the same problem if I try it without installation. By the way, I am installing it from a CD. If you need more details, please tell me.

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I am sort of new to Linux, and completely new to Ubuntu (20.10) as a whole.. I switched from Windows recently and have installed Wine to play Windows games, but it has completely messed up after installation. If I try to "sudo apt-get update" or "sudo apt update", it does nothing and gives an error which is: E: Malformed entry 1 in list file /etc/apt/sources.list.d/archive_uri-https_dl_winehq_org_wine-builds-ubuntu_focal-groovy.list (Component) E: The list of sources could not be read. E: Malformed entry 1 in list file /etc/apt/sources.list.d/archive_uri-https_dl_winehq_org_wine-builds-ubuntu_focal-groovy.list (Component) E: The list of sources could not be read.  I have tried completely reinstalling wine as a whole, and going into the file itself to try and fix it to the best I can but nothing is working. I couldn't even uninstall because it gives me the error. Coming here to ask is my last resort, and hopefully this can be fixed with the help of others.

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


I've recently become interested in the equation for gravitational time dilation, which is as follows:  $$ t_{0}=t_{f}{\sqrt {1-{\frac {2GM}{rc^{2}}}}}=t_{f}{\sqrt {1-{\frac {r_{s}}{r}}}} $$  I understand the concepts of proper and coordinate time, along with the Schwarzchild radius. However, Schwarzchild's other contribution is griefing me, which is the $r$, or "the radial coordinate of the observer" based on the Schwarzchild metric.  I've tried researching this r, but everything I find makes it seem more confusing. If it is really a "sphere centered around the body", then it is not necessarily a physical entity, as I understand it. If that is so, then why does its circumference / radius have any bearing on time dilation?  Could someone direct me to the answer of what it is, and what it's purpose is?

In  as well as on Wikipedia the radial coordinate of the Schwarzschild metric is described as follows:     ...the r co-ordinate is the value you get by dividing the circumference of the circle by 2π.   This circumvents (no pun intended) the problem of talking about the path outwards from the singularity, but what about the circle itself: does it have the length we would measure when flying around it (however this is done) or is it a virtual circle assuming flat space, i.e. no mass at the center.


I want to return the end of the month of i months ago. But near the end of the month my current code breaks because no every month has the same number of days. Today for example (29/04/2021) two months back should return the end of February, but date, 29/02/2021 does not exist, 01/03/2021 if used instead, which results in 31/03/2021 instead of 28/02/2021. Please advise how to change my code to get the correct result even near the end of the month, thx! <!DOCTYPE html>
RPA Date Sandbox

If you provide 0 as the dayValue in Date.setFullYear you get the last day of the previous month:  d = new Date(); d.setFullYear(2008, 11, 0); //  Sun Nov 30 2008   There is reference to this behaviour at . Is this a reliable cross-browser feature or should I look at alternative methods?


I've been trying to remember the title of this short SF story for ages now.   There is a creature (I think its actually immobile) that has a small plot of land on a planet. It starts growing and there is something to do with a small pool of water that it uses to help it breed/grow. It ends up taking over more and more of the planet's surface.   It's likely to be by a science fiction big name from the golden age (I think that's most likely anyway)

Desperate to locate and re-read exceptional book/series, but cannot remember the title. The high concept: The U.S. has just sent the first successful expedition to Mars, and it has just landed. As the astronauts make their initial exploration outside their ship, a tear in the fabric of space opens up right in front of them, and they look through to the insides of a laboratory (at a California university?) and two students who just figured out how to create arbitrary portals between two points in the Universe. The rest of the novel/series is a consequence of this breakthrough. But I can't remember the author and title(s). Surely someone reading this forum will remember it well! TIA.  (Reposted .)


When I do something like this:  x="hi echo hello"   or  x='hi echo hello'   Then x will contain the string hi echo hello.  But when I don't use quotes:  x=hi echo hello   Then x will contain the string hi, and the command echo hello will be executed.    But what about when a variable's value only consists of a single word, is there a difference between the following:  x="hi" x='hi' x=hi

The old advice used to be to double-quote any expression involving a $VARIABLE, at least if one wanted it to be interpreted by the shell as one single item, otherwise, any spaces in the content of $VARIABLE would throw off the shell.  I understand, however, that in more recent versions of shells, double-quoting is no longer always needed (at least for the purpose described above).  For instance, in bash:  % FOO='bar baz' % [ $FOO = 'bar baz' ] && echo OK bash: [: too many arguments % [[ $FOO = 'bar baz' ]] && echo OK OK % touch 'bar baz' % ls $FOO ls: cannot access bar: No such file or directory ls: cannot access baz: No such file or directory   In zsh, on the other hand, the same three commands succeed.  Therefore, based on this experiment, it seems that, in bash, one can omit the double quotes inside [[ ... ]], but not inside [ ... ] nor in command-line arguments, whereas, in zsh, the double quotes may be omitted in all these cases.  But inferring general rules from anecdotal examples like the above is a chancy proposition.  It would be nice to see a summary of when double-quoting is necessary.  I'm primarily interested in zsh, bash, and /bin/sh.


I am flying from USA to India and transit airport is in Amsterdam and Paris.   Forward journey is USA -> Amsterdam -> India and return is India -> Paris -> USA.    I am not planning to go outside airport.    Do I need visa even to stay in the airport?    BTW, I am Indian citizen with valid US visa.  I researched some past questions and found that a Schengen visa is needed if flight is between Schengen countries.

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


What if my statement date is 5th of every month and my monthly due date is 20 days after statement date. What is my billing cycle and what date should I pay my purchased items

First of all, I am a resident of Canada.  I am  new to credit cards, so I hope my question makes sense. I've had my card for a few months ago and I've always paid the balance in full by the time the due date rolls around. Just out of curiosity, say the day after tomorrow was my due date. If I made a purchase tomorrow and didn't pay it off by the day after tomorrow, would I be charged any interest on it? Is there any negative ramifications at all for doing this?  Thanks.


Using Centos.  Situation: I have multiple drives off of two RAID controllers.  I also have multiple entries in the fstab, such as /dev/sdb, /dev/sdc, etc.  What I need to know is how I can identify which drives or set of drives (in the case of RAID) correspond to an entry in the /etc/fstab file.  In other words, I want to be able to look at /etc/fstab, see an entry as /dev/sda, and find that specific disk drive' slot/bay/port/whatever on the actual server.  Seems like this should be a very very simple thing to do, but even my manager who is a sys admin can't really answer this, nor can I find any concrete answers on stackexchange.  Really appreciate the help, and I am happy to elaborate if needed.  EDIT: I imagine this might be able to be done using the hardware RAID controller, however since there are situations where one would have a bunch of single drives, I would instead prefer to know how I identify by using a standard and widely available linux tool, like gparted or something.

First, the situation:  I've got a Linux computer with two eSATA drive bays that accept removable SSD drives.  I'm trying to write a little GUI application that makes it easier for the user to mount/unmount/format/backup/etc the drives that he puts into these bays.  It all mostly works.  One small problem, however, is that I don't know how to find out any information about what's on the inserted drive(s) until after the drives have been successfully mounted.    So, for example, if the user inserts a drive that I can't mount (e.g. because it is unformatted, or formatted with an unexpected filesystem), all my app can say about it is "Drive failed to mount".  This isn't very satisfactory, because if the drive is unformatted, the user will probably want to format it... but if the drive contains data from an unrecognized filesystem, the user will probably NOT want to format it.... or at least, I want to be able to warn him that by doing so he'll be erasing potentially valuable data.  So my question is:  is there any method for querying some basic information (especially filesystem-type) from a drive that doesn't require that the drive already be mounted?  Or do I just have to try to mount it with various known filesystems until one of the mount attempts succeeds, and give a vague "be careful" message if none of them do?  In case it matters, the paths I use to mount the drives in the drive bays are:  /dev/disk/by-path/pci-0000:00:1f.2-scsi-2:0:0:0 /dev/disk/by-path/pci-0000:00:1f.2-scsi-1:0:0:0


I need to create a structure whose member is an character array like below:  struct Person{     char name [100];  };   Why the below results in a incompatible types error? And how to fix it?  struct Person john; john.name = "John";    what is the difference between the assignment above and bellow, which works well:  char str[100] = "this is a string";

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


I'm in a situation where my Comcast cable modem will not resolve URLs hosted locally.   Essentially, if I access my website from the same network, I cannot use www.mysite.com, but instead must use 10.0.0.14 (the local IP address).   Externally, there is no issue.    I found more info on the cause of this here:     That said... the simple solution to this is to either a) access the site using the internal IP address, or b) map the URL to the local IP address using the hosts file.  I've done b on one of my laptops, and this does work.  However, I'm looking for a more robust solution to this problem, to address accessing the site with items such as an iPad that a hosts file can't be edited on.   So the question is... Is there a way to setup a local DNS server that would "feed" a hosts file to all of the devices in the house?   Meaning...  can I configure the server in such a way that all requests are checked first and mapped to local addresses if needed?  Hopefully that's clear... please let me know if I can provide more detail.   I'm currently at a loss...  and mostly just frustrated that this is even an issue.

I am using a local (company) network which provides some servers which are also available from the outside (through one public static IP and port forwarding). And there are some domains which are pointing to the public IP.  What I want is my domains pointing to the local IPs when being inside the local network. I know I will need a local (internal) DNS server which changes the domains to the IPs. I am able to setup the DHCP server to deliver the DNS to the local clients (so this won't be any problem).  What kind of DNS server software can I use to:   repeat all domains like a DNS would do that but for only my domains use the local values


I have Windows 7, and I'm trying to dual boot Windows 7 and Ubuntu. However, when I try to install Ubuntu with a USB, it doesn't give me the option to dual boot. I can only "Replace Windows 7 with Ubuntu", or "Something Else".  I've installed Ubuntu on this computer before, and this option was present. What I'm asking for is a way to get that option, or how to use the "Something else" option.

Whenever I startup from the LinuxLive USB, and try to install Ubuntu 12.04, it only gives me two options instead of the usual 3 or 4. My options are "Replace Windows 7 with Ubuntu" and "Something Else". Whenever I go into "Something else", it looks extremely confusing. How do I install it side-by-side while using the "Something else" section? These are my partitions.   /dev/sda /dev/sda1 ntfs (104Mb, System Required Partition) /dev/sda2 ntfs (1000097Mb, Windows 7 Partition)   Or should I try reinstalling my installer on a CD rather than USB and maybe then it will have the "Install alongside" function?


John entered the hall. On/to his left was a table.      John saw that to/on his left was a table.   On Google, I found more results with "to", but I guess that doesn't make "on" wrong. To my ear, "on" refers to a more generic position, and closer to the subject, whereas "to" refers to a precise direction, that might be very distant. Another example:     On/to his left was a mountain.   To me "on" sounds like the mountain is closer, almost towering the subject. "To" instead make the mountain farther from him. Am I correct? If not, what are the differences? In which contexts one is preferable over the other?

There is a security camera on the building to your left      There is a security camera on the building on your left   Is there any real difference in meaning here? Which sounds more natural to native speakers?


So, I have CHROMEBOOK, and I want install Ubuntu. I download ubuntu files (~1GB), ISO format, but, I dont know, how to put there files to my USB? Just help me please :)

I would like to see a full how-to guide on how to install Ubuntu.


How can I use the find command to recursively list all the file extensions in a directory?  Using wildcards I can find all the files of a certain type:  find . -iname '*.mp3'   but what I want to to list to search a directory and all sub directories and list all of the file extensions found.

I did a website scrape for a conversion project. I'd like to do some statistics on the types of files in there -- for instance, 400 .html files, 100 .gif, etc. What's an easy way to do this? It has to be recursive.   Edit: With the script that maxschelpzig posted, I'm having some problems due to the architecture of the site I've scraped. Some of the files are of the name *.php?blah=blah&foo=bar with various arguments, so it counts them all as unique. So the solution needs to consider *.php* to be all of the same type, so to speak.


I have Fluke 17B+ DMM. When trying to measure DC current, the readings are constantly fluctuating. I tried first with a 9V 1A AC-DC wall adapter and the readings were jumping between 0.485 to 0.300 and then down to 0 A. This pattern keeps on repeating. When I used the same DC source but with a 5V buck converter I get a stable 1A reading. I have tried with different probes and another similar DC adapter but this behavior persists. Unless I use a regulator or measure current in circuit, the current measurement is not stable. Is my DMM gone bad, or could there be some other issue?

I assume that the multimeter should read 2A, why is it only 0.358A? If this is how it is supposed to be, why? If I add a load, how do I measure that this load is being drawn, does the multimeter need to be in series?


I have an old MacBook (model A1342, year 2009) with Ubuntu 18.04 on it. NO MacOSx. I want to install Debian (8 or 9) for which said computer comfortably fulfills the minimum tech specs (barely so with Ubuntu 18.04). So far I have made several bootable USBs (with sudo dd) with different packages of Debian 9 (have yet to try Debian 8), but the computer never recognizes them, much less boots from them. I'm about to make another bootable USB with UNetbootin, let's see how I fare. However, is there any advice or experience you could share on how to change Linux distro on a Mac computer?  Many thanks for your help!

If you select "USB" and "Mac" on , it gives a series of command line instructions to make a USB key which the MacBook will boot into Ubuntu from.  I've followed them to the letter two or three times on different USB keys, and it doesn't work. There's a very great deal of technical discussion about EFI etc. but this set of instructions seems to suggest it should just work, but it doesn't.  Help? I'm increasingly unhappy with the more locked-down approach Apple is taking, and I'd quite like to start using Linux with a view to transitioning over to using it as my main operating system, but booting from the CD takes forever, runs slowly and I'm really hoping to get it moving off USB.  Can anybody help me?


Here is a relatively simple question that I'm unable to solve :/  There are $10000$ closed lockers in a hallway. A man begins by opening all $10000$ lockers. Next, he closes every $2^{nd}$ locker. Then he goes to every $3^{rd}$third locker and closes it if it is open or opens it if it is closed. After his $10000^{th}$ pass in the hallway, in which he toggles only locker number $10000$, how many lockers are open?  Any insight anyone?

There was a security guard in a bank. In front of him were 100 lockers in rows of 10. He thought of something as he saw all the lockers were closed. He started opening all the lockers whose lock numbers were multiples of 1, then closed all lockers whose number was a multiple of 2,and did the same for 3 and so on. If the locker was open, he closed it, if closed, opened it. He went to open multiples of 1 (all),then 2,4,6,8...and then 3,6,9.. And then finally reached 100.  After all the opening and closing,in the end, how many lockers are open and how many closed?


I would like to know how much compatibility can I expect between ARM MCUs from different vendors.  For example, let's say I write a firmware using C language for a Cortex M0 using its CAN peripheral. Will I be able to port it to a Cortex M0 from a different vendor with no changes? (or at least minimal changes) Or peripherals are completely different between them?  And what about if I use an RTOS like FreeRTOS? Does FreeRTOS abstract from the hardware so I'm able to port my software easily?  Finally, are all ARM Cortex M0, M4, etc from all vendors supported by FreeRTOS? Or only specific models of specific vendors?

I have started developing applications on XMC 2 go evaluation board. I, more or less, got the idea. But what if I try to go for, lets say, STM32?   For XMC1100 setting pin 00 as output is   PORT1->IOCR0 &= ~PORT0_IOCR0_PC0_Msk; PORT0->IOCR0 |= 0x0 << PORT0_IOCR0_PC0_Pos;   But I don't think stm32 has a IOCR register. So, should an engineer learn all these different register names?


I am looking for a command line or bash script that would add space 5 times before the beginning of each line in a file.  for example:  abc   after adding spaces 5 times        abc

I usually go to stackexchange when I face programming terminal and I spend most of time trying to append four spaces before my pasted programming code.  Is there any faster way to do it from a terminal? What would you do?


This is a very strange problem I have never experienced before.  I perform these following stataments  //Grabs the currency from the bank account $stmt = $db->prepare("SELECT * FROM accounts WHERE account_id = '$accountid'");         $stmt->execute();         $result = $stmt->get_result();         if($result->num_rows > 0) {             while($row = $result->fetch_assoc()) {                 $bankcurrency = $row['currency'];             }         }         $stmt->close();  //Finds the symbol of the speicific currency         $stmt = $db->prepare("SELECT * FROM currencies WHERE currency = ?");         $stmt->bind_param("s", $bankcurrency);         $stmt->execute();         $result = $stmt->get_result();         if($result->num_rows > 0) {             while($row = $result->fetch_assoc()) {                 echo $symbol = $row['symbol'];             }         }         $stmt->close();   The output of the symbol from these statements are � The output should have been $  You would think I have something wrong with my database input, but no, because if I try:  $stmt = $db->prepare("SELECT * FROM currencies WHERE currency = 'USD'");         //$stmt->bind_param("s", $bankcurrency);         $stmt->execute();         $result = $stmt->get_result();         if($result->num_rows > 0) {             while($row = $result->fetch_assoc()) {                 echo $symbol = $row['symbol'];             }         }         $stmt->close();   This then outputs $ This makes no sense as the data and statements are exactly the same.  You don't need to declare strings or variables in PHP which is why it makes no sense to me?  My database structure is simply:  accounts database:  name: currency Type: TEXT Value: USD   currencies database:  name: symbol Type: TEXT Value: $   Of course I have other rows, but these are the affected ones  You could say my database is the problem, but since the second statement works fine out outputs $ that is clearly not the problem.  I can't understand what is wrong  EDIT: If I add in $bankcurrency = 'USD'; it also displays USD as you would expect, so there is a problem with my first statement

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


Le $\Bbb{K}$ be a field. I want to show wether $\frac{\Bbb{K}[X]}{\langle X^2 \rangle}$ and $\frac{\Bbb{K}[X]}{\langle X^2  + 1\rangle}$ are isomorphic. First thing to note is that there is an nilpotent element $[X]$ in the first quotient. But in the second one I think it will depend on the roots of $X^2+1$ because for example in $\Bbb{F}_2$, $x^2+1=(X-1)^2$ so $[X-1]$ is nilpotent. So in the case where it can't be factorized there is no nilpotent element (how to prove that ?). Otherwise I don't see any morphism we can exhibit. Any hint ?

My first instinct is to go to the 1st isomorphism theorem and say that the two rings are isomorphic if there is a field where $(x^2)=(x^2-1)$, which doesn't seem terribly promising.  But then it seems to me that $F[x]/(x^2)$ is the ring you get when you take $F$ and adjoin an element that satisfies the relation $x^2=0$, which would be $0$ and every field's got one.  Same with $F[x]/(x^2-1)$ which is $F$ adjoined by an element satisfying $x^2=1$.  $1$ does the trick and every field's got one of those too.  Any hints (or answers!) would be appreciated.  Thanks...


I am newbee on python programming language  and I have a problem about accessing list items like this.  My data is data=[[664159, 550946, 1, 1],[665845, 557965, 1, 2],[597173, 575538, 1, 3],[635690, 608046, 1, 5]]  I want to access first two colums of first items that is [664159, 550946] and I am try to this  >data[0][0:1]  but i get only first colums data that is [664159] result. I havent got any idea for solving it. Can you help me please? What is my wrong?  >data=[[664159, 550946, 1, 1],[665845, 557965, 1, 2],[597173, 575538, 1, 3],[635690, 608046, 1, 5]]  >data[0][0:1]   >>[664159]

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


Hi I'm trying to create a regular expression for my date field.  The date format is MM/DD/YYYY.  My current regular expression code is as follows  var RE_DATE = /^[0-12]{2}[/][0-31]{2}[/][2010-2020]{4}$/;   which is wrong but well... I tried. :P  May I know how to get my regular expression to check for dates and months with a 0 in front of them?


In a recent test, we were asked to identify the grammatically incorrect sentence from this:        They gave us the money back less the service charges of three hundred dollars.   This country's expenditure is not less than that of Bangladesh.   The committee initially asked for a funding of 2 million dollars, but later settled for a lesser sum.   This country's expenditure on educational reforms is very less.      The incorrect sentence apparently is the 4th one. But I don't see why.. All 4 sentences sound correct. The only thing one might have doubts about is the use of "country's" in place of "of this country". Is the correct form of the 4th sentence - The expenditure of this country on educational reforms is very less. ?

Can I use "less" in sentences like this:  1 Why do we have so less number of students for this class? 2 My song collection is very less.  "Small" sounds better in both examples, but I would like to know if using "less" in these sentences is correct?


String str1 = "abc:5";      String str2 = "abc:" + str1.length();      String str3 = "abc:" + 5;        System.out.println(str1==str2);      System.out.println(str1==str3);   Output of the program is : false true  But I don't understand why?

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 want to call a .C or .O file from my python script and execute any of the C program function. How can I write my script to call a function in C?

What would be the quickest way to construct a Python binding to a C or C++ library?  (I am using Windows if this matters.)


I recently learned that relativistic mass isn't actually real or popular and that mass is actually invariant and not dependent on velocity. My entire sense of why we couldn't travel faster than light was because I thought that the faster we got the more massive we became. Now I'm lost and trying to understand why we can't travel faster than light.

I know that as the velocity increases, the mass of the object also increases so it becomes tougher and tougher to move the object which ultimately leads to a requirement of infinite energy to accelerate an object to the speed of light. But I have a doubt.  As far as I know only the observable mass (Relativistic mass) increases but not the Proper Mass or Intrinsic Mass, right? The actual mass of the object will remain the same. So if the actual mass ($m_0)$ remains the same and only the observable mass increases, why is more and more energy required? I know that even if the object exceeds the speed of light, we will not be able to say that it is moving faster than the speed of light but is it possible to make it move faster than light?  If rest mass does not change with $v$ then why is infinite energy required to accelerate an object to the speed of light?  I quote Igor Ivanov (a stackexchange user from this question ) to give an insight into my question.     The mass (the true mass which physicists actually deal with when they calculate something concerning relativistic particles) does not change with velocity. The mass (the true mass!) is an intrinsic property of a body, and it does not depends on the observer's frame of reference. I strongly suggest to  popular article by Lev Okun, where he calls the concept of relativistic mass a "pedagogical virus".   EDIT  After reading the answers I have a doubt.  SO can I say that only the overall energy of the system increases while the mass remains constant? But then if mass remains constant, then why is more and more energy gradually required? I mean there should be a reason for that requirement of infinite energy.


I want fo learn (Real) calculus and I've seem those books are very recommended, now I know why, I've given them a look and I think they are worth their reputation. I'm talking about  Calculus by Michael Spivak Calculus by Tom Apostol Introduction to Calculus and Analysis by Fritz John and Richard Courant  I want to read them all, but I have to chose: what should I pick and why? are there any sustactial difference? if I have to read them all, in what order should I read them?

I'm struggling a bit with functions(limits, squeeze theorem, etc).  I have done some research and found a list of books on calculus but I'm not sure which one would be better suited for me, so I would appreciate if some experienced people here could advise me which books would be better to master the basics so I can move on with derivatives, etc. Limits is my main problem, so I need a book which explain this in depth so I can master it. Then I'll keep going on with the same book for other chapters.  Below is the list which I found :   Apostol T.M. Calculus Vol. 1 Burn R.P. Numbers and Functions: Steps into Analysis  Courant R. and John F. Introduction to Calculus and Analysis I - One of the better calculus text in print.  Crowell B. Calculus  Dawkins, P Calculus I and Calculus II  Garrett P. Calculus  Ghorpade S.R. and Limaye B.V. A Course in Calculus and Real Analysis  Gill G.S. Calculus Bible  Guichard D. Whitman Calculu.  Hardy G.H. A Course of Pure Mathematics  Hwang A.D. Calculus for Mathematicians, Computer Scientists, and Physicists: An Introduction to Abstract Mathematics  Santos D. Differential Calculus  Shapiro B.E. Calculus and Analysis  Spivak M. Calculus  Strang G. Calculus  Thomas G.B. and Finney R.L. Calculus and Analytic Geometry  Tranter C.J. Advanced Level Pure Mathematics  Tranter C.J. Techniques of Mathematical Analysis  Veeh J.A. Lectures Notes on Calculus  So far I narrowed my list down to Hardy, Spivak and Apostol based on further research, but I haven't got my hands on these books yet to compare them and I'm not sure if these books will be good for me.  Thanks.


Can I use the clone from "Invoke Duplicity" to cast a concentration spell, since the clone requires concentration itself?  For example, could I use the clone to cast invisibility on one of my allies who is too far away from me to cast it normally?  I know that I would lose concentration on the clone when I cast a concentration spell, but would the clone exist long enough to still cast the spell on my ally?

The book says:     Concentration. Some spells require you to maintain concentration in order to keep   their magic active. If you lose concentration, such a spell ends.   So what happens if, for example, you are already concentrating on a spell, and cast Witch Bolt without concentrating. Would you get the initial arc of blue energy, or would it not even go off?  I am asking if you can cast a spell that says concentration without concentrating for an immediate effect. This would be useful to avoid interrupting your existing concentration. In essence, if you are concentrating on thing A (doesn't have to be a spell since other things need concentration), can you cast a concentration spell getting an immediate effect without losing concentration on thing A?  Since the definition of concentration is to keep the spell active (meaning it is already active) I would think that you would get the initial effect (if it had one) without the need to concentrate on it.


As an example, I have written this sentence: "People are trying to stop them from doing this in other countries, such as the U.N." Should this have a period at the end?

I always stumble when using abbreviations in a sentence, as they inherently contain a period in them. How do I use a comma or a semicolon after an abbreviation? How about a period?  E.g. (This is an example of my quandary)


When I try to rotate a bone on the arm the chest armor deforms as well. I looked around and couldn't find any answers, any help?   Also I did check weight paint and there is no reason the chest should be pulled.

I tried adding weight, removing weight and removing doubles. The mesh popping out won't go away. Any ideas?    Blend File:


I'm writing a program in which a user can create a rectangle by giving the upper left and lower right coordinates. In turn, my program should automatically set the upper right and lower left coordinates using the points the user enters.   Ex: User adds a rectangle with the points (5,25) for upper left and (20,10) lower right. So the upper right point would be (20,25) and the lower left point would be (5,10).  This is how I wrote that out in my Rectangle class:  Point upperLeft; Point lowerRight; Point upperRight; Point lowerLeft; public double area; public double perim;  public Rectangle (Point upperLeft, Point lowerRight){     this.upperLeft = upperLeft;     this.lowerRight = lowerRight; }  public Point getUpperLeft() {     Point p = upperLeft;     return p; }  public void setUpperLeft(Point p) {     this.upperLeft = p; }  public Point getLowerRight() {     Point p2 = lowerRight;     return p2;  }  public void setLowerRight(Point p2) {     this.lowerRight = p2; }  public Point getUpperRight(){     upperRight.setX(lowerRight.getX());      upperRight.setY(upperLeft.getY());     return upperRight; }  public Point getLowerLeft(){     lowerLeft.setX(upperLeft.getX());     lowerLeft.setY(lowerRight.getY());     return lowerLeft; }   In my main class I created a Rectangle called r, and did a println of r.getLowerRight(). Works fine, returns (20,10) as expected.  However, if I try to print one of the points that the user does not input, for example upperRight, I get a null pointer exception for the first line of getUpperRight, which is:  upperRight.setX(lowerRight.getX());    If I print the value of lowerRight.getX() on its own, it works. But for some reason when I try to set the X of the upperRight point to be the same as that of the lowerRight point, it just doesn't work. This is the Point class:  private double x; private double y; private double area; private double perim;   public Point(double x, double y){     this.x = x;     this.y = y; }   public double getX() {     return x; }  public void setX(double x) {     this.x = x; }  public double getY() {     return y; }  public void setY(double y) {     this.y = y; }  public String id() {             shapeID++;     String id = String.valueOf(shapeID);     return id; }  public double area() {     area = 0;     return area; }  public double perimeter() {     perim = 0;     return perim; }  public void hit(Point p) {  }  public String toString(){     return "(" + x + "," + y + ")"; }  public static double distance(Point p1, Point p2){     double distance = Math.sqrt((p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y));     return distance; }   }   Another note: Even if I replace upperRight.setX(lowerRight.getX()) with upperRight.setX(20.0), the getUpperRight println will still give a null pointer exception, which makes me think the problem is with the upperRight.setX part of the statement.   edit: I really don't see how this is a duplicate of "what is a null pointer exception?" That's a much more general question. I know what it is, but I don't see how it applies here.

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 SQL Server 2012 with version 11.0.3000.0 .  I need upgrade my version to SQL Server 2012 SP1 because I need install Cumulation 4 in Sql Server 2012 Cumulative Update 4 for use PowerPivot in Multidimensional Database.  Before install Sql Server 2012 Cumulative Update 4 I need Upgrade my SQL Server to Service Pack 1.  How Can I Update My Version to SP1.  I sow  and download SQLServer2012SP1-KB2674319-x64-ENU.exe and SQLServer2012SP1-FullSlipstream-ENU-x64.iso but this not work in my Server.  I have this error :


I have a list which I give to a function as argument. Inside function, I'm altering the list, but I don't return the list using return. I'm running the function and print the list afterwards. Excpeted result: [] Actual result: [5] How is this possible? def foo(bar):     for i in range(2):         if bar == []:             bar.append(4)         else:             bar[0] += 1              myvar = []   foo(myvar) print (myvar)

I'm trying to understand Python's approach to variable scope. In this example, why is f() able to alter the value of x, as perceived within main(), but not the value of n?  def f(n, x):     n = 2     x.append(4)     print('In f():', n, x)  def main():     n = 1     x = [0,1,2,3]     print('Before:', n, x)     f(n, x)     print('After: ', n, x)  main()   Output:  Before: 1 [0, 1, 2, 3] In f(): 2 [0, 1, 2, 3, 4] After:  1 [0, 1, 2, 3, 4]


I was looking for an example of a non-Noetherian local commutative ring with $1$.    I would appreciate if anyone can point to a reference.

I was looking for an example of a non-Noetherian complete local commutative ring with $1$. I would appreciate if anyone can point to a reference.


Where can I find the how-to guide to install Ubuntu 14.04.02 alongside Windows 8.1? Because I don't know anything about it. I have a brand new system with a Core i5 processor.

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


I read this story when I was younger (middle school), I don't remember much of it as it was a very long time ago.  From what I remember the main character is female and she has a younger brother. They are with another traveler whom I believe was related to them.  At one point in the book their consciousness were being attacked or sucked into a void and in order to protect themselves they each had their own type mantra they repeated. The girl repeated the periodic table and I believe the traveler repeated either the Fibonacci sequence or listed off prime numbers. Her brother on the other hand had been captured in the exchange.

I read a book many years ago that talks about the shortest distance between two points being a line, and if you held a string between those points you can fold the string to connect the points. The book is about teleportation and space travel, and I believe it has a purple cover. Anyone know of this book?


If one is given eleven integers, and told that for any ten of them it is possible to split them into two sets of five with the same total value, show that the eleven integers must be equal.  My thoughts so far:   -if you had 10 equal numbers and one different one, you could swap the different one in so it wouldn't work  -if you had nine equal numbers, then clearly those nine plus a different number couldn't be divided up into two equal sets  -if there were eight equal numbers, then calling the equal numbers N and the other numbers $n_1$, $n_2$, $n_3$. If we exclude $n_3$, then either    $N<n_1,n_2$ or $N>n_1, n_2$, in which case we would require $4N + n_1 = 4 N + n_2$ which implies that $n_1=n_2$. By swapping $n_3$ for $n_1$, we can see that this also implies $n_1=n_2=n_3$. However, then the case of 7$N$s and 3$n$s wouldn't be able to be split into two equal sets.  $n_1<N<n_2$, in which case $5N = 3N + n_1 + n_2$ so $2N=n_1 +n_2$. Similarly $N=n_2+n_3=n_1+n+n_3$. However, this isn't possible because either $n_3>N$ in which case $n_2 + n_3 > N$ or $n_3<N$ in which case $n_1+n_3<N$.

Let $S$ be a finite collection of real numbers (not necessarily distinct). If any element of $S$ is removed then the remaining real numbers can be divided into two collections with same size and same sum ; then is it true that all elements of $S$ are equal ?  (I know the result is true if the "reals" are replaced by "integers".)


Let $G$ be a finite group with normal subgroups $N_{1}$ and $N_{2}$. Find counter examples to the following statements   1) If $N_{1}\cong N_{2}$ then $G/N_{1}\cong G/N_{2}$   2) If $G/N_{1}\cong G/N_{2}$ then $N_{1}\cong N_{2}$.  Thanks for the help.

Let $A,B\triangleleft G$. Give counterexample for the claims: a. $G/A\cong B \Rightarrow G/B\cong A$ b. $G/A\cong G/B\Leftrightarrow A\cong B$  I don't know from where to start. Can you give some counterexamples? addiotionally, what is the intuition of solving question in algebra which requires giving counter-examples


The bash 4.1 manpage states (emphasis added)...     Simple Commands      A simple command is a sequence of optional variable assignments   followed by blank-separated words and redirections, and terminated by   a control operator. The first word specifies the command to be   executed, and is passed as argument zero. The remaining words are   passed as arguments to the invoked command.   Verifying the version on my system (NOT patched for shellshock)...  #  bash --version GNU bash, version 4.1.0(1)-release (i686-pc-linux-gnu) ...   However, preceding variable assignments, without semicolons, are supposed to be a way to localize environment variable values for the life of that one command invocation only, but do not seem to ...   #  x=123 echo $x; unset x; echo $x bash: x: unbound variable #  x=123; echo $x; unset x; echo $x 123 bash: x: unbound variable #  x=123; echo $x | tr '1' 'a'; unset x; echo $x a23 bash: x: unbound variable #  x=123 echo $x | tr '1' 'a'; unset x; echo $x bash: x: unbound variable bash: x: unbound variable #  x="123" echo "$x" | tr '1' 'a'; unset x; echo $x bash: x: unbound variable bash: x: unbound variable #  x="123"; echo "$x" | tr '1' 'a'; unset x; echo $x a23 bash: x: unbound variable   Solution Per  it appears that the command must deliberately use the environment variables of its parent and echo does not. But shell invocations like bash -c do ...  x=123 bash -c 'echo $x'; unset x; echo $x 123 bash: x: unbound variable   Resources

If I run  export TEST=foo echo $TEST   It outputs foo.  If I run  TEST=foo echo $TEST   It does not. How can I get this functionality without using export or a script?


Three weeks on from its debut in April, the film’s domestic gross box   office had barely surpassed $600,000 .

PLease, dear native English speakers, help me to understand the meaning of the expression "a year on" within the context "The reality is that, a year on, a true 4K standard is still very much a work in progress..." Thank you a lot!


Here is a model shown in object and edit mode.  The topology is great, however, the body parts are all separate meshes.  From an animation perspective, what are the pros/cons of this approach, versus a single mesh?  Thanks! Edit- mods believe my question has been answered here:  However, I think my question is sufficiently different as I'm asking about animation of an organic object, not hard surface modelling.

Is there any benefit of creating model in one piece or I can create separate pieces and just overlap them to create a visually joint part.  For example, the below image were made from two parts 1. Blade 2. Spinner  Is there any benefit to model them (e.g. extrude from the spinner) or it is actually ok to have them separated since visually I can achieve the same effect (See picture 2)


This is my first question ever, so please be easy on me for formatting. I tried searching a lot for the answer but couldn't get what I wanted  This is the C program and is working as desired  #include <stdio.h> #include <stdlib.h> int main() {     int i,n;     struct student {         char name[20];         int roll;         int age;         float marks;     };     printf("Enter number of students\n");     scanf(" %d", &n);     struct student a[n];     for(i=0;i<n;i++) {         printf("Enter details of student %d\n",(i+1));         printf("Name : ");         scanf(" %[^\n]s", &a[i].name);         printf("Roll number: ");         scanf(" %d", &a[i].roll);         printf("Age : ");         scanf(" %d", &a[i].age);         printf("Marks : ");         scanf(" %f", &a[i].marks);     }     printf("\n%-20s%-20s%-20s%-20s\n\n", "Name", "Roll no", "Age", "Marks");     for(i=0;i<n;i++)         printf("%-20s%-20d%-20d%-20.2f\n", a[i].name, a[i].roll, a[i].age, a[i].marks);     return 0; }   To write this in Java, I created a Student class first  public class Student {     public String name;     public int roll,age;     public float marks; }   And then a TestStructure class to make the program  import java.util.Scanner; public class TestStructure {     public static void main(String[] args) {         Scanner sc=new Scanner(System.in);         int i,n;         System.out.println("Enter number of students");         n=sc.nextInt();         sc.nextLine(); //To consume new line         Student[] a=new Student[n];         for(i=0;i<n;i++) {             System.out.printf("Enter details of student %d\n",(i+1));             System.out.printf("Name : ");             a[i].name=sc.nextLine();             System.out.printf("Roll number: ");             a[i].roll=sc.nextInt();             System.out.printf("Age : ");             a[i].age=sc.nextInt();             System.out.printf("Marks : ");             a[i].marks=sc.nextFloat();             sc.nextLine(); //To consume new line         }         sc.close();         System.out.printf("\n%-20s%-20s%-20s%-20s\n\n", "Name", "Roll no", "Age", "Marks");         for(i=0;i<n;i++)             System.out.printf("%-20s%-20d%-20d%-20.2f\n", a[i].name, a[i].roll, a[i].age, a[i].marks);     } }   But I get NullPointerException as soon as I enter the first name

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 started to receive emails with the subject: "Mail delivery failed: returning message to sender" for emails I haven't sent.  I host my own mail server at my domain matos-sorge.com (a linode) and I am slightly worried someone is using my mail server for spamming.  The emails I receive look like this:  This message was created automatically by mail delivery software.  A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:  acoperis@ls12.globehosting.net   (generated from ppaxylfg510@acoperisexpert.ro)   mailbox is full: retry timeout exceeded  ------ This is a copy of the message, including all the headers. ------  Return-path: <paulo@matos-sorge.com> Received: from [70.45.238.57] (port=15427 helo=host-70-45-238-57.onelinkpr.net)   by ls12.globehosting.net with esmtp (Exim 4.80)    (envelope-from <paulo@matos-sorge.com>)    id 1WkK88-001FK5-6e     for ppaxylfg510@acoperisexpert.ro; Wed, 14 May 2014 00:20:59 +0300 From: <paulo@matos-sorge.com> To: <ppaxylfg510@acoperisexpert.ro> Subject: regional Asistent manager Date: 13 May 2014 05:42:50 -0800 Message-ID: <002801cf6eb6$056bf74c$152b8580$@matos-sorge.com> MIME-Version: 1.0 Content-Type: text/plain;   charset="ibm852" Content-Transfer-Encoding: 8bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: Acjpbbuaee0o3789jpbbuaee0o3789== X-MimeOLE: Produced By Microsoft MimeOLE V6.1.7601.17514 X-Spam-Status: No, score=2.5 X-Spam-Score: 25 X-Spam-Bar: ++ X-Ham-Report: Spam detection software, running on the system "ls12.globehosting.net", has  identified this incoming email as possible spam.  The original message  has been attached to this so you can view it (if it isn't spam) or label  similar future email.  If you have any questions, see  the administrator of that system for details. Content preview:  Buna ziua! Noua ne-a placut CV-ul dvs si am hotarat ca sunteti   interesati sa lucrati in compania noastra. Ne specializam in consultare in   domeniul de management al afacerilor. Activitatea noastra se desfasoara in   mai multe tari din lume, la fel avem si clienti in Romania. Si in legatura   cu acest fat,dorim sa marim numarul de membrii echipei noastre. Activitatea   poate fi deplina sau partiala. Salariu de la 400 pana la 2000 euro lunar.   [...]     Content analysis details:   (2.5 points, 3.0 required)   pts rule name              description  ---- ---------------------- --------------------------------------------------   2.5 URIBL_DBL_SPAM         Contains an URL listed in the DBL blocklist                            [URIs: myjob-ro.com] X-Spam-Flag: NO  Buna ziua!  Noua ne-a placut CV-ul dvs si am hotarat ca sunteti interesati sa lucrati in compania noastra. Ne specializam in consultare in domeniul de management al afacerilor.  Activitatea noastra se desfasoara in mai multe tari din lume, la fel avem si clienti in Romania. Si in legatura cu acest fat,dorim sa marim numarul de membrii echipei noastre. Activitatea poate fi deplina sau partiala. Salariu de la 400 pana la 2000 euro lunar.  Daca sunteti interesati de oferta propusa,va rugam sa scrieti pe adresa Lizzie@myjob-ro.com pentru a primi mai multe informatii. Cu respect,HR Manager   I never tried to send this message.  I use postfix + dovecot on my mailserver, but I am far from being a professional network administrator.  How can I ensure my server is not being used for spamming.  If it isn't then, why do I get these messages?

I receive Mailer Daemon messages saying certain emails fail. My domain is itaccess.org which is administered by Google apps. Is there any way I can identify who is sending emails from my domain, and how they are doing it without me creating an account for them?  Delivered-To: 7e949ba@itaccess.org Received: by 10.142.152.34 with SMTP id z34csp12042wfd;         Wed, 8 Aug 2012 07:12:46 -0700 (PDT) Received: by 10.152.112.34 with SMTP id in2mr18229790lab.6.1344435165782;         Wed, 08 Aug 2012 07:12:45 -0700 (PDT) Return-Path: <whao@www20.aname.net> Received: from smtp-gw.fsdata.se (smtp-gw.fsdata.se. [195.35.82.145])         by mx.google.com with ESMTP id b9si24888989lbg.77.2012.08.08.07.12.44;         Wed, 08 Aug 2012 07:12:45 -0700 (PDT) Received-SPF: neutral (google.com: 195.35.82.145 is neither permitted nor denied by best guess record for domain of whao@www20.aname.net) client-ip=195.35.82.145; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.35.82.145 is neither permitted nor denied by best guess record for domain of whao@www20.aname.net) smtp.mail=whao@www20.aname.net Received: from www20.aname.net (www20.aname.net [89.221.250.20])     by smtp-gw.fsdata.se (8.14.3/8.13.8) with ESMTP id q78EChia020085     for <7E949BA@itaccess.org>; Wed, 8 Aug 2012 16:12:43 +0200 Received: from www20.aname.net (localhost [127.0.0.1])     by www20.aname.net (8.14.3/8.14.3) with ESMTP id q78ECgQ1013882     for <7E949BA@itaccess.org>; Wed, 8 Aug 2012 16:12:42 +0200 Received: (from whao@localhost)     by www20.aname.net (8.14.3/8.12.0/Submit) id q78ECgKn013879;     Wed, 8 Aug 2012 16:12:42 +0200 Date: Wed, 8 Aug 2012 16:12:42 +0200 Message-Id: <201208081412.q78ECgKn013879@www20.aname.net> To: 7E949BA@itaccess.org References: <20120808171231.CAC5128A79D815BC08430@USER-PC> In-Reply-To: <20120808171231.CAC5128A79D815BC08430@USER-PC> X-Loop: whao@whao.se From: MAILER-DAEMON@whao.se Subject: whao.se:  kontot avstängt - account closed X-FS-SpamAssassinScore: 1.8 X-FS-SpamAssassinRules: ALL_TRUSTED,DCC_CHECK,FRT_CONTACT,SUBJECT_NEEDS_ENCODING      Detta är ett automatiskt svar från F S Data - http://www.fsdata.se      Kontot för domänen whao.se är tillsvidare avstängt.     För mer information, kontakta info@fsdata.se      Mvh,     /F S Data      -----    This is an automatic reply from F S Data - http://www.fsdata.se    The domain account "whao.se" is closed.   For further information, please contact info@fsdata.se    Best regards,   /F S Data