I'm pretty sure the rule is not to put a comma after a conjunction, but sometimes it just seems like that prepositional phrase needs to be comma'd off. Is it just plain wrong to put the comma right after the conjunction?  Ex: I went to the store to buy eggs and milk and, though I shouldn't, I bought a candy bar too.

states:     If a dependent clause, or an introductory phrase requiring to be set off by a comma, precedes the second independent clause, no comma is needed after the conjunction.   Strunk's example illustrates the point:     The situation is perilous, but if we are prepared to act promptly, there is still one chance of escape.   However, I would be tempted to put a comma after the "but," like this:     The situation is perilous, but, if we are prepared to act promptly, there is still one chance of escape.   So, I know you're thinking, "Well, Strunk's Rules of Usage says that you're wrong. No comma."   But is Rules of Usage really the best source? I'd like to see this rule in a more contemporary and authoritative source, like the Chicago Manual of Style.  There are many instances —  — where the comma is included before a parenthetical comment that comes after a coordinating conjunction.  Any authoritative source on the issue?


I watched some of the Harry Potter movies today, and there is something I didn't understand.  In the first movie, Harry's touch hurts Professor Quirrell, but when Voldemort and Harry "fall-fly" during the last scene, the touch doesn't seem to affect him. Is there a canon reason as to why?

In the Goblet of Fire, Harry is cut in the arm by Pettigrew. When Dumbledore learns it, he's extremely worried and wants to check Harry's arm.  Why?     When Harry told of Wormtail piercing his arm with the dagger, however, Sirius let out a vehement exclamation and Dumbledore stood up so quickly that Harry   started. Dumbledore walked around the desk and told Harry to stretch out his arm.   Harry showed them both the place where his robes were torn and the cut beneath   them.      "He said my blood would make him stronger than if he'd used someone else's,"   Harry told Dumbledore. "He said the protection my - my mother left in me - he'd   have it too. And he was right - he could touch me without hurting himself, he   touched my face."      For a fleeting instant, Harry thought he saw a gleam of something like triumph in   Dumbledore's eyes. But next second. Harry was sure he had imagined it, for when   Dumbledore had returned to his seat behind the desk, he looked as old and weary   as Harry had ever seen him.      "Very well," he said, sitting down again. "Voldemort has overcome that particular   barrier. Harry, continue, please.     Edit:  Plz explain this sentence specifically:     "Dumbledore walked around the desk and told Harry to stretch out his   arm."


here's the table:     CREATE TABLE `obits` (   `pid` int(11) NOT NULL,   `surname` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `firstname` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `middlename` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `maiden` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `presuf` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `birth` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `death` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `obitdate` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `obitsource` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `sourcepage` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,   `obittext` text COLLATE utf8_unicode_ci,   `DateCreated` DATETIME COLLATE utf8_unicode_ci NOT NULL DEFAULT(GETDATE()) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;   here is the error I'm getting: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(GETDATE()) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci' at line 14 (line 14 is the datecreated line)  I probably missed something really simple but for the life of me I don't know what. Thank you for any/all help. This table was fine before I tried to re-create it with the datecreated line.

How do you set a default value for a MySQL Datetime column?  In SQL Server it's getdate(). What is the equivalant for MySQL? I'm using MySQL 5.x if that is a factor.


I have A branch which is waiting for MR(changes pushed to remote branch), at the same time I want to open new branch B and continue working(weekend). So I create  new B branch when I am in A branch. But when I do changes in branch B, A also get those changes. So my question is how I can create a copy of that branch without having any connection with changes and commits?

I am working on a git repository with a master branch and another topic branch. I have switched to topic branch and modified a file. Now, if I switched to master branch that same file is shown as modified.   For example:  git status in git-build branch:  # On branch git-build # Changes to be committed: #   (use "git reset HEAD <file>..." to unstage) # #       modified:   cvsup_current #   Switch to master branch  [root@redbull builder_scripts (git-build)]# git co master M       builder_scripts/cvsup_current Switched to branch "master"   git status in master branch  [root@redbull builder_scripts (master)]# git status # On branch master # Changes to be committed: #   (use "git reset HEAD <file>..." to unstage) # #       modified:   cvsup_current #   Why is that the file is shown as modified in master branch even though it was modified in git-build branch?   My understanding was that the branches are independent of each other and when I change from one branch to another the changes do not "spill over" from one branch to another. So I am obviously missing some thing here.   Anyone got a clue stick?


I am using msysgit from behind a proxy. As I said in question   I have set system variable http_proxy to a value. Later I call  git config --global http.proxy $http_proxy   However, if I call something like:   git clone git://git.savannah.gnu.org/gnuprologjava.git   It gives the following error:  git.savannah.gnu.org[0; 140.186.70.72]: errno=No error fatal: unable to connect a socket (No error)

Note: while the use-case described is about using submodules within a project, the same applies to a normal git clone of a repository over HTTP.  I have a project under Git control.  I'd like to add a submodule:  git submodule add http://github.com/jscruggs/metric_fu.git vendor/plugins/metric_fu   But I get  ... got 1b0313f016d98e556396c91d08127c59722762d0 got 4c42d44a9221209293e5f3eb7e662a1571b09421 got b0d6414e3ca5c2fb4b95b7712c7edbf7d2becac7 error: Unable to find abc07fcf79aebed56497e3894c6c3c06046f913a under http://github.com/jscruggs/metri... Cannot obtain needed commit abc07fcf79aebed56497e3894c6c3c06046f913a while processing commit ee576543b3a0820cc966cc10cc41e6ffb3415658. fatal: Fetch failed. Clone of 'http://github.com/jscruggs/metric_fu.git' into submodule path 'vendor/plugins/metric_fu'   I have my HTTP_PROXY set up:  c:\project> echo %HTTP_PROXY% http://proxy.mycompany:80   I even have a global Git setting for the http proxy:  c:\project> git config --get http.proxy http://proxy.mycompany:80   Has anybody gotten HTTP fetches to consistently work through a proxy?  What's really strange is that a few project on GitHub work fine ( for example), but others consistently fail ( for example).


I'm trying to compile bochs. Here is my configure command:  ./configure --enable-fpu --enable-3dnow --enable-x86-64 --enable-a20-pin --enable-cdrom --enable-debugger --enable-debugger-gui --enable-disasm   Then I enter the "make" command and it compiles for some time. But then comes an error.  /usr/bin/ld: gui/libgui.a(gtk_enh_dbg_osdep.o): undefined reference to symbol 'pthread_create@@GLIBC_2.2.5' //lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line collect2: error: ld returned 1 exit status make: *** [bochs] Error 1   Can anybody help me with this error?  Thank you in advance.

I'm trying to compile bochs with this command:  ./configure --with-x11 --with-wx --enable-ne2000 --enable-iodebug --enable-disasm --enable-debugger --enable-e1000 --enable-usb --enable-pci   it works, but then when I run make I got:  usr/bin/ld: gui/libgui.a(gtk_enh_dbg_osdep.o): undefined reference to symbol 'pthread_create@@GLIBC_2.2.5' /lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line   Any Help ? :/


If $a^3=e$, then $a$ has a square root. I have that $a^3=aaa=e$ and applying $a^{-1}$ twice on both sides of the equation gives us $a=a^{-1}a^{-1}$ and so $a=(a^{-1})^2$. Thus $a$ has a square root. Is this correct? Is there another way to do this?

We know that $221 = 17*13$. So we can check if the system has roots to both of those equations separately, which it does:  $x^{5} \equiv 2$ mod $13$ has the solution $6 + 13n$ and $x^{5} \equiv 2$ mod $17$ has the solution $15 + 17n$.   I got these numbers from wolfram, I have no idea how to solve this problem WITHOUT a calculator. And even after finding these numbers. How would one obtain a solution modulo $221$? I was thinking the Chinese Remainder Theorem but I am under the assumption that CRT only applies to problems with powers of $x$ which are $1$.  Thanks.


I'm used to typing !! in bash when I want to reference the last command executed in that shell.  $ ls -la   drwxr-xr-x   4 me  wheel    136 Jan 19  2013 wireshark_stuff   ... (etc) ...   -rw-r--r--   1 me  wheel     11 Mar 13 13:51 old_PS1   $ !! |grep for_something_in_those_results   ls -la |grep for_something_in_those_results   /grep_results   Is there a way to do this in python?  >>> complicated_dict.['long_key_name'][0]   (response)   >>> my_func(!!)    This would get really handy as the interpreter commands become increasingly complicated. Sure, I could just use a plethora of local variables - but sometimes it's handy to just invoke the last thing run...

In many symbolic math systems, such as Matlab or Mathematica, you can use a variable like Ans or % to retrieve the last computed value. Is there a similar facility in the Python shell?


For example, I have a webshop where each product has its unique ID and I want to build SEO friendly URL for a product page.  An old-school way that is mentioned almost in every article looks like this:  where    1111 is ID of the product and is important some_product_name is just for google and users; changing this text to "some_other_product_name" will not have any effect   But some websites (including StackOverflow) uses different format and build URLs like:   So, my question is which URL is better from search engine point of view?  OR ? Is there any reason why forward slash should be used instead of hyphen?  From implementation point of view there is not so much difference. Also, for the end-users they look identical.   UPDATE 2017-03-02 @John Conde: this is not the duplicate. The link that you provided explains how to structure URL if you have hierarchy of entities. I agree that my question looks similar, but in my case I have parts of the URL that will never be part of user's search phrase (i.e., nobody will try to search for "1111", users type in product name).

Let’s take an example of a movie site. So a well structured set of URLs for this site can be:     Movie page - example.com/movies/the-matrix Review for movie - example.com/movies/the-matrix/reviews Trailers for movie - example.com/movies/the-matrix/trailers Specific trailer for movie - example.com/movies/the-matrix/trailers/trailer1   where it’s possible to navigate the resource even by directly deleting/appending resource name seamlessly.  For SEO purpose I read somewhere that for two given pages, Google will prefer the page which have search query up in the URL hierarchy among other things. So for the given 2 URLs and the query "the matrix trailer"    example.com/movies/the-matrix/trailers example.org/trailers/the-matrix/    `     Google might prefer the second URL as it has the keyword "trailer" at first level comparing to first URL which has "trailer" at 3rd level (a resource deeper in URL hierarchy may be less important).    If it is correct, one may be tempted to create URL hierarchy somewhat like      Movie page - example.com/movies/the-matrix Review for movie - example.com/reviews/the-matrix/ Trailers for movie - example.com/trailers/the-matrix/ Specific trailer for movie - example.com/trailers/the-matrix/trailer1     which will break the seamless hierarchy.    My questions are:   Is it true that resource deeper in URL hierarchy is tend to be less important when comparing to URLs of other site?   Is sacrificing meaningful, seamless hierarchy worth for this SEO optimization?


Let $x$ be a non-zero real number such that $x + \frac{1}{x}$ is an integer. Prove that $\forall n\in \mathbb{N}$ the number $x + \frac{1}{x}$ is also an integer.   Attempt at solution using induction:  base case: $n = 1$ then $x^n + \frac{1}{x^n} = x + \frac{1}{x}$ which is an integer  Inductive assumption: Assume that for some $k\in \mathbb{N} : x^k + \frac{1}{x^k}$  We have to show that $ x^{k+1} + \frac{1}{x^{k+1}}$ is an integer.  $$ x^{k+1} + \frac{1}{x^{k+1}} = x^k\cdot x + \frac{1}{x^k\cdot x} =  \frac{(x^k\cdot x)\cdot (x^k\cdot x)+1}{x^k\cdot x}$$  I can't find a way to seperate $x$ and $\frac{1}{x}$ from the term so I can use the inductive assumption.  Edit: I don't think that this question should count as a duplicate since the linked question is asking to specifically solve another problem and one of the answers of that question utilize the proof from this question in their answer but that question itself is different and not related to this question since that question can be solved without using this proof as other answers of that question don't include it.

How do we prove that $\dfrac{\phi^{400}+1}{\phi^{200}}$ is an integer, where $\phi$ is the golden ratio?  This appeared in an answer to a  I asked previously, but I do not see how to prove this..


What's the difference between game-based and simulation-based security? When we use the simulation-based, how to construct the simulator based on the adversary?

what are the main pros and cons of proving the "security" of a crypto scheme under simulation proofs instead of game based proofs?


How can I install psensor and use it my Ubuntu mate? I think my laptop has an overheating problem.

How can I install applications like Google Chrome on Ubuntu?  Are there any commands to install an application?    Index of answers:


I plan to read manga of The World God Only Knows.  I've watched up to and including season 3 of the anime. Which chapters do I need to start at to continue?

I plan to read TWGOK manga, especially the chapters that weren't animated (between Season 2 and Season 3). Which chapters do I need to read?


I have an attribute table with 100 LINES. The table has a DATE field. The 100 LINES have several DATE values.  I would like to combine all LINES with the same DATE value.  How can i do that?

I have joined corresponding Local Enterprise Partnerships table data into a polygon shapefile containing UK Local Authorities.      How do I Dissolve or Merge the the Local Authorities polygons by LEP_NAME as shown in the screenshot?   Ideally, I would like to retain the Local Authority attributes with the resultant merged polygons. I have zero scripting knowledge so am looking for a tool based solution. Any help or pointers much appreciated.    Additional Note: When attempting to use the dissolve tool the LEP_NAME field is not available as shown above. The LEP attribute data was created in Excel, saved as CSV format and joined to the Local Authority polygon shapefile. There are duplicate IDENTIFI0 fields as shown in the other screenshot - could this be the root of the issue?


My nephew (7th grade) has stumped me with this question.  If I spin a top, it eventually stops, because of friction, air resistance etc.  How come the Earth has been spinning non-stop for 4.5 Billion years?  Is there no impeding force (e.g. air resistance), however weak, that could have stopped the Earth from rotating by now?

Why do planets revolve around the Sun if there is a force called frictional force? Why do planets not stop rotating while the objects in motion stop after a while? Why are they continuously moving? Why are planets not affected by frictional force?


The Pareto distribution $P(a,c)$, with positive parameters $a$ and $c$, has density function $$ p(x;a,c) = \frac{ac^a}{x^{a+1}} $$ for $x \geq c$. Then, if $X_1, \dots, X_n$ is a random sample from the above distribution, we are asked to find the MLEs of $a$ and $c$. The likelihood function is $$\mathcal{L}(a,c;x_1,\dots,x_n) = \prod_{i=1}^n \frac{ac^a}{x_i^{a+1}} = a^n c^{an} \prod_{i=1}^n x_i^{-(a+1)},$$ and so, the log-likelihood is $$ \log\mathcal{L} = n \log a + an \log c - (a+1)\sum_{i=1}^n \log x_i. $$ This is a strictly increasing function in $c$, so we see that the MLE for $c$ is $$ \hat{c} = \min_i x_i = x_{(1)}. $$ Taking partial with respect to $a$ gives us that $$ \frac{\partial \log\mathcal{L}}{\partial a} = \frac{n}{a} + n\log c - \sum_{i=1}^n \log x_i. $$ Note that the second partial is always negative. Hence, setting the above expression to zero and solving for $a$ gives us the MLE for $a$: $$ \hat{a} = \frac{n}{\sum x_i - n \log \hat{c}} = \frac{n}{\sum_{i=1}^n \left(x_i/x_{(1)}\right)}. $$  Now, we are asked to find the distribution of $\hat{c}$ or the distribution of $2na/\hat{a}$. Finding the distribution of $\hat{c}$ was pretty straightforward. However, I have no idea how to find the distribution of $2na/\hat{a}$: $$ P\left( \frac{2na}{\hat{a}} \leq x \right) = P \left( 2a\sum \log\left(\frac{x_i}{x_{(1)}} \right) \right) = \cdots $$ and I have no idea where to go from here nor am I sure of my work this far.

Let $X_1,X_2,\ldots,X_n$ be i.i.d variables having a Pareto distribution with density $$f(x)=\frac{a\theta^a}{x^{a+1}}1_{x>\theta}\,,$$ where $a,\theta>0$. What is the distribution of $\sum\limits_{j=1}^n \ln\left(\frac{X_{(j)}}{X_{(1)}}\right)$ ?   Suppose $\mathsf{Gamma}(p,\alpha)$ denotes the density $g(t)\propto e^{-\alpha t}t^{p-1}1_{t>0}$.  We have $$T=\sum_{j=1}^n\ln\left(\frac{X_{(j)}}{X_{(1)}}\right)=\sum_{j=1}^n\ln(X_{(j)})-n\ln(X_{(1)})=\sum_{j=1}^n \ln X_j-n\ln X_{(1)}$$  Now,   \begin{align}&\ln(X_j/\theta)\stackrel{\text{i.i.d}}{\sim}\mathsf{Exp}\text{ with mean }1/a\qquad,\,j=1,\ldots,n \\&\implies\sum_{j=1}^n\ln(X_j/\theta)=\sum_{j=1}^n\ln X_j-n\ln \theta\sim\mathsf{Gamma}(n,a) \end{align}  I could show that $X_{(1)}$ has another Pareto density, so that $$\ln\left(\frac{X_{(1)}}{\theta}\right)=\ln X_{(1)}-\ln \theta \sim \mathsf{Exp}\text{ with mean }1/(na)$$   Not sure if the last two facts help me get the exact distribution of $T$.    Edit:  Turns out this was rather simple had I simply rewritten $T$ as   $$T=\sum_{j=1}^n \ln\left(\frac{X_j}{X_{(1)}}\right)=\sum_{j=1}^n(\ln X_j-\ln X_{(1)})=\sum_{j=1}^n (Y_j-Y_{(1)})\,,$$  where $Y_j=\ln (X_j/\theta)$. Since $aY_j\sim\mathsf{Exp}(1)$, using  result I have $a T\sim \mathsf{Gamma}(n-1,1)$.   This is equivalent to $T\sim \mathsf{Gamma}(n-1,a)$ or $2aT\sim \chi^2_{2n-2}$.


I am using Chromebook Acer C7. Since the BIOS is EFI, how can I install Ubuntu 13.10 from USB on that laptop? Will Unetbootin work on that? As I went to that website it tells that it can't boot from Mac OS X devices, so I suppose it will not work on chromebooks. So if not then what tool will?   I heard that Ubuntu 13.10 will come with kernel 9.12 or something that which will support chromebook. But can I make bootable usb or will it download and install from net as 12.04 and 13.04 do directly? Can anybody help?

I have installed Ubuntu 13.04 on my desktop (runs like a charm). Then I used Crouton to install Ubuntu 12. 04 on my chromebook samsung (ARM). It also works quite well.  Here comes my question. Can we have a true Ubuntu (preferably 13.04) on my ARM chromebook?  It seems that the Crouton/Ubuntu is not 100% the real thing.  The best option would be to have the full Ubuntu 13.04 and remove the Chrome OS.


How do you prove $\neg\neg(\neg\neg P \rightarrow P)$ in intuitionistic logic?   I know this statement to be intuitionistically provable because of Glivenko's theorem. However, I wish to prove it intuitionistically.  The relevant axioms I happen to be using are: (1) $\neg P = P\rightarrow\bot$ and (2) $\bot \rightarrow P$.

I have a feeling it's not, because ¬¬P → P is not provable. If it is, I'm not sure what kind of reductio I'd need to negate ¬(¬¬P → P). I believe a textbook somewhere said it was provable in intuitionistic logic, so am I missing something or is the textbook wrong?


I have a domain, example.com.  Here is my apache2 ReWrite rule:  RewriteEngine on RewriteRule ^([^/.]+)/?$ index.php?uname=$1 [L]   When I go to ,  appears in the address bar of my browser.  I want  to appear in the address bar! (my javascript needs to parse the GET arguments)  Is this possible?  Many thanks in advance,

This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not.


I don't understand how to solve this problem. I don't think I'm allowed to assume its abelian. Also, I know that I will have to use this theorem: If $p$ is a prime and $G$ is a $p$-group with more than one element, then $Z(G)\neq \{1\}$.

So I'm having trouble with this problem. I know that the definition of a simple group means that the group has no nontrivial subgroups. I know that this can be proven somehow with the help of the converse of Lagrange's Theorem for Abelian groups: If G is abelian of order n, and d is a divisor of n, then G has a subgroup of order d.   My attempt: (=>)Assume that G is a finite abelian group and is simple, then G has no nontrivial normal  subgroups.  (Now I don't know how to show that this implies that G has order p, where p is prime.  (<=)Assume that G is a finite abelian group with order p, where p is a prime. (Since the order of p is prime then what does this mean?)  Edit: Can someone check my new attempt at the proof?   (=>) Suppose G is a simple finite abelian group. Suppose for the sake of contradiction that G does not have prime order, then |G|=p*k where p is a prime number and k is an integer such that k>1. Then G has an element of order p. Let the element of order p be called x. Then , the subgroup generated by x, is of order p and  is not all of G. Since G is abelian, this subgroup is normal, which leads us to a contradiction. Therefore, G must have prime order.   (<=) Suppose that G is a finite abelian group and it’s order is p, a prime. Since G has prime order, then the only two subgroups of G are the trivial subgroup and the group G. Then, by definition the group G is simple since there are no nontrivial proper subgroups, and thus no nontrivial normal subgroups.


I have seen this example in a number of course material Show that the hypotheses “It is not sunny this afternoon and it is colder than yesterday”, “We will go swimming only if it is sunny”, “If we do not go swimming, then we will take a canoe trip”, and “If we take a canoe trip, then we will be home by sunset” lead to the conclusion “We will be home by sunset”. and the propositions are identified as p - “It is sunny this afternoon” q- “It is colder than yesterday” r- “We will go swimming” s- “We will take a canoe trip” t- “We will be home by sunset” All of them translate the second premise as r--> p. I am not able to understand why. Doesn't the second premise mean " if it is sunny then we will go swimming" and if yes then it should be p-->r or if the second premise is a biconditional then it should be r<-->p

For some reason, be it some bad habit or something else, I can not understand why the statement "p only if q" would translate into p implies q. For instance, I have the statement "Samir will attend the party only if Kanti will be there." The way I interpret this is, "It is true that Samir will attend the party only if it is true that Kanti will be at the party;" which, in my mind, becomes "If Kanti will be at the party, then Samir will be there."   Can someone convince me of the right way?  EDIT:  I have read them carefully, and probably have done so for over a year. I understand what sufficient conditions and necessary conditions are. I understand the conditional relationship in almost all of its forms, except the form "q only if p." What I do not understand is, why is p the necessary condition and q the sufficient condition. I am not asking, what are the sufficient and necessary conditions, rather, I am asking why.


On my laptop, I forgot the password to my Ubuntu partition, so I logged into the root command shell on the recovery start up option in GRUB so that I could change the password.  On my first attempt to change my user password, I got this error:  root@username-PC:~# passwd username (*not my actual user name*) Enter new UNIX password: Retype new UNIX password: passwd: Authentication token manipulation error passwd: password unchanged   After doing some research, I discovered that I was stuck as read only on the file system, so I ran the following command to remount the file partition as read/write:   mount -rw -o remount /   Afterwards, I change my user password using passwd and it was changed successfully.  I restarted my laptop and tried to login using the new password but the only thing that happened was after entering my password it flashed to a black screen with some text that I couldn't make out except for "Ubuntu 12.04" then another black screen half a second later, and finally back to the login screen. Repeated attempts to login results in only this action.

My Ubuntu is stuck in a login loop when trying to enter my desktop. When I login, the screen gets black and soon after that the login screen comes back.   I've read that the problem might be caused by an error depending on the graphics, here's my graphics card: ATI Radeon 7670M


Google Drive has been telling me I am using close to 15 / 15 GB of the free plan. However, when I check my local Google Drive folder on my computer, the files seem to total actually only about half of that. Is there something I am missing, or is Google displaying wrong information? (Possible in order to make me upgrade to a paid plan?)  This is the quota distribution given on  :   Then here is the Mac desktop app's quota display:   But when I use the du command in terminal, the last line (total) is reading something vastly different:   Also, I've not recently been shifting big files, so this is not a issue about Google's displayed number "pending recalculation". Am I missing something completely obvious, or is this indeed a bit fishy?

I have a paid 100GB Google Drive plan. It is reporting that I am at 99% capacity.  According to the the storage both within the desktop and web application, I have used 90.53GB within Drive.    My Drive is mapped to my OS X filesystem, and when fully synched it reports only 61.28GB used.    So what is going on here? I need to do a cleanup but cannot account for the 30GB difference.


I've heard in some lecture that the weak  implies the existence of $2^{32}$ fixed points in the algorithm, i.e. that $DES_k(x)=x$ for $2^{32}$  such $x$'s.  I couldn't find anything about that issue, can you give some reference or explain it here?

Can someone explain me this  please I am a bit confused?  It's from a texbook I am reading (block cipher companion)  it says that:      each weak key has  $2^{32}$ fixed points $m$ where $\operatorname{DES}_w(m) = m$ ( $w$ is a DES weak key). In other words encrypting a fixed point gives exactly the same point. To see this consider the $2^{32}$ ciphertexts after 8 rounds of encryption for which the two 32 bit halves are equal. For a weak  DES key, the round keys of the eighth and ninth rounds are equal. Thus the intermediate texts after seven rounds and after nine rounds of encryption will be equal. Since the round keys of the 7th and the 10th rounds are equal, the intermediate texts after 6 rounds and after 10 rounds of encryption will be equal. Continuing like this it follows that the plaintext will be equal to the ciphertext.    Now did not quite get :   Why are there $2^{32}$ fixed points?  And why after the eighth round of encryption the two halves must be equal? What does the author mean by the intermediate texts exactly? And how are they being equal?   P.S.: This question is not asking for what the weak keys are. I am asking for "fixed points" not exactly weak keys. For this reason I think it is not a duplicate of any other question. There is one similar question to what I've asked for which I have checked and saw that no satisfactory answer has been given there either.  Here is the similar question with no proper answers:


I am working through the derivation of the Lagrange-Charpit equations presented in this Wikipedia article:   I am interested in the "fully" nonlinear case. Where we have:  $$F(x_1,...,x_n,u,p_1,...,p_n)=0  $$ And $$ p_i=\frac{\partial u}{\partial x_i} $$  I am fine with the derivation up until the point where they say that (Also, $\dot{x_i}=dx_i/ds$):  $$\sum_i(\dot{x}_idp_i-\dot{p_i}dx_i)=0 $$  Follows from taking the exterior derivative of:  $$ du-\sum_ip_idx_i=0  $$  From the little I know about exterior derivatives, it seems like doing this would give (for the two dimensional case):  $$0=\left(\frac{\partial p_2}{\partial x_1}-\frac{\partial p_1}{\partial x_2}\right)dx_1\wedge dx_2 $$  Because $ddu=0$ and the anti-symmetry of the wedge product.  I don't see how this result leads to the one given.  Could someone help me out? I feel like there is something very simple that I am missing.

I am reading the  about applying the method of characteristics in the fully nonlinear case. We have the fully nonlinear equation $$ \tag{1} F(x_1, \cdots, x_n , u, p_1, \cdots, p_n) = 0,$$ here  $$\tag{2} p_i = \frac{\partial u}{\partial x_i}$$ is the partial derivative of $u$ with respect to $x_i$.   In the method of characteristics, we wish to reduce the PDE to a family of ODE. Let assume that $u$ is a solution to (1).  $$s\mapsto (x_1(s), \cdots, x_n(s), u(s), p_1(s), \cdots, p_n(s))$$ be a curve so that (1) is satisfied for all $s$. Then it is claimed that the following holds:   \begin{equation} \begin{split} \sum_i (F_{x_i} +F_up_i)\dot x_i + \sum_i F_{p_i}\dot p_i &=0\\ \dot u - \sum_i p_i\dot x_i &=0\\ \sum_i ( \dot x_i dp_i - \dot p_i dx_i) &= 0. \end{split} \end{equation}  I can see that the first two equations follow from taking total derivative with respect to $s$ of (1) and the expression $u(s) = u(x_1(s),\cdots, x_n(s))$. In the wiki page, it is claimed that      ... the third follows by taking an exterior derivative of the relation $du - \sum p_i dx_i = 0$.    Unfortunately, I fail to see how the third equation are derived using exterior derivative. Could you give me the steps so I could check my work, please?  P.S.: I’ve been struggling a lot lately on Frobenius theorem and systems of total differential equations. If you could explain that, I would deeply appreciate it.


When i add Modifier "subdivision surface" it will happen.Don't know why..   [![enter image description here][3]][3]

When I create a UV sphere and add the subdivision surface modifier, the following wrinkle appears.    How can I avoid it?  I've read the article  but there seems to be no clear solution.  UPDATE 1  I've used the word 'apply' in the first sentence of the initial version of this question. It's misleading since I want to preserve the modifier without 'applying' it. Rather, what I meant is 'adding' the modifier.  UPDATE 2  I followed josh sanfelici's solution, but still there is an artifact at the pole.  Here is the screen: (A rendered view with a sun lamp)    Maybe it's the limitation of the general-purpose subdivision modifier.  BTW, when the cast modifier is added after the subdivision modifier, the sphere becomes perfect (even for my original wrinkled sphere).  But since I want to edit the resulting sphere (for example, scaling X, Y, etc) while modifier is added but not applied, it's not usable.


My Ubuntu stopped saving my files last time I was working on it, saying "insufficient hard disk space". I tried rebooting my PC and it won't open. Rather, a black screen with a single dash appears. I understand that some drivers may be corrupted and would have to be reinstalled from the root shell, but I have no space. I know how to resize or increase partitions on Ubuntu, but I don't have GParted either, through which this is done. When I try to install it from the root shell, it gives me the same space error. What can I do to solve this issue?

I've run into a problem on one of my servers running 16.04: there is no disk space left.  I have no idea what is taking up the space. Is there a command to list the current directory sizes, so I can traverse and end up in the directory taking up all the space?


It is a very basic question of RNN (LSTM). Here is the basic structure of RNN: for a sample $(X^i,Y^i),$ input: $X^i = (x_1,\cdots,x_T);$ output: $Y^i = (y_1,\cdots,y_T).$ $$z_t = Uh_{t-1} + W x_t + b,$$ $$h_t = f(z_t) = f(Uh_{t-1} + W x_t + b),$$ $$y_t = g(h_t).$$  If we want to use RNN for prediction of time series: $(x_1,\cdots,x_n)$ like ARMA: input: $X^i = (x_i,\cdots,x_{i+T-1});$ output: $Y^i = x_{i+T}.$ Then how could we apply RNN (LSTM) to prediction of time series? Is it just changing into: $$y_T = g(h_1,\cdots,h_T)?$$ And is the different between RNN and ARMA for the prediction of time series just the difference between non-linear model and linear model?

I'm trying to understand LSTM, using for instance   I get the overall idea, I guess. But I'm not quite sure I get the maths.  I'll set a very simple problem : I have a sequence of numbers and want to predict next number.   So x_t is of shape (1), and as I understand, h_t will be the prediction, so it should also be of shape (1). (I'm just here ignoring batch size)  Now, the equation producing h_t, using * operation should then have two operands of the same size as the result; that is, C_t and o_t should also be of shape (1).  Following on that idea, equation producing C_t forces also shape of (1) for f_t, i_t and ~C_t.  So... everything reduced to scalar real numbers in that case ?  what am I getting wrong ? because this would just not be able to learn much, would it ?


The professor has to go to Ireland for a bonus trip and can bring with him only one student from its class. Students cannot agree on who should get chosen. One of the student produces a coin and suggests using a coin toss to determine the lucky one. None of the other students trust the coin to be fair. After a few trials, the students see that one side appears more frequently than the other, but they have not idea as to how big the bias is. The problem is to find an algorithm that simulates a fair coin toss while having access only to an unfair coin. Can you help me with this?

Given a coin with unknown bias $p$, how can I generate variates — as efficiently as possible — that are Bernoulli-distributed with probability 0.5?  That is, using the minimum number of flips per generated variate.


I've been using a solution that allows me to:    Use proportional figures in text and tabular figures in tables; Force siunitx to set "symbols", e.g. ( ) - in the text-font instead of the math-font, developed by David Carlisle (,  and ).   I've been using the code for a few years, but I can't get the MWE below to work with MinionPro. It results in the error message: Bad mathchar (32768). When loading MinionPro with onlytext (or using another font), the substitution trickery works fine. The problem is the left bracket, i.e. \xxxl(, the right bracket works fine.  The frustrating thing is that I use this code in my large style files and it works fine - but I want to create a minimal style file, and I just can't find the mistake.  \documentclass{scrartcl}  \usepackage[T1]{fontenc} \usepackage[utf8]{inputenx}  \usepackage{MinionPro}% other fonts work fine as well as using 'onlytext'  \usepackage{siunitx}  \sisetup{%     input-symbols           = ( ) [ ] - +, }  \def\xxxl#1{% \bgroup\uccode`\~\expandafter`\string#1% \uppercase{\egroup\edef~{\noexpand\text{\noexpand\llap{\string#1}}}}% \mathcode\expandafter`\string#1"8000 }  \def\xxxr#1{% \bgroup\uccode`\~\expandafter`\string#1% \uppercase{\egroup\edef~{\noexpand\text{\noexpand\rlap{\string#1}}}}% \mathcode\expandafter`\string#1"8000 }  \def\textsymbols{\xxxl(\xxxr)}% the left bracket ( causes the problem  \begin{document}  \begin{table} \figureversion{tabular,tab} \textsymbols \begin{tabular}{S S S} (0.096) & (0.012)& (0.108) \\  0.136  &  0.021 &  0.024 \end{tabular} \end{table}  \end{document}

This is a follow up question from . The original problem has been solved using siunitx instead of dcolumn. However, the problem is that I am using mathpazo with osf as my main body font and eulervm as my math font. With siunitx used to decimal align tables this results in []() symbols being drawn in the math font, but the digits being drawn in the text font, as the following MWE example illustrates.  Is it possible to draw the symbols in the normal text font or redefine the mathfont for S columns completely?  \documentclass{scrartcl} \usepackage{booktabs} \usepackage[osf]{mathpazo} \usepackage[euler-digits]{eulervm}  % For Tables created by estout \newcommand{\sym}[1]{\ensuremath{^{#1}}} % for symbols in Table \usepackage{siunitx} \sisetup{ detect-mode,            group-digits            = false ,           input-signs             = ,           input-symbols           = ()[]-+ ,           input-open-uncertainty  = ,           input-close-uncertainty = ,           table-align-text-post   = false          } \begin{document} \begin{tabular*}{\textwidth}{     l @{\extracolsep\fill} *{2}{S[table-format=4.4]} @{}} \toprule \multicolumn{1}{@{}l}{\emph{Age}}  \\[0.5ex] 18--24 &   [-1360.228]\sym{*}  &  -1371.941\sym{*}  \\        &       (6.915)         &    (-7.953)        \\ 25--34 &     -219.216          &   -240.271         \\        &     (514.894)         &   (515.348)        \\ 35--44 &     -310.715          &   -311.438         \\        &     (485.780)         &   (486.013)        \\ 55$+$  &       -5.135          &     [2.656]        \\        &      (53.267)         &   (533.875)        \\ \bottomrule \end{tabular*} \end{document}   Edit: Thanks to David the problem has been solved including a fix for amsmath and extending to XeTeX. On a side note, the command for * generated by estoutshould now be simply plain text:  \newcommand{\sym}{#1} % for symbols in Table  \newcommand{\sym}[1]{\rlap{$#1$}} % Thanks to David Carlise again.


This question has been asked many times by many people and when I google it i usually find glitches to make millions. But oftentimes I find glitches sometimes just outright don't work.  I'm pretty poor in GTA Online because as soon as I get money, I spend it on a car I'm working on or a garage I've wanted for a very long time. I want to find a easy way to make a little money, fast, a quick 20,000 or so without trouble.   Anyone found a few money-making strategies in GTA Online?

Everything in the online world is expensive, well the best things are. We all want the luxurious apartment with 10 cars garage and the best weapons but to achieve that, we need money. Which missions or activities give the most cash ?


When I review edits I think I'm rather picky. I just verified that I have rejected 37% of all suggested edits I reviewed so far, usually for the following reasons:   The editor fixes few spelling mistakes in a question/answer that should be completely rewritten to make sense (too minor). The editor tries to format code but fails miserably. For instance, he adds brackets that change the meaning of the code (invalid edit). The editor adds one or two tags that nobody cares about (too minor).   In these obvious cases I can just click the rejection reason "in time". Sometimes the reason why the edit should be rejected is more subtle and I want to type a custom reason. I have noticed, however, that in those cases I'm always "too late" (even when I take only 15 seconds longer) because the edit was approved already before I can even click reject.  As I said, the reason why the edit should be rejected is more subtle in these cases, so I can understand that some others approve. But to me it is frustrating that I take the time to do these reviews seriously and my vote is just ignored. Of course, I can go to the post and do the edit manually, but I feel that the system could benefit from some improvement here.  As a simple proposal I could imagine that the review process is not closed until all reviewers that were asked their opinion have actually responded (or after some timeout of course). But maybe someone has a better idea?

We've been . Some of us were getting frustrated that some users were smashing through 20 reviews in a minute so I decided to lay down the law.  Aaaanyway, as part of this  brought up the problem that if they take too long being diligent (looking into duplicates properly, checking rules, etc) there's a very good chance that somebody else will have reviewed that post and their decision (and the time that went into it) is wasted. That doesn't seem like a fair reward for what is an otherwise thankless task.  So I'm suggesting the a review "reservation" system so only one person can review something at once:   Once something is opened in review, it becomes unavailable to other users to review. That includes other queues. A reservation or lock should be against a post, not a post in a queue. The reviewer should get, for example, two minutes of alone-time with a post. If they review before their time is up, the lock goes away. If they're still reviewing when their time runs out, a notification should pop up (audio too?) and allow them to request an extension... Perhaps with 10 seconds grace to stop somebody else being allocated something. Questions are simply allocated on a first-unlocked-post basis. There should be a safety-limit on the number of times something can be review-locked or extended so that somebody can't wrongfully extend the life of a bad post (offensive/spam/etc) by gumming up review.   It sounds messy (and there's certainly some concurrency issues if you've split the servers out horizontally) but data-wise, it's actually not too hard to implement (speaking as somebody who has implemented an edit-lock system before).  Above all else, it shows reviewers the respect they deserve for a job that few of us really want to do.


True or False: Is there a measurable function $f: \mathbb{R} \to (0,\infty)$ such that $\int \chi_I f d\lambda = \infty$ for every nonempty open interval $I \subset \mathbb{R}$ where $\lambda$ represents Lebesgue Measure on $\mathbb{R}$?  I am pretty sure there is such a function as I am not able to prove the statement. However, I cannot think of an example.

Could give some examples of nonnegative measurable function $f:\mathbb{R}\to[0,\infty)$, such that its integral over any bounded interval is infinite?


Is it possible to make a simple query to count how many records I have in a determined period of time like a year, month, or day, having a TIMESTAMP field, like:   SELECT COUNT(id) FROM stats WHERE record_date.YEAR = 2009 GROUP BY record_date.YEAR   Or even:  SELECT COUNT(id) FROM stats GROUP BY record_date.YEAR, record_date.MONTH   To have a monthly statistic.   Thanks!


I'm not a professional mathematician (nor anything remotely close to that), but for sometimes I've wondered about this.   Would it be possible to magicate some strange mathematical concept (lets call it $ S $), if that's even the correct word, such that:  $$ S \times 0 = 1 $$   Or in other words:  $$ S = \frac{1}{0} $$  I'm imagining something which at first looks absurd, such as the imaginary unit $ i = \sqrt{-1} $, which nonetheless works very well in mathematics and in the real word.  My sparse math skills can't take much further than some basic and sometimes bizarre properties such as the fact that $ S $ seems to be completely indiferente to addition/subtraction, division and exponentiation  for the natural numbers:  $$ n \in \mathbb{N} $$  $$ S + n = \frac{1}{0} + n = \frac{1 + n \times 0}{0 \times 1} = \frac{1}{0} = S \Rightarrow S + n = S $$  $$ S - n = \frac{1}{0} - n = \frac{1 - n \times 0}{0 \times 1} = \frac{1}{0} = S \Rightarrow S - n = S $$  $$ \frac{S}{n} = \frac{1}{0} \times \frac{1}{n} = \frac{1 \times 1}{0 \times n}  = \frac{1}{0} \Rightarrow \frac{S}{n} = S $$  $$ S^n = \frac{1^n}{0^n} = \frac{1}{0} = S \Rightarrow S^n = S $$   For multiplication it's a bit more complicated, but the result is the same and it doesn't violate any of the above (I think). Illustrating for $ n = 2 $:  $$ 2 \times S = S + S = \frac{1}{0} + \frac{1}{0} = \frac{1 \times 0 + 1 \times 0}{0^2} = \frac{1/S}{1/S} = \frac{S}{S} \Rightarrow S = \frac{S}{S} - S = S \Bigl(\frac{1}{S} - 1\Big) = S (0 - 1) = S \times n = S \Rightarrow S \times n = S$$  Would this idea break math? I feel it's the most likely case, but I'm not skilled enough to pursue this much further than the above mentioned basics. Anyway, for me it's an interesting thing to think about, and I'd love the support of the community to come up with ways in which this idea fails or violates it's own rule-set in some manner.

I'm sure this is an obvious question, but I'm having trouble finding the right words to type into Google.  I know that the definition of a ring allows that the additive identity not have a multiplicative inverse, but is this a requirement?  Specifically, is something like $\mathbb{R}\!\left[\frac{1}{0}\right]$ such that $\frac{1}{0} \cdot 0 = 1$ a ring, or does some contradiction arise from allowing the additive identity to have a multiplicative inverse?


I updated my Minecraft to 11.1 and I want to join my cousin's world but it is just giving me the message 'invalid name'  What do I do?

I am having trouble getting onto a server in Minecraft PE on iOS. When I tap on the person's server it just says invalid name:    I have tried turning off and restarting the iPad, going to home screen and logging back into the server but I have had no luck and no change. Is there a reason why this is so?


In my whole problem, I was stuck in one direction, which is to show (i) implies (ii).  (i) Every Cauchy sequence in $\mathbb{R}$ converges to a limit in $\mathbb{R}$. (ii) Every monotone and bounded sequence in $\mathbb{R}$ converges to a limit in $\mathbb{R}$.  Explaining in english, my idea is: Cauhcy is a bounded sequence. Given that (i) is true, i.e: this bounded cauchy sequence is convergent. Then, since not every bounded sequence is convergent, it requires some conditions so that it is convergent. One of a condition is "monotone". So, I try to use this to show (i) implies (ii). But my TA think "this is saying nothing". If I would like to use some maths to explain, like $\epsilon$, a sequence $\{x_n\}$ etc.... How could I use it??

The title is kind of misleading because the task actually to show  Every monotonic increasing and bounded sequence $(x_n)_{n\in\mathbb{N}}$ is Cauchy  without knowing that:   Every bounded non-empty set of real numbers has a least upper bound. (Supremum/Completeness Axiom)    A sequence converges if and only if it is Cauchy. (Cauchy Criterion) Every monotonic increasing/decreasing, bounded and real sequence converges to the supremum/infimum of the codomain (not sure  if this is the right word).   However, what is allowed to use listed as well:   A sequence is called covergent, if for $\forall\varepsilon>0\,\,\exists N\in\mathbb{N}$ so that $|\,a_n - a\,| < \varepsilon$ for $\forall n>N$. (Definition of Convergence) A sequence $(a'_k)_{k≥1}$ is called a subsequence of a sequence $(a_n)_{n≥1}$, if there is a monotonic increasing sequence $(n_k)_{k≥1}\in\mathbb{N}$ so that $a'_{k} = a_{n_{k}}$ for $\forall k≥1$. (Definition of a Subsequence) A sequence $(a_n)_{n≥1}$ is Cauchy, if for $\forall\varepsilon>0\,\,\exists N=N(\varepsilon)\in\mathbb{N}$ so that $|\,a_m - a_n\,| < \varepsilon$ for $\forall m,n>N$. (Definition of a Cauchy Sequence) (Hint) The sequence $(\varepsilon\cdot\ell)_{\ell\in\mathbb{N}}$ is unbounded for $\varepsilon>0$. (Archimedes Principle)   Would appreciate any help.


How and when is keyboard data encoded? I just want to know in basic terms the process from the keyboard to the application; when is the data from the keyboard encoded? Is it encoded by the keyboard processor, by the operating system, by the application?  Just another question on the side: if the keyboard data is encoded by the operating system, what is the default encoding of Windows, MacOS and Linux? Do any of them use UTF-8?

Suppose I press the A key in a text editor and this inserts the character a in the document and displays it on the screen. I know the editor application isn't directly communicating with the hardware (there's a kernel and stuff in between), so what is going on inside my computer?


I am writing a desktop application in Java and I am using a SQLite database. I am fetching data from SQLite studio, and it is fetched but when I get it in the application I'm getting a null pointer.   Below is the database manager class where the database is connected and functions related to db are called:  DB Class:  public class DBManager { Connection con=null;//build connection Statement stmt=null;//execute query static PreparedStatement pst= null; public DBManager(){     try {         Class.forName("org.sqlite.JDBC");         String url="jdbc:sqlite:mobileDB.db";         con=DriverManager.getConnection(url);         stmt=con.createStatement();     } catch (Exception e) {         JOptionPane.showMessageDialog(null, e);     } } public void insertUpdateDelete(String query){     try{         stmt.execute(query);     }catch(Exception ex){         System.out.print(ex.toString());     } } public ResultSet select(String query){     try{         ResultSet rs= stmt.executeQuery(query);         return rs;     }catch(Exception ex){         ex.printStackTrace();         return null;     } } public ResultSet getLogInRecord(String user,String pass, String role) throws SQLException {     String query="select * from Users where Username=? and Password=? and Role=?";     pst.setString(0, user);     pst.setString(1, pass);     pst.setString(2, role);     pst=con.prepareStatement(query);     ResultSet rs=pst.executeQuery();     return rs;  }   Function Calling:   btnLogin.addActionListener(new ActionListener() {         public void actionPerformed(ActionEvent arg0) {             try {                 String username=txtUsername.getText(),password=txtPass.getText(),role=cmbRole.getSelectedItem().toString();                 if(username.equals("")||password.equals("")||role.equals("Select")) {                     JOptionPane.showMessageDialog(frame, "Please input all the data. No empty data allowed.","Empty Fields",JOptionPane.ERROR_MESSAGE);                 }else {                     DBManager dbm= new DBManager();                     //ResultSet rs= dbm.getLogInRecord(username, password, role);                     ResultSet rs=dbm.select("select * from Users where Username='admin' and Password='admin' and Role='Admin'");                     if(rs.next()) {                         JOptionPane.showMessageDialog(frame, "True","Error",JOptionPane.ERROR_MESSAGE);                     }else {                         JOptionPane.showMessageDialog(frame, "False","Error",JOptionPane.ERROR_MESSAGE);                     }                 }             }catch (Exception e) {                 JOptionPane.showMessageDialog(frame, e,"Error",JOptionPane.ERROR_MESSAGE);             }         }     });

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 recently bought a new PC and i had no Windows available (my stick broke, had to buy a new one). So i just used a 4 GB Stick to install Ubuntu. Now i though i just can install Windows like normally but i cant event get the windows Iso on my Stick. I used WinUSB and it just stucks at installing for i386-pc some thing some thing. Also i tried using the Methos where i copy the iso files onto the stick, that didnt work either because even tho i changed the boot priority and safe mode + UEFI Boot it still booted to Linux instead of the Windows Installation Programm. My Question now is: How do i install Windows and Remove Linux (Ubuntu)? If possible a Version that is very easy! Iam not very technical. I dont want to Dual Boot or something like that, just want to get rid of Ubuntu and install Windows.  Hope you can Help me.  edit. I do not have a CD nor a Drive for one.

I'd like to create a Windows bootable USB stick, but I don't have a Windows machine with me at the moment to do so. How could I achieve the same using Ubuntu?


I want to prove that if $Ref(z)$>0 for every $z$ in the complex plane, then the function is constant  I know that if $Ref(z)$>0 and $f$ is entire then $Ref(z)$<0 and $-f$ is also entire the |$e^{-f(z)}$|= $e^{Re(-f)}$ so how can I conclude that $f$ is constant?  Thanks

So the question asks me to prove that an entire function with positive real parts is constant, and I was thinking that this might somehow be related to showing an entire bounded function is constant (Liouville's theorem), but are there any other theorems that might help me prove this fact?


A user posted an answer on Stack Overflow which was incorrect.  I downvoted it (and upvoted the other correct answer besides my own), and told him why I downvoted it, and he proceeded to downvote my answer, unjustly.  What can I do about this? What are my options?

I don't like such kind of questions on Meta, so I will try to make it a good question and describe all with a details.  Today I down-voted  added a comment with explanations why I down-voted it, and flag it as non constructive (my flag was marked as helpful). An hour later  was downvoted, without any comment left about the reason. Yes, that wasn't my best answer, but in my opinion it answers the question. Well, even if somebody considered my answer incorrect he could add the correct answer, or up-vote the competitive ones. I checked the  who made competitve answer, and he didn't get any rep today for that answer.   It was my second down-vote on Stack Overflow, so I was a little bit down, after that. I think who could considered my answer so completely wrong, and that I thought that maybe it was revenge down-vote. So I checked  of the user I down-voted today, and it was clear that he down-voted some answers today. After I checked that that user cast only 19 downvotes in 8 months, so chances were very big that this was revenge down-voting.  I came to this meta, and searched what I should do in this case. I found that most questions about down-votes, were closed as duplicates. After I found , and found that a team member of Stack Exchange suggested to cast a flag for moderator attention, and explain the situation there.  I did that, and create next flag:     I think after I down-voted this question (and a comment about this), the OP down-voted me in revenge; it's clear from his today's reputation and from timing of my down-vote of his question, and time when one of my answers was downvoted. I cannot be 100% sure about that, but if somebody can check this, and point him that it's not the good way to do.   As you can see, I didn't ask for returning any reputation, or banning that user, I just wanted, somebody to point him, that he did wrong. And after I get this respons on my flag: "declined - flags should only be used to make moderators aware of content that requires their intervention." So in the end I also lost 10 points of the flag weight.  After describing all situation in details, I want to know were exactly I was wrong here. And what should I do next time something like this happens?


I'm trying to optimise my code and when I try to use a loop-invariant I get a segfault for a reason that I can't find. This my function: #include "kernel.h"  double baseline(unsigned n, double** a, double* b){      unsigned i,j;     double k;     double s=0.0;      for(j=0; j<n;j++)         k = b[j];         for(i=0;i<n; i++)             s += a[j][i] * k;      return s;  }   My malloc looks ok:          double** a = malloc(sizeof(double*)*n);         for(i = 0; i < n; i++)             a[i] = malloc(sizeof(double)*n);         double* b = malloc(sizeof(double)*n);     and I fill my array like this: //For tab a void RempTabrandDouble(double** a, int n){      for(int i=0;i<n; i++)         for(int j=0;j<n;j++)             a[i][j] = rand();   //On fera tjrs un random avec le meme seed  } //For tab b void RempTabAlea(double* b,int n){     for(int i=0;i<n; i++)         b[i] = rand(); }   Can you identify where is the seg problem please? Thanks for your help

Why does everyone tell me writing code like this is a bad practice?  if (foo)     Bar();  //or  for(int i = 0 i < count; i++)     Bar(i);   My biggest argument for omitting the curly braces is that it can sometimes be twice as many lines with them. For example, here is some code to paint a glow effect for a label in C#.  using (Brush br = new SolidBrush(Color.FromArgb(15, GlowColor))) {     for (int x = 0; x <= GlowAmount; x++)     {         for (int y = 0; y <= GlowAmount; y++)         {             g.DrawString(Text, this.Font, br, new Point(IconOffset + x, y));         }      }  }  //versus using (Brush br = new SolidBrush(Color.FromArgb(15, GlowColor)))     for (int x = 0; x <= GlowAmount; x++)         for (int y = 0; y <= GlowAmount; y++)             g.DrawString(Text, this.Font, br, new Point(IconOffset + x, y));   You can also get the added benefit of chaining usings together without having to indent a million times.  using (Graphics g = Graphics.FromImage(bmp)) {     using (Brush brush = new SolidBrush(backgroundColor))     {         using (Pen pen = new Pen(Color.FromArgb(penColor)))         {             //do lots of work         }     }  } //versus using (Graphics g = Graphics.FromImage(bmp)) using (Brush brush = new SolidBrush(backgroundColor)) using (Pen pen = new Pen(Color.FromArgb(penColor))) {     //do lots of work }     The most common argument for curly braces revolves around maintance programming, and the problems that would ensue by inserting code between the original if statement and its intended result:  if (foo)     Bar();     Biz();     Questions:   Is it wrong to want to use the more compact syntax which the language offers? The people that design these languages are smart, I can't imagine they would put a feature which is always bad to use. Should we or Shouldn't we write code so the lowest common denominator can understand and have no problems working with it?  Is there another argument that I'm missing?


Is this sentence correct?  Here you can find Jaume Casals's biography.   I think the final " 's " is unnecessary, but I am not 100% sure. Could anyone help?  Thanks.

According to my grammar book, but at variance to the answer to , the correct singular possessive if a word ends in ‑s is:     James’s car   The grammar book allows exceptions for historical nouns, so the examples in the answer to the above-linked question would pass muster.  However, I’m sure that I learnt at school (which, admittedly, was a while ago) that for a singular (proper) noun ending in ‑s, the apostrophe went after the s and there was no additional s.  I don’t wish to start a flame war on which is correct, though my question doesn't really make sense if my grammar book is wrong!  What I’m curious about is when the change occurred.  :  So my question is when did James’s become the correct form and James’ the incorrect one?


When two charges are separated there is an electrostatic field between two. Quantum mechanically, is it actually the discrete energy packet or photons that's travelling from one charge to another? If yes, what is its wavelength? How can I better understand the interaction between two charges with the perspective of quantum theory?

Does coulomb field contain photons?  As 1 THz and 1 kHz fields differ only in frequency, how does 0 Hz field differ from them?


When using Airpods with iPhone only everything works great, you put it on and start listening.   When you start to switch between your Mac and iPhone, I have problems. Most of the time, if I open the Airpods and connect them to the Mac, I will have this problem where every few seconds there is a second interrupt on sound (it stops). You can't hear music like that.   I'v tried to turn off Bluetooth on iPhone before connecting to the Mac, but this didn't work. I'v tried to restart the Mac - and sometimes this doesn't work either. I also ensured I have the latest firmware on the Airpots.   The experience is really not fun for a Mac user that switches between the Mac and an iPhone.   Does anyone have any other solutions or suggestions I can try to resolve this issue?

Problem In my apartment, when using the AirPods with my Mac, the audio is significantly choppy, fluttery and unreliable. There are frequently small "pops" when listening to music. The issue is not present when using the AirPods with my iPhone. The Apple Stack Exchange question you are reading now, is actually an update to my question on the same topic that was posted and resolved here previously. I had this very same issue while on macOS Sierra 10.12.4. We found out that the culprit was a bug introduced in that particular macOS version, and the problem went away with 10.12.5. I am now on 10.12.6 and having a quite identical problem. But I'm not confident that the OS is at fault this time. The reason is that I recently swapped my AirPods for a new pair, via an unrelated Apple support ticket. The new ones arrived via mail and I was instructed to pair them with my original case. The new pair of AirPods seem significantly more prone to skipping, stuttering and losing connection. I did not have this problem with my original AirPods, which I also used with 10.12.6 without problems (at least that I am cognizant of). Possible explanation I think I have found what's causing the skipping (albeit not the root cause), and it seems to be my iPhone Bluetooth signalling with its environment. Whenever that happens, there is a glitch/pop on the Mac ←→ AirPod connection. When I disable Bluetooth on the iPhone, the problems go away. I haven't changed anything in my environment except swapping the AirPods. No microwave in the background etc. I am quite confident that the reason is Bluetooth interaction from the iPhone. I am just not sure how to proceed, because the weird thing is that the problems started just when I replaced the AirPods for a new pair. Some plausible root causes are:  The new AirPods are in fact defect or come from a batch that are not as 'good' with Bluetooth. macOS 10.12.6 introduced a bug similar to the one in macOS 10.12.4, but I didn't realize it until much later (not that likely IMO, knowing how sensitive I am to audio quality). The pairing process whereby new AirPod buds were paired with an original case didn't go exactly right, and there is a firmware or software problem somewhere.  What I have tried  'Hard Reset' of the AirPods according to ; Resetting the iPhone Network Settings after "Forgetting this device" (the AirPods) as part of the AirPod 'Hard Reset'. Resetting the Mac Bluetooth Module according to .


Does the hard drive need to be accessed or is everything done in memory? Basically I would like to constantly get updated values from meminfo and cpuinfo.  Do I need to reopen the file and then reread in order to get an updated value or can I just reread? I don't have access to a Linux install at the moment.

What happens when I write cat /proc/cpuinfo. Is that a named pipe (or something else) to the OS which reads the CPU info on the fly and generate that text each time I call it?


What mean in python when i'm after function set [::-1] or [:64] for example? Here is code example  var = binascii.unhexlify(data)[:64]

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.


Actually, we know that the matrix group $M (n,\Bbb R)$ can be viewed as a topological space with respect to a point of the respective co-ordinates in $\Bbb R^{n^2}$ and the norm function can be defined as $||A||$ corresponding to the norm of the co-ordinate of the matrix $A$ .And, under this norm, obviously $||A||=||A^t|| , A^t$ is transpose of $A$ .  Now, under the norm, $||A||=\sup_{\Vert x\Vert=1}\Vert Ax\Vert$, for any matrix $A$ in  $M (n,\Bbb R)$, how to prove $||A||=||A^t||$ ?  [Obviously, the above norm is well-defined as $S^{n-1}$ is compact in $\Bbb R^n$ and $x→\Vert Ax\Vert$ is continuous.]

With the definition of matrix norm as  $$\|M \|=\sup_x \{  |Mx|: |x|=1 \},$$   where $M$ is square and $|\cdot|$ denotes the standard euclidean 2-norm. I'm trying to prove that   $$\|M\|^2=\|M^T\|^2 = \mathrm{largest \; eigenvalue \; of \;} M^TM?$$


I have an Object gameControl, which I'd like to recall when a Method reset is called and just re-create the Object, because there are a lot of references created in the gameControl Object to other classes.  What I've already tried to do is as following:  public void reset() {   gameControl = null;   gameControl = new GameControl(); }   and  public void reset() {   gameControl = new GameControl(); }   and  public void reset() {   gameControl = null;   System.gc();   gameControl = new GameControl(); }   reset is a function in Commands, Commands is called in Main and the object of GameControl is being created in Main().  Note that reset gets the GameControl object by reference.  Reset function is in an enumerator, so Syntax might be a little weird  RESET("reset") {     public void execute(MatchResult matcher, GameControl gameControl)             throws ArgException{         gameControl = null;         gameControl = new GameControl();     }   Expected result is when the new Object is created:  Object and Object reference values should be cleared.  Actual result:  Not sure if its the same object, but the reference values are still saved, so I think it is. For instance Two-Dimensional array is being created in gameControl and after the recreation, the object still exists with modified values.  Thanks in advance!

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


When multiple MP3 files are selected in Windows Explorer on windows 7 there is no Open option. I have an Open and Edit option via the . This has nothing to do with the "Open with" sub-menu. How do I restore the context option when multiple files are selected?

Using . Everything works fine, but it appears there are limits - when selecting more than 15 folders, "Take Ownership" context menu entry disappears. Same goes with files, 15 is maximum. Where does that limit of 15 come from and why does it exist?


I've got the Early-2015 13" MacBook Pro (2.7 GHz i5) and whilst I was building Smart Previews for all my 1600+ photos in Lightroom 5 I noticed that the fan had come on (unusually) and that the laptop was starting to get rather hot.  When I had a look at Activity Monitor, I saw that Lightroom was using around 300% CPU. Fair enough, I'm sure it's an intensive process. However, I also saw the usage for Lightroom jump higher than 400% on several occasions (usually up to around 410%).  I understand how my CPU is Hyper-Threaded so that it has 4 cores/400% CPU available, but how could it possibly use more than that (bearing in mind several other processes were running as well)?  Cheers, Dan

Several responses to a question  suggested I try Opera kiosk mode, so I decided to download it and give it a try. Once the download had completed and the disk image was being verified, Safari hung for over a minute and there were periods where Safari used a very high %CPU:    In Mac OS X 10.5, I was accustomed to seeing Safari freeze, but it never used up more than 200% CPU (2 cores x 100%). Is this a bug in Activity Monitor? Or does this mean that %CPU is now more akin to ?


I've got an Acer Aspire E5-773G notebook with those graphics-related specs:  Card-1: Intel Sky Lake Integrated Graphics Card-2: NVIDIA GM108M [GeForce 940M] Display Server: X.Org 1.18.3 driver: nvidia Resolution: 1920x1080@60.03hz GLX Renderer: GeForce 940M/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 367.35   I would like a keyboard shortcut that rotates the screen (internal display) ±90°.  In System Settings → Screen Display, the Rotation setting only has the option Normal though.  xrandr --rotate fails rotating the screen:  bytecommander@BC-AlkaliMetal:~$ xrandr --output eDP-1 --rotate right xrandr: output eDP-1 cannot use rotation "right" reflection "none"  bytecommander@BC-AlkaliMetal:~$ xrandr --output eDP-1 --rotate left xrandr: output eDP-1 cannot use rotation "left" reflection "none"   Here's the output of plain xrandr as well:  $ xrandr Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384 eDP-1 connected primary 1920x1080+0+0 381mm x 214mm    1920x1080     60.03*+  59.93      1680x1050     59.95    59.88      1600x1024     60.17      1400x1050     59.98      1280x1024     60.02      1440x900      59.89      1280x960      60.00      1360x768      59.80    59.96      1152x864      60.00      1024x768      60.04    60.00      960x720       60.00      928x696       60.05      896x672       60.01      960x600       60.00      960x540       59.99      800x600       60.00    60.32    56.25      840x525       60.01    59.88      800x512       60.17      700x525       59.98      640x512       60.02      720x450       59.89      640x480       60.00    59.94      680x384       59.80    59.96      576x432       60.06      512x384       60.00      400x300       60.32    56.34      320x240       60.05   HDMI-1 disconnected DP-1 disconnected HDMI-2 disconnected

I am trying to rotate a dual monitor which is attached to the VGA output of my laptop. My system is Ubuntu 15.10.  However, here is the outcome I get when I use xrandr:  xrandr --output VGA-1-0 --rotate right xrandr: output VGA-1-0 cannot use rotation "right" reflection "none"   I have seen other posts on this subject, which all recommend editing xorg.conf. I have tried that, too. Here's my current xorg.conf file:  Section "ServerLayout" Identifier "layout" Screen 0 "nvidia" Inactive "intel" EndSection  Section "Device" Identifier "intel" Driver "modesetting" BusID "PCI:0@0:2:0" Option "AccelMethod" "None" Option "RandRRotation" "True" EndSection  Section "Screen" Identifier "intel" Device "intel" EndSection  Section "Device" Identifier "nvidia" Driver "nvidia" BusID "PCI:1@0:0:0" Option "ConstrainCursor" "off" Option "RandRRotation" "True" EndSection  Section "Screen" Identifier "nvidia" Device "nvidia" Option "AllowEmptyInitialConfiguration" "on" Option "IgnoreDisplayDevices" "CRT" Option "RandRRotation" "True" EndSection   Still, I keep getting the same error when trying to use xrandr to rotate that screen.   Is there another way of doing so?


I tried to install skype using this tutorial   But I got troubles at the first step  sudo dpkg --add-architecture i386   When I wrote this, I got this message  $ sudo dpkg --add-architecture i386  dpkg: error: unknown option --add-architecture Type dpkg --help for help about installing and deinstalling packages [*]; Use `dselect' or `aptitude' for user-friendly package management; Type dpkg -Dhelp for a list of dpkg debug flag values;  Type dpkg--force-help for a list of forcing options;  Type dpkg-deb --help for help about manipulating *.deb files; Options marked [*] produce a lot of output - pipe it through `less' or`more' !   What should I do ?  I will be very thankful if you will explain all this step by step, because I never had Ubuntu before.

Note: The legacy Skype for Linux application (v4.*) is now discontinued and was removed from Canonical’s partner repositories, so this question and its answers are obsolete. Please refer to  of our .  Skype 4.3 is just released with considerable improvements. As a regular Skype user I want to use the latest Skype on my Ubuntu 14.04, but there is no updates from Update Manager. Even in Skype website only Skype 4.3 is available only for Ubuntu 12.04. Is there anyway to use this latest Skype on Ubuntu 14.04 or how much we have to wait for the update?


How can I get my external  IP address using the Command Line?

If I check with , I can see my public IP. Is there something on the Ubuntu command-line which will yield me the same answer?


I have the following code:   \documentclass{article}  \usepackage{caption}  \usepackage{booktabs}  \begin {document}  \begin {table} [ht]  \caption*{\bf{Table 6: Pattern of Share Ownership, 2011}}  \centering  \begin{tabular}{l r}  \toprule  \bf{Ownership Category} & \bf{2011}\\  \midrule   Foreign Ownership  & 28.99\% \\   PIC & 6.05\% \\   Official Pension Funds & 8.43\% \\   Private Pension Funds & 5.47\% \\   Long Term Insurers & 11.62\% \\   Corporate Ownership & 22.30\% \\   Private Direct Ownership & 17.14\% \\ \bottomrule   \end{tabular}   \end{table}   \end{document}   which produces the following table:    Is it possible to get the caption closer to the table? Another question - is it possible for the caption to be "wrapped" around the table?

I want to put several tables in the same table float like this:  \documentclass[a4paper, 12pt]{article} \usepackage[T1]{fontenc} \usepackage{subfig} \begin{document}  \begin{table}  \caption{Internal exon scores}\label{tab:internal} \begin{tabular}{|c|l|l|} \hline Ranking&Exon Coverage&Splice Site Support\\ \hline E1&Complete coverage by a single transcript&Both splice sites\\ E2&Complete coverage by more than a single transcript&Both splice sites\\ E3&Partial coverage&Both splice sites\\ E4&Partial coverage&One splice site\\ E5&Complete or partial coverage&No splice sites\\ E6&No coverage&No splice sites\\ \hline \end{tabular}  \caption{External exon scores}\label{tab:external} \begin{tabular}{|c|l|l|} \hline Ranking&Exon Coverage&Internal Splice Site Coverage\\ \hline X1&Complete coverage by one or more transcripts&Splice site covered\\ X2&Exon coverage >= 80\%&Splice site covered\\ X3&Exon coverage < 80\%&Splice site covered\\ X4&Exon coverage < 80\%&Splice site not covered\\ X5&No coverage&Splice site not covered\\ \hline \end{tabular}  \end{table} \end{document}   When I build the document, table 2's caption is closer to the bottom of table 1, which makes things confusing. hspace{} doesn't seem to work in the table environment. I've worked out that the subfloat package appears to be causing the spacing behaviour of the captions. Is there anything else that I can do to introduce a blank horizontal break to space out the captions?


Can anybody please tell me the summation formula for:     $$\sum_{i=1}^NC(k+i-1, i) = ?$$  Where ' k ' is some constant. Here C(x, y) stands for Combinatorics formula e.g. C(12, 6) = 924.

What is the sum of number of ways of choosing $n$ elements from $(n+r)$ elements where $r$ is fixed and $n$ varies from $1$ to $m$ ? Can this be reduced to a formula ?  $$ \sum ^m _{n=1} \binom{n + r}n $$


I had proved the statement as the following,  Suppose $a,b \in G$ and $a^{-1} = a$ thus $b^{-1} = b$.   Consider $a^{-1}b^{-1}$.   Let $e$ be an identity element in $G$ this will get $baa^{-1}b^{-1} = beb^{-1} = bb^{-1} = e$ .   Thus $a^{-1}b^{-1} = (\, ba )\, ^{-1}$   Since $(\, ba )\, ^{-1} = ba$, $ab = a^{-1}b^{-1} = (\,  ba )\, ^{-1} = ba$   $\therefore G$ is an abelian group. Quod Erat Demonstrandum  Can you check the errors for me please?

Is the following statement true or false:  If $G$ is a group with the property that $g=g^{-1}$ for all $g \in G$, then $G$ is abelian.   I believe it is false since I know that abelian or commutative property implies that every element in $G$ must have an inverse. Thus $g\cdot g^{-1}= g^{1}\cdot g = e$. I need someone to check my attempt.


I decided to make Dual-Boot. I have 120Gb SSD and 500Gb HDD. Windows 10 is in SSD and I allocated HHD in two 250Gb partitions. So I installed Linux in that 250Gb partition.   EasyBCD: EasyBDC tells me that it can't add new entry of boot option because of UEFI system.  BIOS boot option: If i want to go to linux I have manually change boot-able drive, in my case HDD. In GRUB 2 menu there is no Windows option.  So my question is how can I add Windows 10 to grub2 menu or how can I add Linux to Windows 10 efi boot?

I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install.  What can I do to fix this?


There is an exercise which is used to illustrate how normal distribution works. The exercise starts by saying "Suppose scores on an IQ test are normally distributed..."; What does it mean for the scores to be normally distributed.   Also there is a curve associated to the Normal Distribution, what does this curve tell, what stands on the axis?   An intuitive explanation with a supporting example (optionally), would be much welcomed.

I know very little of Probability and Statistics, and am wishing to learn.  I see the word "distribution" used all over the place in different contexts.  For example, a discrete random variable has a "probability distribution."  I know what this is. A continuous random variable has a probability density function, then for $x\in\mathbb{R}$, the integral from $-\infty$ to $x$ of the probability density function is the cumulative distribution function evaluated at $x$.   And apparently just "distribution function" is synonymous with "cumulative distribution function," at least when talking about continuous random variables (question: are they always synonyms?).  Then there are many famous distributions.  $\Gamma$ distribution $\chi^2$ distribution, etc.  But what exactly is a $\Gamma$ distribution?  Is it the cumulative distribution function of a $\Gamma$ random variable?  Or the probability density function of a $\Gamma$ random variable?  But then a frequency distribution of a finite data set appears to be a histogram.  Long story short: in Probability and Statistics, what is the definition of the word "distribution"?    I know the definition of distribution in Mathematics (an element of the dual space of the collection of test functions equipped with the inductive limit topology), but not Probability and Statistics.


I could calculate the following $$2+1=3$$ $$2^2+1=5$$ $$2^{2^2}+1=17$$ $$2^{2{^{2^2}}}+1=65537$$  Now how can I prove or disprove the formula always gives a prime number


In the below code of mine, I am trying to click on profileSettings but having a null pointer exception.    public void ProfileHomePage(){         PageFactory.initElements(driver,this);     }      public  void expandProfileSettings(){         //System.out.println(profileSettings.getAttribute("aria-expanded"));        // String status = profileSettings.getAttribute("aria-expanded");        // if(status == "true"){            // System.out.println("Profile settings is already clicked on ");         //}         //else         System.out.println("driver=" + driver);              profileSettings.click();     }      public String getProfileName(){         String profileName;         expandProfileSettings();         profileName = profile.getText();         return profileName;      }   I am calling this from  public void Login() {      initBrowser();     HomePage homePage = new HomePage();     LoginPage loginPage = new LoginPage();     ProfileHomePage profileHomePage = new ProfileHomePage();     homePage.signIn();     loginPage.dologin();     String profileName = profileHomePage.getProfileName();     System.out.println("Profile name is" + profileName);  }   Exception I get is      java.lang.NullPointerException    at   pages.AccountPages.ProfileHomePage.expandProfileSettings(ProfileHomePage.java:31)     at   pages.AccountPages.ProfileHomePage.getProfileName(ProfileHomePage.java:36)   I have tried printing driver value as it might be null but it returned below which is expected.     driver=ChromeDriver: chrome on XP (77c67bafb1d57a6e3652301670ea3f41)   I have initialized the elements in constructor. So not sure why

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


I have a string (())(("I am) a(. text"(((( I need to break it down to three parts:  The first group should include anything that is not a \w or \d or " or '. BUT ALSO should be at the start of the string.  The second group should be literally any characters before group 3  The third group should be as the first group but AT THE END of the string  So the groups of the string above should look like this:  1. (())((  2. "I am) a(. text"  3. ((((  I have tried to do it like this: ^([^\w\d'\"]*)(.+)([^\w\d'\"]*)$ But the thing is (.+) just eates everything...  I understand that my regex is wrong, but I have no idea how to do what I want to do

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


This very well might be a stupid question, but from my understanding a computer saves his memory using binary bits, so if electricity runs through the bit it is 1 and if there’s no electricity it is 0, my question is if that is how information is stored how does my computer remember things even if I would unplug him for years?

I have 8GB RAM with and it have variables and stuff. I close the computer and most of the data on the RAM is no longer there.  If the normal hard drive make files on overwriting mode when they get deleted what happens with RAM when I shutdown my computer does they just disappear to the air? Or what?


I am on a Surface Pro 3. I want do a full install of Ubuntu on my flash drive. I  saw in a tutorial that it can be done by running Ubuntu from live cd mode. Since my Surface does not have a cd drive, I ran Live CD Mode in VirtualBox. Unfortunately, my USB Flash Drive does not get detected.   I am assuming this is essentially a VirtualBox issue and I was wondering if anyone has any experience with this? I can see my USB Drive listed in the ports but when I click on it nothing happens and it is not an option for installing when I click on install Ubuntu.

I'm using Ubuntu Maverick and Virtual Box 3+. I have Windows 7 Ultimate. The problem is that it doesn't detect USB drives in Windows 7, but USB peripherals (mouse + keybord) are working.  I followed , but I can't find the user group vboxusers. How can I continue? I would also like to upgrade to the latest version without any risk (without losing my virtual hard disk drive).


Having trouble understanding how (and why) this conversion will not work.   I have class A, class B derived from class A, and class C derived from class B.   class A {}; class B : public A {}; class C : public B {};   I want to make a HashTable that has two template typenames <K, V>, where the K is a char and V is a binary search tree template class (BST<T>). These BSTs will have typenames A, B, and C.  template <typename K, typename V> class HashTable { public:     bool put(K key, V value);   // adds key value pair to table private:     V* table;   // table stores values     int size;   // size of table };  template <typename T> class BST { public:     bool insert(T item);    // adds item to tree private:     struct BSTNode {        // node structure         R data;             // item data         BSTNode *left;      // left child pointer         BSTNode *right;     // right child pointer     };     BSTNode *root;          // pointer to root of tree };   The following code has an error with putting a BST<C> in the hashtable because it cannot convert from BST<C> to BST<A>. However, the last line in main is legal.  int main() {     HashTable<char, BST<A>> inventory;     BST<C> foo;     inventory.put('C', foo);      A *bar= new C(); }   I though because of polymorphism, BST<C> is-a BST<A>? How can I get around this type difference so I can add BST, BST, and BST to my hashmap?  I've already tried using typedef in the declaration and that did not work.

Someone mentioned it in the IRC as the slicing problem.


I've looked at several videos and webpages explaining how to color individual faces, but none of them work for me.  When I select a face and change the material in v2.8, the entire object changes color. This is in solid mode, rendered, and look dev.

I selected a single face in the object (car wheel, see picture) to be given a particular material (rubber, red color). However, when I press "assign" in the material tab, the whole object (wheel) is painted in the material. How can I limit this to the face?


I had been preparing for a tennis event since March, but it has been postponed until next year.  Question: Can "it has been postponed" be replaced with "was postponed" grammatically without changing its meaning?  One of my friends (Canadian) received this question from a Chinese learner, and she asked me for help.

Regarding actions taken in the past, besides the differences those two tenses have semantically, my teacher shared that it could be a British vs American English case.   When talking about past action, British prefers present perfect because they take into account that the effect from their past action still happens until now. As for American, they prefer to state the action only. It happened in the past, so past tense it is.     I have had dinner. [British]   vs.      I had dinner. [American]   I hope to hear it from the native speakers, both British and American. What do you think about this? Is it true?  If it is, I don't think it can apply to all cases of past actions. There have to be cases when both style agree to use the same tenses. Could you please help me define the situation when this kind of difference applies and when doesn't?


For email validation, i have following conditions: 1. username should be alphanumeric only(a-z,0-9,A-Z) 2. website name should be a-z 3. extension should be a-z  i am writing a python code as :  import re  def check(email):     #complete the function     #the function should return the strings "invalid" or "valid" based on the email ID entered     if(re.search('^[a-zA-Z0-9]+$@^[a-z]+$.^[a-z]+$',email)):           return("valid")        else:           return("invalid")    email=input() print(check(email))     My input: vk@google.com But it returns me "Invalid" It should return as "Valid". What am i doing wrong here?

I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them?


Evaluate   $$\lim_{n\to\infty}\left[\left(\frac1n\right)^n+\left(\frac2n\right)^n+\cdots+\left(\frac{n-1}n\right)^n+\left(\frac nn\right)^n\right]$$    I tried to solve this by taking logs on both sides and got this form: $$\log l = \lim_{n\to\infty} n\log\frac{n!}{n^n}=\lim_{n\to\infty}n\log\frac{n!}{n^n}$$ After applying limit, $\frac{n!}{n^n}\to0$, so $\log\frac{n!}{n^n}\to-\infty$ as $n\to\infty$. Then I am stuck. How to solve these type of problems?

How should I calculate the below limit  $$\lim_{n\rightarrow \infty} \frac{1^n+2^n+3^n+...+n^n}{n^n}$$ I have no idea where to start from.


$$d = \frac{ab}{a + b + 2\sqrt{ab}} = \frac{ab}{(\sqrt{a} + \sqrt{b})^2}$$  What are the positive integer solutions?  The majority of solutions are when $a=b$, so that $a = 4d$.

I am writing a program to output all $a,b \in \mathbb{N}$, where $a \le b \le n$ (for a given $n \in \mathbb{N}$), such that  $$ \frac{ab}{2\sqrt{ab}+a+b}=c\in \mathbb{N} $$  For example, $a=9$, $b=36$, and $c=4$ satisfy this equation.    My program runs at a tolerable speed for values of $n<10^5$, but is not efficient enough for higher values.  Is there anything of value from number theory that I can use to eliminate my options?  For instance, I know that $\sqrt{ab} \in \mathbb{N}$ is a necessary (but not sufficient) condition.


I am trying to construct a simple timeline in LaTeX with dates below points on the line and words above the line referring to a range.   I have included an image of what I am looking for that I constructed in Powerpoint. When adding this as an image into latex, the scaling makes the image unclear. Figured it will also be more professional to include actual latex timeline.

In history-books you often have timeline, where events and periods are marked on a line in the correct relative distance to each other. How is it possible to create something similar in LaTeX?


I just got question banned from Stack Overflow this afternoon, sadly. I read through the FAQ on that, and it suggests editing old posts to improve them.  My first question is: How exactly is that credited? I mean, it seems unlikely that someone who downvoted a question a long time ago would for-no-reason-at-all revisit it months later, notice the edit, and remove/change the downvote. So are moderators tasked with reviewing old question edits just for this, or is there some other process?  It looks like the number to the left of the question was the number of upvotes; on StackOverflow (but not here) the number of downvotes only displays when you click it. That's why it didn't match my actual reputation change.  Yes, this link () is what I meant by the FAQ. But it didn't explain how edits to old posts are credited; so I wanted to ask here.

If you are reading this, you may have been affected by one of our post quality bans. If so, it is important that you  to understand what has happened and how to regain the permissions that you lost. While trying to ask a question, one could see:  We are no longer accepting questions from this account. See  to learn more.  Likewise, for answers:  We are no longer accepting answers from this account. See  to learn more.   Why am I getting this message? Are deleted posts taken into account too? Is a question/answer ban the same as a suspension? How do I avoid getting a question ban? How long do I have to wait before I can post again? What can I do to release the ban? How can I reactivate my account? Can I simply create a new account? I'll just ask somewhere else on the SE network, and they'll migrate my question to the correct site! Will a ban on one Stack Exchange site affect my standing on other sites in the network? Does this apply to meta sites too? My account is in good standing. Why am I still blocked?


I'm building a network emulator to help realize different speeds. Basically, this system would shape a given user's network metrics (such as upload speed/download speeds/packet loss/jitter etc) based on the user's request. For instance, if a user selected 3G, the system would transform his/her connection to behave like a 3G connection. I imagine doing this by using the user's IP address.  I have been searching for some help on this but couldn't find a lot. I wonder if this is feasible at all.

We have a transparent proxy setup. I tried looking for traffic shaping in Linux, and all I could find online was to limit traffic by interface (eth0/eth1...).  I need to limit the bandwidth (never exceeding a specific limit) by IP address or IP ranges and I can't find a way to do that.  Is there any way to do that?


Let $A \subseteq B$ be commutative rings with identity, $\mathfrak q$ a prime ideal of $B$, and $\mathfrak p = A \cap \mathfrak q$.  Is the 'identity' ring homomorphism $A_{\mathfrak p} \rightarrow B_{\mathfrak q}$ always an injection?  The 'obvious' method of proving this seems to lead to a dead end: if $\frac{a}{s} \in A_{\mathfrak p}$ is the zero element in $B_{\mathfrak q}$, then there exists a $t \in B$, but not in $\mathfrak q$, such that $ta = 0$.  But it isn't clear whether $t$ may be chosen to lie in $A$.  So my guess would be that this map doesn't need to be an injection.  The reason I'm asking is that it is an exercise in Hartshorne (II, 2.18) to show that a homomorphism of rings $\phi: A \rightarrow B$ is injective if and only if the corresponding morphism of sheaves $f^{\#}: \mathcal O_X \rightarrow f_{\ast} \mathcal O_Y$ is injective ($X$ and $Y$ are the spectra of $A, B$, and $f: Y \rightarrow X$ is the map $f(\mathfrak q) = \phi^{-1} \mathfrak q$).  Assuming $\phi$ is injective, I want to show that $f^{\#}$ is injective by showing the corresponding homomorphism on the stalks $A_{\phi^{-1}\mathfrak q} \rightarrow B_{\mathfrak q}$ is injective.  But if I am not mistaken, this homomorphism on the stalks is exactly the map $\frac{a}{s} \rightarrow \frac{\phi(a)}{\phi(s)}$ I just described.    EDIT: Someone has asked the same question before, and as I suspected the homomorphism $A_{\mathfrak p} \rightarrow B_{\mathfrak q}$ does not have to be an injection.  So my question now is why this counterexample does not invalidate exercise II.2.18(b) in Hartshorne.  EDIT 2: I just now realized the homomorphism on the stalks isn't the natural map $A_{\phi^{-1}\mathfrak q} \rightarrow B_{\mathfrak q}$; the codomain isn't correct.  Rather, if $\mathfrak p = \phi^{-1}\mathfrak q$, $(f_{\ast} \mathcal O_Y)_{\mathfrak p}$ is the direct limit of the rings $\mathcal O_{Spec B}(f^{-1}U)$, where $U$ runs through the open neighborhoods of $\mathfrak p$.

Let $\alpha:A\to B$ be a ring homomorphism, $Q\subset B$ a prime ideal, $P=\alpha^{-1}(Q)\subset A$ a prime ideal. Consider the natural map $\alpha_Q:A_P\to B_Q$ defined by $\alpha_Q(a/b)=\alpha(a)/\alpha(b)$. Suppose that $\alpha$ is injective. Then is $\alpha_Q$ always injective?    I think so, but I'm clearly being too dense to prove it! My argument goes as follows.  Let $\alpha(a)/\alpha(b)=0$. Then $\exists c \in B\setminus Q$ s.t. $c\alpha(a)=0$. If $B$ is a domain we are done. If not we must exhibit some $d\in A\setminus P$ s.t. $da=0$. Obviously this is true if $c =\alpha(d)$. But I don't see how I have any information to prove this!  Am I wrong and this is actually false? If so could someone show me the trivial counterexample I must be missing?   Many thanks!


There has been much written on getting the beep sound from Ubuntu releases over the years.  Example:   My needs are slightly different in that I do not want to ensure sound card beeps are functioning.  Instead, I want PC speaker beeps, the kind produced by the original built-in speaker because I believe they will produce less CPU load.  I have confirmed that my computer has the PC speaker by unplugging the external speakers and shutting down Ubuntu.  At some point in the shutdown and restart process a beep is heard even though the external speakers have no power.    I have tried the following:  In /etc/modprobe.d/blacklist.conf, turn these lines into comments:  #blacklist snd_pcsp #blacklist pcspkr   In .bashrc  /usr/bin/xset b on /usr/bin/xset b 100   Enable in the gnome terminal: Edit > Profile Prefs > General > Terminal Bell   Ensure no "mute" selections in: System > Prefs > Sound > various tabs (uncheck them all).  Select "Enable window and button sounds" in: System > Prefs > Sound > Sound Effects  In gconf-editor desktop > gnome > sound, select the three sound check boxes.  In gconf-editor apps > metacity > general select the audible bell check box.  Still I get no PC speaker beeps when I send code 7 to the console via my Java program or use   echo -e '\a'   or equivalently  echo -e "\a"   on the bash command line. (The -e option means enable escape sequence interpretation.) What else should I try?  Update Since my goal is to minimize load on the CPU, here is a comparison of elapsed times.  Each test is for 100,000 iterations.  Each variant was performed three times so three results are presented for each.  printwriter.format("%c", 7);  // 1.3 seconds, 1.5 seconds, 1.5 seconds  Toolkit.getDefaultToolkit().beep();  // 0.8 seconds, 0.3 seconds, 0.5 seconds  try { Runtime.getRuntime().exec("beep"); } catch (IOException e) { }  // 10.3 seconds, 16.3 seconds, 11.4 seconds   These runs were done inside Eclipse so multiply by some value less than 1 for standalone execution.  Unfortunately, Toolkit's beep is silent on my computer and so is code 7.  The beep utility works but has the most cost.

I'd like to use a beep sound in a shell script. Unfortunately none of the methods I found via Google work for me.  I tried  echo -e '\a'  echo -ne '\007'   and the command beep after I installed it via apt.  What could be the reason?