I would like to keep the angle 90 in the area indicated as I apply the subdivision surface modifier on the object. I appreciate help.

How can I use the subdivision surface modifier to create more high poly meshes without ruining sharp edges? For example this mesh  The sphere should be subdivided but the rim of the cylinder should stay the same because it is a sharp edge. This is the result of the subdevision  How can I get sharp edges to not be affected by the sub surf mod?


I'm running this line on my shell script  sudo npm install -g yaml-cli -y 2>&1 >/dev/null   I would expect to get no output, but I still get  npm WARN deprecated minimatch@2.0.10: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue

I don't quite understand how the computer reads this command.  cat file1 file2 1> file.txt 2>&1  If I understand, 2>&1 simply redirect Standard Error to Standard Output.  By that logic, the command reads to me as follows:    concatenate files file1 and file2.  send stdout from this operation to file.txt. send stderr to stdout. end?   I'm not sure what the computer's doing. By my logic, the command should be   cat file1 file2 2>&1 > file.txt   but this is not correct.


I am using Dev c++ as IDE and I am a student and new here I am trying out to see what values the program give so when ever i was putting float main() and return some float value it is giving some long integer numbers and when i put nothing liKe main() it is simply returning some integer value why is that any particular reason ? Thanks in advance

What is the correct (most efficient) way to define the main() function in C and C++ — int main() or void main() — and why? And how about the arguments? If int main() then return 1 or return 0?  There are numerous duplicates of this question, including:       — For C++, with a very good answer indeed.     Related:


Show that there is a countable set $X$ that contains an uncountable family $Y$of subsets that if the sets $W,Z \in Y$ and $Z \cap W  \neq \varnothing $ then $W \subset Z$ or $Z \subset W$ I think that if I had two real numbers I could find two sequencies of rational numbers which converged to them and they might have some common numbers but these sequencies dont contain each other . Any ideas please ?

Prove that there exist uncountable family of subsets of $\mathbb{N}$ which is linearly (totally) ordered by realtion of inclusion.  I do not know how to prove it. Actually I cannot concieve that such family of set can be uncountable. I would be thankful for help


There is no snowflake on the mobile site, and there does not appear to be any other way to see Winter Bash notifications.    Workaround is to switch to desktop site on mobile to check.

I was wondering why there is not hats available on the mobile version. No hats on avatar, no hats counts, etc ..    Is it because it seems to be an ajax layer over all websites? or the same reason there is no helpful tag counts?


I am using Inkscape version 0.48.2 on Mavericks OS X. I have to add latex formulas in some of the images but when I tried it through Extensions > Render > couldn't find the option there. After going through several blogpost I have installed the package pstoedit (through fink install) as well. But still I don't the option to type latex over my images. Can someone help please?

I've seen somebody asked this question a year ago, but no answers given so I'm hoping this might attract some more/new/different attention.  Simple question. I want to use LaTeX with Inkscape on mac. I already use a tex editor so I should have most of the LaTeX stuff I need. However when I go to "Extensions>Render>", there's not a LaTeX option there as other online sources suggest.  As a fudge I tried using the application Latexit to generate SVG/EPS images to import but I can't seem to get import of those to work either.


So, I was playing Skyrim (with mods) and I have this character I tried some mods with, animation mods to be exact. Everything was all and well until I got stuck in 3rd person view, not like I can't go back to 1st person, I can go back, but it won't let me stay there. I have problems with the bow because I can't aim that well in 3rd.   I did some research, I read someones else's post about a glitch that sounded very similar, many replied and said it could only be fixed with a previous save, Unfortunately my last save was 27 levels back. I know it's small, but if you played Skyrim that long it would be a nightmare to go back a lot of levels.  I uploaded a video on YouTube about this glitch here it is:                                  Is there a way to solve this without loading an older save?

So, I've finally obtained the Werewolf form. After returning out of the form, fully naked...  I seem to be stuck in third person view! How can I fix this? Scrolling or pressing F does not work.  I want to get back in first person view...    Mouse wheel allows to zoom in/out but not get me into the first person view but rather behind and slightly to the right of the character. The command animcam locks me at a certain distance, doing it again brings me back into the mode that I'm stuck in third person view. Hitting F after this doesn't work. tfc doesn't help me either, although that command is nice to take screenshots...


Consider  on Mathematics. It was first answered by  and then better explained by . both answers are correct but the second one better addressed corner cases to explain what I was not able to grasp from the first answer.  As a general rule, is it better to mark the original answer as correct or the one that helped me more?

I asked  that turned out to have multiple correct answers. How do I pick between them to determine which to accept?  All of the answers were different. They were not the same answer given multiple times.


I tried to destroy a monster nest in Witcher 3 but it says I didn't have the right bomb.    I tried to craft a Samum bomb and it says I already have it, but I can't find it. I have read other comments about using a strong alcohol but I can't work out how to do it.  Does anyone have some advice?

I'm sure I have the recipe for the Samum Bomb (to destroy monster nests). But after using two of my own crafted bombs, I see 0/2 in my inventory.  If I try to recreate such bombs with the matching ingredients, I get the hint: "You already have this item". That's not really true .-) Actually I have 0 of 2 of this bombs and can not destroy a third nest.  How can I replenish my stock of Samum Bombs?


I am trying to create a slide: on the left is an itemized list, on the right is a figure. It seems I can use tabular in beamer, however, the following code doesn't work - it complains about extra \frame. I also tried fragile option, but no avail. Can someone help?   \RequirePackage[demo]{graphicx} \documentclass{beamer} \begin{document}  \begin{frame} \begin{tabular}{ll}      \begin{itemize}         \item test 1         \item test 2     \end{itemize}      & \includegraphics{demo}  \end{tabular} \end{frame}  \end{document}

I am new to Beamer and LaTeX itself. Right now, I want to create a simple slide with an image on the right and text and the sidebar (using the Hannover theme) on the left. I cannot figure out how to do that. Any suggestions?


Using the \boxed environment in mathtools seems to ignore the default size considerations LaTeX makes with nested fractions: \[ \frac{\frac{1}{2}}{\boxed{\frac{1}{2}}} \]  I would like the \boxed 1/2 to be the same size as the numerator, instead, the following is produced:  How can I resolve this, preferably in a general way so that \boxed doesn't change affect the font size in any situation? EDIT: This also happens for exponents, as in the following: \[ e^x, e^{\boxed{x}} \]

So far everything I found on the matter of borders only applies to the text mode.  I want to be able to do something like  $x_i = y$   so the result will be like the ordinary "xi = z" formula with the border around "i"?  The common answers seems to be the fbox or boxed commands. Yet they render their argument in the standart mode, unless specified to do otherwise with the specific mode. For example, the following code  \[ x_i, \boxed{x}_i, x_{\boxed{i}}, \boxed{x}_{\boxed{i}} \]   produces two normal xi figures, and another two with an oversized i.


I am trying to read in from a .txt file that has students' first names, last names and averages. I'm trying to read the data and store them in an array of objects, however, I am running into the following exception:   Exception in thread "main" java.lang.NullPointerException     at bubblesort.Bubblesort.readin(Bubblesort.java:34)     at bubblesort.Bubblesort.main(Bubblesort.java:49)   This is my code  package bubblesort; import java.io.*; import java.util.Scanner;   public class Bubblesort {  public class students{    public String name;    public String lastname;    public double average; }      public static students[]readin(students[] studentinfo){     String info = "src/Files/numname.txt";     int count = 0;     String catcher = null;     try {             File InputFile = new File(info); //createsa new file input             Scanner Input = new Scanner(InputFile);                for (;count<25;count++){                 studentinfo[count].name = Input.nextLine();                 studentinfo[count].lastname = Input.nextLine();                 studentinfo[count].average = Input.nextDouble();                 catcher=Input.nextLine();             }      }     catch(IOException ex){         System.out.println("Error reading in file");     }     return studentinfo; }      public static void main(String[] args) {         students[] studentinfo = new students[25];         readin(studentinfo);       }    }   If someone could please help me understand I would appreciate it a lot, thank you

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?


Breaking of a local symmetry is impossible. It is often said that therefore the role of the Higgs mechanism in the standard model is a different one.   ,     Once a gauge is fixed, however, to remove the redundant degrees of freedom, the remaining (discrete!) global symmetry may undergo spontaneous symmetry-breaking exactly along the lines discussed in the previous chapter. The phrase "spontaneous breaking of local gauge symmetry" is therefore in some sense a misnomer, but a convenient one, if we think of it as a short circumlocution for "spontaneous breaking of remnant global symmetry after removal of redundant gauge degrees of freedom by appropriate gauge fixing".   Or here's a similar statement from a :     But is the gauge symmetry actually broken spontaneously? In the above exposition of the Higgs   mechanism, there were two instances when a symmetry was broken. First, when we selected one   minimum out of infinite amount of equivalent minima, a spontaneous breaking indeed took place, but   only of a global symmetry. This minimum represents a vacuum, and in order to perturbatively describe   the quantum field theory, we need to quantize the fields. Quantization of gauge field theories requires   introduction of a gauge-fixing procedure, and during this procedure we break the gauge symmetry by   hand, explicitly, not spontaneously. Thus, the two notions, EWSB and SSB, are in certain sense correct,   but they do not refer to the same symmetry. [...] As Englert says in his Nobel lecture [54]: “… The vacuum is no more degenerate and strictly speaking there is no spontaneous symmetry breaking of a local symmetry. The reason why the phase with nonvanishing scalar expectation value is often labeled SSB is that one uses perturbation theory to select at zero coupling with the gauge fields a scalar field configuration from global SSB; but this preferred choice is only a convenient one.   What global symmetry are they referring to? (I find it extremely strange that they don't specify the allegedly broken global symmetry.)

In talking about Higgs mechanism, the first part is always some introduction to the concept of spontaneously  symmetry breaking (SSB), some people saying that Higgs mechanism is the results of SSB of local gauge symmetry, some people says that we can formulate Higgs mechanism in a gauge invariant way, some people also says that we need only a non-zero vaccum expectation value... I am confused about this different or maybe same point of views.  In this post:  , the most highly voted answer, I still can't feel how SSB worked in Higgs mechanism. It seem that the validity of last part, the appearance of a mass term for $A$, is guaranteed if we have a non-zero equilibrium value $\phi_0$ to expand around. I do not see that the requirement that the phase of the field $\phi$ need to be fixed at some particular value to generate mass term. Thus it seems to me it is not true that SSB is really indispensable for Higgs mechanism.  To put it simply:  The spontanously breaking of what is attributed to Higgs mechanism?   local gauge symmetry global symmetry, since breaking of a "gauge symmetry" should not have any effect on physics. In higgs mechanism, the really broken symmetry is a global one. Mathematically, it is similar in looking as fixing a gauge, but one should not think it as a spontanously breakdown of local gauge symmetry. other.   Is SSB really indispensable for Higgs mechanism?    yes, Higgs mechanism is relied on the SSB of some symmetry (above question), the other approches of description eventually has spontanously broke some symmetry. No, the SSB is just one way to describe Higgs mechanism (or even not a complete way), what is really need is the non-zero vaccum expectation value, for example in the linked post the requirement for the mass term to occur is to have some non-zero expectation value of $\phi$ to expand around, we do not need the phase of the field to be fixed, thus the symmetry is not broken. Other.   some reference materials:    States that SSB of local gauge symmetry is impossible.  in the abstract states that:       gauge symmetries merely reflect a redundancy in the state description   and therefore the spontaneous breaking can not be an essential   ingredient. Indeed, as already shown by Higgs and Kibble, the   mechanism can be explained in terms of gauge invariant variables,   without invoking spontaneous symmetry breaking     In the introduction it says:      In particular, we emphasize that global U(1) phase rotation symmetry,   and not gauge symmetry, is spontaneously violated, and show that the   BCS wave function is, contrary to claims in the literature, fully   gauge invariant


Looking at the /admin/posts/migrated/stats page, I noticed this oddity:    Three of them were migrated while it was still on http - and the link on the icon is still without the s, and one of them was from https (with an https link back to the question from before it was migrated, on the /admin/posts/migrated/here page).

I was just looking at the statistics for migrated questions in the  mod tools, and noticed this oddity:    The actual statistics, as visible to any 10k+ SFF user , are: 6 migrated to Worldbuilding, 2 to Literature, 2 to SFF meta, 1 to Movies & TV, 1 to Writers, and 1 to Aviation.  Why is one of the meta migrations showing up with a blank icon rather than with the other?  Both migrated questions were closed as duplicates on meta. Both were migrated by 5 community members without mod involvement. One of the stubs on main has since been deleted, but so have the stubs for some of the other migrated questions. I can't think of anything to explain this discrepancy.


I have selected 'Nursery' data set from UCI machine learning repository and run 2 different clustering algorithm on, K Means and Hierarchical clustering. How should I compare these to algorithm to see which one did a better job on the data set? I have calculated the parameters:   adjust_rand_score adjust_mutual_info_score silhouette_score     for each 2 clustering model. Is that true to compare the calculated parameters to see which one did better? For example: K Means model:    adjust_mutual_info_score = 0.044 silhouette_score = 0.56   For Hierarchical Clustering model:     adjust_mutual_info_score = 0.16    silhouette_score = 0.59   So can I say the Hierarchical model has did a better job? Or there is another parameter to compare these 2 clustering algorithms?

One of the biggest issue with cluster analysis is that we may happen to have to derive different conclusion when base on different clustering methods used  (including different linkage methods in hierarchical clustering).  I would like to know your opinion on this - which method will you select, and how. One might say "the best method of clustering is which gives you the right answer"; but I may question in response that cluster analysis is supposed to be an unsupervised technique - so how do I know which method or linkage is the right answer?  In general: is a clustering alone robust enough to rely on? Or we need a second method and get a shared result to be based on both?  My question is not only about possible ways to validate / evaluate clustering performance, but is broader - on what basis do we select/prefer one clustering method/algorithm over another one. Also, is there common warnings that we should look around when we are selecting a method to cluster our data?  I know that it is very general question and very difficult to answer. I only would like to know if you have any comment or any advise or any suggestion for me to learn more about this.


In document class book, and package caption, creating index with makeidx. Index entries for the main text and for footnotes collate properly; but those for captions create their own entries.  Example: for the tag \index{New York!Custom House!\textit{Cartouche}}, text and footnotes collate properly; but used in a caption, a new entry is created at the third level, and is also out-of-alphabetic-sequence. Note: the top level, and first sub are correct; only the second sub is duplicated.  How to get the caption index entries under the same entry?

Dear all I think I have a problem with the collation of makeidx.  following some suggestions found here I have got in the text something like this  \index[p]{Plutarco!demalignitate@\textit{De Malignitate Herodoti}!00855 @855A|qt}  \index[p]{Plutarco!demalignitate@\textit{De Malignitate Herodoti}!00868 @868f-869b|nn{\thefootnote}}   the first is an \index entry in the text, the second in a footnote. My problem is that even if I put the sort also on the second level of indexing it keeps keeping them separated.  I use this package information  \usepackage[splitindex]{imakeidx} \makeindex[name=n, title=Nomi di persone e luoghi]  \makeindex[name=p, title=Passi citati nel testo] \makeindex[name=t, title=Altri testi citati] \makeindex[name=pap, title=Papiri e manoscritti citati nel testo]  \newcommand{\nn}[2]{#2 \textit{n}#1} \newcommand{\qt}[1]{\textbf{#1}}   in the .idx file I get this  \indexentry{Plutarco!demalignitate@\textit{De Malignitate Herodoti}!00855 @855A|hyperindexformat{\qt}}{8}  \indexentry{Plutarco!demalignitate@\textit  {De Malignitate Herodoti}!00868 @868 b-c|hyperindexformat{\nn{33}}}{10}   can somebody advise me on what I am doing wrong here, please? I have tried to use \string after the first sort with no effect.    sure, sorry: this is the file I'm using  \documentclass[12pt,a4paper]{book} \usepackage[utf8x]{inputenx}  \usepackage{palatino}        \usepackage[LGR,T1]{fontenc} \usepackage[english,german,polutonikogreek,italian]{babel}  \usepackage[splitindex]{imakeidx} \makeindex[name=p, title=Passi citati nel testo,columns=1] \newcommand{\nn}[2]{#2 \textit{n}#1} \newcommand{\qt}[1]{\textbf{#1}} \usepackage[hidelinks]{hyperref} \begin{document}  (855A\index[p]{Plutarco!demalignitate@\textit{De Malignitate Herodoti}!00855 @855A|qt})% \footnote{DHM 868 B-C\index[p]{Plutarco!demalignitate@\textit{De Malignitate Herodoti}!00868 @868 b-c|nn{\thefootnote}}} \printindex[p] \end{document}


In a discrete space, everything is centered around the function "P". Every event has a probability associated with it, and random variables simply map outcomes to numbers. P(X = x) is basically just a weird way of saying P({e | X(e) = x}). From "P", people can define f(x) = P(X = x), g(x|y) = P(X = x, Y = y) / P(Y = y), and so on.   But in the continuous space it seems like everything is reversed! Whenever I look in a textbook, authors will just define a pdf (e.g. f(x,y)) and then derive "P" from it! (e.g. P((X,Y) $\in$ A) = $\int\int$f(x,y). How can this be?   A related question would be how random variables work in continuous spaces, too. Do they still map events to probabilities? Surprisingly, none of my textbooks talk about this...  Hi Michael Chernick, thank you for directing me to those other posts, but I just read the accepted answer in the first one, and it only talked about discrete variables. The second post supposes that I know what sigma algebras are, which I've never heard of before. The accepted answer talks about it, but also doesn't really answer why textbooks go from pdf -> P()

What do they mean when they say "random variable"?


Sorry for the vague title but I wasn't sure how to describe my wish/problem.   A while ago I made a sidebar with a few widgets that I can add.    It displays time, date, windows volume, how many % my phone is charged (once connected), some equalizer bars and song + artist currently playing on Spotify.    At the moment the bar is on the right hand side of my main monitor. What I want is to put it on the left side of my secondary monitor. (not quite relevant)  I would like this sidebar to act as if its the end of the screen. So if I would maximize an application it would end at the border of my sidebar.  I made a little image to illustrate the goal. Red is the sidebar and blue is a random application.    Does anyone know if and how this can be achieved? If anything else is unclear let me know :)  Thanks in advance.

Is there any complete guidance on doing AppBar docking (such as locking to the screen edge) in WPF? I understand there are InterOp calls that need to be made, but I'm looking for either a proof of concept based on a simple WPF form, or a componentized version that can be consumed.  Related resources:


I realised that I may need more space for Linux as kind it is shifting towards being my primary workspace, hence I decided to extend its size. I un-alloacated a chunk of memory from windows'(  ) partition and tried merging it to the Linux's but I could not. I am using Gparted. My OS is Ununtu Budgie. Attached is a screenshot of my partitions.

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


A seemingly simple question that I could not figure out. Pgfplots uses very narrow bars in the following image. How can I make them wider? Ideally, they should also be closer together. I just want to make use of the available space...    Using , I was already able  to get fairly close to what I want.    However, there is still some space wasted on the left and the right side...  Edit: Apparently, this is possible using enlarge x limits={abs=1,rel=0.4}.    Code for the first Figure:  \documentclass{standalone} \usepackage{pgfplots} \usetikzlibrary{}  \begin{document}  \pgfplotstableread[row sep=\\,col sep=&]{     x & y & z \\     0        & 1       & 2           \\     1        & 3      & 1           \\ }\data  \begin{tikzpicture} \begin{axis}[ ybar, %bar width=2cm, legend columns=2,  legend style={at={(0.5,1.12)},anchor=north}, symbolic x coords={0,1}, xtick={0,1} ] \addplot table[x=x,y=y]{\data}; \addplot table[x=x,y=z]{\data}; \legend{y, z} \end{axis} \end{tikzpicture}  \end{document}   Code for the second Figure:  \documentclass{standalone} \usepackage{pgfplots} \usetikzlibrary{}  \begin{document}  \pgfplotstableread[row sep=\\,col sep=&]{     x & y & z \\     0        & 1       & 2           \\     1        & 3      & 1           \\ }\data  \begin{tikzpicture} \begin{axis}[ ybar, width=5cm, xmin=0, xmax=1, bar width=11, enlarge x limits={abs=1}, legend columns=2,  legend style={at={(0.5,1.22)},anchor=north}, xtick=data ] \addplot table[x=x,y=y]{\data}; \addplot table[x=x,y=z]{\data}; \legend{y, z} \end{axis} \end{tikzpicture}  \end{document}

I am trying to use PGFPlots to display a large amount of bars, and I run into the problem that it cuts off the last of them.  MWE:  \documentclass[crop,tikz]{standalone}  \usepackage{pgfplots} \usepackage{pgfplotstable} \pgfplotsset{compat=1.13}  \begin{document}  \pgfplotstableread{ row label runtime 0 1 5264 1 2 2971 2 4 1866 3 8 1384 4 16 1205 5 32 1144 6 64 1109 7 128 1095 8 256 1108 9 512 1178 10 1024 1335 11 2048 1667 12 4096 1588 13 8192 2843 14 16384 5541 15 32768 10985 16 65536 21873 17 131072 43687 18 262144 87064 19 524288 174119 }\mytable   \begin{tikzpicture}   \begin{axis}[         ylabel={runtime (${\mu}s$)},         xticklabels from table={\mytable}{label},         xtick=data,         ymin=0,         ymax=10000,         ybar,         xticklabel style={           anchor=north west,           align=left,           rotate=-45,           font=\tiny,           inner sep=1pt,         }, ] \addplot+ [] table [y=runtime, x expr=\coordindex] {\mytable}; \end{axis} \end{tikzpicture}  \end{document}   Result:    By adding the following to the axis options, I can make all the bars fit. But I need to manually adjust bar width (and xmax)  xmin=-1, xmax=20, bar width=7pt,     Is there a way to handle many bars in a barplot automatically?


Bought a laptop with the OS "Boot-up Linux".  How can I install Ubuntu / which instructions should I follow?  I have installed Ubuntu on a Windows PC before but this laptop (as mentioned before) only has "Boot-up Linux"

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


What is the difference between cards that say   Card A: "Put a +1/+1 "Counter" on each Creature you control." Card B: that say "Each creature you control gets +1/+1 and gains Flying"    Does card B also has a counter? Card A states that it has a "+1/+1 Counter" Does the +1/+1 in Card B still count as a counter or not?  If the cards are different between +1/+1 Counters and +1/+1 abilities are different.  Will the +1/+1 ability cause Undying not to trigger, or will it still trigger.

Is a +1/+1 counter I get from, say Unleash or Undying different than +1/+1 from something like  or ?


Suppose that $f:\mathbb{R}\rightarrow\mathbb{R}$ is integrable with repsect to Lebesgue measure. Prove that for almost every $x\in[0,1]$ the sequence $\{f(x+n)\}_{n=1}^\infty$ tends to $0$ as $n\rightarrow\infty$.   Let $g_n(x)=f(x+n)$ for $x\in\mathbb{R}$. Then above claim is equivalent to show that $g_n\rightarrow0$ pointwise on $[0,1]$ almost every. I'm puzzled by this problem. Could someone give useful hints or solution?

I want to show that for $f: \mathbb{R} \rightarrow\mathbb{R}$ Lebesgue integrable  $\displaystyle{\lim_{n \to +\infty} f(x+n) =0}$ almost everywhere.  It is clear to me that this statement is true and I have tried to prove it by contradiction, by assuming that either $\displaystyle{\lim_{n \to +\infty} f(x+n) =\infty}$ or$\displaystyle{\lim_{n \to +\infty} f(x+n) =K}$ with $K\in \mathbb{R}$ .  In the first case  we can follow that $|f|=\infty$ so that $\int_\mathbb{R}f=\infty$ and we have a contradiction.  In the other case we know that there must be an $a\in \mathbb{R}$ so that $\forall x>a$ we have $f_+(x)>K/2$ and by that:  $\int_{{\mathbb{R}}+}|f|>\int_{\mathbb{R}_+}f_+=\int_{[0,a]}f_++ \int_{(a,\infty)}f_+>\int_{[0,a]}f_++\int_{(a,\infty)}K/2=\infty$  Would this be enough to show the statement? Can I even make the assumption that the limit of $f(x+n)$ "exists"? Any hints would be great.


How to call function with "this" from event? If remove "this", it will work.    function Parent() {  this.child = function()  {   alert("called child");  };     $("#btn1").click  (   function()    {    this.child(); // doesn't work   }  ); } var objp = new Parent(); <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <button type="submit" id="btn1">Submit</button>

I have created a 'control' using jQuery and used jQuery.extend to assist in making it as OO as possible.  During the initialisation of my control I wire up various click events like so  jQuery('#available input',              this.controlDiv).bind('click', this, this.availableCategoryClick);   Notice that I am pasing 'this' as the data argument in the bind method. I do this so that I can get at data attached to the control instance rather from the element that fires the click event.   This works perfectly, however i suspect there is a better way  Having used Prototype in the past, I remember a bind syntax that allowed you to control what the value of 'this' was in the event.  What is the jQuery way?


I'm attempting to reference a figure containing a tikzpicture from pgfplots. However, for some reason, I'm getting ?? instead of the figure number when I \ref it.  Any ideas what I'm doing wrong?  The section is below:  \subsection{Graph of Results} Figure \ref{fig:ResultsGraph} shows the data gathered in Table \ref{tbl:ResultsData}. \begin{figure}[H] \centering \begin{tikzpicture} \begin{axis}[legend pos=north east,anchor=west, xlabel={$\dfrac{1}{T} / K^{-1}$}, ylabel={$ln P*_a$}] \addplot table [only marks, x=1/T,y=lnPa]{GraphData.txt}; \addplot [thick, red] table[y={create col/linear regression={y=lnPa}}]{GraphData.txt}; \addlegendentry{$\dfrac{dy}{dx} = \pgfplotstableregressiona$} \addlegendentry{$y_{intercept} = \pgfplotstableregressionb$} \end{axis} \label{fig:ResultsGraph} \end{tikzpicture} \caption{Graph to show the relationship between the natural log of pressure and the inverse of temperature} \end{figure}

\documentclass{article} \usepackage{algorithm}  \begin{document} \setcounter{section}{54} \section{A section with no label} \begin{algorithm} \label{myalg} \caption{An algorithm with the label `myalg'.} \end{algorithm} Reference to myalg: \ref{myalg}. \end{document}   With this code, the reference givens 55 (the section number); if I move the label after the caption command, I get the correct reference (1).  Why should this be the case? I find it confusing: when thinking about an algorithm as an environment, you expect to be able to label it right after you began it. At the very least I would expect some kind of error or "??" to appear, rather than the previous environment or reference-able entity being used.


I am currently a PhD student in a biomedical related field. I came a long way. I first did my undergraduate and worked for a few years, though not research related. Later, I identified my research interest before embarking in the PhD with the hope of fulfilling my career dreams. I used to love and enjoy science, but that was long ago. I was happy when I got into the PhD program. Now I'm nearly 2 years into my study, mostly 'wet' lab and basic sciences research.    Unfortunately, my experiments - most of them - fail. Initially, that was due to lack of skills and experience - with time things have improved but I am still lacking good results that can give clear direction in my work. My project has been modified a few times because initially there were problems with the biological samples so I had no choice. Then, I tried to 'reproduce' a piece of result done by a colleague few years ago but the results were always 'off' no matter how many times I did it. Even someone else with better experience in the lab tried but could not replicate the same result. The conclusion was perhaps, change in phenotype of biological samples over time. Then my project changed again, and the technique is now becoming more complicated and 'taxing'. Partly, because my supervisor is not very happy and feels that it is time I should be producing good data and should aim for higher impact. With more complicated experiments, I also need to beef up my basic sciences knowledge but as someone coming from a different background it is taking me extra time to grasp. With my confidence going in a downward spiral.    I am finding more and more difficult to articulate my thoughts clearly to my peers and I feel constant 'rejection' and 'guilt'. Most of my colleagues are actually good people, but harsh words, although not ill-meaning, are slowly eroding my confidence. When I ask questions because there is something that I don't fully understand (without prior knowledge and not something I can read up on), people appear impatient and ask back (e.g. "why are you asking?",  "what do you think?", or just "I can't give an answer to you on this"). It feels more and more difficult for me to ask questions or speak up for myself.    One day, I was blamed for something (from someone outside the lab) that I didn't even do. The accusation was pretty unreasonable - others who witnessed the event felt the same - but to me I felt I was just a bully target. I just broke down and cried because I realized I couldn't take the stress and frustration of rejections and failure. My friend in the same lab gave me some counseling but also at the same time asked me whether working in this lab is truly what I want to do. I don't want to quit my PhD, but then again I don't know how I can get out of this situation.     Should I change project? But my PhD qualifying exam is coming up and I am having a massive problem with writing up a good proposal because of all the frustrations happening.   Should I change to dry lab? I am afraid of talking to my mentor because I don't know whether at my current mental state I'll just suddenly break down again.    In summary, my resentment and contradictory statements that I receive:     Ideology: To do a PhD, perseverance is more important than being smart. Reality: You need to be smart. REALLY SMART.  Ideology: There's not such thing as a stupid question. Ask if you don't understand. Reality: Huh? Why do you even ask?

I am a third year (starting fourth year in the fall) PhD student in mathematics. I've passed all qualifying exams and am currently doing research. As far as I can tell, I am not doing poorly. I have the good fortune of having a great advisor, being in a very supportive department, and having friends and family who genuinely care about my success.   The fact is research is hard. It appears to consist primarily of staring at a problem for days and days and days without getting anywhere. Sometimes, rarely, I do figure something out and that feels wonderful, but the overwhelming majority of my time appears to be spent banging my head against a mostly figurative wall. I am not complaining about the material being hard, and I am not averse to putting in hard work, but I get frequently discouraged when I realize the vast volumes of mathematics that I yet know nothing about (and probably never will). It's very hard to quantify progress - in particular, there are too few tangible returns after too many hours worked. I find myself thinking along the lines of "Oh, if only someone actually smart were thinking about this problem they would have solved it in moments" and so on.   I've talked about this to some number of people; here is some advice I have received:   Take a day off. Putting in hours upon hours of trying things doesn't magically lead to a solution, particularly if the brain is tired and just wants to sleep. Have a hobby. Since math research doesn't exactly provide instant gratification, a hobby might provide some instead.  Talk to other graduate students. Realize that many graduate students go through this.   I'm interested to know how other folks have dealt with being discouraged as a graduate student. Does it get better with time and experience? Is this a sign that research is not for me and that I should seriously consider a life outside academia?


I know this question is very common and I know mostly the answer is a hard NO. But I think my case is special in a way. I would like to come to the USA to do handyman work basically. Therefore I will not be taking away any jobs from US citizens, and I will not be paid from a employer but from my own clients that I find. Handyman isn't required to have any kind of certification in California, only think he needs to follow is that no job can be more then 500$ which that isn't a problem for what I have in mind. And he/she needs to pay taxes which I was thinking to apply for ITIN to pay my taxes, I have got friend in the US who could help me with that. So I guess the question is can I be self-employed handyman in the USA on B1/B2 visa ? I apreciace all answers thank you.

Can I get lifeguard work with my B1-B2 visa?


I'm looking for a way to change the color of the text output from my python scripts as it runs.  The basic idea is something like this:  if (Data < LowerLimit):     print "Failed" # Output Failed as Red Text elif (Data > UpperLimit):     print "Failed" # Red Color else:     print "Passed" # Blue Color   The scripts are being used on windows machines for quick data analysis.

How can I output colored text to the terminal in Python?


I'm using Ubuntu 18.04 LTS.  My system boots properly and works fine, but during boot, I can see the verbose details about what is happening during the boot process:     Is this supposed to happen?  Can it be changed?

Is there a way to easily turn on/off showing the boot messages (loading the services) when Ubuntu starts? Is it something in Grub2?  I am running 10.04.


I need some help with running commands on system startup.  So, I need these two commands to be executed every time I start my machine, due a problem with my Realtek driver (doesn't really matter):  sudo ifconfig myCode up sudo service network-manager restart   How do I manage that to work?  I'm getting confused with sudo command and not knowing when will I enter my password or will the script even be run. Sorry for my low knowledge of Ubuntu system.  Thank you for your time!

I have a script in a folder:  /path/to/my/script.sh   I need this script to run every time the system starts (even if no one logs in to the system). What do I need to do in order to make this happen?


For certain pre-release builds of software products it is guaranteed that they can be used already in production - and more importantly can be upgraded to the final version.  Is there such a thing for Ubuntu's LTS versions?    Alternatively, do you have any guidance for the scenario described below.  I want to set up a new Ubuntu Server and would like to start preparations for this right now. Does it make sense to use the daily build  and set it up already, despite potential bugs? Will the system be equivalent to a freshly installed system after the final release, if I run apt-get dist-upgrade? Or would I have to start over anyway?  Obviously I would prefer not to use 12.04.4 right now and then upgrade to 14.04 in a month. Instead it seems to make sense to start with a daily build. But can it be upgraded to the final release version?

I installed an Ubuntu alpha or beta and have been keeping it up to date.   So, Should I presume that my system has automatically updated to the next alpha or beta, and will be running the official release when it's finished?


python:  m=[[0]*3]*2 for i in range(3):     m[0][i]=1  print m   I expect that this code should print  [[1, 1, 1], [0, 0, 0]]   but it prints  [[1, 1, 1], [1, 1, 1]]

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


and I am newbie for linux, I am sorry if this question is so dumb. I would like to know to create crontab properly, I create job as below:  * * * * * /usr/src/debug/http/cron_job.sh >/dev/null 2>&1   inside cron_job.sh as below  pidof html if [ 0 = $? ] then  echo running else   cd /usr/src/debug/http/  ./html fi   but when I check the running program it show that  2738 ? ... ./html 2748 ? ... ./html 2788 ? ... ./html   its seems duplicate it running the application, is there any wrong with my setting? kindly let me know how to solve this issued?  thank you for your help.

This is a  about using cron & crontab.   You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you gather information that will help the community help you. This information should be edited into your original question.  The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below.  This addresses the cron system with the crontab highlighted.


My player's fighter has just reached 11th level, He duel wields Scimitars. On his normal attack action, he gets 3 attacks plus one additional attack for his bonus action. If he then decides to use Action surge, on the same turn he is then receiving three additional attacks. As I understand it; action surge does not grant a second bonus action is that correct? SO if he also happens to be hasted does he get 3 more additional attacks or just 1 additional attack? Haste states that he gets another "action" and as the multi-attack class feature applies would I be correct in my interpretation that he would indeed get 10 attacks that round in 6 seconds?

A fighter, once per rest, can use Action Surge to gain an additional action on his turn.  The target of a Haste spell also gains an additional action on his turns (until the spell ends).  If a fighter is Hasted by a fellow mage and then uses his Action Surge, does he gain two additional actions on his turn (for a total of 3 actions, plus the eventual bonus action & reaction) ?


The only options on the location privacy prompt are 'Allow' or 'Don't Allow', with a 'Remember my decision for one day' modifier checkbox as well. But what if there's a site that I trust in perpetuity? I want to give it permission to access my location forever. Why can't I do that?  Safari 8.0 on Mac OS X 10.10 Yosemite

In iOS, I only need to be asked once whether I want to allow a website to share my location data. Is it possible to permanently do this in OS X version of Safari as well?


When I was playing around with the equations for Gravitational Time Dilation, I discovered that when a negative value was plugged in for $M$, the equation gave the exact same answer, and it would never give an imaginary answer if $r$ was positive. Why exactly does this happen?

Time tends to slow down near objects with large amounts of positive mass relative to observers in micro gravity.  Considering that negative mass is the opposite of normal mass and would time tend to speed up near a body of negative mass relative to observers in micro gravity?


Please can some one give me rutherfords observations and his conclutions from each onbservation, I have looked in text books but they only give them sepratly with no direct link betweeen which observation led to which conclution thus this is what i am looking for. THanks

For  scattering  where he fired alpha particles at a thin sheet of metal to determine the size of the nucleus, please can someone give me the direct link between his observations and his conclusions e.g. this observation lead to this conclusions.


I am afraid that BBC TV has put me into a bit of a muddle.  Programs set in modern times seem to use "nowt" most often to mean "nothing," whereas programs set in Victorian and earlier periods say "naught" (pronounced like "not").  In periods between, usage of the word seems less frequent.   Perhaps nowt is simply slang or perhaps a recognized dialect?

In a movie that I watched recently, I heard-        for aught I know,    for aught I care.      I work with a lot of native speakers, and they all told me it's not in formal or informal usage anymore.  What's the ground reality?


Consider a dataframe ("df") with three variables (Happiness, Smoke, Depression), where (1) Happiness (DV) = continuous measure of happiness on 1-10 scale, (2) Smoke (IV1) = categorical variable of whether the person smokes (yes/no), and (3) Depression (IV2) = continuous measure of depression on 1-10 scale. Happiness <- c(1, 2, 5, 6, 2, 7, 7, 3, 8, 9) Smoke <- c("yes", "yes", "no", "no", "yes", "no", "yes", "yes", "no", "no") Depression <- c(6, 8, 2, 1, 10, 4, 5, 1, 2, 3) df <- data.frame(Happiness, Smoke, Depression)  Suppose I want to test whether Smoke x Depression interaction predicts Happiness (in other words, if the interaction between two Independent Variables predicts the Dependent Variable). So I use this formula: summary(lm(data = df, Happiness ~ Smoke*Depression))  which gives me this: Call: lm(formula = Happiness ~ Smoke * Depression, data = df)  Residuals: Min      1Q  Median      3Q     Max  -2.0000 -1.0460 -0.3788  0.8905  3.7826   Coefficients:                     Estimate Std. Error t value Pr(>|t|)   (Intercept)           5.6154     2.4745   2.269   0.0637 . Smokeyes             -1.3110     3.2748  -0.400   0.7028   Depression            0.5769     0.9489   0.608   0.5655   Smokeyes:Depression  -0.7943     1.0011  -0.793   0.4578   --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  Residual standard error: 2.164 on 6 degrees of freedom Multiple R-squared:  0.6098,    Adjusted R-squared:  0.4147  F-statistic: 3.125 on 3 and 6 DF,  p-value: 0.1092  I need help interpreting this result.  Is it correct to use Smoke*Depression instead of Smoke + Depression, or Smoke:Depression if I want to see the main effect of each independent variable and their interaction? Do the values under Pr(>|t|) mean the significance of main effect for each variable? If so, how do I test the main effect of non-smokers? (ie, why is there only "Smokeyes" and no "Smokeno"?) What does Smokeyes:Depression indicate? I am suspecting that it means the interaction between Smoke and Depression. If so, how is Pr(>|t|) of this different from the p-value?  Any help would be much appreciated. Thank you!

The help pages in R assume I know what those numbers mean, but I don't. I'm trying to really intuitively understand every number here. I will just post the output and comment on what I found out. There might (will) be mistakes, as I'll just write what I assume. Mainly I'd like to know what the t-value in the coefficients mean, and why they print the residual standard error.   Call: lm(formula = iris$Sepal.Width ~ iris$Petal.Width)  Residuals:      Min       1Q   Median       3Q      Max  -1.09907 -0.23626 -0.01064  0.23345  1.17532    This is a 5-point-summary of the residuals (their mean is always 0, right?). The numbers can be used (I'm guessing here) to quickly see if there are any big outliers. Also you can already see it here if the residuals are far from normally distributed (they should be normally distributed).  Coefficients:                  Estimate Std. Error t value Pr(>|t|)     (Intercept)       3.30843    0.06210  53.278  < 2e-16 *** iris$Petal.Width -0.20936    0.04374  -4.786 4.07e-06 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1    Estimates $\hat{\beta_i}$, computed by least squares regression. Also, the standard error is $\sigma_{\beta_i}$. I'd like to know how this is calculated.  I have no idea where the t-value and the corresponding p-value come from. I know $\hat{\beta}$ should be normal distributed, but how is the t-value calculated?  Residual standard error: 0.407 on 148 degrees of freedom   $\sqrt{ \frac{1}{n-p} \epsilon^T\epsilon }$, I guess. But why do we calculate that, and what does it tell us?  Multiple R-squared: 0.134,  Adjusted R-squared: 0.1282    $ R^2 = \frac{s_\hat{y}^2}{s_y^2} $, which is $ \frac{\sum_{i=1}^n (\hat{y_i}-\bar{y})^2}{\sum_{i=1}^n (y_i-\bar{y})^2} $. The ratio is close to 1 if the points lie on a straight line, and 0 if they are random.  What is the adjusted R-squared?  F-statistic: 22.91 on 1 and 148 DF,  p-value: 4.073e-06    F and p for the whole model, not only for single $\beta_i$s as previous. The F value is $ \frac{s^2_{\hat{y}}}{\sum\epsilon_i} $. The bigger it grows, the more unlikely it is that the $\beta$'s do not have any effect at all.


Is it possible to set session in wordpress. If yes can you please tell how to do it? My sample code is.  <?php session_start();  if(!isset($_SESSION['impression'])) {     $_SESSION['impression'] = 100;   }else {     if($_SESSION['impression']<=0)         $_SESSION['impression'] = 100; }  echo $_SESSION['impression']    = $_SESSION['impression'] -1;  ?>

I'm wondering why WordPress does not support sessions and many people out there claim that putting the following code in functions.php might not be a good idea (it in fact works for me but returns PHP warnings, too):  function cp_admin_init() { if (!session_id()) session_start(); }  add_action(‘init’, ‘cp_admin_init’);   Is it good idea to enable sessions in WordPress? What would be the correct way to do this?


I'm going to build a new PC in the next few days that I want to be dual boot Ubuntu 16.04 and Windows 10 Home.  Which OS should I install first, and are there any special details for installing both OS on a new build?   I've only added Linux & Ubuntu to machines with an existing OS.  Thanks!

I currently have Windows 7 on my computer and I want to install Ubuntu alongside Windows safely.  Could someone please provide clear instructions?


Prove that if $a_1, a_2, \cdots , a_n$ are all distinct, then $$f(x)=1+\prod_{i=1}^{n}(x-a_i)^2$$ can never be written as the product of two polynomials with integer coefficients.  Write ${f(x)=g(x)h(x)}$. Then, $f(a_i)=1=g(a_i)h(a_i)$.  Now, if both $g(a_i)$ and $h(a_i)$ equals $+1$ or $-1$ for all $i\in\{1,2,\cdots, n\}$ then, we can say that $g(x)-1$ or $g(x)+1$ will have $n$ roots. Now since there can be at most of $n$ roots for $g(x)$ assuming that $\text {deg}(g(x)) \leq \text {deg}(h(x))$, we get that there exists all $n$ roots. Then continuing that way we get a contradiction.   But what if for some $i \in \{1,2,\cdots , n\}$, we have $g(a_i)=1$ and for the rest $g(a_i)=-1$? It may be possible because $g(a_i) h(a_i)=1=\{(1,1),(-1,-1)\}$  EDIT (Please check) :  A link has been provided below but $g(a_i)h(a_i)=1$ also implies that $g(a_i)=h(a_i)=-1$ for $i=\{1,2,\cdots , k\} \ni k < n\}$ and $g(a_i)=h(a_i)=1$ for $i=\{k+1,k+2,\cdots, n\}$. And this case isn't justified in that thread.

Suppose that $a_1,a_2, \cdots, a_n$ are $n$ different integers. Then $[(x-a_1)(x-a_2) \cdots (x-a_n)]^2 +1$ is irreducible over $\mathbb Q$.   I've no idea why it is true. Thanks very much.


During my mechanics class I studied that moment of forces is measured in $N \cdot m$ and I also studied that kinetic energy is measured in Joules $J$. I understand that one is a scalar quantity and the other is a vector quantity, but from a dimensional point of view, $N \cdot m$ and $J$ are the same. So, since they have the same dimensional equation, does it make sense to express moment of forces using Joules? I am asking this question since I have never heard of a moment of force that is expressed in Joules, so I was wondering whether it is just a convention to express them with a different unit of measurement or if there is a more involved difference.

Recently, I was doing my homework and I found out that Torque can be calculated using $\tau = rF$. This means the units of torque are Newton meters. Work & Energy are also measured in Newton meters which are Joules.  However, torque isn't a measure of energy. I am really confused as why it isn't measured in Joules.


With a hardware-based RAID0, what happens when a drive fails?  For example, on brand name servers like HP DL120G7 with HP P410, when running FreeBSD on a zfs with a zpool mirror, or DragonFly BSD with mirroring through HAMMER etc.  The following questions come to mind:   Will the data on the non-failed drive that is part of a RAID0 still be usable? Or do the controllers spread the RAID0 data between the drives in a pseudorandom manner? Would ZFS at all know how the data is spread between the drives for its mirror functionality to function properly? I've heard some controllers don't let you avoid a hardware RAID (with P410 being such); in such case, do they generally make an exception so as to allow RAID0 arrays of just one disc, instead of a common minimum of two? When the failed drive is replaced by a datacentre technician, would it affect the data on the drive that has not failed?

This is a  about RAID levels.    What are:   the RAID levels typically used (including the RAID-Z family)?  deployments are they commonly found in? benefits and pitfalls of each?


This is Exercise 6.1.14 from Dembo's notes found .  At this point, we are just beginning a discussion of Markov chains.  I have no prior experience with estimators and so I am a bit lost with this problem.  The problem is as follows:  Let $\theta$ and $(U_k)_k$ be independent and uniformly distributed on $(0,1)$.  Let $X_k = sgn(\theta - U_k)$ and $S_n = \sum_{k=1}^n X_k$.  (a) Compute $\mathbb{P} [ X_{n+1} = 1 \mid X_1, \ldots, X_n]$  (b) Show that $(S_n)_n$ is a Markov chain.  Is it homogeneous?  I am having trouble with part (a) (I'm guessing part (b) will be not so difficult given part (a), but I could be wrong).    I thought I had a semi-sensible attempt at a solution, but while writing it out here, I realized it actually doesn't make sense. So I am know back at square 1, and any help would be much appreciated.    Thanks in advance.

Let $\pi_1,...,\pi_n$ be a random permutation of numbers $1,...,n$. If you are told that $\pi_k > \pi_1,...,\pi_k > \pi_{k-1}$, what is the probability that $\pi_k = n$?  What I've tried:  Let $A_j$ be the event that $\pi_k = j$. Let $H$ = be event that $\pi_k > \pi_1,...,\pi_k > \pi_{k-1}$.  Then $P(A_n|H) = \frac{P(H|A_n)P(A_n)}{\sum_{j = 1}^n P(H|A_j)P(A_j)} = \frac{\frac{1}{n}}{\sum_{j=1}^n P(H|A_j)\frac{1}{n}} = \frac{1}{\sum_{j=1}^n P(H|A_j)} = \frac{1}{\sum_{j=1}^n P(j > \pi_1,...,j > \pi_{k-1})}$.  How to calculate that last sum?


Why would bash claim that a file doesn't exist when it clearly does?  $ ls -l a -r-x------ 1 configurator configurator 3904 Dec  7 10:36 a  $ file a a: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.2.5, stripped  $ ./a -bash: ./a: No such file or directory

I compiled a small "hello world" C program on Ubuntu 10.04 32 bit machine. Then I put the executable(a.out) on Ubuntu 12.10(64 bit) VMWare virtual machine and tried to execute it(./a.out). The OS does not identify the file and says 'No such file or directory'. But when I put the same executable on a Ubuntu 12.10(64 bit) running on a 64 bit laptop, it runs fine and I get the desired output. The VM is running on IBM Blade Servers. I wanted to know why the results for a VM?


how to create a user on a linux box where it - can be used for scp from the remote system - can't be used for ssh login from the remote system  Thanks in advance

Is it possible to disable direct login for normal users (like oracle) in Linux but allow scp and sftp for that use?


I know that putting a bag of holding in a bag of holding destroys both and creates a portal to the astral plane, but what would happen if a player chooses to put a bag of holding in a back of holding while being in the astral plane? Would nothing happen? Would you be transported to a realm of chaos? Any answers would be appreciated!

What would happen if someone were to place a Portable Hole within a Bag of Holding while being within the Astral Plane? Would it be the reverse effect?


Is it possible to identify the font used in a specific document/picture?  Answers to this question should identify:   Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y").   This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's  tag.


I know that this question has been posted already, but I saw that is possible to draw the triangle of the question inside of the russian triangle. Can someone help me to finish the question using this?    I find a lot of angles and I got the equation $∠UFO+∠UFN=100°$, but I couldn't find the value of $∠UFN$

I sent this problem to Presh Talwalkar who suggested me to send it to this site. I tried many things but was not able to find the correct solution.   I made various segments trying to get an equilateral triangle similar to the Russian triangle problem, but no success.  I also tried to flip the triangle UFO over side NO but again no success.   I tried to find like triangles, but not enough.  Could you please give me a hint?   Thanks, R. de Souza


Is the set of all functions from $\mathbb{N}$ to $\lbrace 0,1\rbrace$ countable or uncountable ? I have no idea on how to start. Any hint or guide will be much appreciated.

Recall that a countable set $S$ implies that there exists a bijection $\mathbb{N}\to S$. Now, I consider (0,1). I want to prove by contradiction that $(0,1)$ is not countable.  First, I assume the contrary that there exists a bijection $f$, and I can find an element in $S$, but not in the range of $f$. But I can't find such element. How can you construct such $f$?


I have finished an animation and am going to fully render it. Is there a way to know the estimated time of how long a whole animation will take to render? I mean the whole animation, not just each frame. Like when you render something it shows on the top of the animation:                       Frame: 0|Last: 00:00.00 Time: 00:00.00 | Remaining 00:00.00| Is there something that will calculate the time that it will take for the whole animation to render?

When rendering an animation in the render window on the top right you can see the render time of the last frame. But where can I see the sum of the render times of all frames?


I hope somebody can help me with this.   I read this book like 15 years ago which places it before the year 2000. The main plot of the book is that 2 universes (ours and another one?) are "colliding" Some humans are taken by alien "engineers" (I think that was their name) to their world in order to help to find a solution to the collision problem.

I'm trying to remember a book title, with a telepathic woman. She was sleeping in some kind of stasis, locked for years in a sort of capsule in space. Her consciousness was preserved, so she had to do something in the meanwhile so that when she was awakened by an space explorer or something like that she already gained a telepathic skill.


My sister has a netbook with this configration :  LG X110-G.A7HBG weiss XP Home Atom N270 1.60GHz, 1GB RAM, 160GB HDD,   Which Ubuntu version should I install on it? I already tried the current version 13.10 but it crashes often and i don't want to repair it again and again.  Could you recommend the version which suits the above specs best?

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


The HDD on my trusty Mac has given up the ghost, and an attempt at repair this weekend resulted in failure to boot. It originally had 10.5, which I updated through to Mavericks. I still have a Snow Leopard install disk so I can at least get it running after HDD replacement, but Sierra will not run on it due to age and is the current offering in the App Store. Is there some way that I can obtain and upgrade to Mavericks to ensure my backup works? Thanks in advance.

Apple now allows you to run OS X inside a Virtual Machine as long as the host is running Apple hardware. Because we need to test our web site on various versions of Safari, we picked up a Mac Mini running Yosemite for testing purposes. The idea is to run Mavericks (currently our largest user base) and possible Mountain Lion in a VM on demand, similar to what .  However, I've yet to be able to find a place to download prior installer apps. I've found other StackExchange posts referring to the App Store, but since this is a new Apple ID there are no previous purchases for old versions, and as far as I can tell they are no longer available to "purchase". Likewise, I have not been able to find any OS X Installer apps on the Apple Developer site.  Am I missing something? Is there an easy-ish way to get these apps to install OS X to a VM?  (For VM host, we are currently using Virtualbox, but would be willing to use VMWare or Parallels if needed)


i have looked at tons of tutorials and stuff, and even looked at other responses, but I still can't find .minecraft and %appdata%. I tried using run, reinstalling the launcher, etc, but nothing helps.

I don't have a minecraft folder. I've looked through forums and videos, followed all the steps. I just don't have one. I have windows 7, and I have "view hidden files" turned on. I have look in the roaming folder of my app data folder, with hidden files turned on. I want to find my folder so I can install a mod, could someone please tell me why my folder isn't showing up?


Can someone please give me the proof that if you don't assume the axiom of choice, you can prove that there exists a vector space without a basis. I have the book, The Axiom of Choice by T.J.Jech, but don't really understand his proof. So any help in understanding it will be great,  Thanks.

I know that the proof that every vector space has a basis uses the Axiom of Choice, or Zorn's Lemma. If we consider an axiom system without the Axiom of Choice, are there vector spaces that provably have no basis?


I know someone who is working on a LaTeX document requiring pst-plot, geometry, and hyperref, and I recently gifted him some TikZ improvements of diagrams that didn't seem to be working out for him.   However, TikZ is clashing with the other packages, hyperref being the most critical. How does one circumnavigate around such an obstacle without sacrificing much?  Edit: Minimal example:  \documentclass[z,11pt]{amsart} \usepackage{pst-plot} \input xy \xyoption{all} \usepackage{mathptmx,tikz} \usetikzlibrary{matrix,arrows} \begin{document} Test \end{document}   The error produced seems to be  /usr/local/texlive/2013/texmf-dist/tex/generic/pgf/frontendlayer/tikz/tikz.code .tex:19: No room for a new \dimen . \ch@ck ...\else \errmessage {No room for a new #3}                                                    \fi  l.19 \newdimen\tikz@lastxsaved

I have this error message:  ! No room for a new \dimen . \ch@ck ...\else \errmessage {No room for a new #3}                                                 \fi   which I can not find a cure for.


(first picture is normal, and in the second if I click the second viewport it turns like this. I can't work with colorful models, bcs its transparent/invisible. Also same with the third viewport but its darker...) How do I fix it to make it be visible. Because if I try to work with colorful models. It turns like this too. Maybe I pressed something? Help.

I don't know why but now, when i go in material preview or rendered (in solid mode it works fine), my object is entirely gray, or invisible idk, because it has the same color of the background. I've been working for days on this project without having this issue, it suddenly showed up. I tried opening other old projects and suddenly they all do the same so i guess it is some blender program setting that applies for all the projects, but idk how it happened cuz i didn't change anything :/, anyone got any tips?


Is the latest version of Pantheon desktop compatible on Ubuntu 18.04.2?  I haven't seen anything posted about anyone trying it yet.

I want to install Pantheon desktop environment from elementaryOS on Ubuntu, is that possible?


As we have discussed , it's OK for English sites in the SE network to place dots and commas inside quotes, because it's correct in US English, and in the interface US English is used.  But for Russian, it's incorrect. Commas and dots should be outside the quotes.                  The text access to site analytics is translated, as you can see, but the quotes and dot are hardcoded, so we don't have the ability to fix it.  Could you change that, so we will be able to correctly localize it?

If you don’t have 25k reputation, the  contains a stub text:        As you can see on the image, the dot should be moved outside the quotes. Also, on ruSO we need to  from “” to «», but this is not possible via Transifex, because there is no full sentence available to translate.


Many frequency adverbs can be placed at the start, in the middle or at the ending of a sentence. In , in the answer  is analyzed the difference between the end placement and others. But what is the difference between the start and middle placement? Does this placement make any difference to the meaning?  Sometimes I go running. I sometimes go running. I go running sometimes.  Do those sentences mean the same or not? If not, is there any difference in feeling, mood or something else? Is there some context in which they have different use?

He swam slowly to the island.  He slowly swam to the island.    Some experts say that there is a “slight difference” in meaning. Would you please tell me that difference?


I have been in the US for 90 days and I want to go to holland for 3 weeks. After that I want to return to the US for another 90 days. My question is, can I do this?

I am a British citizen visiting the USA in early August for a two week vacation with friends. After the holiday I'm returning to my home in the UK for three weeks. After that I will return to the USA and will be working for my British employer under the Visa Waiver Program for a period of 80-85 days.  I have read already that there is technically no problems with this under ESTA rules, but should I limit this working period to a shorter time frame (e.g. 70 or so days) so that it does not negatively affect the decision made by the POE officer? Ideally I would love to be over in the states for the near-full 85 day period.  Any advice or previous experiences anyone can offer?  Some clarifications: As confirmed by the immigration attorney, as I am employed by my UK employer, it will be regarded as a business trip, the important part being that I will be working officially as a consultant for my UK employer just overseas for the allotted 85 or so days


At what n is the number $1!+2!+3!+4!+...+n!$ a square of another integer number? All in all I have found $2$ values: $1$ and $3$. I think they are the only ones, but the only thing left is to prove it. How?

How to prove that the number $1!+2!+3!+...+n! \ \forall n \geq 4$ is never square?  I was told to count permutations but I cannot figure out what we are permuting.... Thanks!


$$\sum_{n=1}^\infty \frac{n}{3^n}$$  How do you find the sum?  I don't know how to start this problem and no other website I found talks about a problem like this.

I came across following  bi-infinite sum:  $\sum_{k=-\infty}^{\infty} 2^k x^{2^k}$  Is this a known series? After some plotting I have the feeling that it could be equal or very similar to  $-\frac{1}{\ln(2) \ln(x)}$  for all $x\in(0,1)$. Is my assumption correct?


I am an absolute beginner in Linux and I have problems with partitioning my disk space while installing Ubuntu 12.04. I have 300 GB of unallocated space on my hard disk. How can I divide the available space? My music collection is almost 170 GB and how can I make space for these music files (Like D: drive in Windows)

I have a Laptop with 1TB hard disk space. I can allocate 100GB for Ubuntu. Currently there is only Windows 7 installed. I am new to Ubuntu & am confused by terms like mount point, root partition, swap partition, etc. The doc over  gives some details, but I dont know what they mean. For installing Ubuntu I have shrunk 100GB from a drive & now that space is unallocated. So what should I do now? In how many partitions should I divide that space & what conventions should be followed. Should I do this in the Ubuntu installer or should I do all this before installing Ubuntu? Please I dont understand the terminologies used on that doc so please tell me in simple language. Thank You.


I have two XML outputs from a program that I would like to include in a LaTeX document. I would like them to appear side-by-side each in its own box. So that a reader can compare the two outputs while reading the document. Can't seem to find a way to do this, without making images for each output and adding both as images/graphics. Could there be a better option?

I would like to have two listings, side by side.  They have approximately the same length, therefore I don't care about how it's layed out if one part is longer.  I tried  \begin{minipage}{\textwidth} \begin{parcolumns}{2} \colchunk{\begin{lstlisting}[caption=code 1,frame=tlrb]{Name} void code() {  } \end{lstlisting}}  \colchunk{\begin{lstlisting}[caption=code 2,frame=tlrb]{Name} void code() {  } \end{lstlisting}}  \colplacechunks \end{parcolumns} \end{minipage}   while the border of the listings end up in chunks as follows:   Btw I'm using the texlive-package & pdflatex on Ubuntu and the document class is  \documentclass[ a4paper, 10pt, twoside, openright, notitlepage, parskip=half, ]{scrreprt}   Any idea is appreciated.


I need a script I can call in crontab that equates out to ---   find all files < 1 week old | rm files.   I use macrium reflect free edition to back up my windows machines to a samba share dedicated to macrium. But the free edition doesn't come with the ability to delete files older then a week and therefor my drive will eventually fill up or require constant monitoring. I would like to learn how to do this, not just to continue using free Reflect (It's so good I'm just waiting till I can afford a 4 pack @ 140$) but so I can use it for other purposes as well. Any Ideas?  Its tricky because It cant say anything older then April 5th, as that's useless in a week, it needs to be a mathematical equation in the command like, find all files < 1 week old | rm files.  Thanks for your time...  Donut

By the time, many files are still on my system and I don't need them anymore, so how to delete all files that are one year old at least?


Site    here, in this 9 is the user id.it is different according to register users.   When add link in main menu there is an option Path textbox in that text box if i add "user/9/edit" then link is created but here 9 is login user id. then it is accessible only whose user id 9. but other not access. I want to add link dynamic which user are login then that user access that user edit page.user/*/edit

Ok, I must be missing something obvious, but I'm having trouble adding a link to user/%/edit to the main menu.  In the Menu UI, I clicked "add link," set the title to "Account settings," and then was at a loss about what to put for the path.  I know how to generate a link to the account edit page using views, which is what I've always done before, but this time I actually need to add the link to the "Main Menu."


I have a drive that throws this kind of messages. I'm running 16.04.2 amd64 with the hwe kernel.  I'm searched a bit and I'm not sure what to understand here. Some people are saying that this is not a drive issue, some other are. How can I check that my drive is in a good state for sure considering this error?  [31919.519017] ata4.00: exception Emask 0x10 SAct 0x200 SErr 0x400100 action 0x6 frozen [31919.519036] ata4.00: irq_stat 0x08000000, interface fatal error [31919.519048] ata4: SError: { UnrecovData Handshk } [31919.519058] ata4.00: failed command: WRITE FPDMA QUEUED [31919.519069] ata4.00: cmd 61/00:48:50:fc:70/01:00:08:00:00/40 tag 9 ncq dma  131072 out                     res 40/00:48:50:fc:70/00:00:08:00:00/40 Emask 0x10 (ATA bus error) [31919.519095] ata4.00: status: { DRDY } [31919.519104] ata4: hard resetting link [31919.861466] ata4: SATA link up 6.0 Gbps (SStatus 133 SControl 300) [31919.861975] ACPI Error: [DSSP] Namespace lookup failure, AE_NOT_FOUND (20160930/psargs-359) [31919.862009] ACPI Error: Method parse/execution failed         [\_SB.PCI0.SAT0.PRT3._GTF] (Node ffff8d12be536e88), AE_NOT_FOUND (20160930/psparse-543) [31919.862241] ACPI Error: [DSSP] Namespace lookup failure, AE_NOT_FOUND (20160930/psargs-359) [31919.862259] ACPI Error: Method parse/execution failed [\_SB.PCI0.SAT0.PRT3._GTF] (Node ffff8d12be536e88), AE_NOT_FOUND (20160930/psparse-543) [31919.862331] ata4.00: configured for UDMA/133 [31919.862338] sd 4:0:0:0: [sdl] tag#9 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [31919.862339] sd 4:0:0:0: [sdl] tag#9 Sense Key : Illegal Request [current] [31919.862340] sd 4:0:0:0: [sdl] tag#9 Add. Sense: Unaligned write command [31919.862341] sd 4:0:0:0: [sdl] tag#9 CDB: Write(10) 2a 00 08 70 fc 50 00 01 00 00 [31919.862341] blk_update_request: I/O error, dev sdl, sector 141622352 [31919.862361] ata4: EH complete

It seems to be the same three errors repeated:  $ tail -n15 /var/log/syslog Apr  5 23:32:01 detoo kernel: [ 6042.078785] ACPI Error: [PGRT] Namespace lookup failure, AE_NOT_FOUND (20150619/psargs-359) Apr  5 23:32:01 detoo kernel: [ 6042.078787] ACPI Error: Method parse/execution failed [\_GPE._L6F] (Node ffff8808554d42d0), AE_NOT_FOUND (20150619/psparse-536) Apr  5 23:32:01 detoo kernel: [ 6042.078788] ACPI Exception: AE_NOT_FOUND, while evaluating GPE method [_L6F] (20150619/evgpe-592)   I noticed something was wrong when I was getting low disk space warnings. I've flashed to the latest UEFI available, I've tried enabling/disabling the C states in my UEFI.  I'm running Linux Mint 17.3 Cinnamon 64-bit with kernel 4.2.0-34-generic. I have a skylake processor and z170 motherboard.  I'm quite new to linux and am at a lost as what I should do next.  EDIT: I have the same problem when booting from a USB with Ubuntu 16.04, and nearly identical error logs being constantly spammed:  Apr  6 01:01:48 ubuntu kernel: [  152.594053] ACPI Exception: AE_NOT_FOUND, while evaluating GPE method [_L6F] (20150930/evgpe-592) Apr  6 01:01:48 ubuntu kernel: [  152.594994] ACPI Error: [PGRT] Namespace lookup failure, AE_NOT_FOUND (20150930/psargs-359) Apr  6 01:01:48 ubuntu kernel: [  152.594996] ACPI Error: Method parse/execution failed [\_GPE._L6F] (Node ffff8808554e02d0), AE_NOT_FOUND (20150930/psparse-542)


I am writing a PHP+PDO function to check if the usernames and email addresses are already stored in the database. The SQL code returns an error(see bottom of post).   Similar posts recommend that I should change "reserved keywords", which I have checked and I have not used any from what I can see ().    I tested the SQL string on phpMyAdmin and it works. the string looks as follows:      SELECT COUNT(Email) FROM `contactdetails` WHERE 'Email' = 'example@example.com'    PHP code:      <?php      function CheckAvailability($ValueToCheck, $FieldToCheck, $TableToCheck){      //Database connection.         $dbservername =   "localhost";         $dbusername =     "root";         $dbpassword =     "";         $dbname =         "db";          $db= new PDO("mysql:host=$dbservername; dbname=$dbname", $dbusername, $dbpassword);         $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);        //assigned 1 for value to be false         $count=1;       //SQL String            $result = $db->prepare("SELECT COUNT(:Field) FROM :Table WHERE :Field = :Value");      //Binding of parameters to SQL string         $result->bindParam(":Table", $TableToCheck, \PDO::PARAM_STR);         $result->bindParam(":Field", $FieldToCheck, \PDO::PARAM_STR);         $result->bindParam(":Value", $ValueToCheck, \PDO::PARAM_STR);      //String execution and data fetching         $result->execute();         $count = $result->fetchColumn();      //If the result of the string returns 0 return true if 1 or more return false.            if($count==0){return true;}else{return false;}                      }?>   Result is as follows:     ERROR: SQLSTATE[42000]: Syntax error or access violation: 1064 You   have an error in your SQL syntax; check the manual that corresponds to   your MariaDB server version for the right syntax to use near   ''ContactDetails' WHERE 'Email' = 'example@gmail.com'' at line 1.   What am I doing wrong? Can I fix it? Is there a better way of doing this?

Why can't I pass the table name to a prepared PDO statement?  $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) {     var_dump($stmt->fetchAll()); }   Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do  $sql = "SELECT * FROM $table WHERE 1"


I want to fix my laptop charger cord, I used a multimeter to check the voltage and it gives me less than one volt. It feels very flexible near the plug, but I don't know if I can cut before or after the part marked in red. What is this part used for? Can I remove the red part?

What is the name of this component (circled in red) of a charger?    What are the uses of this component?


I was writing some code, and went to get the length of an IEnumerable.  When I wrote myEnumerable.Count(), to my surprise, it did not compile.  After reading , I realized that it was actually Linq that was giving me the extension method.  Using .Length does not compile for me either.  I am on an older version of C#, so perhaps that is why.  What is the best practice for getting the length of an IEnumerable?  Should I use Linq's Count() method?  Or is there a better approach.  Does .Length become available on a later version of C#?  Or if I need the count, is an IEnumerable the wrong tool for the job?  Should I be using ICollection instead?   says that ICollection is a solution, but is it the right solution if you want an IEnumerable with a count?  Obligatory code snippet:  var myEnumerable = IEnumerable<Foo>();  int count1 = myEnumerable.Length; //Does not compile  int count2 = myEnumerable.Count(); //Requires Linq namespace  int count3 = 0; //I hope not for(var enumeration in myEnumerable) {     count3++; }

private IEnumerable<string> Tables {     get     {         yield return "Foo";         yield return "Bar";     } }   Let's say I want iterate on those and write something like processing #n of #m.   Is there a way I can find out the value of m without iterating before my main iteration?  I hope I made myself clear.


This in not a duplicate of this . I want to swap values vertically while in other question swap is horizontally.  I have table Products:  id  |   holder_id ---------------  1   |   2        2   |   2    3   |   13   4   |   13   5   |   1        6   |   12   7   |   16       8   |   20   --------------   Where holder_id is reference to User id. And table conversations:  id  |   user1   |   user2   |   product1    |   product2     ------------------------------------------------------- .. 2   |   12      |   2       |   6           |   2     What I want is to have a single statement to swap holder_id's for two products by conversation id. So for conversation id 2 it should look like this:  id  |   holder_id ---------------  1   |   2        2   |   12   3   |   13   4   |   13   5   |   1        6   |   2    7   |   16       8   |   20   --------------   So now the holder_id's for id 2 and 6 are swapped.  I have tried:  UPDATE products as p INNER JOIN conversations as c ON p.id=c.product1 SET p.holder_id=c.user2 WHERE c.id=2;   and with this I manage two do this:  id  |   holder_id ---------------  1   |   2        2   |   2   //still have to change this 3   |   13   4   |   13   5   |   1        6   |   2   // changed this 7   |   16       8   |   20   --------------   Now I have to do onother join to same table and I cant understand how to do that.

I have a MySQL table with coordinates, the column names are X and Y. Now I want to swap the column values in this table, so that X becomes Y and Y becomes X. The most apparent solution would be renaming the columns, but I don't want to make structure changes since I don't necessarily have permissions to do that.  Is this possible to do with UPDATE in some way? UPDATE table SET X=Y, Y=X obviously won't do what I want.    Edit: Please note that my restriction on permissions, mentioned above, effectively prevents the use of ALTER TABLE or other commands that change the table/database structure. Renaming columns or adding new ones are unfortunately not options.


If I decide to write a simple game both text and graphical (2d) what libraries would I use? (Assume we are using a HTML5 compatible browser)  The main things I can think of   Rendering text on screen Animating sprites (using images/css) Input (capturing the arrow keys and getting relative mouse positions) Perhaps some preloading resource or dynamically loading resources and choosing order Sound (but I am unsure how important this will be to me at first). Perhaps with mixing and chaining sounds or looping forever until stop. Networking (low priority) to connect a user to another or to continuously GET data without multiple request (I know this exist but I don't know how easy it is to setup or use. But this isn't important to me. Its for the question).


The proof is required to be made through the binomial theorem. I will expose the demonstration I was tought, and forward my questions after exposing it. You'll see question marks like this one (?-n) on points I don't quite understand, where $n$ is the numeration of the mark. This are the doubts I have about the demonstration, the which I hope someone can clarify.  Prove that $\binom{n}{0}^2 + \binom{n}{1}^2 + ... + \binom{n}{n}^2 = \binom{2n}{n}$.  We will use the following equality, and call it $P$:   $(1+x)^n(1+x)^n=(1+x)^{2n}$    (?-1)  The result will be proved finding the $x^n$ coefficient of both terms of this equality (?-2).  According to the binomial theorem, the left-hand side of this equation is the product of two factors, both equal to  $\binom{n}{0}1+\binom{n}{1}x+...+\binom{n}{r}x^r+...+\binom{n}{n}x^n$  When both factors multiply, a term on $x^n$ is obtained when a term of the first factor has some $x^i$ and the term of the second factor has some $x^{n-i}$. Therefor the coefficients of $x^n$ are  $\binom{n}{0}\binom{n}{n}+\binom{n}{1}\binom{n}{n-1}+\binom{n}{2}\binom{n}{n-2}+...\binom{n}{n}\binom{n}{0}$ .  Since $\binom{n}{n-r}=\binom{n}{r}$, the previous summation is equal to $\binom{n}{0}^2 + \binom{n}{1}^2 + ... + \binom{n}{n}^2$. So the left hand side of the equation we are asked to proove is a coefficient of $x^n$. When we expand the right-hand side of the equation $P$, we find that $\binom{2n}{n}$ is a coefficient of $x^n$. Therefore (?-3) the left-hand side of the equation we were asked to prove is in deed equal to $\binom{2n}{n}$. In conclussion,  $\binom{n}{0}^2 + \binom{n}{1}^2 + ... + \binom{n}{n}^2 = \binom{2n}{n}$.  This was all the demonstration. My doubt one (?-1) goes about where the heck does this equation come from? How would I know what equation to come up with if requested to prove a different equality?  Doubt two (?-2) goes about why would the solution of the first equation would have anything to do with finding the $x^n$ coefficients of the one I just made up (see doubt one).  Doubt three (?-3) goes about why demonstrating that $a$ is a coefficient of $x^n$ on the left hand side of the equation I made up, and that $b$ is a coefficient of $x^n$ on the right-hand side of this equation as well, would prove my original equation, the one I was supposed to prove on the first place?  I know there are many doubts here, I hope you guys can help me. Sorry for the long post, it's a long demonstration.

I was hoping to find a more "mathematical" proof, instead of proving logically $\displaystyle \sum_{k = 0}^n {n \choose k}^2= {2n \choose n}$.  I already know the logical Proof:  $${n \choose k}^2 = {n \choose k}{ n \choose n-k}$$  Hence summation can be expressed as:  $$\binom{n}{0}\binom{n}{n} + \binom{n}{1}\binom{n}{n-1} + \cdots + \binom{n}{n}\binom{n}{0}$$  One can think of it as choosing $n$ people from a group of $2n$  (imagine dividing a group of $2n$ into $2$ groups of $n$ people each. I can get $k$ people from group $1$ and another $n-k$ people from group $2$. We do this from $k = 0$ to $n$.


I want to determine the convergence of the following improper integral:$$\int_0^{\infty} \frac{1}{1+x^4\sin^2x}\,dx.$$  I have tried comparison tests for the same. $$\int_0^{\infty} \frac{1}{1+x^4}\,dx$$ comes out to be convergent while $$\int_0^{\infty} \frac{1}{1-x^4}\,dx$$ comes out to be divergent. Thus we can't say actually anything about the convergence of this integral from these two comparisons. How can I proceed from here? Please suggest.

Task: find all values of the parameter, such that integral converges. $$\int_0^{+\infty} \frac{dx}{1+x^a \sin^2x}$$ I tried a lot and I used Cauchy and Weierstrass method but it was useless. And now I know that I must use $$\sum_n \int_{\pi n}^{\pi(n+1)}$$


I have made building with "Ian Hubert's tutorial: modeling building in blender-lazy tutorial". when I adjusted the glass material to my windows,in front view everything is OK, but when I pan in the viewport the windows are fixed and get appear in incorrect location. how to solve this?

I have a weird problem with my viewport. As the images show, there are some very basic objects. But some textured objects are shown through other objects, although they should be hidden. It's obvious with the gravel – the object with grass texture should conceal a part of the object with gravel texture. On the other hand, the gravel goes some way under the plain white object, and is hidden by it, as expected.    I'm anything but a noob with Blender, but switched recently to 2.82. This problem happens with different objects and different materials, even with Cycles or Eevee. Could this be a graphical glitch? My PC isn't anything but bleeding edge, more kind of usable ol' buddy. Never had this behavior with 2.79b.  Thanks in advance.


Why is there a null pointer exception error where prev.value.compareTo(v)<0 and if(cur.value.compareTo(v)<0 ?  public void insert (T v) {         Node prev = head, cur = head.next;           if(prev==null)             {             prev=head;              }          else if(prev.value.compareTo(v)<0)  //v belongs in the front         {             prev.value=v;             prev=prev.next;         }          else         {              //iterate through the list             prev=prev.next;             cur=cur.next;             while(cur!=null)             {                 if(cur.value.compareTo(v)<0)                  {                     prev=cur;                     cur=cur.next;                 }              }          } }

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 set up TIM3 to fire an interrupt in my project and it just wouldn't work. I tried everything I could and still couldn't find whats the problem. Then I created a clean project and copy/pasted only the code that sets up TIM3 and interrupts and it magically worked. I literally wasted half a day trying to find what causes the problem and it turns out... interrupts don't like C++.  I wrote my code in C++ because I needed classes in my project so naturally I renamed all my prject .c files to .cpp and also compile with the --cpp directive. Everything worked fine, no problems so far until I decided to use interrupts. So I renamed everything to .c and everything worked, renamed everything back to cpp and it stopped working.  I use Keil uVision5 and my projects are generated with STM32CubeMX (only RCC config).  Anyone had this happen to them? Any workarounds?

I have a problem with writing interrupt handlers in Keil ARM compiler for LPC1114. When I write program in C++ and specify --cpp compiler option all code from interrupt handlers disappears, it is replaced with infinite loop. I wrote simple program that illustrates my trouble.  #include "LPC11xx.h"           // LPC11xx definitions #define SYSTICK_DELAY 120000   // for 10 ms systick @ 12MHz osc  void SysTick_Handler(void) {   __NOP(); }  int main (void)  {   SystemInit();                   // from system_LPC11xx.c   SysTick_Config(SYSTICK_DELAY);  // from core_cm0.h   // Loop forever   while (1) __NOP(); }   When trying to compile this code with --cpp compiler option I get infinite loop in disasm:  SysTick_Handler PROC             EXPORT  SysTick_Handler           [WEAK]             B       .             ENDP   This is the place where __NOP() from above program must be. And it is there when I'm compiling code with --c99 compiler option or without additional options. Keil MDK version is 4.12. Can anyone tell me is there any solution or workaround ?


I'm confused between "will" and "would"        I will/would attend the party.      Which is the correct one?

Consider the following sentence     It will/would rain tomorrow.   I understand "would" usually means something that is really improbable.  So "it would happen" means it might happen but it is very unlikely; while "it will happen" means it is going to happen  But what if I want to say      It will not happen?   Because the meaning of "it will not happen" represents something that is unlikely or, worse still, not going to happen, shouldn't it be more accurate to say "it would not happen"?  However, to contravene the aforesaid suggestion - if I am confident that the thing is not going to happen, should I use "will" to indicate the definite nature of my statement?  To further complicate the issue, what if I want to say     I think you will not be able to do it.    or      I think you would not be able to do it.    Which one is more accurate/correct,  given that "I think" already conveys a sense of "less than definite" and "will/would not be able to" conveys the same sense as "unlikely"?


Basically, the problem is:   Given a list of chars, do the following until it has only 1 element:   Starting from the beginning, remove each second node of the list, for example  doing this to "abcdefghij" should return "acegi" Starting from the end of the list produced by step 1, remove each second node, so doing this to "acegi" should return "aei" Do these steps until the list has only 1 element    The final solution to this particular list should be "i".  My solution to this is :  public class listexercise {      public static DLL<Character> removeFront(DLL<Character> list){          DLLNode<Character> tmp = list.getFirst().succ;          while(tmp != null){             list.delete(tmp);                 if(tmp.succ == null) {                     tmp.pred.succ = null;                     break;                 }             tmp = tmp.succ.succ;         }          return list;      }     public static DLL<Character> removeEnd(DLL<Character> list){          DLLNode<Character> tmp = list.getLast().pred;          while(tmp != null){             list.delete(tmp);             if(tmp.pred == null) {                 tmp.succ.pred = null;                 break;             }             tmp = tmp.pred.pred;         }          return list;             }     public static DLL<Character> rec(DLL<Character> list, int n){         if(list.length() == 1)             return list;         else if(n%2 == 1)             return rec(removeFront(list), n++);         else if(n%2 == 0)             return rec(removeEnd(list), n++);              return list;     }      public static void main(String[] args) {          Scanner s = new Scanner(System.in);          DLL<Character> list = new DLL<Character>();         String input = s.nextLine();         char[] parts = input.toCharArray();          for(int i=0; i<parts.length; i++)             list.insertLast(parts[i]);          System.out.println(rec(list,1).toString());     } }   This gives me NPE on the removeFront or removeEnd. However if I use specifically only one of them at a time, they work perfectly, but when I put them in a recursion, there's a problem.   Any ideas how to fix this??


the Ctrl+Super+Right/Left does not seem to have any function on Ubuntu 16.04 on the contrary to the answer about the Ubuntu 15  How could I set up a shortcut Ctrl+Super+Right/Left to make a current window to fill right/left side of the screen? I have checked the system -> keyboard shortcuts and neither the Ctrl+Super+Right/Left nor "tile windows" shortcut is present there under any category.

At some point recently the tile windows feature stopped working for me. Hence if I drag a window to the left or right of the screen it no longer fills half the screen. Similarly, dragging a window to the top does not maximize it.  Ctrl  + Super + Up still maximizes  Ctrl + Super + Down still minimizes  Ctrl + Super + Left/Ctrl + Super + Right do not make the current window fill the left/right of the screen.  I am guessing this is a failed update somewhere. Does anyone know which packages to try reinstalling to regain this feature?


I have a problem with a hard disk. This used to be in my Lacie Network Space 2, but it crashed.  Under Windows I don't get to see anything, of course, so I ordered a USB - SATA cable, and a live boot USB from Ubuntu.  So far, that's what I have done. Because otherwise I am a layman and I try everything to get my photos/videos back.  To be precise, when I start Ubuntu, I get the following message when I click on the disk:  Error mounting /dev/sda2 at /media/ubuntu /cea89a46-6cf3-492e-80f3-d270280237ac: can't read superblock on /dev/sda2

I'm trying to mount my HDD,  /dev/sdb, which is connected via an enclosure but every time I try do so I get an error message   mount: /dev/sdb: can't read superblock   How do I solve this problem and mount my HDD?


I have a textarea to display the HTML content from the database. Here my code is:               <textarea name="cont" id="cont"></textarea> <textarea name="name" id="cont"></textarea>   When I try to load content dynamically, #name is working perfectly but the #cont shows an console error like:     Uncaught SyntaxError: Invalid or unexpected token   This is the content I am attempting to load in to the #cont
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What is the easiest way to encode a PHP string for output to a JavaScript variable?  I have a PHP string which includes quotes and newlines.  I need the contents of this string to be put into a JavaScript variable.  Normally, I would just construct my JavaScript in a PHP file, à la:  <script>   var myvar = "<?php echo $myVarValue;?>"; </script>   However, this doesn't work when $myVarValue contains quotes or newlines.


I am working on a proof and I came across a combinatorial identity on the internet that would really help me, but I cannot prove it. The identity is:  $$\sum_{n≥0}\left[\binom{n}{m}(z^n)\right]=\frac{z^m}{(1-z)^{m+1}}$$  I imagine it has something to do with the binomial theorem, but I just cannot figure it out. So, I am hoping that someone can either tell me what this identity is or help me prove it.

I was wondering if there is also a closed expression for the series   $$\sum_{n=0}^{\infty} \binom{n+k}{k} x^n$$ where $|x|<1.$  A few examples suggest that the answer is $\frac{1}{(1-x)^{k+1}}$ but I don't see how to show this.


I'm US citizen.Social Security Office asked me to prove I did come back to US on time because I get SSI(Supplementary Security Income), I can't go abroad over 30 days.US customs didn't stamp on my passport.How can I prove to Social Security Office?  Peter Doan

how can I prove to Social Sec. office that I did return to US on time without the stamp on my passport ??


I want to download two Minecraft maps, and then put them together. Side by side, as in the builds. Like, specifically, a city, and a couple of districts or neighborhoods. How do I do it in the sense that its merged?

Is there any way to merge two worlds? Like take chunks from World A, and put them somewhere in World B?