We've just briefly learnt a little bit about black bodies at college and I'm confused as to how radiation from a cavity which is based on a standing wave model can be compared to black bodies made of atoms, i.e. No cavity  ???

I don't see why you can derive the black body spectrum from the mode density of the radiation inside a reflecting cavity. I do understand the mathematical side of the derivation and I know that an absorbing cavity with a small hole is the best approximation of a black body. But aren't the standing EM waves inside the cavity only there because the cavity is perfectly reflecting, determining the boundary condition of a vanishing field at the boundaries? How is this releated to a cavity with black, (perfectly) absorbing walls? Again, I do understand that the walls can't reflect all of the incoming waves, because there must be a possibility for the matter and EM waves to interact in order to establish the thermodynamic equilibrium, but then how can you look at standing waves inside the cavity, if it is not perfectly reflecting?


I have a file $ocsp_resp_file with the following content:  1432599306989.cer.tmp: good     This Update: May 23 12:54:14 2015 GMT     Next Update: May 30 12:54:14 2015 GMT   I am only interested in the lines starting with "This Update:" and "Next Update:". I would like to retrieve those lines and strip out the spaces and text before the timestamp.  It should end up looking like this:  May 23 12:54:14 2015 GMT May 30 12:54:14 2015 GMT   I am using the following code to return each one but not quite how i want it.  $search = 'This Update';         $lines = file($ocsp_resp_file);         foreach($lines as $line)         {         $line = ltrim($line);           if(strpos($line, $search) !== false)           //$line = str_replace('This Update: ', '', $line);             echo $line;         }   The above code returns this:  This Update: May 23 12:54:14 2015 GMT   I then tried to remove "This Update: " using the following code (now commented out) but it breaks the logic of the code and each line is returned  $line = str_replace('This Update: ', '', $line);

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


Note: as pasted in the comment, it is called backtick for the symbol ``, and there's already an answer in:   Original question: In bash, people may use reverse quote(``) as result for quoted commands, and integrated in another command. For example: cmake -DVAR1=VALUE1 `cat ../custom-options.txt`  where ../custom_options.txt contains many lines like: -DBUILD_ZLIB=OFF -DBUILD_TIFF=OFF -DBUILD_OPENJPEG=OFF -DBUILD_JASPER=OFF -DBUILD_JPEG=OFF -DBUILD_PNG=OFF -DBUILD_OPENEXR=OFF -DBUILD_WEBP=OFF -DBUILD_TBB=OFF -DBUILD_IPP_IW=OFF -DBUILD_ITT=OFF -DWITH_AVFOUNDATION=OFF  For Windows system, it is powershell instead of bash in Linux. My question: what is the equivalent of reverse quote in PowerShell?

Redirecting command output:  For example:  echo "Foo `./print_5_As.rb`"   would echo "Foo AAAAA"


I want to see if it is possible to see questions tagged with only the tag(s) I specify and no others?  Lets say, I want to be able see new questions with only the [c#] tag only and no others.  I just want to see questions with that single [c#] tag.  I don't want to see question tagged with say, [c#] and [asp.net]  Is this possible?  In a similar question I found the following suggestion but it does not work for me:  "You can build a bookmarlet using 'or'. Here is an example which shows the questions tagged 'C' along with the questions tagged 'C++':  http://stackoverflow.com/questions/tagged/'c'%20or%20'c++'"   The problem is this provides others tags also.

Is there a way to search for question which contains a specific tag (or set of tag), but no other tags.  For example if I wanted to have only pure [php] questions I would input in the search filed the following:  ![php]   Or for question only concerning html and css I would input:  ![html+css]  Is there already such a feature hidden in the SO Engine? If not, with the high number of question in SO, I feel like it would be a good feature.


When I use epl2 format  and the tikz package it causes a compilation error an appears an empty page at the begining of the document.  \documentclass[doublecol]{epl2}  \usepackage{tikz} % or \documentclass[page-classic]{epl2} for one column style  \title{Title of the paper} \shorttitle{Title} %Insert here a short version of the title if it exceeds 70 characters  \author{F. Author\inst{1,2} \and S. Author\inst{1} \and T. Author\inst{2}} \shortauthor{F. Author \etal}  \institute{                       \inst{1} First Institute - Address\\   \inst{2} Second Institute - Address } \pacs{nn.mm.xx}{First pacs description} \pacs{nn.mm.xx}{Second pacs description} \pacs{nn.mm.xx}{Third pacs description}   \abstract{ Abstract of the paper.}   \begin{document}  \maketitle  \end{document}

When compiling a document using my university's thesis class file and the TikZ package I receive an error message (missing number, treated as zero). Would someone know how I can solve this problem?   \documentclass[phd,bottom,nosig]{usbthesis} \usepackage{tikz} \begin{document} Test 1-2-3 \end{document}   The class file can be found here:


"a zero magnetization" or "the zero magnetization" or "zero magnetization"? "a zero magnetic field" or "the zero magnetic field" or "zero magnetic field"? Are there any specific rules for articles before the word zero? Is not "zero magnetization" equivalent to "magnetization 0" which comes with zero article? Thanks!

How are articles used with scientific quantities, such as mass, force, impulse, field and others?


Question:   Let $\{a_n\}$ be a sequence defined by $$a_1 = 2, a_{n+1} = \frac{1}{3 - a_n}, \text{ if } n \geq 1$$  Does $\{a_n\}$ converge or diverge?  My solution:  I just wrote down some terms.  $a_1 = 2, a_2 = 1, a_3 = \frac{1}{2}, a_4 = 5/13, a_5 = 13/34$. Basically eventually $a_n$ will be zero, so I say this converges to $\frac{1}{3}$. What is the most simple but a good solution to prove this?

Let $\{a_n\}$ be defined as follows: $$a_1 = 2, a_{n+1}=\dfrac{1}{3-a_n}$$ $n \geq 1$.   Does $\{a_n\}$  converge?    Using the monotone convergence thereom, if the sequence is both bounded below and decreasing, $\forall n\in\mathbb{N}, n\geq 1$, then we can say the sequence converges.  I'm having trouble proving that the sequence is bounded below by induction.    Claim: The sequence is bounded below by $0$.  Base Case:  $n=1$  $a_1 = 2 \geq 0$, so this holds.  Induction Step  Suppose that $a_k \geq 0$, for some $k \in\mathbb{N}$. (IH)  Prove $a_k \geq 0\to a_{k+1} \geq 0$  I have some difficulty here.  $a_{k}=\dfrac{1}{3-a_{k-1}} \geq 0$  $a_{k+1}=\dfrac{1}{3-a_{k}}$, but we know $a_k \geq 0$, but we don't know how much bigger. It could be that $a_k = 4$, and then I have $a_{k+1}=\dfrac{1}{3-4}$, which is negative, and does not confirm with my claim of being bounded below by $0$. Have I gone somewhere wrong in my induction?


I am doing a study on the verbal forms "Simple Past". I have doubts with the construction "were scattered", because I do not know if it is the verb to be conjugated in Simple Past and followed by an adjective, or it is a Passive Construction, which I would therefore exclude from my study.  Therefore, is the verb that I have highlighted in bold written as part of a passive construction? Why? Or why not?     ...One, with his chin propped on his knees, stared at nothing, in an intolerable and appalling manner: his brother phantom rested its forehead, as if overcome with a great weariness; and all about others were scattered in every pose of contorted collapse, as in some picture of a massacre or a pestilence.   from Heart of Darkness, by Joseph Conrad.

How can I reliably and accurately identify the passive voice in writing or speech? I'm not interested in advice about whether or not to use it yet... I just want to know for sure what it is, so that I don't look as stupid as .


I am new to Linux and I am trying to install AMD drivers on my system. For this I downloaded the file from AMD website. It is called amdgpu-pro-17.30-465504.tar.xz. In the website it says that I have to extract the file using the following command  tar -Jxvf amdgpu-pro-17.30-450654.tar.xz   But when I do this, I am getting the following error.  username@Lenovo:~/Downloads$ tar -Jxvf amdgpu-pro-17.30-465504.tar.xz xz: (stdin): File format not recognized tar: Child returned status 1 tar: Error is not recoverable: exiting now   How can I install extract it? What is the cause of this error?

I'm running Ubuntu 17.10, and I can not extract a certain tar file. When trying to extract the file, I get the following message:  There was an error while extracting”amdgpu-pro-17.40-492261.tar.xz” “Not an archive”   Any help would be appreciated.


My linux PC has suffered the occasional application crash, desktop crash, and kernal panic over the last few months. I also started noticing error dialogs on login, and some parts of the desktop do not look the same. Over the last week, this crash rate has increased to more than 3 per day, so I investigated with logs and diagnostics.  The MemTest86 program indicated a memory module fault. I removed the faulty module and my system is now stable.  My problem is there are many inital errors and small failures (eg: cups printing, an icon missing from the toolbar, the purple bacground disappeared from the Ununtu boot screen, etc), that suggest bit errors during configuration writes or apt-get upgrade binary updates.  Is there a apt-get checksum all-packages type command that can check my binaries with a global repository (and perhaps re-install corrupted files)?  Debian installs have the debsums utility (as mention here: ). Is there a similar utility in the Ubuntu world (using "apt")?  I would like to avoid a complete re-install of OS and all applications.  OS: Ubuntu 14.04.2 LTS (14.04) 64 bit

I've been having some memory corruption issues, causing random crashes, but I've fixed them now. However, I'm concerned that some packages may be corrupted (as naturally any package update has to go through memory before it's written to disk).  Is there any way to automatically checksum all of the package files on a Debian system, and compare them to the archives, and if they're incorrect, update them?


what is the difference between the following syntax        1.  var dtm = new DataTableManager();       2.  DataTableManager dtm1 = new DataTableManager();   Many thanks,

The  keyword does away with the need for an explicit type declaration and I have read with interest the  of when it might be appropriate.  I have also read about (but not used)  which seems to take things a step further by making it .  With Boo, both the type and the declaration can be implied.  Which leads me to wonder, why did the C# language designers bother to include a var keyword at all?    Update: Yes, var supports Anonymous types, but anonymous types by themselves do not necessitate the var keyword...  var anon = new { Name = "Terry", Age = 34 };   versus  anon = new { Name = "Terry", Age = 34 };


I have a website that looks like below. When a text is clicked, the clicked text will get a class called large and the text size will change to 25pt. To see how I am assigning the event and the class large, please look at the js code. The problem I have is when the text "I like swimming" is clicked the large class gets added to the text "I like basketball". Why is this happening? Can anyone help me to fix this issue?   const arraySportsText = Array.from(document.getElementsByClassName('sportsText')); for (index in arraySportsText) {   arraySportsText[index].addEventListener("click", () => arraySportsText[index].classList.add('large')) } body {   font-size: 15pt; }  .large {   font-size: 25pt; } <!DOCTYPE html>      <meta charset="UTF-8">   <meta http-equiv="X-UA-Compatible" content="IE=edge">   <meta name="viewport" content="width=device-width, initial-scale=1.0">   <title>Document</title>   <link rel="stylesheet" href="styles/style.css">
Sports

I like swimming

I like basketball

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


I've noticed that the classical title bars are missing from Nautilus and Document Viewer. It has been going for a sleeker hidden title bar. However, I prefer the older version. Is there anyway to bring back normal title bars?

I'm using Ubuntu GNOME 17.04. One encounters client side decoration (CSD) as most of the official GNOME applications (Nautilus, gedit, Evince etc.) use  (a combined title bar and toolbar, see linked screenshots) whereas other applications don't. This feature is disabled in Unity, all the applications use traditional separate title bars.  Screenshots (from ):     Nautilus with GtkHeaderBar   Nautilus without GtkHeaderBar     For consistency I want to disable GtkHeaderBars globally (in all the applications using it) and use separate title bars. Is there a way to achieve that?  I have heard of gtk3-nocsd package, but couldn't make it work with GNOME for all the applications.


Tried opening an existing project (created in 2.92) in 2.93 and Blender freezes on render.  Then I discovered that when I reset the program to defaults, cycles is no longer available.  However, it is enabled in Add-ons.  Am I missing something? NOTE: I have tried enabling "filter add-ons" in the Workspace settings, to no avail.  The other topic "why is cycles render engine missing" is not relevant to my issue.

I was on the latest version before this, 2.92. Everything was fine. I just updated, I clicked to import settings from 2.92 at the first run popup window, all ok. Then I loaded one of my scenes, everything ok. But now, if I try to render, the viewport remains grey, and once I try to revert the viewport to EEVE render, the program simply enters an infinite loop and freezes. The grey space in the middle of the image is the object "rendered" in "Cycles".  And this below is what happens after I click another render method: menu stuck and mouse pointer rolling.  The same happens if I switch to another panel with a different render method. Update: this only happens when using GPU computer. If it's on CPU, it works. I have just tried with a brand new scene with the cube, where Cycles is set on CPU, and it worked. Once I tried to switch to GPU, again it rendered grey. Then when I reverted again to CPU, the program froze.


const doSomething = (foo) => {   foo.push('rsa')   foo = ["World"]   return foo; }  let blah = ["Hello"]; console.log(blah); doSomething(blah); console.log(blah);    Please Explain me the output  output will be like below I am really confused with javascript so please can anyone explain this.  output will be like below I am really confused with javascript so please can anyone explain this. output will be like below I am really confused with javascript so please can anyone explain this. [   "Hello" ] [   "Hello",   "rsa" ]

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


How can I check if my wireless card supports monitor mode, e.g. for use with aircrack-ng?  I know there is a command that shows something like wifi adapters attributes or something, but I can't remember.

Can someone please tell me how to check if a wlan card supports promiscuous mode


Let $G$ be group of all square matrices of order $2$ $$\begin{bmatrix} a & b\\ c & d \end{bmatrix}$$  such that $a$, $b$, $c$, and $d$ are integers modulo a prime number $p$, such that $ad-bc\ne0$. $G$ forms a group relative to matrix multiplication. What is order of $G$?  I have tried for smaller values of $p$ by explicitly writing matrices. But how do I do this for general $p$.  Thanks

I'm having a hard time counting. I need to count the number of elements for the multiplicative group of invertible $2\times 2$ matrices $GL_{2}\left( \mathbb{F}_{p}\right) $ with elements from the field $\mathbb{F}_{p}$ where $p$ is any prime number. David S. Dummit and Richar M. Foote's Abstract Algebra (3rd edition) has a solution on page 413 but that approach is by counting the possible number of basis of vector spaces but I wanted to see if there was a direct way. The book says that $\left\vert GL_{n}\left( \mathbb{F}_{p}\right) \right\vert =\left( p^{n}-1\right) \left( p^{n}-p\right) ...\left( p^{n}-p^{n-1}\right) $ so my case reduces to $p^{4}-p^{3}-p^{2}+p$. For any matrix $\left(  \begin{array}{cc} a & b \\  c & d% \end{array}% \right) $ with $a,b,c,d\in \mathbb{F}_{p}$, I understand that $p^{4}$ is the total number of 2x2 matrices and that we need to subtract the possible combinations for $ad=bc$ (non-invertible elements) but I can't account for the rest. In particular, that plus sign is absolutely baffling. Any hint would be appreciated. I'd then take this up for the general $n$x$n$ case but first I need to dispose the 2x2 case.  P.S. I tried looking for a pre-existing answer and a related answer is present  but it's by the same approach as the book and I'd like to have an approach without resorting to linear independence. This , too, was a case for $p=3$ but I couldn't see the pattern.


I have a custom post type in my plugin named members, along with two custom fields; first_name and last_name. I am trying to order my listing my the last name, then the first name. The only solution I have found is one that utilizes a function to pull in the first two query meta fields and replaces them (I followed a tutorial at dotnordic.se). However, whenever I try this I have no posts returned. I have posted my code below. Any help on fixing the problem I have with my code or suggesting another way is greatly appreciated.     // Shortcode Function   function mba_members_list_code() {    // WP_Query arguments   $args = array (   'post_type'       => 'member_data',   'post_status'     => 'active',   'fields'          => 'ids',   'posts_per_page'  => -1,   'meta_key'        => 'last_name',   'orderby'         => 'meta_value',   'order'           => 'ASC',   'meta_query'      => array(     array(       'key'         => 'first_name',     ),     array(       'key'         => 'last_name',     ),     array(       'key'         => 'publicly_listed',       'value'       => 'true',     ),   ), );  // The Query $posts = get_posts( $args );  // The Loop if( $posts ) {    echo "Total Members Found: " . count($posts) . "
";     foreach ( $posts as $post ) {       $q = get_post_meta($post);       echo "" . $q['first_name'][0] . " " . $q['last_name'][0] . "
";       echo $q['city'][0] . ", " . $q['state'][0] . " " . $q['zip'][0] . "
";       echo "" . $q['email'][0] . "
";       echo "
";     }    unset( $post );        }else{   echo "Sorry, we found no active members. Please be sure to check back soon."; } }   EDIT  function customorder($orderby) { global $wpdb; return ' {$wpdb->postmeta}.meta_value, mt1.meta_value'; //return str_replace('menu_order', 'mt1.meta_value, mt2.meta_value', $orderby); }   I know that there are other questions on this with an answer to implement this same function; however, whenever I implement it, I have no records/posts returned.

I'm triyng to display hotels (taxonomy which i have created) by two 'orderby' with wp_query but i'm not success.  Results looks likes:  Hotel 1 :       2 persons          5 stars Hotel 2 :       2 persons          4 stars Hotel 3 :       2 persons          3 stars Hotel 4 :       3 persons          5 stars Hotel 5 :       5 persons          5 stars Hotel 6:        10 persons         2 stars Hotel 7:        10 persons         1 star   The first 'order by' is on the number of persons(the biggest in first) and the second 'order by' is on the rating in stars (so, if several hotels have the same number of persons, the hotel with the biggest stars rating would be in first).  Below my code. I have tried to add an array inside an array with meta_query but it doesn't work.  $args=             array(                                     'post_type' => 'hotel',                                     'Services' => $Services,                                     'Town' => $Town,                                      'meta_key' => 'Number_persons',                                     'orderby' => 'meta_value_num',                                     'order' => 'ASC',                                        'meta_query' => array(                                                            array(                                                                'meta_key' => 'Rating',                                                                'orderby' => 'meta_value',                                                                'order' => 'DESC',                                                               )                                                        )                  );   $the_query = new WP_Query( $args );   Thanks a lot :)


I was studying Set theory (on a self-study basis, reading O’Leary’s book on logic and set theory and Warner’s book on Set Theory) and I came across the notation for an ordered pair. I was just wondering if that notation is just a convention.  I’ve read Eric Steinheart’s explanation in his book More Precisely:     Since sets are not ordered, it might seem like we can't use sets to define ordered pairs. But we can. Of course, the ordered pair (A, B) is not identical with the set {A, B}. It is identical with some more complex set. We want to define a set in which A and B are ordered. We want to define a set that indicates that A comes first and B comes second. We can do this by indicating the two things in the ordered pair and by distinguishing the one that comes first. One way to do this is to distinguish the first thing from the second thing by picking it out and listing it separately alongside the two things. For example: in the set { {A}, {A, B}}, the thing A is listed separately from the two things {A, B}. We can thus identify the ordered pair (A, B) with the set { {A}, {A, B}}. Notice that {{A}, {A, B}} is not identical with { {B}, {A, B} }. Hence (A, B) is not identical with (B,A).    But it doesn’t seem enough. So, I checked Enderton’s book on Set Theory and he gave a detailed explanation, but I don’t get it. Here his explanation:     I still can’t see why the notation  { {x}, {x, y}} represent an ordered pair (x,y) instead of a single element and a pair.  I know this is basic stuff, but I would appreciate if you could help me understand it.

My book says  \begin{equation} (a,b)=\{\{a\},\{a,b\}\} \end{equation}  I have been staring at this for a bit and it doesn't make sense to me. I have read several others posts on this, but none made any sense to me.  For example,   Based on how my ignorant brain is viewing this, I don't see why the definition could not be.  \begin{equation} (a,b)=\{\{a\},\{b\},\{a,b\}\} \end{equation}  aka the power set. What is the significance of the {a} in that definition? Please keep things simple if possible. Normally definitions have a valid and clear reason for being defined that way.    Clarification  First, I understand what an ordered pair is. I just don't see how the set notation says that.   Second,  \begin{equation} (a,b) = \{\{a\},\{a,b\}\}=\{\{a,b\},\{a\}\} \end{equation} Sets don't preserve order, but ordered pairs do. How does the third part of the equality apply to the definition?  Third, another issue with the notation that I have starts with the Product Property of Sets  \begin{equation} \text{Let $X$ and $Y$ be sets} :\ X=\{a,b,c\}\text{ and }Y=\{a,d,e\}. \end{equation} \begin{equation} \text{Then }X \times Y = \{(a,a),(a,d),(a,e),(b,a),(b,d),(b,e),\dots,(c,e)\} \end{equation} If we look at the first ordered pair and our given definition we have  \begin{equation} (a,a)=\{\{a\},\{a,a\}\} \end{equation}   How can this be so, you can't have duplicates in sets? I guess what I am looking for in an answer, is not a proof or a definition of ordered pairs, but rather something like, "This notation says what it says because...". Except for the second to last point I get the terminology, I just don't get the connection between the two different uses of notation.


I have a usb powerbank(w 1.1 & 2A outputs) and I would like to power a router since I have no access to a power source. My issue is the least I've seen routers rated for are 9v min. usually 12v. Im assuming I don't need to worry about amperage because that is built into USB to self-regulate. However I'm worried about voltage. I'm wondering if there is a way around this? I've searched the internet and come up with nothing.

Power supplies are available in a wide range of voltage and current ratings.  If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to specify?  What if I don't know the device's specs, but am replacing a previous power supply with particular ratings?  Is it OK to go lower voltage, or should it always be higher?  What about current?  I don't want a 10 A supply to damage my 1 A device.


While I feel that SO or SE helps people especially programmers and sysadmins to get knowledge on things they really need to do or work on I tend to feel the down votes, regulation of questions and answers, harsh words thrown to newbies tend to make it dangerous as you grow from a new contributor especially at the moment. Don't you think SO should be considered as both dangerous and helpful just like other social sites to help people with questions to ask them without fearing to get whipped with down votes or strong words.

I've posted a question or an answer, and I have received one or more downvotes. I am not really sure why I was down voted, or I think I know why, but I disagree.  Why did this happen, and what should I do about it?


I am a web designer and wanting to get into photography, so the photos I take will be mainly for websites, and sometimes for graphic design work.  Can someone please give me some suggestions on which camera model should I get? I prefer Canon. So far I got suggested Canon 1200D and 700D, but not sure on any. I don't want to spend massive money just yet, but at the same time it would be great if the camera has a bit potential so I can keep it for a while.  Thanks! Please let me know if this is dulplicate so I can remove it, but please let me know where I shall look. Thank you.

I am thinking of buying a digital SLR camera. What things should I be looking for?


I want to create a symlink that should point to another directory.   Like inside directory /var/www/vhosts/ecash-staging.com/ should be a symlink named as ecash_root   that should pointing to --> /var/www/vhosts/ecash_cfe.  How is this possible ?   I have googled but there some people said that there should be a dir ecash_root exist in /var/www/vhosts/ecash_cfe/...  but I do not want that.   i just have to create symlink in /var/..../ecash-staging.com/ name as ecash_root that should point to /var/www/vhosts/ecash_cfe but should not be a ecash_root dir inside /var/www/vhosts/ecash_cfe.  thanks to all

I am installing p4v in /opt, but /usr/bin is on my path.  Is it possible to create a soft or symbolic link for p4v from /opt to /usr/bin, so I can just type "p4v" since /usr/bin is in my path?


I'm using Linux (centos) machine, I already connected to the other system using ssh. Now my question is how can I copy files from one system to another system?  Suppose, in my environment, I have two system like System A and System B. I'm using System A machine and some other using System B machine.  How can I copy a file from System B to System A? And, copy a file from System A to System B?

If I'm logged in to a system via SSH, is there a way to copy a file back to my local system without firing up another terminal or screen session and doing scp or something similar or without doing SSH from the remote system back to the local system?


I am going to Madrid for one night so I want to see downtown Madrid.  Because I am just a student with limited budget I am wondering what is the cheapest way to go from the airport of Madrid Terminal 1 to downtown Madrid?

I've seen several options using bus and subway in Google Maps, but I am looking for both the fastest and the cheapest way. I am also looking for a way to do that with the least number of line or interface changes.


This problem is from a past qualifying exam.  Definition A group $G$ has exponent $e$ if $g^e=1$ for all $g\in G$.  Problem     Let $G=\left(\mathbb{Z}/n\mathbb{Z}\right)^\times$. Find all the integers $n$ for which $G$ has exponent $2$.   My work so far: Need to find $n$ such that $\overline{b}^2=\overline 1$ for $\overline{b} \in G$. So I need to find $n$ such that $n \mid (b^2-1)$ and $(b,n)=1$. Well, how do I now go about finding all the $n$'s. I tried a few examples like $n=1$ etc. But then I still have to deal with $b$. This kind of problem is new to me. Can somebody kindly show me what I've done wrong/right here?  May be suggest a way to go about finding these $n$'s.  Thank for your help.

I have a hard time formulating proofs.  For this problem, I  can see that if $n$ is equal to $8,$ this statement is true.  $(\mathbb{Z}/8\mathbb{Z})^{\times}$ includes elements:  $1,3,5,7$, and all of these are roots of $1-x^2 \pmod 8.$  And obviously $8$ divides $24.$  But how do I prove this without depending on number calculations and only using theorems?  Help Please?  I need a step by step walk through of how to do this proof and what theorems would be appropriate to use.


Is there a simple way to declare variables in Python similar to R's ifelse?   In R for example:  outgroup <- ifelse(politics == "Republican", 1, 0)   In Python, I'm doing:  outgroup = 0 if politics == "Republican":     outgroup = 1   Is there a simpler way of doing this in Python?

If Python does not have a ternary conditional operator, is it possible to simulate one using other language constructs?


So what's the explanation behind the difference between list() and dict() in the following example:  glist = (x for x in (1, 2, 3)) print(list(glist)) print(list(glist))  gdict = {x:y for x,y in ((1,11), (2,22), (3,33))} print(dict(gdict)) print(dict(gdict))  >>> [1, 2, 3] [] {1: 11, 2: 22, 3: 33} {1: 11, 2: 22, 3: 33}

When should you use generator expressions and when should you use list comprehensions in Python?  # Generator expression (x*2 for x in range(256))  # List comprehension [x*2 for x in range(256)]


In non-degenerate time-independent perturbation theory we see that the second order correction to the eigenstate energy exhibits 'level repulsion'. Is this a purely mathematical curiousity or is there physical intuition that can be gained here?

What is the physical/deeper reason for the  shift of the ground state energy in time independent  to be always down?  I know that it follows from the formula quite straightforwardly, but I could not find a deeper reason for it even if if I took up examples like the linear Stark effect.  Would you please tell me why?


I have two input boxes in same page.  <input type="number" class="q"  /> <input type="number" class="q"  />   if i click on 1st input box it alerts the current value.But if i click on the 2nd input box it againt alerts the 1st input box value. How would i get the current value of that 2nd input box?  Here is the jQuery function:  $(".q").on("click", function() { var orderQty = $('.q').val(); alert(orderQty) });   Problem Solved:  Working jQuery Code:  $(".q").on("click", function() { var orderQty = $(this).val(); alert(orderQty) });

I have HTML code like this :
        Link A1        Link A2        Link A3

        Link B1        Link B2        Link B3
   When user clicks a link from above HTML, I want to get the jQuery object of the corresponding  element, and then manipulate its sibling. I can't think of any way other than creating an ID for each  element, and passing that ID to an onclick event handler. I really don't want to use IDs.   Any suggestions?


Why speed of light is same in all reference frames? How classical mechanics and quantum mechanics approach this? Do they have two different answers to the question? If no, how is Classical mechanics different from Quantum mechanics?

I was told that the Galilean relative velocity rule does not apply to the speed of light. No matter how fast two objects are moving, the speed of light will remain same for both of them.   How and why is this possible?   Also, why can't anything travel faster than light?


Harry has part of Voldemort living within himself. When Voldemort's spell rebounded when he first tried to kill Harry, part of Voldemort's soul latched on to Harry, which basically makes him and Voldemort the same person (that's why Voldemort didn't kill Harry in the forest, he essentially killed part of himself).    We know that the wands choose the wizard. Draco defeated Dumbledore and became owner of the wand, then Harry "defeated" Draco and won the allegiance of the Elder Wand. However, he did this when there was still a part of Voldemort's soul living within him.    So, when Voldemort killed Harry in the forest and the two had their final battle, why was the Elder Wand not conflicted on who its master was?   Did it not recognize the part of Voldemort that lived in Harry?    Why would the wand not answer to the both of them since Harry was still part Voldemort when he "defeated" Draco?

It is possible for a wizard to be chosen by two wands, this makes me wonder if the reverse is true.  Can two or more persons having similar qualities be CHOSEN by a single wand? Moreover, is it necessary that a wizard would be chosen by a wand at all? What if the wandmaker hasn't created that particular wand by that time that would choose him.  Update:  If the wandmaker makes a wand specifically for a child, how can he be sure that the wand would choose him/her at all. At such a young age, how can a wandmaker make an idea about the child's specific qualities and temperament?


Im learning python but I dont understand what this line does? or how many options there is?

Pretty simple question: In Linux, why does Python require the line   #!/usr/bin/python   at the start of a python file, since Windows doesn't?  What does it do? 'cause the description "Links to Python" is a bit vague...


I'm using a Bootstrap template for my web app. Now in one form I'm accepting a US Zip code value from the user, submitting the form to the desired page and showing the result.  Now I have to put validations for it as follows:   The value entered by user in input field "zip_code" should only be Valid US zip code. If he/she enters invalid value then the error message in red color should appear above the text field intended for entering zip code. The form should not get submit. This validation should be done by using jQuery and on clicking of a map-marker icon which I made to behave like a submit button.   Following is the necessary HTML code snippet :

 LOGIN

 REGISTER

 STATUS

 CONTACT

 MY ACCOUNT

 SHOP DESTINATOR

       <form action="abc.php" class="navbar-form pull-right" id="formzip" method="post">         <input style="width: 115px;" type="text" placeholder="Enter the zip code" name="zip_code" id="zip_code" value="">        </form>

   As I'm a relatively new to the Bootstrap framework can someone please help me in this regard?  Thanks for spending some of your valuable time in understanding my issue. If you need any other information regarding my issue please do let me know. Any kind of help would be greatly appreciated.  Waiting for your precious replies.

I thought people would be working on little code projects together, but I don't see them, so here's an easy one:  Code that validates a valid US Zip Code. I know there are ZIP code databases out there, but there are still uses, like web pages, quick validation, and also the fact that zip codes keep getting issued, so you might want to use weak validation.  I wrote a little bit about zip codes in a side project on my wiki/blog:    There is also a new, weird type of zip code.     I can do the javascript code, but it would be interesting to see how many languages we can get here.


I'm failing at getting an acceptably positioned tick label multiplier in the following MWE of a 3D plot:  % !TeX program = lualatex \RequirePackage{luatex85} \documentclass[border=1pt]{standalone}  \usepackage{fontspec}   \usepackage{mathtools} \usepackage{siunitx}  \usepackage{xcolor}  \usepackage{tikz} \usetikzlibrary{     pgfplots.groupplots,     babel } \usepackage{pgfplots} \pgfplotsset{compat=newest} \usepackage{pgfplotstable}  \usepackage[main=ngerman,english]{babel}  \begin{document}  \centering \begin{tikzpicture}     \begin{axis}[         grid=both,         clip=false,         view={120}{45},         xmin=0,         xmax=0.01,         ymode=log,         ytick={0.01,0.1,1,10},         ymin=0,         ymax=100,         zlabel={C},     ]     \addplot3 [surf,samples=4,domain=0:0.01, y domain=1:100] {x+y};     \node at (rel axis cs:0.5,0,1) [above,sloped like x axis] {A};     \node at (rel axis cs:0,0.5,1) [above,sloped like y axis] {B};     \end{axis} \end{tikzpicture}  \end{document}   Behold how extremely far the tick label multiplier 10^-2 is away from the axis;    I'd like to have it closer or even better, at the other end of the axis.

When i use scale ticks in my plots i can't get those multiplicators to move anywhere. So basically i use plots like:   \documentclass[border=5mm]{standalone} \usepackage{pgfplots}  \begin{document}   \begin{tikzpicture}      \begin{axis}[scaled ticks=true]     \addplot coordinates { (20000,0.0005) (40000,0.0010) (60000,0.0020)};      \end{axis}   \end{tikzpicture}%  \end{document}   which gives:     So my Question is: How can i get this x tick scale label to move onto the right side of the right y-axis? So that it is above the x-axis?  (The mind behind this question is, that i sometimes have large x-labels, which then are very close to the scale label)


I want to create a custom axis for a bone to rotate around, which won't be along any one of the axis X, Y or Z. I want to use it for a concept car which uses some body panels to use it as an active air brake. So they'll be operated in an angled way.  Can anyone help...

I've been modeling an F-15, but when I rotate the flaps on Y-Axis the Flaps offset from the wing and they look like they are about to fall out, so I end up correcting it by rotating in the X and Z-axis to align them correctly.  However when I rotate them back from the Y-Axis they look distorted again because I did rotations on the X and Z axis. I tried riding it, no help. I saw something about custom orientation to fix it but that was not clearly explained and it was done on an ideal plane that was (0,0,0); mine is pre-rotated on all axis.   I'll take scripts if needed and I'm using Blender 2.8.  When I rotate it on the Y-Axis:    Fixing it using X and Z rotation:    Rotating it back on the Y distorted it again:    Here's the wing with ailerons and flaps:


I have all levels 100%, a few levels over 100%. I have 13814 gems and 140 eggs. But my game total is only 91%?  I have gone through the guidebook over and over, I can't seem to find the rest of what I'm missing.

I’ve just finished Spyro Year of the Dragon on the Reignited Trilogy and want to play the bonus mission, but I’m missing 3 eggs and 400 gems.   I have 100% in all levels and 111% in midnight mountains. I also have all the skill points if that matters. Anyone know where I’m missing the gems and eggs???


I was watching "Shattered Sight" in season 4 again, and I realized something. When Emma asks Ingrid the reason she didn't grow up, she said that no one grows up in Storybrooke.  But Ingrid was not cursed, just like Henry. So why did Henry grow up and she didn't?

I just started watching the second season of the show so if my question will be answered later just let me know without any spoilers please. Now my actual question: Henry was born when Emma was 18. She gave him up for adoption at Storybrook. People in Storybrook have had the same age for 28 years. I suppose for the last 28 years they did not notice time passing and they did not create any new memories? (similar to the Memento guy?). But Henry was aging. He was taken to the village at age 0 and he found Emma when he was 10. Since all other characters do not age didn't anyone notice Henry changing classes every year while they stayed in the same class? Didn't anyone notice him growing up every year and them staying the same? If it's a memory thing (they forget at the end of the year or something like that) then wouldn't Regina expect that Henry would eventually realise that something is really wrong? (as he did at the start of the show)


I'm in Junior High and I still have some confusion towards speed and velocity. They sound like the same thing, where some object moves in a given direction, but there is a difference from both topics. So where does speed and velocity differ from their characteristics?

What is the difference between Speed, Velocity and Acceleration? Could any one describe it pictorially?. I am more over confused even after investigating many times. I am unable to relate myself practically.


I have noticed (with tea bags, etc) that if you get the whole string wet, and you have one end inside the cup and the other end below the level of the liquid (outside), the water drains down the string outside the cup at a slow pace... Seeming to defy gravity and move its way up the string until it gets to the cup edge...  What is this effect called, and do we observe it in nature at a larger scale somewhere?

When I dip a paper towel in a cup of water the water gets drawn up due to . How is this reconciled with conservation of energy, as it would seem on the surface that the potential energy of the system has gone up with no work being done?


Currently, I am creating something that will simply allow me to create tasks, click them when they are done and swipe left to get rid of them. The problem I am having is that when the new tasks are appended, they are not affected by any of the JQuery events on in the script.  Tl;dr: appended divs are not affected by the below javascript, how can I fix this issue?

Tasks
      <form class="createTask">       <input type="text" class="createTaskInput" size="10" maxlength="25" placeholder="Type here to create your task..." //>     </form>

This is an example task
When you complete a task, click the red button
Should you want to remove a task, swipe left on the task.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Heart hammering, Harry pushed his trolley after them. They stopped and so did he, just near enough to hear what they were saying.   'Now, what's the platform number?' said the boys' mother.   'Nine and three-quarters!' piped a small girl, also red-headed, who was holding her hand.   'Mum, can't I go...'   'You're not old enough, Ginny, now be quiet. All right, Percy, you go first.'   (Harry Potter and the Philosopher's Stone, Chapter Six, "The Journey from Platform Nine and Three-Quarters")   Now, as far as I'm aware, Hogwarts Express always departs from Platform Nine and Three-Quarters.  And Molly have been there innumerable times, both as a student, and many many years prior to Book 1 with older Weasley kids going to school.  Hell, she even knows easily how to get onto a platform:     'Not to worry,' she said. 'All you have to do is walk straight at the barrier between platforms nine and ten. Don't stop and don't be scared you'll crash into it, that's very important. Best do it at a bit of a run if you're nervous. Go on, go now before Ron.'   So why did she not know/remember the platform #?

In the first Harry Potter book, Molly is seen asking her children "what platform number is it again?"      Heart hammering, Harry pushed his trolley after them. They stopped and so did he, just near enough to hear what they were saying.   'Now, what's the platform number?' said the boys' mother.   'Nine and three-quarters!' piped a small girl, also red-headed, who was holding her hand. 'Mum, can't I go...'   'You're not old enough, Ginny, now be quiet. All right, Percy, you go first.'   (Harry Potter and the Philosopher's Stone, Chapter Six, "The Journey from Platform Nine and Three-Quarters")   Why didn't she remember on her own? She would have been bringing kids there for the past 10 or so years, not to mention her own years at Hogwarts.


I am building a site with 5 different custom post types on and would like to create an archive page that pulls in all of these posts and then sorts them by the standard WP date order.   Instead of adding this 'all' category manually each time I add a custom post type post, is there anyway of giving a custom post type a custom taxonomy that is created / assigned each time a new post is created? I would then add any additional custom taxonomies manually when I do a post.  To show this 'all' taxonomy I would add a custom taxonomy archive page that would then show all of the custom post types.  Any help would be wonderful.

Wordpress default taxonomy (Categories) has the item Uncategorized by default. How to add a default item to a new custom taxonomy?  functions.php:  // === CUSTOM TAXONOMIES === // function my_custom_taxonomies() {     register_taxonomy(         'block',        // internal name = machine-readable taxonomy name         'static_content',       // object type = post, page, link, or custom post-type         array(             'hierarchical' => true,             'labels' => array(                 'name' => __( 'Blocks' ),                 'singular_name' => __( 'Block' ),                 'add_new_item' => 'Add New Block',                 'edit_item' => 'Edit Block',                 'new_item' => 'New Block',                 'search_items' => 'Search Block',                 'not_found' => 'No Block found',                 'not_found_in_trash' => 'No Block found in trash',             ),             'query_var' => true,    // enable taxonomy-specific querying             'rewrite' => array( 'slug' => 'block' ),    // pretty permalinks for your taxonomy?         )     ); } add_action('init', 'my_custom_taxonomies', 0);   EDIT: I just want to have the taxonomy item there when the theme is installed. It doesn't have to automatically be added to any empty term.


In  (page 16), Prof. Sanjoy Mahajan states that $$ \displaystyle\int_{0}^{\infty} \frac {1}{1+x^2} \, \mathrm{d}x = 2 \cdot \displaystyle\int_{0}^{1} \frac {1}{1+x^2} \, \mathrm{d}x $$  I realize this is equivalent to saying that  $$\displaystyle\int_{0}^{1} \frac {1}{1+x^2} \, \mathrm{d}x = \displaystyle\int_{1}^{\infty} \frac  {1}{1+x^2} \, \mathrm{d}x, $$  but why  is this true?

I was reading an article in which it was stated that, with a change of variable, one could show that:  $$\int_{0}^{\infty} \frac{dx}{1 + x^2} = 2 \int_0^1 \frac{dx}{1 + x^2}$$  I tried with $t = 1 + \frac{1}{x}$ but that doesn't work out, especially because the lower bound doesn't become $0$.


I've been racking my brain on this one! It aired in the 80s as what could have been an Outer Limits or Twilight Zone episode?   The woman had the perfect family when suddenly, the program shuts down and she finds herself in a VR pod or chamber. There are technicians discussing a malfunction in her pod and the camera zooms out to show hundreds of other chambers. I know; it sounds like 50 other movies or tv shows that do exactly the same thing.

Back in the mid/late 90s I saw a show where a woman and man were having a picnic in a beautiful park. The woman fell asleep and woke up with (maybe) doctors around her that told her everything was okay and to close her eyes. She woke back up at the picnic with the man, and thought she had a bad dream. Then things started “glitching” in the park, kind of like when the holodeck malfunctions in Star Trek.  She then wakes back up with several people around her (maybe doctors) who say she’s in shock and dying. After she dies, the (maybe doctors) say something like “she’s the third one this week” or something like that. The camera pans out and shows that everyone was in a giant building or maybe a ship, and she had been plugged in some kind of machine like The Matrix.


I'm getting E: The repository 'http://ppa.launchpad.net/deadsnakes/ppa/ubuntu hirsute Release' does not have a Release file. While running sudo apt update in a LTS 20.04 server, I'm currently trying to install python3 but it seems it's not being found either. Not sure what to do. Any assistance?

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


This output/plot i want to create:   How can i do this? Thank you in advance. Best Regards. This is my 2D diagram code. I have 3 input colums (x-coordinate,y-coordinate,value)  \documentclass{article} \usepackage{tikz,pgfplots}  \begin{document} \pgfplotsset{width=15cm,height=10cm} \begin{tikzpicture} \begin{axis}[colorbar sampled,     colorbar style={samples=13},     grid=both,     scale only axis=true,     width=10cm,     height=15cm,     xtick={0,1,...,10},     ytick={-8,-7,...,10},     xmin=0,     xmax=10,     ymin=-8,     ymax=8,     ]  \addplot3[     scatter,mark=text, text mark={\rule{6mm}{3mm}},only marks,     point meta=\thisrow{myvalue}     ]     table {     x y color myvalue 2 3 1 100 4 3 2 3 2 7 3 0.75 7 7 4 45 8 5 2 3 2 5 1 10 4 -4 2 1 4 1 3 75 5 -1 4 4 5 2 2 3 1 -2 1 10 2 5 2 5 3 -8 3 75 4 5 4 42 7 -2 2 2     }; \end{axis} \end{tikzpicture}  \end{document}

I have a simple 3d histogram    which I want to import into pgfplots, e.g. using matlab2tikz or by hand.  PGFplots does not offer 3d histograms.  Is there an easy way to do this?


Can I "upgrade" my old 32-bit IBM ThinkPad to 64-bit by installing a new hard disk?  I am running Ubuntu 14.04 but want to upgrade to a newer Ubuntu system. Can Anyone help this novice with that?

As per title, I wish to know if I can, after a successful 32bit setup and consequent software installations, update to a 64bit version.  I know how to partition (actually one of the solutions is to set /, /etc, /home, /var/www, and /opt as separate partitions) and I know that a clean install is way better than a dirty one, yet I would like to know if/how it's possible to do that.


Short story, published before 1976.  Humanity has spread along the circumference of the galaxy (apparently avoiding the core), and diversified.  The main characters are a married couple of a hairless race. They charter(?) a ship to follow evidence of alien intelligence (humanity having never found any before). The captain of the ship is of The Men, an all-male society who celebrate nature by always going naked.  (One of the couple says, “I'd swear they sort their genes for hairiness. Did you notice he actually has eyebrows?”)  We track down the aliens and make contact.  They like sulfur in their air, but upon comparison of biochemistry we find that they are humans too, whose ancestors spread around the galaxy in the other direction.  The two parties then turn their gaze to the Andromeda Galaxy, remarking that it's a forbidding project but we must do it.

I'm looking for a plot line (it should be a short story) that depicts Earth population (or their close descendants) establishing contact with another intelligent life form deep into space.   After careful studying of DNA samples and language / communication symbols they then realize that the civilization in question is also from Earth but that they departed very long ago and travelled throughout the galaxy in the completely opposite direction so that they are now meeting practically at the point of the circle opposite to Earth. There might have been some anatomical differences as well.  As far as I can remember, the story concludes shortly after that.  This should be a work of a well-known SF author, so I'm hoping for a quick response (if time didn't corrupt my memory too much).  I don't think it was part of an anthology, but it's entirely possible it was in a magazine.  As for the timeline, I've read it about 2-3 years ago, but since I have a passion for older SF works it might not be of much use.  Edit: Not sure if this could help but for what it's worth, it might be contained in .


I'm using the tufte-handoutclass, but I want to deviate slightly from the template. I would like to separate paragraphs through a small space, not through indentation.   I usually do this in my Latex documents by adding:  \setlength{\parskip}{1.2ex} % show new paragraphs with a space between lines \setlength{\parindent}{0em} % get rid of indentation for new paragraph   This works for the extra space between the paragraph, but it doesn't get rid of the indentation.  Here is a working example:  \documentclass{tufte-handout}  \setlength{\parskip}{1.2ex} % show new paragraphs with a space between lines \setlength{\parindent}{0em} % get rid of indentation for new paragraph  \begin{document}  Lorem ipsum dolor sit amet, consectetur adipiscing elit. Maecenas libero erat, bibendum ut tellus quis, rhoncus viverra lacus. Donec vestibulum, arcu tempor aliquam posuere, odio risus consectetur lectus, nec vestibulum lorem tellus vitae est. Interdum et malesuada fames ac ante ipsum primis in faucibus. Maecenas neque ligula, euismod non vulputate sit amet, ultricies congue velit. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Phasellus eget quam massa. Donec facilisis tempus consequat. Donec tempor viverra justo. Praesent tempus rhoncus massa sit amet hendrerit. Interdum et malesuada fames ac ante ipsum primis in faucibus. Mauris non leo justo. Donec dapibus laoreet luctus. Sed rhoncus mi ante, quis tristique libero tempor at.  Quisque sit amet sem nec nunc pellentesque ultricies sed quis mauris. Donec vitae condimentum lacus. Fusce nec pretium tellus. Nulla molestie at nulla ut sagittis. Pellentesque imperdiet elit in neque convallis vestibulum. Aliquam lorem libero, vehicula sed semper sit amet, dapibus eget sem. Morbi eu ultrices odio.  Morbi mattis mi in mauris condimentum, non viverra orci ullamcorper. Aenean auctor erat a commodo convallis. Nunc metus nisl, ornare a ligula vel, aliquet accumsan erat. Sed id finibus magna, non porttitor odio. Nunc ut faucibus nisl. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Proin lacinia venenatis mi. Morbi massa metus, mattis vel nulla quis, molestie fermentum ligula. Donec vitae lacus ac tellus imperdiet mollis. Aliquam quis augue vitae mi finibus scelerisque ac id nisi. Quisque orci eros, placerat in dui sit amet, sodales euismod elit.  \end{document}   Which looks like this:   Any comments would be highly appreciated.

I'm using tufte-latex and I want paragraphs to have no indent, but a line skip instead. Normally you can achive this with:  \usepackage[parfill]{parskip}   Using tufte-latex this does not work however. So how do I do this?


we are working on the online exam system, which supposed to have much traffic at the same times, more than 15000 students will log in and make an exam at the same time, we are developing this system using laravel + MySQL database. recently we purchase a dedicated server with 64G ram, 42 core. what is the best architecture for this dedicated server to handle these many requests at the same time , I am thinking to install containers inside that server and split it as  2 containers as web servers with Nginx and apply load balance between them using haproxy . 2 for MySQL database and apply load balancing. 1 for cache server using Redis server  but I am not sure if this way is good or not. please advise me to handle this issue, I am waiting for your recommendation best regards

This is a  about capacity planning for web sites. Related:      What are some recommended tools and methods of capacity planning for web sites and web-applications? Please feel free to describe different tools and techniques for different web-servers, frameworks, etc., as well as best-practices that apply to web servers in general.


OK we can change the content at any frequency. But what about <title>, description-meta tag, keywords meta tag. I think if we change title, description, keywords of any website daily, then that may affect page ranking. What is the real fact? What is the minimum and maximum rate of frequency to change these items? Legal practice may different from successful practice. Please explain me.  NOTE:  If this type of question answered before, then mention the link and please don't close or ban the question.

Lets say my website looks like this:  News -Hello world -Foo -Bar  So the parent page will list the last 3 news messages. For each news message there is a sub-page. For the parent page I was thinking of setting the page title to: News - Hello world, Foo, Bar.  Now if somebody adds a new message the title tag will also change. I googled this and read a few blog posts where people said that changing the title actually hurts the ranking of that page.  So is this true? Should I just set a static title tag for all my pages?


I want a query or trigger that will identify what changes done in the database tables from the Third Party Software such CMS etc. I want to check that which data is modifying with time. There is no log maintained in that Third Party Software so i want to check it thorugh SQL Server

I'm working on a request to start logging some additional data for PCI compliance.  I need to log who, when, and what changed on a set of tables.  I set up SQL auditing which would work fine except for the fact that the values of what is being changed is coming through as @1, @2 etc instead of the actual data.  What are my other options for logging the needed information?  CDC does not track who made the change.  This is currently running on SQL Server 2012 but a possible upgrade to 2014 is possible if that would provide a better solution.  Thanks, Tim


Using K-Fold, I chose to use Logistic Regression for a project of mine.  I made it learn on my X_train (80% of data), and tested it on my X_test, with good results.  My question is : now that I need the model to be used, can I rebuilt the model with the same parameters but on all my data ? Will there be overfitting, or maybe as I saw that those parameters doesn't, will it be safe ?

A common technique after training, validating and testing the Machine Learning model of preference is to use the complete dataset, including the testing subset, to train a final model to deploy it on, e.g. a product.      My question is: Is it always for the best to do so? What if the   performance actually deteriorates?   For example, let us assume a case where the model scores around 65% in classifying the testing subset. This could mean that either the model is trained insufficiently OR that the testing subset consists of outliers. In the latter case, training the final model with them would decrease its performance and you find out only after deploying it.   Re-phrasing my initial question:     If you had a one-time demonstration of a model, such as deploying it   on embedded electronics on-board an expensive rocket experiment, would you trust a   model that has been re-trained with the test subset in the final step without being   re-tested on its new performance?


I need some help with a proof:  Let $gcd(k,n)=1, w_n = e^{2*\pi*i/n}$ and $w_n^k = e^{2*\pi*i*k/n}$. Show that the equation $ <w_n> = <w_n^k>$ holds, where $<x>$ = {$x^n|n \in N_0 $}   Is it necessary to show, that $w_n^k$ is primitive, if $gcd(k,n)=1$ holds?

Say a cyclic group of order $9$ is denoted by $G = \langle g \rangle$. I have a claim that  $\langle g^k \rangle = G $ whenever $k$ is a unit in $\mathbb{Z}_9$. I'm struggling to understand why this is true. Is this specific to order 9? In general, for a group of order $n$, do we require that $k$'s multiplicative inverse in $\mathbb{Z}_n$ be $n$ itself? Otherwise the generating group will be of order less than $n$, and thus cannot be equal to the group.


I am working with Facebook API using the restfb library of Java. I wrote a code to get a user's timeline posts but I am keep getting the java.lang.NullPointerException error.  import com.restfb.Connection; import com.restfb.DefaultFacebookClient; import com.restfb.FacebookClient; import com.restfb.types.Page; import com.restfb.types.Post; import com.restfb.types.User; import java.util.List;  public class FacebookAPI {       public static void main(String[] args) {         String accessToken = ""; //No I did not forget that         FacebookClient fbClient = new DefaultFacebookClient(accessToken);         //For some reasons the "DefaultFacebookClient" object is shown strikethrough formated in my IDE, idk what it means.          Page page = fbClient.fetchObject("BillGates", Page.class);         Connection<Post> postFeed = fbClient.fetchConnection(page.getId()+"/feed",Post.class);             for(List<Post> postPage : postFeed){                 for(Post aPost : postPage){                     System.out.println(aPost.getFrom().getName());                     System.out.println("-->"+aPost.getMessage());                     System.out.println("fb.com/"+aPost.getId());                  }             }      }  }      Output:      Exception in thread "main" java.lang.NullPointerException     at   facebookapi.FacebookAPI.main(FacebookAPI.java:34)   Line 34 is the second for loop.

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?


Android OS can be used on desktop computers or laptops ? I mean like a windows or IOS or linux something.

How to install Android OS and Android Apps on PC ? If possible , android 4.0.3 .


I co-signed my boyfriends auto loan so he could trade in his car and opt for lower car payments. I received a red light traffic ticket in the mail with my name on it, which i thought was odd. So I contacted the financial company (Ally) and turns out I am the primary account holder.  After looking into it some more turns out the car dealership ran several inquires to get approved without notifying me that they were going to do so. Is there anything I can do legally to get my name off the loan or sell the car back to the dealership. Everything was done over the phone, so I never signed any legal documents.  Thank you!

I co-signed a car and want to be removed. My first thing is that I am listed as the primary account holder for the loan, but I signed the papers as the co-signer/co-buyer. If to fix the situation as being the primary account holder means refinancing needs to be done, what can the primary buyer do to be refinanced if she needed my credit score in able to get the car.  Also, what can I do if she is not able to be refinanced?


so please tell me whether the windows data is wiped out or still it is accessible

I have a Toshiba satellite A-200 laptop with a Vista OS on it with 4 NTFS partitions  (C:) Vista  (D:) Entertainment  (E:) Work  (F:) Sources   and I wanted to start using Ubuntu instead. So I tried it first from the live CD and everything was OK and all the partitions were shown and working and so I decided to install Ubuntu to replace Vista on the (C:) drive. After I did that I can no longer find my folders and files on the (D:), (E:), (F:) partitions and the only file system that is shown is one 198 GB although my HDD is 320 GB.  I can't access the lost data on the remaining 120 GB which I hope is still there and not totally lost  I am now working from the live CD but I am unable to install testdisk. Can I recover the Vista partitions by the product recovery CD to get my laptop back to the factory settings? Can I recover the NTFS partitions using a recovery program for Windows or will that make the problem worse?   I need these data badly as I don't have a backup for them.


I recognize that a rational number a/b means that b does not divide a and also that a and b are relatively prime. Does that mean rational numbers are always expressed in their simplest form? Or is my statement about coprime wrong? I have tried using Euclid's Algorithm and Bezout's Identity, since that is the section that the question comes from but I have not gotten it to work out. Please Help.

It is well known that $\sqrt{2}$ is irrational, and by modifying the proof (replacing 'even' with 'divisible by $3$'), one can prove that $\sqrt{3}$ is irrational, as well.  On the other hand, clearly $\sqrt{n^2} = n$ for any positive integer $n$.  It seems that any positive integer has a square root that is either an integer or irrational number.        How do we prove that if $a \in  \mathbb N$, then $\sqrt a$ is an integer or an irrational number?      I also notice that I can modify the proof that $\sqrt{2}$ is irrational to prove that $\sqrt[3]{2}, \sqrt[4]{2}, \cdots$ are all irrational.  This suggests we can extend the previous result to other radicals.        Can we extend 1? That is, can we show that for any $a, b \in \mathbb{N}$, $a^{1/b}$ is either an integer or irrational?


I was looking at the question "what feedback exactly means"(applied in Op-amps). In the negative feedback even though there is a decrease in the op-amps overall gain, it's widely used because it improves the frequency response of the operational amplifier. So what does this mean exactly?

Have a look at the diagram above.  It shows an op-amp with negative feedback.  Ignoring the feedback loop for now, the voltage (pressure) coming from the 5V battery, acting on the inverting pin, should amount to 5V.  Now, I understand that the feedback loop is adjusting the voltage on the inverting pin to make it equal to the reference (non-inverting) pin or 3.3V and you can clearly see that the output is producing a negative voltage to achieve this.  I also understand that the input pins have a very high impedance.  What's confusing me is how it actually does this (considering my rudimentary knowledge of electronics).  I considered that the output was sinking some of the current produced (by the battery) to alleviate the pressure on the input pin and bring it down to 3.3V, but clearly that isn't the case (since the 1 ohm resistor is passing 5A).  So, I'm struggling to understand how 5V of pressure from the battery results in 3.3V on the input pin.  I'd appreciate it if somebody could explain this in an intuitive way.  Much Appreciated.  Edit:  Many thanks for your all your comments and insights.  The circuit itself is a distraction.  At the heart of this is my attempt to understand op-amp and negative feedback behaviour.  I wanted to understand the following:  a) if you could apply an input voltage to the op-amp that was different to the reference voltage (more specifically that you have voltage "pressure" acting on the input pin that is higher than the reference pin). This also assumes that you have some other input other than the feedback loop.  b) if a is true (and assuming that the op-amp adjusts its output to equalize the voltage on both pins) how is this achieved?  Clearly the feedback loop plays a part and the only thing I could think of was that the output was sinking current to take the pressure off the input pin and thus explain the voltage drop between the between the higher voltage source and the voltage appearing at the input pin.  Incidentally, the question would still stand even if you had a resistor between the source voltage and the feedback loop/input pin junction.  A better circuit example is shown below (taken from ):    But with V1 set to some voltage other than 0V.  Final Edit (Promise!):  From the electronics tutorial article linked above:  "This negative feedback results in the inverting input terminal having a different signal on it than the actual input voltage as it will be the sum of the input voltage plus the negative feedback voltage giving it the label or term of a Summing Point."  This is exactly where my confusion lies.  As I understand it voltage is simply pressure exerted measured with respect to some reference point (usually ground).  What the paragraph above is suggesting is that at the "summing point" there's a change in voltage (pressure) because of the addition of the feedback voltage.  Intuitively, I'm thinking that the output pin "sinks" some current to reduce the voltage at the summing point.  But that sinking of current would reduce Iin (since no current flows through the inverting pin).  The result would seem to be that Vin drops.  But is this the case?


Is there any way to create and access multiple workspaces in Ubuntu 15.04.

I was reading about , however since Compiz is replacing Mutter how do I go about adding and removing workspaces in Compiz version of Unity?


In this when it comes to for loop and "id" it's shows null point exception. i commented all intgers and then code works fine.can anyone say what's the wrong of my code...   public List<HotelRoom> getallstudent() {             String sql = "SELECT * FROM hotelroom";              List<HotelRoom> list = new ArrayList<HotelRoom>();              List<Map<String, Object>> rows = jdbcTemplate.queryForList(sql);              int id = 0;             int numBed = 0;             long prce = 0;             int size = 0;              for (Map row : rows) {                 HotelRoom hm = new HotelRoom();                   id = Integer.parseInt(row.get("id").toString());                  numBed = Integer.parseInt(row.get("numberOfBeds").toString());                  prce = Long.parseLong(row.get("price").toString());                  size = Integer.parseInt(row.get("size").toString());                  hm.setId(id);                 hm.setGuestHouseName(row.get("guestHouseName").toString());                 hm.setImageLocation(row.get("imageLocation").toString());                 hm.setLocation(row.get("location").toString());                 hm.setNumberOfBeds(numBed);                 hm.setPrice(prce);                 hm.setRoomType(row.get("roomType").toString());                 hm.setSize(size);                  list.add(hm);             }             return list;          }


This is a rather strange bug, it's not terribly crippling, and I can only reproduce it a small number of times for obvious reasons, but here you go:   I followed a link to a Q&A in the Hot Network Questions (to crypto.SE, if that matters). I found the Q&A interesting so I wanted to upvote them, but didn't have an account on crypto.SE yet. I clicked "join this community" at the top, confirmed the account creation, and was redirected to the Q&A. I was able to upvote the question, but when I tried to upvote an answer I was told by a little red popup "You must be logged in to upvote an answer" (or something to that effect). When I reloaded the page I was no longer logged in. I logged in again, and was then able to upvote the answer. From then on everything worked as expected.   What happened here?

I've created account on Server Fault with the "Join this community" button. It seems to be created as I see my picture and a starting 101 reputation on top. But when I tried to upvote I got a message I need to login and where I clicked on a different question it showed me I'm not logged in.    I think it didn't even create my account since later I clicked the signup button again, it asked me with which Google account I want to create it (I've two associated with my Chrome browser).


Can  anyone  explain  me  on  a  simple  example  the  difference  between  mutable  and  immutable  objects  in  java?

I'm trying to get my head around mutable vs immutable objects. Using mutable objects gets a lot of bad press (e.g. returning an array of strings from a method) but I'm having trouble understanding what the negative impacts are of this. What are the best practices around using mutable objects? Should you avoid them whenever possible?


I have a valid US B-1 visa, so just wanted to check if I can transit via Seattle.  And if my connection flight is only 1.30 hours, will I be still able to  make it?

I'm passing through Canada, on my way to somewhere else. I'm staying only a short time.   Is there a website, or some other way of find out out if I need a visa?


I'm used to insert a space after a command by using the {}, e.g. \mycommand{} some other text, in order to circumvent the space-gobbling of commands.  I'm wondering if it's best or what are the specific drawbacks or differences between the following:  \mycommand{} some text  \mycommand\ some text  \mycommand\space some text   is it a matter of habit or do the spaces and mechanics differ?  Thanks

I have a definition:  \newcommand{\arnold}{Arnold Schwarzenegger}   When I refer to it by:  \arnold is a   it is rendered as:   Arnold Schwarzeneggeris a    In order to have a space in front of "is" I would need to write  \arnold\ is a   Is there some other shorter way?


I am editing a document that includes sentences such as "John Doe is a Professor of English" and "Jane Doe is the Director of Public Policy." In this context, are the titles of their jobs, "Professor of English" and " Director of Public Policy," supposed to be capitalized?

Would you capitalize the job title in the following sentence?      I am writing this letter in regard to Joe Brown who is applying for the director of teaching and learning position in the XYZ School District.


On my laptop Ubuntu 18 is installed. But I want windows 10 back. So I created win10 bootable usb stick on another computer using rufus. But I couldn't boot it when computer starts. I select usb on boot selection, but still purple screen appears. And then ubuntu starts like normally. I dont know what to do now. Please help me, how can i get to windows 10 installing screen? Thanks.

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


I found a feature request at  but it doesn't seem easy to get a column view with Nautilus while with Mac OS X it's a default feature.  Have I missed something or is this not currently possible?

How can I navigate folders and subfolders at the same time?  Like "column view" in Mac OS X.    Edit 2: I use Ubuntu 14.04 and I couldn't install Marlin, so I installed "Pantheon File Manager" instead.


What does the "5k1" stands for it is a normal 5k Ohm resistor?   (Marked with "A" in the picture)   The chip is an  LIN-transceiver.

While reading a datasheet for an IC I came across the pin voltages being presented as 3V3 or 1V8. What does this representation stand for?


I have program called gen.exe, which prints 1 to ..... It just keeps prints and saves them in file. Now, in my .net application I'm using the following code to create a process and to run the program : process = new Process                 {                     StartInfo =                     {                         FileName = "gen"//defined in filepath or in the same directory                      }                 };                 process.Start();  Now I want to terminate this process. But when I use kill, it closes the console and some numbers printed at very last doesn't appear on the file and sometimes it says file is corrupted. All I want is a simple cancellation of the process, just like pressing CTRL + C. How can I achieve this ? I have tried Dispose, Close, Kill.

I'm writing a wrapper class for a command line executable.  This exe accepts input from stdin until I hit Ctrl+C in the command prompt shell, in which case it prints output to stdout based on the input.  I want to simulate that Ctrl+C press in C# code, sending the kill command to a .NET Process object.  I've tried calling Process.Kill(), but that doesn't seem to give me anything in the process's StandardOutput StreamReader.  Might there be anything I'm not doing right?  Here's the code I'm trying to use:  ProcessStartInfo info = new ProcessStartInfo(exe, args); info.RedirectStandardError = true; info.RedirectStandardInput = true; info.RedirectStandardOutput = true; info.UseShellExecute = false; Process p = Process.Start(info);  p.StandardInput.AutoFlush = true; p.StandardInput.WriteLine(scriptcode);  p.Kill();  string error = p.StandardError.ReadToEnd(); if (!String.IsNullOrEmpty(error))  {     throw new Exception(error); } string output = p.StandardOutput.ReadToEnd();   The output is always empty, even though I get data back from stdout when I run the exe manually.  Edit: This is C# 2.0 by the way.


It's been like this for me since my first day on SE.  While typing text into bounty comment text field, when the text stops fitting, the text field (or the whole pop-up window even) scrolls to the right a bit to maintain visibility of the last few characters, shortly after that it forcefully word-wraps while leaving the scroll position slightly to the right, and creates the following visual artifact:    I'm using Firefox Aurora and this has been my experience for a long time.

I was attempting to create a bounty for a question over on Stack Overflow and ran into a rendering glitch on the last page. After entering a sentence that exceeds the length of a single line, the popup contents scroll slightly to the right and strange characters start showing up:    There is no '(' in my sentence so it's strange that it's showing up in the textarea. When you move the cursor it around the line edge, the textarea scrolls from right to left and back.  Here's what I've got:   Ubuntu 12.10 64-bit Firefox 18.0.2   This is also occurring on Firefox 24.0 on Windows 7 Enterprise Service Pack 1.    The data entry starts out fine:    Then it goes all wacky as I complete the second line:


I have a male aggron in an pokeball and a ditto in a luxury ball. i have tried breeding them but i get babies in an pokeball instead of the luxury ball. is there something im missing?  i also have Pokemon Y if that may be a problem?

I plan on breeding two pokemon (one in a timer ball and one in a pokeball) and I want the pokemon to be in a normal Pokeball. Which one will it get?


Is there any shorter way of doing this?  Map<String, Integer> values = new HashMap<String, Integer>(); values.put("A", 1); values.put("E", 1); values.put("D", 2); values.put("R", 2); values.put("B", 3); values.put("M", 3); values.put("V", 4); values.put("Y", 4); values.put("J", 8); values.put("X", 8);   With arrays in Java you can do this for example  int[] temp = {1,2};   instead of  int[] temp = new int[2] temp[0] = 1; temp[1] = 2;   I am looking to something similar with the Map above. Is that possible?  Thanks for the help, as always :)

How would you initialise a static Map in Java?  Method one: static initialiser  Method two: instance initialiser (anonymous subclass) or some other method?  What are the pros and cons of each?  Here is an example illustrating the two methods:  import java.util.HashMap; import java.util.Map;  public class Test {     private static final Map<Integer, String> myMap = new HashMap<>();     static {         myMap.put(1, "one");         myMap.put(2, "two");     }      private static final Map<Integer, String> myMap2 = new HashMap<>(){         {             put(1, "one");             put(2, "two");         }     }; }


I downloaded and installed the latest version of Ubuntu the other day. I rebooted after the install. Got the four dots okay but then instead of getting the logon screen, the screen went black. I have to restart the computer. I can run: Advanced options Ubuntu, with Linux 3.13.0-24-Generic (Recovery Mode) or Ubuntu, with Linux 3.11.0-19-Generic

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


If the Hilbert curve maps the interval [0,1] onto the unit square, is there a formula that tells us where a given point $x \in [0,1]$ will be taken?  EDIT: For example, it seems intuitive that $0$ is mapped to $(0,0)$, $1$ is mapped to $(0,1)$, and $\frac{1}{2}$ is mapped to $(\frac{1}{2},\frac{1}{2})$, ...

The Hilbert curve has always bugged me because it had no closed equation or function that I could find. What is its equation or function? For example, if I wanted to find the Hilbert's curve point at 4/7, how would I find it?


This is the listing that I have created. I want to highlight eg. lines 8,9 and 10. Using and escaped \colorbox  didnt work to my expectations because it altered the style of the code making the font smaller thus messing up the alignment of the code.  \begin{lstlisting}[breaklines,caption=Output of disassemble main] (gdb) disassemble  Dump of assembler code for function main: 0x08048344 <main+0>:    lea    0x4(%esp),%ecx 0x08048348 <main+4>:    and    $0xfffffff0,%esp 0x0804834b <main+7>:    pushl  -0x4(%ecx) 0x0804834e <main+10>:   push   %ebp 0x0804834f <main+11>:   mov    %esp,%ebp 0x08048351 <main+13>:   push   %ecx 0x08048352 <main+14>:   sub    $0x10,%esp 0x08048355 <main+17>:   movl   $0x57,-0x10(%ebp) 0x0804835c <main+24>:   movl   $0x3,-0xc(%ebp)} 0x08048363 <main+31>:   mov    -0xc(%ebp),%eax 0x08048366 <main+34>:   add    -0x10(%ebp),%eax 0x08048369 <main+37>:   mov    %eax,-0x8(%ebp) 0x0804836c <main+40>:   mov    $0x0,%eax 0x08048371 <main+45>:   add    $0x10,%esp 0x08048374 <main+48>:   pop    %ecx 0x08048375 <main+49>:   pop    %ebp 0x08048376 <main+50>:   lea    -0x4(%ecx),%esp 0x08048379 <main+53>:   ret     End of assembler dump.   \end{lstlisting}   Is there a package where I can comfortably tell it to highlight some lines  I feed into it ?

I’m using the listings package for code listings. Now I try to highlight some part of the code using \hl from the soul package.  Here’s an example of a resulting query where the injected part of a SQL injection should be highlighted:  \begin{lstlisting}[escapechar=@,language=SQL] SELECT name, password FROM users WHERE name='@\hl{' UNION SELECT "10", 1 \#}@'; \end{lstlisting}   But inside the highlighted part the SQL syntax highlighting is not applied.  So I tried to use \lstlinline for the code part inside \hl as well but it didn’t work:  \begin{lstlisting}[escapechar=@,language=SQL] SELECT name, password FROM users WHERE name='@\hl{\lstinline[language=SQL]$' UNION SELECT "10", 1 #$}@'; \end{lstlisting}   Although this \lstinline part works outside the lstlisting block, it doesn’t work inside it. The error I get for that particular line is:     Extra }, or forgotten \endgroup.   Maybe I’m just missing just some special syntax to get this working. Or is it not possible at all to get proper syntax highlighting for the \hl-highlighted part as well?


Ive installed Ubuntu 20.04 on my Dell inspiron 1545 model (2010), purely for use as self hosted cloud storage server, but Ive been struggling to get the wifi to work ( I also tried installing virtualbox on it, but because my chip does not support virtualization i cannot use ubuntu on virtual box). I just want to know if ubuntu 20.04 will be able to run successfully on my older dell computer or am I wasting my time trying to set it up ? So far I cannot even pick up the wifi signal with the wifi router a meter away (but it does pick up my neighbor’s wifi for some reason). Im very new to ubuntu and would really appreciate some help.

I have a device on which I would like to install Ubuntu. How do I find out if Ubuntu will work on it?


Let's say you need to take a photo of a 200 feet wide wall, but can't move further away from it than 50 feet (won't get the entire wall in one photo).  Currently, I stand still, and take a bunch of photos from side to side in a rotating motion, and then stitch them together (like a panorama function would do). But that gives a heavily distorted image.  I wish there was a panorama function that let you walk sideways along the wall, instead of using a rotating motion. Does this exist? Does anyone have any tips?

Here in Argentina, we have . All the houses and walls on that street have some kind of mosaic stuck to it, and it's very cool. It was made by a local artist .  Because to this piece of urban art is two blocks long, I've decided to make a panorama of it, by moving myself on an horizontal axis while taking photos. I mean, I took one photo, walked one step deeper along the street, took another photo, and so on.  When I tried to stitch it in AutoPano, the following deformed thing came out:   ()  And the other side of the block:   ()  After this, I've learned about parallax error and why you have to avoid moving when making panoramas. I mean, there are a lot of connection errors on both images. Especially in the second one, the part with the corner is quite problematic to stitch because to as I moved, the perspective of the view changed a lot.  So, is there any way to stitch this kind of panorama correctly? Would this only work on plain walls?


Say that we have the following:  template <class T, int i>   I understand that T will be whatever type being passed to some function. But, what does the int i portion mean?  Thanks.

When declaring a template, I am used to having this kind of code:  template <class T>   But , they used:  template <unsigned int N>   I checked that it compiles. But what does it mean? Is it a non-type parameter? And if so, how can we have a template without any type parameter?


My primary partition is running out of space (/dev/sda1). The main partition (/dev/sda) having much more free space. I want to transfer space from (/dev/sda) and extend to (/dev/sda1) partition which is my primary partition and have all linux boot, kernel etc files.   sudo fdisk -l Disk /dev/sda: 204.8 GB, 204803670016 bytes,400007168 sectors  Units = sectors of 1 * 512 = 512 bytes  Sector size(logical/physical): 512 bytes / 512 bytes I/O size(minimum/optimal): 512 bytes / 512 bytes  Device Boot      Start         End      Blocks   Id  System /dev/sda1            2048   199997439    99997696     Linux

I have a Virtual machine using centos 7 with 200GB disk.For some reason my layout is:  df -h Filesystem               Size  Used Avail Use% Mounted on /dev/sda1                100GB  95GB  5GB      Running fdisk -l:  Disk /dev/sda: 204.8 GB, 204803670016 bytes,400007168 sectors  Units = sectors of 1 * 512 = 512 bytes  Sector size(logical/physical): 512 bytes / 512 bytes I/O size(minimum/optimal): 512 bytes / 512 bytes Disk label type: dos Disk identifier: 0x0006c283  Device Boot      Start         End      Blocks   Id  System /dev/sda1            2048   199997439    99997696     Linux   I would like to increase my space on my partision /dev/sda1.


Every time I create new file this file keeps opening:

I accidentally opened too many menus (or windows) and I want to reset them to default.  It is really annoying, and effecting my animation.  Thanks


I'm looking into the c++ source code of a library I'm using, full source available . I've got a fair idea of how c++ templates work, however I have no idea why one would use a typename within a function body, i.e. in the code example below, why would one put typename before unordered_map<Token*, BaseFloat>::const_iterator iter = final_costs.find(tok);?  NB: No I don't consider this a duplicate, It's a specific question in order to understand why typename is used within the function body for given function. I notice people mark it as duplicate and then refer to a generic template question such as where / when to use template / typename keywords, I've been through the info of provided links, however I haven't seen the answer there, so if marking as duplicate please be specific as to why you think it answers the question here.  template <typename FST> typename LatticeFasterOnlineDecoderTpl<FST>::BestPathIterator LatticeFasterOnlineDecoderTpl<FST>::BestPathEnd( ... .....       typename unordered_map<Token*, BaseFloat>::const_iterator           iter = final_costs.find(tok); ... ....   The full code block of the above function:  template <typename FST> typename LatticeFasterOnlineDecoderTpl<FST>::BestPathIterator LatticeFasterOnlineDecoderTpl<FST>::BestPathEnd(     bool use_final_probs,     BaseFloat *final_cost_out) const {   if (this->decoding_finalized_ && !use_final_probs)     KALDI_ERR << "You cannot call FinalizeDecoding() and then call "               << "BestPathEnd() with use_final_probs == false";   KALDI_ASSERT(this->NumFramesDecoded() > 0 &&                "You cannot call BestPathEnd if no frames were decoded.");    unordered_map<Token*, BaseFloat> final_costs_local;    const unordered_map<Token*, BaseFloat> &final_costs =       (this->decoding_finalized_ ? this->final_costs_ :final_costs_local);   if (!this->decoding_finalized_ && use_final_probs)     this->ComputeFinalCosts(&final_costs_local, NULL, NULL);    // Singly linked list of tokens on last frame (access list through "next"   // pointer).   BaseFloat best_cost = std::numeric_limits<BaseFloat>::infinity();   BaseFloat best_final_cost = 0;   Token *best_tok = NULL;   for (Token *tok = this->active_toks_.back().toks;        tok != NULL; tok = tok->next) {     BaseFloat cost = tok->tot_cost, final_cost = 0.0;     if (use_final_probs && !final_costs.empty()) {       // if we are instructed to use final-probs, and any final tokens were       // active on final frame, include the final-prob in the cost of the token.       typename unordered_map<Token*, BaseFloat>::const_iterator           iter = final_costs.find(tok);       if (iter != final_costs.end()) {         final_cost = iter->second;         cost += final_cost;       } else {         cost = std::numeric_limits<BaseFloat>::infinity();       }     }     if (cost < best_cost) {       best_cost = cost;       best_tok = tok;       best_final_cost = final_cost;     }   }   if (best_tok == NULL) {  // this should not happen, and is likely a code error or     // caused by infinities in likelihoods, but I'm not making     // it a fatal error for now.     KALDI_WARN << "No final token found.";   }   if (final_cost_out)     *final_cost_out = best_final_cost;   return BestPathIterator(best_tok, this->NumFramesDecoded() - 1); }

In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway?    I have the following code:  template <typename T, typename Tail> // Tail will be a UnionNode too. struct UnionNode : public Tail {     // ...     template<typename U> struct inUnion {         // Q: where to add typename/template here?         typedef Tail::inUnion<U> dummy;      };     template< > struct inUnion<T> {     }; }; template <typename T> // For the last node Tn. struct UnionNode<T, void> {     // ...     template<typename U> struct inUnion {         char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U     };     template< > struct inUnion<T> {     }; };   The problem I have is in the typedef Tail::inUnion<U> dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion<U> names a type and not a function?


I'm working in Linux.  My connection to PuTTY times out very quickly and I need to have it remain active as long as I wish.  I set the TMOUT in my Linux .profile but that has not seemed to make any difference.    How do I set TMOUT or whatever for PuTTY?

Each time putty is closing the session after some time if it is idle.  There is no time parameter on putty, so how can I keep my putty ssh session always Alive?


This question has been , and some six years ago, so i would like to reiterate this with a focus on Pages. I am trying to understand how it works. If i run File -> Export to -> PDF from Pages and i do a Print -> Save as PDF i get results that to the naked eye show no difference. Filesizes differ though: 97.7 MB and 97.8 MB. The document i work on has 296 pages, contains hundreds of graphics and pictograms and many hundred line elements, as well as multiple fonts. Can someone enlighten me in regard to how these two print/export functions work and what the differences are? Because even if i change settings in the Print dialogue before hitting Save to PDF i still get the same result as if i don't make any changes.

What is the difference between to File > Export as PDF and File > Print > Save As PDF?


I have ubuntu 12.04 and want to install win7 with dual boot because mi CLARO modem (Argentina) doesn`t work with ubuntu. How I do it?

I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go  for UEFI only!


There is a problem with using \colorbox command. As you can see in the example and its output, the statements in the \colorbox doesn't correctly wrapped. Is there any suggestion for that?  \documentclass[review]{elsarticle} \usepackage{color}  \begin{document} \begin{frontmatter} \begin{abstract} This is an example to show that without using the colorbos command in latex, the text is correctly wrrapped as the formatting suggests.  \colorbox{red}{I am trying to understand how the colorbox command works in latex. As you can see, adding the a phrase inside the colorbox command causes the text to exceed the page boundary. However, I want to see a wrap!}  \end{abstract} \end{frontmatter} \end{document}     The Elsevier tex package is available .    UPDATE  Apart from the solution by SoundsOfSilence, which is a working solution, I found that \usepackage{soul} and \hl{the text} is much better and supports line breaking. More info is available .

I have following text chunk:  \colorbox{gray}{[862401.693536] sd 2:0:0:0: [sdb] Write Protect is off\hfill \break [862401.693548] sd 2:0:0:0: [sdb] Mode Sense: 45 00 00 08\hfill \break [862401.700884]  sdb: sdb1\hfill \break [862401.705538] sd 2:0:0:0: [sdb] No Caching mode page present\hfill \break [862401.705551] sd 2:0:0:0: [sdb] Assuming drive cache: write through\hfill \break [862401.705562] sd 2:0:0:0: [sdb] Attached SCSI removable disk}   The output is visible in attached screenshot. Why \hfill and \break combo does not work?


I want to find the solutions $(a,b)\in\mathbb{Z}^+\times\mathbb{Z}^+$ of $7^a+2=3^b$. One such solution is $(a,b)=(1,2)$.  Looking modulo $4$, we have $(-1)^a+2\equiv(-1)^b$, so $a$ and $b$ are of different parity.  Modulo $3$: $1+2\equiv 0$, which is always true.  Modulo $7$: $2\equiv 3^b$, so $b\equiv 2\pmod 6$. This means $a$ is odd.

I've tried using mods but nothing is working on this one: solve in positive integers $x,y$ the diophantine equation $7^x=3^y-2$.