Using ubuntu 16.10 on 32bit computer.  Have a following sources.list in etc/apt  ###### Ubuntu Main Repos deb http://in.archive.ubuntu.com/ubuntu/ yakkety main restricted universe multiverse  deb-src http://in.archive.ubuntu.com/ubuntu/ yakkety main restricted universe   ###### Ubuntu Update Repos deb http://in.archive.ubuntu.com/ubuntu/ yakkety-security main restricted universe multiverse  deb http://in.archive.ubuntu.com/ubuntu/ yakkety-updates main restricted universe multiverse  deb http://in.archive.ubuntu.com/ubuntu/ yakkety-proposed main restricted universe multiverse  deb http://in.archive.ubuntu.com/ubuntu/ yakkety-backports main restricted universe multiverse  deb-src http://in.archive.ubuntu.com/ubuntu/ yakkety-security main restricted universe  deb-src http://in.archive.ubuntu.com/ubuntu/ yakkety-updates main restricted universe  deb-src http://in.archive.ubuntu.com/ubuntu/ yakkety-proposed main restricted universe  deb-src http://in.archive.ubuntu.com/ubuntu/ yakkety-backports main restricted universe    and it gives me following error on sudo apt-get update      Ign:17 http://ppa.launchpad.net/ubuntu-on-rails/ppa/ubuntu yakkety/main DEP-11 64x64 Icons                                                     Fetched 102 kB in 7s (14.2 kB/s)                                                                                Reading package lists... Done W: The repository 'http://ppa.launchpad.net/ubuntu-on-rails/ppa/ubuntu yakkety Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: http://deb.playonlinux.com/dists/precise/InRelease: Signature by key 74F7358425EEB6176094C884E0F72778C4676186 uses weak digest algorithm (SHA1) E: Failed to fetch http://ppa.launchpad.net/ubuntu-on-rails/ppa/ubuntu/dists/yakkety/main/binary-i386/Packages  404  Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.


Intuitive explanation of different types of "infinity"

I have been taught in some computer science theoretic courses that two types of infinities exist: dense and countable, e.g. dense (uncountable) : real numbers, countable: integers.  And that therefore dense "sort of" > countable...  I would be interested if someone develops these concepts..  Moreover, could an ''intuitive'' definition be given for ''dense'' with regards to infinities ? Also, can you disscuss if it makes sense to say thant the reals are larger than the integers ? (as it is sometimes said informally)


Which one of this two sentences is correct?   I need you to help me do this job I need you to help me to do this job   Can you also provide me some explanation?


Can't install Ubuntu, getting error 'failed to load fecs_inst'

I am currently using windows 10 and created a bootable USB drive with universal USB. I used the ubuntu 16.04 iso and am getting the initial page that shows the Ubuntu logo then the screen cuts to a black screen.  The first line says gr failed to load fecs inst and there are about another 15 lines with memory addresses or something of the sort.  I tried this with 2 different USB and 2 different ports and had the same issue.  I am running a core i5 4590 with 8GB ram, 850 evo, GTX 970, and an additional 1TB hard drive. I've looked for this error but couldn't find any viable solution. Any ideas?


How can I return NULL from a generic method in C#?

I have a generic method with this (dummy) code (yes I'm aware IList has predicates, but my code is not using IList but some other collection, anyway this is irrelevant for the question...)  static T FindThing<T>(IList collection, int id) where T : IThing, new() {     foreach T thing in collecion     {         if (thing.Id == id)             return thing;     }     return null;  // ERROR: Cannot convert null to type parameter 'T' because it could be a value type. Consider using 'default(T)' instead. }   This gives me a build error      "Cannot convert null to type parameter   'T' because it could be a value type.   Consider using 'default(T)' instead."   Can I avoid this error?


chmod is used to change permissions of files/directories and generally use syntax like - chmod xyz <file-or-directory>  where x, y, z numeric values of permissions for user, group and others but from , I can see 4 numeric values for permission like - sudo chmod 4755 /opt/google/chrome/chrome-sandbox  I'm unable to understand what is that 4th numeric value for. Please help to understand it.


Combinatorics question about cube with vertices marked as + or - 1 and faces marked with the product of 4 vertices

This question is from a practice workbook for a college entrance exam. Let each corner of a cube is represented by +1 or -1 arbitrarily and on each of the six faces of the cube we write the product of numbers written at four corners of that face. Let $s_1, s_2, s_3,...,s_8$ be the numbers written on the corners and $p_1,p_2,...,p_6$ be the product of numbers written on the faces. Then the total number of ways to make the solution of the equation- $$\Sigma_{i=1}^8s_i + \Sigma_{i=1}^6p_i = 0 $$ So my first thought was to work case by case. $\Sigma_{i=1}^8s_i$ can take values of {-8,-6,-4,-2,0,2,4,6,8} and $\Sigma_{i=1}^6p_i$ can take values {-6,-4,-2,0,2,4,6} even if we ignore possible configurations and just give each $p_i$ a value equal to -1 or 1. Now clearly $\Sigma_{i=1}^8s_i = -8,8$ will not give any solutions to the equation. For the case where $\Sigma_{i=1}^8s_i = 6$. There are 7, +1 vertices and 1, -1 vertex. This will hence give $\Sigma_{i=1}^6p_i = 0$ Because that single (-1) vertex will make three products -1. For the case where $\Sigma_{i=1}^8s_i = 4$. There are 2, (-1)vertices and three ways to place them. If you take body diagonals, the product will be -6, if you take face diagonals, the sum of products will be -2 and for adjacent vertices the sum of products will be +2. Now while this approach of taking cases does work and will get the answer, it is rather long(the $\Sigma_{i=1}^8s_i = 2$ case will have way more possibilities) and also leaves plenty of scope to go wrong or miscount. So I was looking for maybe an organized way to check these cases or an alternate method entirely which utilizes maybe some different intuition. Also I'm unsure what to tag this question under, so if someone would comment some tags or edit this post to include useful tags, I'd appreciate it.


I need to print the data below line contains "New External Cmd" and above line contains "Apply Succeeded", form the text file.   New External Cmd  ccs_mon  ldapaddm  root  cyberrec  Info    Apply Succeeded


How do I disable bluetooth startup (by default, with every boot) in 17.04?

I was just wondering how to disable bluetooth startup by default in 17.04. I would like to be able to boot, and not have to turn off bluetooth every time.  Any help would be greatly appreciated.  Thanks


Is there any difference in setting path for golang, python or java in ubuntu?

In some tutorials path is set in ~/.profile however in some other tutorials they use etc/path or ~/.bashrc, can you explain whats the difference and how it works in linux ubuntu. I am sorry for such a basic question but I am using linux for the first time in my life. Or if someone could guide to a tutorial which explains the whole path setting concept.


Question: Show $\lim_{n \rightarrow \infty} (n!)^{1/n}$ I am not able to come up with a satisfactory proof for the same


How to find out on what framework or in which language was the website created?

How can I find out on what framework or in which language was the website created?  For example, if a person sends me a link to his own website that he has created and he claims that this website was build with (For example) Ruby on Rails (or CodeIgniter (or whatever)), how can I be sure, that he truly used this framework or language to create this website?  Why am I asking... On websites like Elance clients ask freelancers to show them the examples of their previous projects. So, if I am a client, how can I be sure, that this person sends me the project, that is created in the language and framework I need? Because he can have (for example) a lot of CodeIgniter projects, but he will tell me that those are created via Rails to get hired.  It can be his own server, with a free domain name and free hosting, (I don't care). What I mean is how to know this information I need, not using different internet tools where you can simply put the URL and get the description of the website. Because he can have his own server, with a free domain name and free hosting... So his website would not be listed there.


If I miss the outbound in round trip booking, do I use the inbound ticket?

I want to book a one-way flight from QatarAirways from Tehran(IKA) to Montreal(YUL) and the price is 1100$ for one-way trip but the price of a round-trip from YUL to IKA (YUL to IKA as outbound ~450$ and IKA to YUL as inbound ~350) is 800$ If I notify the airline that I can not join the first leg, and I was not in YUL at all, could I use the inbound flight only? I do not want to refund the first even.


How can I recognize Mir runing on tablet/phone running Ubuntu Touch Saucy Salamander?

Phones and tablets behaves differently from ubuntu on desktop. So this is why mir can not be found the same way however the system with  does run on . There isn't any Unity-system-compositor running on my system. I do see unity8 and lightdm running.


How does an electron deexcites during stimulated emission?

During stimulated emission in laser,the electron de-excites by supplying energy,generally it must excite,right? My doubt is then why does it de-excites?


How to add a lookup field value to an sObject list

Since I started coding in Apex, I've gotten used to working with lists of IDs of objects not the objects themselves.  This time around, instead of creating a List<ID> of account ids, I created a List<Account>.  Now, I'm trying to add account records to this list, via a lookup field on a related custom object. However, when I do this, I get an error back telling me I'm trying to add an ID to an sObject list.   So what I'm wondering is, how would I best indicate that it's the sObject record as a whole I want to add, not just the ID indicated by the lookup field? And if it involves a SOQL query, wouldn't that be problematic in terms of hitting governors limits?


Systemic Functional Linguistics - clause boundaries, theme composition

Is my analysis correct that the following use of wh- question words and how is two clauses linked by a conjunction:      I don't understand || how/why/when/where he did it   here's || why I have a problem   Furthermore are these to be considered textual themes, while in     I don't know || what he did   I don't know || where he did it   I don't know || who did it   what, where and who would be ideational themes?


How to solve the equation $yy''-y'y^2-(y')^2$?

I am asked to solve this ODE: $$yy''-y'y^2-(y')^2=0.$$ Can I get some guidelines on how I can solve it? I am not sure how to approach without initial conditions.


Create screen and run command without attaching

I am working on automating a maintenance routine that involves starting and stopping a script that is running in a screen session.  My approach is to kill the screen session, and then restart it and run the command from within a script using the abilities to both create a screen and pass a command without needing to attach to the screen.  However, I am having difficulties with this.  I can create the screen correctly without it attaching using screen -d -m -S screen_name.  However, if I run a command based on:  screen -S screen_name-X stuff "command 1"'echo -ne '\015''"command 2"'echo -ne '\015''  with the echo -ne '\015' being wrapped with backticks rather than single quotes.  It is to simulate the user pressing the enter key as the commands I use are moving to a directory and executing a script located there.  This command works, but only if the screen has been attached to once it has been created.  As I am trying to automate the process of creating the screen and running the commands within it I would like to avoid having to attach and detach within a script.  I will be trying the suggestion of creating a shell script containing the commands I need to execute within the screen and edit according to my results.  Is there a way to create a screen and run a command within the screen either in one command, or without having to attach to the screen after creating but before execution of the command?  Thanks in advance.  **Update - having tried the suggestion to place the commands I need to execute within a shell script I have been able to successfully create a screen and execute the commands from within the screen, but I am getting the behaviour that when the script stops running the screen closes as well.  This shouldnt be a problem as the script is a logging script that should only stop with the knowledge of the sys admin or through the script I am trying to develop, however it would be preferable to have the screen setup in such a way that the screen does not disappear if the script is stopped.  Is it possible to achieve this behaviour? **


How I draw the symmetrical difference of three sets with Venn diagrams using tikz?

The title says it all, here is the code:  \documentclass{article} \usepackage{tikz} \usetikzlibrary{shapes,backgrounds} \begin{document}  \def\lcirc2{(-.7,-.5) circle (1cm)} \def\rcirc2{(.7,-.5) circle (1cm)} \def\ucirc{(0,.5) circle (1cm)} \def\rect{(-2.5,-1.8) rectangle (2.5,1.8)} \begin{tikzpicture}   \begin{scope}     \clip \rcirc2;     \fill[gray] \rcirc2;     \fill[white] \lcirc2;     \fill[gray] \ucirc;   \end{scope}   \begin{scope}     \clip \lcirc2;     \fill[gray] \lcirc2;     \fill[white] \rcirc2;   \end{scope}   \begin{scope}     \clip \ucirc;     \fill[gray] \ucirc;   \end{scope}   \draw \rect;   \draw \lcirc2;   \draw \rcirc2;   \draw \ucirc;   \draw (0,2.1) node {$(A\bigtriangleup B)\bigtriangleup C$};   \draw (0,-.2) node {$X$};  \end{tikzpicture} \end{document}     I need to shade X gray in addition to each circle without the other. Thanks in advance.


Can't install Skype 4.3 on Ubuntu 14.04 64 bit

First of all, I think this question is not duplicated, because I have tried all other solutions I found here, but nothing solved my problem.  I use Ubuntu 14.04 64 bit.  I have tried until now: sudo apt-get install skype -> It didn't work. The error was:   The following packages have unmet dependencies: skype : Depends: skype-bin E: Unable to correct problems, you have held broken packages.   I have tried sudo dpkg add-architecture && sudo dpkg -i skype-ubuntu-precise_4.3.0.37-1_i386.deb but it didn't work either. The error was:  dpkg: dependency problems prevent configuration of skype: skype depends on libqt4-dbus (>= 4:4.5.3); however: Package libqt4-dbus is not installed. skype depends on libqt4-network (>= 4:4.8.0); however: Package libqt4-network:i386 is not installed. skype depends on libqt4-xml (>= 4:4.5.3); however: Package libqt4-xml:i386 is not installed. skype depends on libqtcore4 (>= 4:4.7.0~beta1); however: Package libqtcore4:i386 is not installed. skype depends on libqtgui4 (>= 4:4.8.0); however: Package libqtgui4:i386 is not installed. skype depends on libqtwebkit4 (>= 2.2~2011week36); however: skype depends on libstdc++6 (>= 4.2.1); however: Package libstdc++6:i386 is not installed. skype depends on libx11-6; however: Package libx11-6:i386 is not installed. skype depends on libxext6; however: Package libxext6:i386 is not installed. skype depends on libxss1; however: Package libxss1:i386 is not installed. skype depends on libxv1; however: Package libxv1:i386 is not installed. skype depends on dpkg: error processing package skype (--install): dependency problems - leaving unconfigured Processing triggers for hicolor-icon-theme (0.13-1) ... Processing triggers for gnome-menus (3.10.1-0ubuntu2) ... Processing triggers for desktop-file-utils (0.22-1ubuntu1) ... Processing triggers for bamfdaemon (0.5.1+14.04.20140409-0ubuntu1) ... Rebuilding /usr/share/applications/bamf-2.index... Processing triggers for mime-support (3.54ubuntu1) ... Errors were encountered while processing: skype   I have tried to use after sudo apt-get -f install but it didn't solve the issue.  I have tried to install by using Gdebi. The error was:  Cannot install 'libqtwebkit4:i386'   I have tried to install using Ubuntu Software Center. The error was:  Cannot install 'libqtwebkit4:i386'   I have tried changing the server in "Software and Updates". I have tried to use "Main Server" and "Servers for United States". But it couldn't solve my problem.  Anyone has any idea how to solve that?  SOLVED  Well, I formatted my pc and I installed Skype first of all. Probably another installation that I had done before the Skype installation was the problem, i guess.  Thanks people!


Find the extent of a GeoJSON FeatureCollection

How can I get of the extent of all features within a GeoJSON FeatureCollection with Python 3? One extent for all features, not one per feature.   The Feature collection includes multiple points features and multiple LineStrings features.


How does planking burn calories if there is no force * distance?

In plank position, the body is not moving, but it still burns calories. Work is defined as force multiplied by distance ($Fd$). There is force, but no distance, so the energy should be $0$ ($F \times 0 = 0$), as anything multiplied by $0$ is $0$. Someone please explain how planking burns any calories.


Windows Autostart App Not Running Anymore

I'm not sure if it is due to the latest Windows 10 update or something else. But recently, OpenVPN won't start up automatically anymore. Even though it is placed in the user autostart folder for the start menu.  Any advice on how to trouble shoot this?


The way to convert error function to matrix form in linear regression?

In linear regression squared error function is calculated as:  $$ Error(w) = \sum_{i=0}^{m} W^{T}x_i - y_i $$   In which $W^T$ means the transpose of weights vector. $x_i$ is the ith input in vector x and $y_i$ is the ith desired output.   We can write it in matrix form as follows:  $$ (Xw - y)^T (Xw-y) $$  My question is that according to what matrix algebra rules or sequence of manipulation, the summation can change into the above matrix form? Please let me know if there is any resource that I can learn the corresponding matrix algebra?  Any help is appreciated.


To prove that $\frac{|x-y|}{\sqrt{1+|x|^2}+\sqrt{1+|y|^2}}$ is a metric on $\mathbb{C}$

I am practically clueless on how to prove the triangle inequality here. The case is evident when $|z|≤|x|$ and $|z|≤|y|$. But how do I prove it in general?   Any hint/answer would be much appreciated.


Does pokemon size (XS/Normal/XL) influence attack power?

I've noticed that for the same pokemon at the same Power Up cost, the attacks of the XS pokemon are better than that of normal or XL.  Is there official data confirming/debunking this hypothesis?  Notice, that this is a different question to the one . That question is focused on the size of the pokemon--and mentions that larger pokemon have higher health. My question here is then, do smaller pokemon have higher attack power? If there's no health benefit, then does this mean that there's an attack bonus?


How to put an sRGB image on top of a filmic render in the compositor while retaining their own sRGB-colors?

When I put an half-transparent sRGB image on top of a filmic render in the compositor, the transparent image will take the color-modus of the render (filmic in this case).  Is there a way to keep the sRGB-colors of the overlay image while using filmic for the  render image?


When it comes to completely anonymous appreciation of videos. What is better to use: 'Likes' vs 'Upvotes'?  I've read elsewhere that likes seem more personal and there is a network involved. But what if it's completely anonymous and it's just a statistic? With a user base ranging between 10 to 50 years old.


When is it worth it to use the Sharpshooter -5/+10?

I took the Sharpshooter feat at level one, as a variant human.  Let's say I have a hit bonus of ATK_MOD and I do on average AVG_DMG damage. Based on the perceived enemy's AC, when is it worth it to use the sharpshooter's -5/+10 feature?


I am creating a shortcode to display data based on some options.  function dot_irt_top_posts ( $atts, $content = null ) {      // get our variable from $atts     extract(shortcode_atts(array(         'before' => '
',         'after' => '
',         'number' => '10',         'post_type' => 'post',         'year' => '',         'monthnum' => '',         'show_count' => '1',     ), $atts));      global $wpdb;      $request = "SELECT * FROM $wpdb->posts, $wpdb->postmeta";     $request .= " WHERE $wpdb->posts.ID = $wpdb->postmeta.post_id";      if ($year != '') {         $request .= " AND year=$year";     }      if ($year != '' && $monthnum != '') {         $request .= " AND &monthnum='$monthnum'";     } elseif ($monthnum != '') {         $request .= " AND monthnum='$monthnum'";     }      $request .= " AND post_status='publish' AND post_type='$post_type' AND meta_key='_recommended'";     $request .= " ORDER BY $wpdb->postmeta.meta_value+0 DESC LIMIT $number";     $posts = $wpdb->get_results($request);      $return = '';       foreach ($posts as $item) {         $post_title = stripslashes($item->post_title);         $permalink = get_permalink($item->ID);         $post_count = $item->meta_value;         $return .= $before.'' . $post_title . ' ';          if ( $show_count == '1') {             $return .= '' . $post_count . ' ';         }          //$return .= get_the_post_thumbnail($item->ID, 'showcase-thumbnail');         $return .= $after;      }     return $return;  } add_shortcode('irt_top_posts','dot_irt_top_posts');   And then the shortcode would be like:  <?php echo do_shortcode("[irt_top_posts post_type='showcase' number='10' monthnum='9']"); ?>   UPDATED QUESTION's   There seems to be some issue with my query. The Codex  has an example for using the date to retrive results when using WP_Query. I want to know what changes I need to make to my code to have YEAR or MONTH in the query when getting results I noticed most shortcodes when communicating with database use wpdb class and not wp_query. Is there a reason behind this?


Any algorithm or theorem to decide whether two functions are equivalent?

Any algorithm or theorem to decide whether two functions that are polynomials,rationals and analytic over $\mathbb{N}$ or $\mathbb{Q}$ or $\mathbb{R}$ or $\mathbb{C}$ are equivalent ?


How to get other people's question updates in global inbox?

When I see some good question I'd like to star it and pay attention to its updates (answers, edits, comments). So it's good to see new message from the inbox messages, but it seems that I can only check these questions under my Favorites tab which I forget to do sometimes.  So, is there any way to get other people's question updates in an inbox message? If not, I think I'd like to have this new feature.


Let the permutation group $S_3$ act on $\mathbb{R}^3$ by permuting the elements.   How can we show that this action can be written as  $\sigma (x_1, x_2, x_3) = ( x_{\sigma^{-1}(1)}, x_{\sigma^{-1}(2)}, x_{\sigma^{-1}(3)})$ for $\sigma \in S_3$, $(x_1, x_2, x_3) \in \mathbb{R}^3$.  For instance, if $\sigma = (123)$, we have $\sigma (x_1, x_2, x_3) = (123)(x_1, x_2, x_3) = (x_3, x_1, x_2)$.  Just looking at some examples, this seems so obvious, but I'm not sure how to go about showing it.


Wrong function of the code in C. the program seems to display garbage

I wrote a program to run the insertion sorting algorithms. Everything seems good.  But when I execute it there is a strange result.  It seems that the programs uses garbage in memory.  How could I fix it?   #include<stdio.h> #include<stdlib.h> #include<time.h>  void insertion_inc(int Array[], int size) {      int i, j, key;      for (i = 1; i < size; i++)     {         j = i - 1;         key = Array[i];         while (j >=0 && Array[j]>key )         {             Array[j + 1] = Array[j];             j--;         }         Array[j++] = key;     } }   void insertion_dec(int Array[], int size) {      int i, j, key;     for (i = 1; i < size; i++)     {         j = i - 1;         key = Array[i];         while (j >= 0 && Array[j] < key)         {             Array[j + 1] = Array[j];             j--;         }         Array[j++] = key;     } }  void print_array(int arr[], int size) {      for (int i = 0; i < size; i++)         printf(" %d ", arr[i]); }   /////////////////////////////////////////////  int main() {      time_t t;     srand((unsigned)time(&t));     int Arr[10];     int size = sizeof(Arr);     printf("The unsorted Array : \n ");     for (int i = 0; i < size;i++)         Arr[i] = rand()/10;     print_array(Arr, size);     printf("\n\n\n The sorted Array : \n");     insertion_inc(Arr, size);     print_array(Arr, size);     return 0; }   **The output always looks like this : **  The unsorted Array :  12  23  54  87  2  68  29  57  97  12  -858993460  272204808  7601072  7742451  1  15039136  15044096  1  15039136  15044096  7601164  7742023  272204692  7738189  7738189  8462336  0  0  0  0  0  0  0  0  7775604  7775616  0  7601080  0  7601272  The sorted Array :  23  23  23  23  23  23  23  23  23  23  23  23  23  23  23  57  68  7601272  7738189  7738189  7738189  7742023  7775616  8462336  8462336  8462336  15039136  15039136  15039136  15039136  15044096  272204692  272204808  272204808  272204808  272204808  272204808  272204808  272204808  272204808  Even when I ignore the use of srand() and rand(), there is still the problem.


Generating even-sized clusters in scikit-learn

I'm attempting to generate approximately even-sized clusters of a PCA'd feature set in Scikit-learn, but I'm not having any luck. I'm only familiar with KMeans clustering, and with that algorithm the largest cluster contains the majority of the examples (in the case of K=2 it's 80%, in K=4 it's 65%, etc...). I've done some basic experiments with default MeanShift and AffinityPropagation, but I've had no luck there.  This is where a graduate degree would have come in handy, but in the meantime can anyone point me in the direction of some good resources on what types of clustering algorithms can control cluster size (specifically any that are implemented in sklearn!)  I realize this question is super vague, but I'm not sure what information is relevant to the problem. My data set begins as a combination of normalized continuous variables and one-hot encoding for categorical variables. 36 original features are reduced with PCA to 20 features that describe 99%+ of the variance. Attempts to modify my pre-PCA data set don't really effect how the clustering divides up the examples.  Thanks for any suggestions/input!


Can anyone provide my the sample cover letter or can assist my what and how to write cover letter?

My UK visit visa got refused and nw I want to apply again immediately. I had applied for UK visit visa but it got refused due to some reasons as mentioned in refusal letter. The mistake I did is that I forgot to submit my salary account statement but apart from this.they raised some more concern regarding my trip. Please see the attached refusal letter and advice me. I had submitted the imvitation letter from my brother in law with all required docs(his account statement, invitation, letter, passport copy,telephone bill). My suggest me what all things i should consider for reapplying and content for cover letter. This was my first visa and have no visa history. They refused my visa  under paragraph V4.2(a), (c) and (e) of Appendix V of the immigration letter. Should I apply it again immediately or not? Thnaks]


Make AES more secure by randomising the blocks in an encrypted file

I am developing a software with hybrid encryption (RSA-4096 and AES-256-CBC). The iv and key of an AES encrypted file will be RSA encrypted end exchanged through a different way than the encrypted file. Thats ok for me to this point.  I am thinking about where it is most easy to break the encryption of my own files and always come to the point where a key and iv guessing would take ages but is theoretically easy. It just takes time with the computing power we have today.  In my application the transfer of the encrypted file will not be possible if there are bits lost in any case.  Version 1: Since CBC is always based on the the pre block, why do I not just change the order of the blocks in the file and write a map together with the key and iv into the RSA part? Is this a stupid idea?  Version 2: Why do I not just replace a random character in each AES block with its "value" + 1 or so and write into my RSA a map of the chawed characters?  In my opinion in Version 1 the "guessing power" would be the "AES blockcount"*"time for a single file" and after that the order would sill be wrong. I have no idea what effort it would take to get the right order...  In the second Version it would be even to hard for me to calculate. It could be any bit in a block with a wrong value and a guessing of iv and key per block.  Does that make sense? Who knows about the computing power we will have in a few years. And I also don't want people to read the files in a few years ;-)


I'm having trouble with pdo->prepare in mysql, heres the query:  $stmt = $this->pdo->prepare("SELECT * FROM :tabletype where name like :name");   Its parsing as  SELECT * FROM 'type1' where name like 'souza'   its ok with the name string but the tabletype  its not working with quotes, is there a way to make it work without the quotes ?  Thanks


What does it mean by independently and identically distributed random variables?

A coin toss is referred as IID in several websites. What I want to know that if I'm understanding the concept right.  If X denote a random variable which means the "result of a coin toss" then $x_1, x_2, ... , x_n$ are the results of repeated coin tossing. Are $x_1, x_2, ... , x_n$ IID? If yes, how can observations be variables?  Or are $X_1, X_2, ... , X_n$ all considered as random variables if we want to consider them IID? How can a random sample be IID?


Auto-implemented getters and setters vs. public fields

I see a lot of example code for C# classes that does this:  public class Point {     public int x { get; set; }     public int y { get; set; } }   Or, in older code, the same with an explicit private backing value and without the new auto-implemented properties:  public class Point {     private int _x;     private int _y;      public int x {         get { return _x; }         set { _x = value; }     }      public int y {         get { return _y; }         set { _y = value; }     } }   My question is why. Is there any functional difference between doing the above and just making these members public fields, like below?  public class Point {     public int x;     public int y; }   To be clear, I understand the value of getters and setters when you need to do some translation of the underlying data. But in cases where you're just passing the values through, it seems needlessly verbose.


Why is the approximation of Hessian$= J^TJ$ reasonable?

I met this equation frequently in Guass-Newton optimizations. But I dont understand why the left and right side of the equation can be equal.  Lets say the Jacobian is $2$ by $2$   and Hessian is $$\begin{bmatrix}\frac{\partial^2f_1}{\partial^2 x_1 } & \frac{\partial^2f_1}{\partial^2 x_2  } \\ \frac{\partial^2f_2}{\partial^2 x_1 } & \frac{\partial^2f_2}{\partial^2 x_2  }\end{bmatrix}$$   But the right hand side of the equation is  $$J^TJ =\begin{bmatrix} \left( \frac{\partial f_1}{\partial x_1} \right)^2 + \left( \frac{\partial f_2}{\partial x_1} \right)^2  &  \frac{\partial f_1}{\partial x_1}\frac{\partial f_1}{\partial x_2} +\frac{\partial f_2}{\partial x_1}\frac{\partial f_2}{\partial x_1}\\ \frac{\partial f_1}{\partial x_1}\frac{\partial f_1}{\partial x_2} +\frac{\partial f_2}{\partial x_1}\frac{\partial f_2}{\partial x_1} &\left( \frac{\partial f_1}{\partial x_2} \right)^2 + \left( \frac{\partial f_2}{\partial x_2} \right)^2\end{bmatrix} $$  Why can these two be equal as presented in papers?


Which site is best to ask a question about web proxies?

I'd like to ask a question about how to use a web proxy to access a server in a different network. Which is the best Stack Exchange site for this question?


I have an array of dictionaries with birthday in Python how do i sort it by ascending birthdays based on current day?


Preventing multiple answers to same question in search results?

I've found that there are times that I do not like seeing multiple answers to the same question returned when I try a search.  While I wouldn't suggest removing the default behavior, I would like to see a search option that allows me to indicate that I want only one result per question in search results.  To give a general idea of why this is desirable to me lets run through a general use case, in fact were use my current search that inspired this post, though it's only a partial example.  Lets say I have something I want to know about which is either obscure or hard to search for due to the difficulty of good search terms.  In my recent case I was looking for some specifics about how various languages handled branch prediction, so I did a search on "branch prediction".  In this example I probably could create a better search so it's not a perfect example, I have had other searches that were harder to narrow down in the past where I had similar complaints; but since this is the one I remember lets use it as an example for now and ignore that I could have written a better search for it.  Not liking the relevance searches I switch to search by votes, expecting a good highly ranking result will exist which does a through analysis of exactly what I want, it's a common enough question.  What I get back includes a list with more then half the starting results being answers to the question: .  When I see the first answer I open it up and jumped to the question and looked at the first few results.  They were interesting but not what I needed; I'm willing to rule out this question as unlikely to give me the analysis I want, and I have already scanned through many of the top answers.  Having ruled this out I would prefer not never see it again in my results, so I can focus on the results I want.  I could try filtering by question only, to never see answer responses.  Again in my use-case this is pretty viable; but that isn't always the case.  if I filter by question the above linked question, with it's massive votes and wonderful answers, would never show up in my results.  In fact many of the highest voted questions don't show up, because the users didn't know that "branch prediction" was the answer to their problem they didn't know to include it in their question.  While the above question didn't suit my needs I imagine it could have suited another, and missing out on it and related questions with wonderful answers, but which didn't use the phrase "branch prediction" in the original question, would be a lose.  What I would like to see is a way to specify that I want to see any question once in my results, be the result a question or an answer.  This way I would detect answers to questions like the above where the questioner didn't know what to ask about; but I wouldn't see the same question multiple times forcing me to skip each answer to a question I ruled out as unlikely to be useful to me.  It seems this problem is less severe when you use the relevance search, the other search options are all more prone to this issue, with "votes" seeming the most likely search to have a problem with.  That may mean that this comes across as too rare to be worth addressing, but I've personally run into the frustration a few time (mostly when I'm just looking for interesting Q&A to look at rather then hunting down specific answers admittedly).  I don't think it would be hard to toss in a search option to avoid duplicates either.  Could this be implemented?


A person who is really interested in knowing another private life or business.   Many thanks


I have a list with a people column called AssignedTo.  I'm making a rest call:  .../_api/web/Lists/GetByTitle('listname')/Items?$expand=AssignedTo&$select=*,AssignedTo/Title   Which is successfully returning the name of the person the item was assigned to. I'm trying to get other user information like email or their user id.  Most tutorials online show how to expand ID and Title (Name) and  I found a list of these properties that can be expanded:   ID FirstName LastName Title Department SipAddress   And those all work. But I can't find the email and or the login ID. I've tried $select=AssignedTo/LoginName and several other variations on that, but they all return that the field is not valid. I was hoping $select=AssignedTo/* would expand all the fields, but that doesn't rework either.  Anyone know if the above are the only fields that can be expanded off a people column?


Looping through files with spaces in the names?

I wrote the following script to diff the outputs of two directores with all the same files in them as such:  #!/bin/bash  for file in `find . -name "*.csv"`   do      echo "file = $file";      diff $file /some/other/path/$file;      read char; done   I know there are other ways to achieve this.  Curiously though, this script fails when the files have spaces in them.  How can I deal with this?  Example output of find:  ./zQuery - abc - Do Not Prompt for Date.csv


macOS Big Sur Dictionary.app doesn't use system proxy

When using Wikipedia in Dictionary.app on macOS Big Sur 11.0.1, Dictionary.app sends HTTPS requests to *.b.akamaiedge.net and is not utilizing system proxy (HTTP or socks5). How do I fix this?


I try to delete Action.005 permanently.    But I don't know how. If I click on the X    then it is still in the list.    I already researched without success, I even managed to loose all my animations by attempting to apply a fix, so I want to be cautious now... How can I do this?


How does Stack Overflow save and show tags?

I am a user on Stack Overflow, and I think every page that shows questions, display all tags and the questions. Are the tags saved in a tags table or are they included together with the questions table?


Which has better efficiency: step-up or step-down switching voltage regulator?

I have a  that converts 4.2V  (two 4.2V cells in parallel) to 5V. Another option is to use a  from 8.4V (two 4.2V cells in series) to 5V. Considering both cited circuits are well implemented, which choice would be more efficient in terms of power dissipation?  I am looking for some general rule as "step-down is always preferable than step-up" or "the absolute voltage difference matters" etc.


I have exported game archive with all objects. I also have CSV file with all their details, such as model name, location, rotation (XYZW). How do I import CSV file, and make blender read it and put all objects on the places?  Ps. Z rotation axis must be multiplied to '-1'.


Find a generating function involving a tiling problem

Let $h_n$ be the number of ways to tile a $1 \times n$ rectangle with $1 \times 1$ tiles that are red or blue and $1 \times 2$ tiles that are green, yellow, or white. Find a closed formula for $$H(x)=\sum_{n\geq0}h_nx^n.$$  I am unsure how to start this problem. Is there a way to solve this without using recurrence relations?


What medium should be used for long term, high volume, data storage (archival)?

This question was inspired by . There have been other similar questions, but none with the same criteria.  This is two questions in one.   How do you store financial/critical records that should survive anything but a fire and should be available for decades? Lets say I want to store family photos/videos and want people do be able to find them in storage 100 years from now and still be able to use them. How would this be done?   Criteria   Long term means 30+ years guaranteed. 100+ years average. [If this is not practical, use the closest solution] High volume means a couple terabytes. Answers can be 'no-compromise/industrial' solutions or practical solutions for the home office/small business user. Media will not be active during the timespan. (i.e., if you suggest hard drives, they will not be spinning).  Further, there is no expectation of needing to read these archives. They are there for emergency or "for future generations" purposes. Should not require maintenance (if at all possible).    My thoughts:   CD-R/DVD-Rs have proven to me, even in the short term, to be a terrible medium for backups. They seem to be very fragile and seem to lose their data a very short time even when in pristine condition. I can't help but think that storing data on a couple of 1TB hdd's and then expecting them to spin up correctly a decade or two later to be a terrible idea. Am I wrong? Industrial tape drives seem like a viable option?


How to install Ubuntu alongside Windows 8.1 with multiple hard drives

I have only used Linux Mint before and installation was very straightforward and automatic. I just got a new laptop with a 128gb SSD and 1tb HDD. I have two questions:   I don't need Ubuntu on the SSD but I still want Grub to ask me which OS to boot. Can I install Ubuntu on the HDD and still get this feature, even though it's not technically "alongside" the Windows boot manager? During installing, I choose "Something else" when prompted for where to install. This partition menu makes no sense to me and I don't know if I should, or how to, create a new partition from here for Ubuntu. Here is a screenshot of the partial list (and this is the factory state of the laptop):     Any advice? Thanks!


What is more fundamntal? Fields, the excitations of which are particles, or particles, from which fields are formed?

I'll try to ask a naive question. In quantum field theory, which is more fundamental, fields or particles? And in string theory?


In very recent publications, two groups in Maryland  and Harvard  have separately worked on constructing  following the path paved by the previous works of Norman Yao (e.g.  ). For example Chris Monroe et al. (Maryland) have realised (or claim to have) a time crystal by entangling the electron spins of a set of ytterbium ions while keeping the system out of equilibrium by alternately hitting the ions by a laser (to apparently create an effective magnetic field) and by another laser to flip their spins, in a repetitive manner.   Now time crystals have been previously theoretically predicted to exist  and , representing an out-of-equilibrium form of matter, in contrast to the commonly well known equilibrium forms of matter (solid, gas, liquids, liquid crystals...). So it is really great to see such works emerging and the field gaining steam on an experimental level.   That said, admittedly, it is very difficult to grasp these works for someone not involved in the field, but it would be incredibly valuable if, briefly, just the idea of time crystals could be explained at a conceptual level.  As in, what qualifies them as a new form of matter? Surely this form is dependent on some external drive to be kept out of equilibrium, right?   Which then begs to ask "how can it be a naturally occurring form of matter". On the other hand, what does it have in common with the usual concept of crystals, whose whole structure can be represented by spatially replicating the unit cell.  Is the time crystal an addendum to the latter by extending its spatial symmetry to also include a time symmetry?    This is merely an attempt to get more input in order to understand some of the main ideas involved in the original works of Frank Wilczek and Norman Yao. These new experimental realizations (see first paragraph) are very exciting to find out about.


What happens if Superman is near a white dwarf star?

With the Superman lore, we know that light from a yellow star gives him his powers, light from blue stars makes him stronger, and light from red stars weakens him.  However, what happens if he is near a white dwarf, or a neutron star?  Has there been any evidence of Superman visiting a star system that wasn't red/yellow/blue?


Last element in each row of a matrix getting pushed to next line

The following matrix is not displaying all elements in each row on the same line, the last element in each row is getting pushed to the next line. If I delete the last element then the matrix displays correctly. I am getting this error when I compile -     You have given more \span or & marks than there were in the preamble   to the \halign or \valign now in progress. So I'll assume that you   meant to type \cr instead.   \documentclass[a4paper,12pt,times,numbered,print,index]{article}    \RequirePackage[left=37mm,right=30mm,top=35mm,bottom=30mm]{geometry} \RequirePackage{libertine}  \RequirePackage[small,bf,labelsep=space,     tableposition=top]{caption}  \usepackage{multirow}   \usepackage{subfig,amsfonts,amsmath,amssymb,braket} \usepackage{algorithm}% http://ctan.org/pkg/algorithms \usepackage{algpseudocode}% http://ctan.org/pkg/algorithmicx  \begin{document}  \begin{figure}[ht] \centering H_{ab}= \begin{bmatrix}     1 & 1 & 0 & \dots   & \dots   & 0 &  0    & 0 & \dots   & \dots & 0 \\     0 & 0 & 0 & \dots   & \dots   & 1 & -1    & 0 & \dots   & \dots & 0 \\     0 & 0 & 0 & 0       & \dots   & 1 & 0     & 0 & \dots   & 0     & 0 \\     0 & 0 & 0 & 0       & \dots   & 1 & 0     & 0 & \dots   & 0     & 0 \\     0 & 0 & 0 & 0       & \dots   & 1 & 0     & 0 & \dots   & 0     & 0 \\  \end{bmatrix} $$ \caption{Transition matrix for a $1$-step memory walk where the number of steps $n = 2$.} \label{qw_mem_p_transition_mat} \end{figure} \end{document}   How can I get all the elements on each row to display on the same line?


Building Python add-ins without needing to restart ArcMap?

Using the Python add-in wizard I need to restart ArcMap every time I want to test something.  For example, when I've got syntax errors or something little that I need to troubleshoot.    What approach would you recommend to negate the need to start ArcMap repeatedly?  It has been noted in comments that this question has already been asked and vaguely answered; however it's totally unclear to me how you integrate this into your script.    Can someone give me an example?  I've tried to include the following script as noted in the other question linked here.  import os  esri = "C:\Program Files\Common Files\ArcGIS\bin\ESRIRegAddIn.exe" cwd = os.getcwd()  mapdoc = "C:\Data\Shaun Pilot Area\PilotAreaMXD.mxd"  try: os.system("TASKKILL /F /IM ArcMap.exe") except: pass  os.system(os.path.join(cwd, "makeaddin.py"))  os.system('"{0}" {1} /s'.format(esri, os.path.split(cwd)[-1] + ".esriaddin")  os.system(mapdoc)   Here's the output I get  ERROR: The process "ArcMap.exe" not found. 'C:\Data\Shaun' is not recognized as an internal or external command, operable program or batch file. 'C:\Program' is not recognized as an internal or external command, operable program or batch file. 'C:\Data\Shaun' is not recognized as an internal or external command, operable program or batch file.


Since latest android app update I can't scroll the feed sideways

This only happens with the top few feed items (new since refresh maybe, or actually, maybe feed items before the update are OK, ones after aren't) but when I drag right to left to scroll between questions as soon as i get half way it snaps back. Sometimes I can get it to scroll and when I can scrolling back (left to right) works fine.  I'm on a stock Nexus 5.  P.s. On the plus side the app has some really nice ui improvements.


Can a community edit its How to Ask page?

The How To Ask page is written for Stack Overflow only. If the community desires to edit its How to Ask page to be better adapted to its site, can they?   I asked it  but got no answer.


Illustrator CS5 (Mac) Pathfinder Tool Messing up Paths

So I'm trying to cut an image out of a solid background in Illustrator CS5 (Mac). I do this fairly often and my typical workflow is to:   Place the image to be cut out on top of the background Group the image to be cut out if there are multiple pieces Select the top image and the background and use Minus Front on the Pathfinder   If the Minus Front doesn't work, I will sometimes use Divide instead. This usually works just fine and I can then delete the section that belong to the upper image, leaving me with the solid background with a shape cut out of it.  However, today I'm having an issue with the Pathfinder options messing with my paths. As you can see below, my shapes are perfectly symmetrical when I place them on the background. (The pink shape is the one I want to be cut out of the background).   I then tried using the Minus Front tool from the Pathfinder, and these were my results:    As you can see, my shapes have been distorted and messed up after applying the Pathfinder option. I tried this with the Divide tool as well and got the exact same results. I've done this process with much more complex shapes in the past, so I know the Pathfinder can handle it, I'm just not sure what could be causing this.  I've also tried using "Expand Appearance" because that usually fixes my wonky problems with shapes in AI, but I had no luck there as well.  Does anyone have any idea why this shape might not be cooperating with the Pathfinder tool?


How can I use mathematical symbols and other special characters in URLs in footnotes?

I want to footnote a URL which contains mathematical signs such as = and LaTeX asks me for a $ sign to take it to mathematical space (and therefore changing the font which is not suitable). How should I overcome this situation, i.e. put url in footnotes without using a $ sign and evading mathematical space?


Is it valid to use "literally" to mean "actually" when composing a hyperbole?

Whenever I see someone corrects another person on their use of "literally", it often seems to me like the corrector did not realize the sentence was supposed to be a hyperbole, and in fact depends on the correct usage of the word "literally" (to mean "actually") in order to be a hyperbole. For example:  "It is so amazing it will literally make your head explode".  Sure, nobody's head is going to "literally" explode from the sheer awesomeness of whatever "it" is, but isn't that exactly the point? If heads do not explode from something being awesome, then something would have to be extremely awesome in order to actually explode someone's head. This sentence basically says: "The intensity of how amazing this thing is is so great, that your head will actually explode from it."   This seems semantically correct to me, but people seem to criticize this use of "literally", as if it actually isn't semantically correct. Why is that?


The professor wants to retire. Here 'to retire' is used as object or complement? Also, in "The man gave Amy some good advice" Is 'some good advice' an object or complement?


uniqueness of embedded submanifolds proof in Lee ITM

I am looking at the proof of Proposition 5.2 from John Lee's ITM. It says below that the uniqueness of smooth structure part of the proposition is obvious. I wasn't sure how to prove this obvious statement. After some thought, I think the formal argument is as follows. Let $\tilde{S}$ be the set $S$ endowed with another smooth structure making it into an embedded submanifold of $M$ with the property that $F$ is a diffeomorphism onto its image. Then $S$ and $\tilde{S}$ have the same smooth structure if and only if the identity map between the two sets is diffeomorphic. Say this map is $I_S$. Then $I_S = F \circ I_N \circ F|_S^{-1}$ where $I_N$ is the identity map for $N$. Since all three maps are diffeomorphisms, so is $I_S$.   Is this argument correct?


I am using the Kolmogorov–Smirnov two-sample test to compare distributions, and I noticed a $p$-value is frequently reported as the test statistic. How is this $p$-value determined? I know it's the probability of obtaining a result at least as large as the one obtained, but how is this $p$-value determined given this is a nonparametric test? That is, we can't assume Gaussian fluctuations in the distribution and compute the $p$-value using a $t$-test.  Thanks!


Why does an Adobe Illustrator document saved as a PNG that are then converted to PDF files look blurry and pixelated?


Why do my arrows drop after flying a few meters?

I'm playing as a khajit in skyrim, going to assassinate Beitlid in Dawnstar. Now, the first time I did it on her porch and just killed her with the Blade of Woe. I got caught somehow, whatever, so I loaded a previous save because mid-jailbreak the guards decided to just attack instead of attempt an arrest.  Then I tried sniping her... and now my arrows have FED, Flight Erectile Dysfunction. They fly... like two feet before suddenly dropping off. It's weird. It doesn't matter how long I hold the trigger, it just droops.


I'm trying to open a page, and the function does not return. When I click on the button, the function works, but the render_template does not happen and I remain on the previous page


dynamically building select statement from DOM data element

I need to dynamically build a select dropdown based on form data provided an ajax query. my DOM contains an element "organizations" with 4 children. The children with an org id and org name  Organizations = {     { id="2", name="Systems"}     { id="4", name="Network"}     { id="5", name="Operations"}     { id= "7", name="Security"} }   I need to build the following select clause  <select name='organization'>     <option value="2">Systems</option>     <option value="4">Network</option>     <option value="5">Operations</option> </select>   How do I dynamically build the select statement?


If the universe turns out to be infinite, would we have to reject the Big Bang Theory?

As per my understanding of the big bang theory, it stipulates that the entire universe was contained in this single point of "pure energy" and that the big bang happened when the universe rapidly expanded out. This, again as per my understanding, is derived from the observation that the universe seems to be expanding right now (Red-shift etc.) and so if we were to go back in time, the universe would be smaller and at some point back in the past, the universe would've been contained in one single point.   However, my question is that if the universe turns out to be infinite then how can something infinite be smaller or contained in a single point? If you go back in time, the universe should be the same size as it is now (infinite) because it has always been infinite. An expanding universe would not be infinite but be finite, you would be able to traverse the entire diameter of it. A universe that expands out of something has a boundary, and so by definition should not be infinite. So, if the universe turns out to be infinite, will we have to look for an alternative to the big bang theory? I hope my question based on a meagre understanding of physics is clear.


Novel where time travel has been discovered, and is used for imprisoning criminals

I read this book in the mid 80's, and what I remember of it, is that time travel has been discovered (invented if you will), but it only works one way. It's possible to send poeple back in time, but it's impossible to go forward. That which has been sent back can't even be brought to its original time again.    This would seem fairly useless, but for one thing, namely imprisonment. The main character is, as far as I can remember, the leader of a group of prisoners. They regularly search they're surroundings for time junk1, which is what they call stuff that was sent back during early stages of testing the time travel. I also distinctly fossils of trilobites being mentioned.    One day a man arrives on The Anvil1, which is what they call the device (platform, scaffold, or whatever) where new prisoners and supplies appear. He claims to be a prisoner, but for some reason the main character gets suspicious of this new man, and starts following him. And in the end it is revealed that this man is an agent of the government, and that they have discovered a way to go forward in time, and that it has been decided that they have all been pardoned, and that they are free to return home. However, the main character decides to stay and he is employed as a guide to time tourists.    1Time junk and anvil are direct translations from my native language to English, but it's perfectly possible that those are not the names used in an official English version.


I am writing a research paper and intend to write this sentence :     Even a cursory reading of the news reveals how grossly inaccurate that assumption is.    Is that an accurate and appropriate sentence for an academic paper?


How can I get the name of the original function?  def wrap(f):     def wrapped_f(*args, **kwargs):         # do something     return wrapped_f  @wrap def A(params):    # do something  print(A.__name__)   result: wrapped_f, but I need A!


Database pattern with two types of owners for an object. Like how users and groups can make posts in FB

Please help. There is a problem I have tried to resolve for some time now. I want to come up with a pattern where i have a table with advertisements on a web platform. These advertisements shall be owned either by individual users (accounts) or by an entity which represents a group of users (accounts) the members of which have permissions on the advertisement. There shall also be a manager of the advertisement. When the advertisement is owned by a group, the accounts dont matter and the info for the group shall be displayed. My problem is that I always come with anti patterns for this schema. Can you suggest me something?  Your help will be highly appreciated.


Why primitive array of polymorphic types is dangerous

To help better understand my question, I'm referring to a topic discussed in the book "The C++ Programming Language 4th edition" chapter 27 section 2.1.  The author is talking about the danger of polymorphic types and built-in arrays. He gives the following example:  void maul(Shape∗ p, int n) // Danger! {     for (int i=0; i!=n; ++i)         p[i].draw(); //looks innocent; it is not }  void user() {     Circle image[10]; // an image is composed of 10 Circles     // ...     maul(image,10); // ‘‘maul’’ 10 Circles     // ... }   We're told that Shape is an abstract size of size 4 and Circle inherit Shape and add an extra 2 members, center and radius which adds to the type size, hence, sizeof(Circle)>sizeof(Shape). Now the author explains that given the following view for example:  user() view: image[0] image[1] image[2] image[3]<br/> maul() view: p[0] p[1] p[2] p[3]   The call of p[1].draw() (emphasis on p[1], for p[0] it will call the right function) will fail because there's no virtual function pointer where it's expected.  Now I know how virtual function tables works, but I don't understand how the size of the type or its layout affect a virtual function call? When the compiler see a call to a virtual function doesn't it replace it with something similar to:  p[1]._vfptr->draw_impl();   Assuming I'm right, how is the size of the derived object/its layout broke the call for it.


What is the difference between luminance and illuminance?

The more I read about this, the more confused I become. Illuminance, as I understand it,  measured in lux, is the perceived brightness of light on a surface. It's what you'd measure with an incident light sensor. Luminance, then, is how much reflected light you'd perceive looking at that surface. This is what the light meter in a camera measures. Am I correct so far?  In both cases, the word "perceived" is important, because the scales are weighted using a  to map wavelengths to . However, in the case of illuminance, there's only actual perception if your eye happens to be the surface in question.  I can basically grasp this, but then I come across charts saying things like "family living room: 50 lux". Wait, hold on! Does that really mean that the typical lights in a house are that bright, or is it just confused and wrong, or am I confused and wrong?  If you're not taking pictures of light sources directly, why would an incident light meter reading ever be useful in photography? Reflected light recorded on film or by a sensor is usually what makes a photograph. So, if I have an incident light meter, how does that reading relate meaningfully to my camera settings?  Since incident light meters are sold and used, this implies that there must be some useful conversion. But this is where my brain explodes. Google tells me that 1 lumen equals 1 candela, so therefore 1 lumen/m² (i.e. 1 lux) must equal 1 candela/m2 (i.e. 1 nit). But clearly something is missing from this. There's something called a "steradian". Cones are involved. I'd never heard of this before; how does it fit in? I can see how it might be determined when calculating the usefulness of LED home lighting, but for a photo, I'm at a loss.  Some part of my (exploded, from the last paragraph) brain is trying to relate this to the difference between flash metering with TTL and with an incident meter. But how can the incident meter work without knowing the reflectance properties of the objects in the scene? Is this what the "C" in the  is all about? Is it just an average-this-probably-will-work value, or is there more to it than that? And if it is just an average, what knowledge is necessary for compensating for off-averages scenes? (As with the , where the photographer simply judges if the scene should be rendered brighter or darker than the average given by the meter.)  So yeah, so much confusion. In short:   What's the difference? Can one meaningfully convert between the two? When and how are illuminance / incident light measurements useful for photography?     Update: I appreciate Stan's answer, which covers the third point of when and how pretty well. And I think I've basically got the first point figured out, as described above. But I'd appreciate some answers covering the issue of conversion as well, both in the mathematical abstract and as the practical for photography. And I wouldn't mind more why and how, either.


Why can't I download Wine on Ubuntu 14.04

When I try to download wine from the software center, there is no install button to click on it only more info, then  a there is a line says that it is available from universe and a use this source button, when I click it nothing happens. Please help me.


Is this WUBI? What is "Installation size" setting for?

I'm new to Ubuntu... I went to the downloads page and downloaded the Windows Installer as I am hoping initially to have a dual boot on my currently Win 7 PC (I would consider preserving my Win7 install as a VM under Ubuntu instead - advice?)  It's asking me to choose an "Installation size" but there's no explanation as to what the significance of this is. Is this a disc partition?  Can I increase it easily later if it's too small?  I came here to ask these questions and now I see a bunch of threads about 'WUBI' and possible downsides of installing Ubuntu this way. Is the Windows Installer I just downloaded going to give me WUBI?


How to add query parameters in twig using path()?

I am following the code snippet provided here  {# Link to frontpage view. #} {{ 'View all content'|t }}  {# Link to user entity/profile page. #} {{ 'View user profile'|t }}  {# Link to node page. #} {{ 'View node page'|t }}     As the function says path($name, $parameters, $options), I want to add a link which has query parameters as shown in below  blue?destination=blue-search&cookie[blue_referrer]=3622&cookie[blue_type]=node   I tried implementing it as follows   Find a Distributor   but it gives an error     The website encountered an unexpected error. Please try again   later.Twig_Error_Syntax: An   array element must be followed by a comma. Unexpected token   "punctuation" of value ":"   ("punctuation" expected with value ","). in Twig_TokenStream->expect() (line 124 of /templates/node/node--product.html.twig).   Twig_ExpressionParser->parseArrayExpression()   (Line: 205)


How to symmetrize the canonical stress-energy tensor?

Given the Lagrangian density for a real scalar field $\mathcal{L}(\phi, \partial_\mu \phi)$, we obtain from Noether's theorem the canonical stress-energy tensor $$ T^{\mu\nu} = \frac{\partial \mathcal{L}}{\partial (\partial_\mu \phi)} \partial_\nu \phi - g^{\mu \nu} \mathcal{L} $$ Can anyone tell me, or provide a (hopefully detailed) reference, why there is always (I think?) a rank $3$ tensor $X^{\lambda \mu \nu}$ such that $$\widetilde{T}^{\mu \nu} = T^{\mu \nu} + \partial_{\lambda} X^{\lambda \mu \nu}$$ is symmetric? I'm fine with assuming $g$ is the Minkowski metric, but I can only find this done in particular cases of $\mathcal{L}$ and no general argument.


Solution for outdated Ubuntu Version 12.04

we are running a system using Ubuntu Version 12.04 and realize there are associated security risks running outdated, unsupported version.  What would your recommendation be to remediate this issue?  Of course upgrading would be, but what version should we be considering and what challenges might we face going from 12.04 to newer supported version(s)?  Thank you,


If $a_0+\frac{a_1}{2}+\dots + \frac{a_n}{n+1}=0$ then $a_nx^n+\dots + a_0$ has a root in $[0,1]$

Let $P(x)=a_nx^n+a_{n-1}x^{n-1}+\dots +a_0$ be a real polynomial such that $a_0+\frac{a_1}{2}+\frac{a_2}{3}+\dots + \frac{a_n}{n+1}=0$.  Show that $P$ has a root in $[0,1]$. I would like proof verification and alternative proofs.  My solution:      notice that the antiderivative of $P(x)$ is $\frac{a_nx^{n+1}}{n+1}+\frac{a_{n-1}x^n}{n}+\dots + \frac{a_1x^2}{2}+a_0x+C$. From here $\int_{0}^1P(x)dx=a_0+\frac{a_1}{2}+\frac{a_2}{3}+\dots + \frac{a_n}{n+1}=0$. If $P$ had no roots then $P$ would be a strictly positive(or negative) continuous function, so its integral would be strictly positive ( or negative), a contradiction.


What am I doing wrong with the qtree function?

I have been trying to figure out what is wrong with my code, but no matter what I do it does not compile.  \documentclass[12pt]{report} \usepackage{tikz-qtree, qtree, graphicx} \usepackage[margin=1in]{geometry} \newtheorem{theorem}{Theorem}[section] \author{My Name} \title{title}   \begin{document}     \maketitle     \pagebreak       \begin{tikzpicture}           \Tree[.sentence            [.{noun phrase}              [.article the]              [.adjective young]              [.noun ball]]            [.{verb phrase}              [.verb caught]              [.{noun phrase}                [.article the]                [.noun man]]]]     \end{tikzpicture}   \end{document}


Scale out methods with high availability

We have a two site AlwaysOn Cluster and looking to do a High Available multi-site write solution. We have looked at Replication, Sharding, and SQL Elastic options for having multi-site write for a single application. End goal is to have N number of sites that can host the application closest to the user requesting the service, with high availability. We have scaled up, now we want to scale out. It looks like sharding might be the best option. Does anyone have solid experience with implementing a solution like this in MS SQL?


How to install OpenCV 3.1 for Python 3.5 On Ubuntu 16.04 LTS?

How to install OpenCV version 3.1 on Ubuntu 16.04 LTS to work with Python 3.5.1?  I tried  on a VM but obviously that is useful to do if you want to work with Python 2.


How to "cat" or "less" a libreoffice writer .odt file?

Is there a way to cat or less a .odt file just as antiword does for .doc files?


How to divide numbers and return as float in #!/bin/sh

Hi I have to divide two numbers in #!/bin/sh  $x = 5678 $x/1000   but calculations return only integer: 5.  I need 5,678.  I've tried   $x/1000.0  $x/1000.0 | bc   on first method expect integer  second method: I don't have bc.


How can I call the 'base implementation' of an overridden virtual method?

Given the following code, is there a way I can call class A's version of method X?  class A {   virtual void X() { Console.WriteLine("x"); } }  class B : A {   override void X() { Console.WriteLine("y"); } }  class Program {   static void Main()   {     A b = new B();     // Call A.X somehow, not B.X...   }


unmet dependencies, I can't install ubuntu-sdk

I have been trying to install the ubuntu developer environment so that I may begin gaining practice in app development. But once I try to install ubuntu-sdk I get the following error:  The following packages have unmet dependencies: ubuntu-sdk : Depends: ubuntu-html5-container but it is not going to be installed   for which I then proceed to insert the command:  sudo apt-get install ubuntu-html5-container   in which I then receive the following error message:  The following packages have unmet dependencies: ubuntu-html5-container : Depends: qtdeclarative5-ubuntu-ui-extras-browser-plugin but it is not installable   at which point I would feel logical to insert the command:  sudo apt-get install qtdeclarative5-ubuntu-ui-extras-browser-plugin   and my new error message is:  Package qtdeclarative5-ubuntu-ui-extras-browser-plugin is not available, but is referred to by another package.   This may mean that the package is missing, has been obsoleted, or is only available from another source  I have no idea what I'm doing wrong and I have updated my repository libraries several times and still nothing. Could someone please tell me what it is that I'm doing wrong? Why isn't this working like it should?


In Xubuntu I have marked the .sh file as executable, but it still opens in mousepad, and there is no "execute" button on right click, just "open with", I can execute the script only by dragging it in terminal, I would like to execute it by doubleclick.


Is it true that $\sum_{k=3}^{n}\binom{n}{k}\binom{k}{3} = \binom{n}{3}\binom{n-3}{k-3}$?

I was asked to find a closed formula for $$\sum_{k=3}^{n}\binom{n}{k}\binom{k}{3}$$ To remove the $\sum$ if you will.  Here's my reasoning, let's say we have a football team with $n$ players. First we choose $k$ players from those $n$ to be on the starting lineup, and then we chose $3$ out of those $k$ players to play defense.  That is what $\sum_{k=3}^{n}\binom{n}{k}\binom{k}{3}$ means (I think).  Now, that is the same thing as first choosing $3$ out of the initial $n$ to play defense, and then choosing $k-3$ out of the remaining $n-3$ to be on the starting lineup, and that's $\binom{n}{3}\binom{n-3}{k-3}$, so I inferred from that:  $$\sum_{k=3}^{n}\binom{n}{k}\binom{k}{3} = \binom{n}{3}\binom{n-3}{k-3}$$ is this true?


Prove $\sqrt{n+1} < \sqrt{n} + 1 $ for all $n \ge 1$.  I have proven the base step for $n = 1$. $\sqrt{2}$ is less than $2$. The inductive hypothesis is $\sqrt{n+1} < \sqrt{n} + 1$. From here, I am unsure of how to proceed. How can I show that the inequality $\sqrt{(k+1)+ 1} < \sqrt{k+1} + 1$? After simplifying the expression $\sqrt{(k+1)+1}$, it becomes $\sqrt{k+2}$. Perhaps I can use this somehow to come up with an expression? The right hand side does not have a radical over the 1, so I do not think it is a duplicate question that has an answer in the suggested question.


Why won't my ISO go below 6400 when I shoot indoors?

I'm having an issue with my Canon 6D. Whenever I shoot photos inside my house they turn out so grainy! I've tried turning the ISO down but anything lower than 6400 and my photos are basically black. Mind you this is mid-day, lots of light in our house, and yet the ISO on my camera will not go below 6400 and it is making my photos look terrible because they are grainy instead of sharp! Please help!!  Lens is 24 - 105mm f4.0. I shot at 24mm, f5.0, shutter 1/160th, ISO 6400 (this is on auto, but only because anything lower I set it at makes the photos black!).  I'm still kind of new to this, but I do understand ISO, aperture, and shutter speed need to be in certain places for light to come in!


What affects the chances of a shiny pokemon encounter?

For example, if I encounter a Charmander, see that it is not shiny and exit the encounter, will the odds of a shiny Charmander appearance change on my next encounter?


How many times must you roll a die in order to be $99\%$ sure that it is fair?

How many times must you roll a die to be within $99\%$ confidence that it is fair? What if you were to use a die with more sides?


In pgfplots is it possible to have several plots in one datafile?  The goal is to add about 20 plots, which has different number of points and not the same x-value, to the same axis. (app. 350 points)    One posible solution is to have the plots in separate column, and then use loads of 'nan' because of the different x values:      x  p1   p2  P3  ...     1  3    nan nan ...     2  nan  5   nan ...     6  4    8   nan ...     8  7    nan nan ...     ...   I do not like this solution:o(    The  solution is nice: the different plots are separated in the datafile by two newlines, and they are selected by 'index'. Does something similar exist in pgfplots? or any other solution?


I encountered this sentence and the word "before" disappointed me. Can you explain why there is the future tense and this word in the end. If the meaning of "before" is "after your back or in the past" it can't be with future tense. The sentence: Here's some really nice cheese that I don't think you will have tasted before. Thanks.


How to get random color variation on a single mesh?

I am trying to get color variation and to bake it in a single mesh but the Object Info Random only works if i separate the meshes. Is there an alternative way to get the same result with the meshes combined, they aren't attached between them.


RNDIS Connection Lag On Windows, Not Linux

I have two Android smartphones that can provide their internet connection to a computer over USB via the RNDIS (Remote Network Device Interface Specification) protocol. I also have two computers dual-booting Windows 7 Ultimate and some flavor of Linux (one of them has Fedora 17, the other has Ubuntu 12.04).  When I connect either smartphone to either computer and the computer is running Windows, I have to wait about 90 seconds before I can use my internet connection after enabling tethering from the phone.  When I connect either smartphone to either computer and the computer is running Linux, I have to wait about 2.5 seconds before I can use my Internet connection.  My question is, why is there such a ridiculously long delay on Windows?  On Windows, it says "Identifying..." on the adapter for about 60 seconds, then says "Limited Or No Access", then if I keep refreshing my browser, EVENTUALLY it will let me browse. After that it's OK.  On Linux, it connects instantly, just like plugging in an ethernet cable. Boom, done.  I don't think it's hardware related because I have two phones from different manufacturers (Motorola and HTC) running two different versions of Android (2.3.6 and 4.0.4). On the computer side, I have a Lenovo ThinkPad T530 and a hand-made desktop. I've actually tried it on two separate hand-built desktops; one a Nehalem system and one Ivy Bridge. As far as I can tell, they have absolutely nothing to do with one another.  Things I've tried to improve the performance on Windows:   CLEAN install of Windows. Absolutely nothing except base drivers, SP1 and critical updates. No VPN software, no security software, no virtualization software, no custom netfilt drivers whatsoever except those drivers absolutely required to tether to the phone. Unchecking all but TCP/IPv4 in the network connection properties (so unchecking QoS, Client for Microsoft Networks, Link-Layer Topology, etc. Setting static IP and static DNS servers.   None of this helps at all. I simply cannot navigate anywhere on the computer until about 90 seconds after enabling tethering on the phone, and the problem ONLY occurs on Windows. On Linux it's fine.  Pretty stumped about this. For what it's worth my RNDIS driver is version 6.1.7600.16385 and the name is "Remote NDIS based Internet Sharing Device" followed usually by a number like #2, #9, etc. I'm using a genuine copy of Windows in all cases and I've tried both an OEM buildout of Windows from Lenovo (on the ThinkPad) as well as a clean Microsoft install from the retail CD on my desktops.


How well will a Canon 2x extender work with a 60D and 100-400mm L?

I have a Canon 60D (APS-C) body and I want to use a Canon 100-400mm L lens with the Canon 2.0x extender.  I want to know if this combination will work well or not?  I read that extenders have some problems working with APS-C bodies but my one is high end APS-C so I thought it should work well, especially with a good lens like the 100-400 L.


Show that the function $f = \frac{xy}{x^2 + y^2}$ is continuous along every horizontal and every vertical line

Consider the function $ f:\mathbb{R^2} \rightarrow \mathbb{R}$ given by   $ f(x,y) = \left\{   \begin{array}{l l}     \frac{xy}{x^2 + y^2} & \quad \text{if (x,y) $\neq$ (0,0)}\\     0 & \quad \text{if (x,y) = (0,0)}   \end{array} \right.$  Show that f is continuous along every horizontal and every vertical line (i.e. for every $x_0, y_0 \epsilon \mathbb{R}$, the functions $g,h:\mathbb{R}\rightarrow \mathbb{R}$ given by $g(t) = f(x_0,t)$ and $h(t)=f(t,y_0)$ are continuous).  I know that this function is not continuous at $(0,0)$, but the horizontal/vertical line issue is proving difficult to work with. Any help/hints appreciated!


Solving for initial velocity required to launch a projectile to a given destination at a different height

I need to calculate the initial velocity required to launch a projectile at a given angle from point A to point B. The only force acting on the projectile after launch will be gravity – zero air resistance. The projectile is launched within a simulated, virtual environment; however, I am asking for help with the physics rather than the simulation itself.  I have had success (with a different equation) when point A and point B are at the same height; however, once point B is at a different height, my calculations become less precise – well, wrong in fact.  I researched the following formula for finding the range of a projectile on uneven ground. The parameters are all available to me, except the initial velocity that I need to solve for.     $d$ : range or distance   $v_i$ : initial velocity   $g$ : gravity   $\theta$ : launch angle   $y_0$ : launch height   $$d = \frac{v_i \cos\theta}{g}(v{_i} \sin \theta + \sqrt{(v_i \sin\theta)^2 + 2gy_0})$$  I attempted to solve for initial velocity (eq: A):  $$v_i = \sqrt{\frac{d^2g}{2\cos\theta^2(y_0+d \tan\theta)}}$$    Using this equation in my simulation I apply the velocity to a normalised displacement vector and launch the projectile. It gets close to its target but:   $x_{final}$ is always correct $z_{final}$ is always incorrect - it is close to the desired $z$ but always offset by a seemingly proportional amount.    I have spent many hours trying to review the equation but I have been unsuccessful. Any advice would be most appreciated:   is this the correct equation? have I solved for $v_i$ correctly? I have looked for an example equation online but I have not found one structured how I need it, i.e. solving for $v_i$ I have spent hours researching online - perhaps I have missed some good (but entry-level) resources. Do you know of any reference material that may help me?   Update - I have now named the equation above for referencing below  Following on from the answer by @Pygmalion, which I am still gratefully working to understand:  I agree that your derived equation is equivalent to mine (A). Using yours (@Pygmalion's) in my simulation, I therefore observe the same failures: the projectile always lands short of the target.  I have simplified the simulation keeping the launch height and target height the same. I still encounter the same problem with equation A; however, when passing the same parameters to the following equation the projectile always hits the target precisely (eq: B):  $$v_i = \sqrt{\frac{dg}{\sin2\theta}}$$  Given the success of equation B when the launch and target heights are the same and the failure of equation A given the same conditions, I question whether equation A is the correct one to solve the problem since I would expect it to work for any combination of launch|target height.  I think the help I need is around why equation B works. Does it cater for conditions that  equation A overlooks? If equation A is unsuitable, are you able to recommend an alternative?  In short, the $v_i$ calculated by equation A (in my simulations) is always less than $v_i$ from equation B given the same inputs - the projectile therefore always falls short of its target.


Python 3.x: How to manipulate vars in all functions? (w/o Global) (UnboundLocalError)

I'm trying to put some code into a function but I get an Unbound Local Error - I sort of understand why, I just don't know how to fix it.  edit: specifically I was told not to use global because global "is a bad idea". Surely there must be another way?  In the overall code I have multiple variables which need to be altered by user_input and those altered values then need to be passed through one or more different functions (repeatedly (with new values) until a certain conclusion is drawn).  How can I use the variables in multiple functions (cleanly)? If I define them in one function then they're only available there, right? And I can't alter their values from/to elsewhere?  Thank you for any help.  This is a sketch of the code I want to put in a function:  #variables that need to be used (and altered) within multiple functions Var1 = #a_number Var2 = #a_number Var3 = #a_number  def a_function(): #created Unbound Local Error     output() #prints original vars     while True:         inp = float(input("Enter a number: "))          Var1 += inp         Var2 -= inp         Var3 *= inp         output() #prints new values for vars          if/elif/else....         #when Vars are a certain number new calculations are done         #on them. Regardless, there is always only one output of         # the 3 Vars         #some Var vals trigger certain functs which print those new value         #or functions which may even manipulate the values further


Steam missing package libcurl3.7.34 on ubuntu 14.04 64bit?

Here is my problem: I'm trying to install steam and I got this error:  sudo apt-get install steam-launcher  The following packages have unmet dependencies: steam-launcher : Depends: curl E: Unable to correct problems, you have held broken packages.   So I try to install curl and i got this:  sudo apt-get install curl  The following packages have unmet dependencies: curl : Depends: libcurl3 (= 7.34.0-1ubuntu1) but 7.35.0-1ubuntu2 is to be installed E: Unable to correct problems, you have held broken packages.   I have the latest version of libcurl3 (7.35).    So how can I install an old version of libcurl3 (7.34)?  I searched  but have not found anything.


How to upgrade nginx to mainline version from stable version?

I installed nginx 1.1.19 on my ubuntu 12.04 Server.  Now I want to upgrade it to 1.7.6, I add nginx_signing.key and apt source for nginx, then run sudo apt-get install --only-upgrade nginx. But I got this error:  The following packages were automatically installed and are no longer required:   libjpeg8 libgd2-noxpm nginx-full libjpeg-turbo8 nginx-common Use 'apt-get autoremove' to remove them. The following packages will be upgraded:   nginx 1 upgraded, 0 newly installed, 0 to remove and 168 not upgraded. Need to get 0 B/466 kB of archives. After this operation, 904 kB of additional disk space will be used. (Reading database ... 47117 files and directories currently installed.) Preparing to replace nginx 1.1.19-1ubuntu0.6 (using .../nginx_1.7.6-1~precise_i386.deb) ... Unpacking replacement nginx ... dpkg: error processing /var/cache/apt/archives/nginx_1.7.6-1~precise_i386.deb (--unpack):  trying to overwrite '/usr/sbin/nginx', which is also in package nginx-full 1.1.19-1ubuntu0.6 No apport report written because MaxReports is reached already                                                               dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing:  /var/cache/apt/archives/nginx_1.7.6-1~precise_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   What's the problem and how to fix it?


Why doesn't an electron's charge rip the electron apart?

Like charges repel.     What keeps an electron's charge from repelling itself?  This problem would come up if an electron was divisible and its parts had fractional charge.   A related question is, what keeps an electron from being divisible?


Simple question on perturbation theory for a function with two small parameters

Suppose I have an analytic function $f(x;\epsilon, \delta)$ that depends on two small parameters that are of the same order, $0 < \epsilon << 1$ and $0< \delta <<1$ . For example in the context of odes, $\dot{x} = f(x; \epsilon, \delta)$, and so expanding $f$ in Taylor series, we have $f(x;\epsilon, \delta) = f(x;0,0) + \epsilon \frac{\partial f}{\partial \epsilon}(x;0,0) + \delta \frac{\partial f}{\partial \delta}(x;0,0) + O(\epsilon \delta)$   In the consequent computations with $f$, and any other related functions that arise that also depend on $\epsilon$ and $\delta$, is it justifiable to denote $$\frac{\epsilon}{\delta} = c$$ for some constant $c$ that is $O(1)$? Or do I need to impose some more restrictions on $\epsilon$, $\delta$?


i try to add onClick this button then create contact in database  Here is code i try to add it to main_fragment    final Button addBtn = (Button) view.findViewById(R.id.btnadd);     addBtn.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View view) {             Uri imageUri = Uri.parse("android.resource://org.intracode.contactmanager/drawable/no_user_logo.png");             import_fragment.Contact contact = new import_fragment.Contact(dbHandler.getContactsCount(), String.valueOf(nametxt.getText()), String.valueOf(phoneTxt.getText()), String.valueOf(emailTxt.getText()), String.valueOf(addressTxt.getText()), imageUri);             if (!contactExists(contact)) {                 dbHandler.createContact(contact);                 Contacts.add(contact);                 contactAdapter.notifyDataSetChanged(); // Error in this line                 Toast.makeText(getActivity().getApplicationContext(), String.valueOf(nametxt.getText()) + " has been added to your Contacts!", Toast.LENGTH_SHORT).show();                 return;             }             Toast.makeText(getActivity().getApplicationContext(), String.valueOf(nametxt.getText()) + " already exists. Please use a different name.", Toast.LENGTH_SHORT).show();         }     });   When i press this button in my app, 'app has stopped working'  Here is my logcat  01-22 08:31:04.014 29398-29398/com.al3almya.users.al3almya E/AndroidRuntime: FATAL EXCEPTION: main                                                                          Process: com.al3almya.users.al3almya, PID: 29398                                                                          java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ArrayAdapter.notifyDataSetChanged()' on a null object reference                                                                              at com.al3almya.users.al3almya.main_fragment$1.onClick(main_fragment.java:77)                                                                              at android.view.View.performClick(View.java:4848)                                                                              at android.view.View$PerformClick.run(View.java:20262)                                                                              at android.os.Handler.handleCallback(Handler.java:815)                                                                              at android.os.Handler.dispatchMessage(Handler.java:104)                                                                              at android.os.Looper.loop(Looper.java:194)                                                                              at android.app.ActivityThread.main(ActivityThread.java:5637)                                                                              at java.lang.reflect.Method.invoke(Native Method)                                                                              at java.lang.reflect.Method.invoke(Method.java:372)                                                                              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)


How do you check for player death in 1.14.4?

I've been googling this for a while to find nothing that works. When someone dies, I want a message like "Lmao you suck"


raggedleft (right-aligned) entries in pmatrix?

I'm using pmatrix from amsmath package and would like the output to align all entries in the same column to be align on the right hand side, as shown here in the code:  \[ \begin{pmatrix}   -1 &  1 & -2\\    0 & -1 &  4\\    0 &  0 &  1 \end{pmatrix} \]   by default, pmatrix will center.  Any way to do this?


If the pair $(X,A)$ is good, then of course we have that $H_n(X,A) \approx \tilde{H}_n(X/A)$. For a counterexample to the converse, what is a nice example of a reasonably non-pathological bad pair $(X,A)$ such that $H_n(X,A) \not \approx  \tilde{H}_n(X/A)$ ?   I would appreciate if $n = 1,2$ (so it can be visualized).


Entries I can safely exclude doing backups

I'm planning a backup strategy based on .  I want to do a full system backup excluding files and directories that would be useless for the restore to have a working system again. I already excluded:  # System: exclude /dev/* exclude /proc/* exclude /sys/* exclude /tmp/* exclude /run/* exclude /mnt/* exclude /media/* exclude /lost+found  # Application: exclude /*.pyc exclude /*.pyo   I wonder which other entries I can add to the exclude list without compromising the restored system. Talking about a "generic" Linux system, can you suggest further glob extensions, temporary directories, caches, etc. I can exclude safely?


I'm trying to figure out a simple script:  If the URL hash is #commercial (like ) -> then "call a trigger", but I don't really know how to get this started.   Thoughts?


What are the key aspects of a strongly typed language?

What makes a language strongly typed? I'm looking for the most important aspects of a strongly typed language.  Yesterday I asked if PowerShell was strongly typed, but no one could agree on the definition of "strongly-typed", so I'm looking to clarify the definition.  Feel free to link to wikipedia or other sources, but don't just cut and paste for your answer.


Where can I set the value for authConfig.getUsernamePasswordEnabled

In the out-of-box Salesforce lightning component, I could see this configuration. But have no idea where we can setup this value for the  getUsernamePasswordEnabled. Any thought?  @AuraEnabled public static Boolean getIsUsernamePasswordEnabled() {     Auth.AuthConfiguration authConfig = getAuthConfig();     return authConfig.getUsernamePasswordEnabled(); }


In the notes I'm following to understand the proof that $L \vDash GCH$, there is this crucial following passage:     "Let $A \subseteq X$. There is some $\alpha$ such that $A ∈ L_\alpha$ , and it suffices to show that the least such $\alpha$ is strictly smaller than $\kappa^+$ . Because then $\mathcal{P}(X) \subseteq L_{\kappa^+}$"   It is probably very simple, but why every $A \in L_\alpha$ where $\alpha < \kappa^+$ implies that $P(\kappa) \subseteq L_{\kappa^+}$? My doubt is because $sup\{\alpha: \exists A  \subseteq \kappa \; A \in L_\alpha\}$ is not necessarily less than $\kappa^+$ if the $\alpha$ are.  Does $L$ "see" $|L_\alpha| = |\alpha|$?


External HDD fails to mount "exit status 13: `$MFTMirr does not match $MFT (record 0)"

When I plug in my external hard disk I get this error message:  Unable to access “1.0 TB Volume”  Error mounting `/dev/sdb1` at `/media/jonny/4E1AEA7B1AEA6007`: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sdb1" "/media/jonny/4E1AEA7B1AEA6007"` exited with non-zero exit status 13: `$MFTMirr does not match $MFT (record 0).`  Failed to mount '/dev/sdb1': Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run `chkdsk /f` on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the `/dev/mapper/` directory, (e.g. `/dev/mapper/nvidia_eahaabcc1`). Please see the 'dmraid' documentation for more details.   What shall I do now?


Whenever I apply mirror modifier to my mesh the mirrored part becomes deformed and wrinkled as shown in the image. I exported the mesh as obj and opened it in another window and tried to mirror it again but the same thing still happens. How can I fix this? Thanks in advance  .blend file:


quick question, i was just wondering when cononical made and released snaps, I checked the wikipedia  and i couldn't find it, thank you


According to  from 2015, changes were made so that all close votes age away after 14 days, and your ability to cast a close vote on a question you already voted to close resets 14 days after your previous vote ages away. In practice, this means you should be cast a new close vote on a given question every 28 days. And this is my experience, and I think it works well.   Except when it isn't and it doesn't. Here is a  I voted to close in 2011:    The close vote aged away, but my ability to vote again to close it has never been restored. As a result, there is an 8 year old, completely unanswerable question which I can't do anything about.  Is this really by design? If not, is there an easy fix? The changes to the close voting requirements on Stack Overflow has given new hope to those of us that lurk on minor and not busy tags that we might actually be able to get questions closed, but this is another unexpected roadblock I just tripped over....


Did minecraft pe from android is the same with ios?

Can we transfer minecraft from android to ios with computer? Cause my brother is changing his phone and didnt want to lose his worlds. I want to transfer the minecraft file is it possible?


Uninstall, Activate, Deactivate a plugin: typical features & how-to

I'm making a WordPress plugin. What are typical things I should include in the uninstall feature?  For example, should I delete any tables I created in the install function?  Do I clean up my option entries?  Anything else?


Regarding ,  it is not possible to combine complex powers in the usual way:  $$ (x^y)^z = x^{yz} $$  There was mention of multi-valued functions, is there some theory that makes this all work out correctly?


Blender 2.8 How to delete hierarchy in the outliner? I've been searching for this. I can't find a straight foward answer. Can it be done? How?


When looking through the users pages, there appears to be users with negative reputation on the last page.  But, when the page is visited, the users have fairly large amounts of reputation.  Is this some sort of short-overflow bug, or a joke maybe? EDIT: Someone stated that negative reputation would be cruel here:


Is there any statistical test to confirm if a dependent variable converges to a value as the independent variable approaches infinity?

I have a very large table with 40,000 elements, and the dependent variable appears to approach a value as the independent variable gets larger. Is there any test I can perform to confirm if the dependent variable approaches a value as the independent variable goes to infinity?  I have considered using a chi square independence test and a linear regression slope test, but I do not know if these are the best tests for this case. Can someone please help?


Is true that $\sum_{k=1}^n\frac{[kx]}{k}\leq[nx]$, for every $x\in\mathbb{R}$ and for every $n\in\mathbb{Z}^+$?

Is true that $\displaystyle\sum_{k=1}^n\dfrac{[kx]}{k}\leq[nx]$, for every $x\in\mathbb{R}$ and for every $n\in\mathbb{Z}^+$?  My work:  Let $x\in\mathbb{R}$ be given. For every $k=1,\dots,n$, define $i_k\in\{0,1,\dots,k-1\}$ such that  $$ [x]+\frac{i_k}{k}\leq x<[x]+\frac{i_k+1}{k}\hspace{20mm} (*). $$  On one hand, we have that $[kx]=k[x]+i_k$ for every $k=1,\dots,n$.  So  $\displaystyle\sum_{k=1}^n\dfrac{[kx]}{k}=n[x]+\displaystyle\sum_{k=1}^n\dfrac{i_k}{k}=[nx]+\displaystyle\sum_{k=1}^n\dfrac{i_k}{k}-i_n$  Thus  $$\displaystyle\sum_{k=1}^n\dfrac{[kx]}{k}\leq[nx]\Leftrightarrow\displaystyle\sum_{k=1}^n\dfrac{i_k}{k}\leq i_n\,.$$  On the other hand, from $(*)$ is direct that $i_k=[k(x-[x])]$. Thus  $$\displaystyle\sum_{k=1}^n\dfrac{[kx]}{k}\leq[nx]\Leftrightarrow\displaystyle\sum_{k=1}^n\dfrac{[k(x-[x])]}{k}\leq [n(x-[x])]\,.$$  In other words, we can assume that $x\in[0,1)$.   Now the questions is:  Is true that $\displaystyle\sum_{k=1}^n\dfrac{[kx]}{k}\leq[nx]$, for every $x\in[0,1)$ and for every $n\in\mathbb{Z}^+$?  Any simpler approach? Any thoughts?