I was wondering, if I login to the app store with a different Apple ID on a device, will I be able to still use the apps on the device not downloaded or purchased from the current Apple ID?  Example: My wife has an iPhone with many different apps she's downloaded. If I took her phone, logged out of her app store Apple ID, then logged in with my Apple ID, and downloaded other apps, would I be able to use the apps she already downloaded on the phone without having to log her back into the App Store?

Can you have multiple Apple ID's on the same iOS device?  My girlfriend and I have both got an iPad and an iPod Classic and may well be getting iPhones at some point, we each have our own apple ID and I was wondering if I could have both Apple IDs logged into one of our iPads to avoid us having to buy Apps twice.  I would have thought that Apple wouldn't allow this, but I just wanted to check as I can do this on my current Android phone (Two Google accounts rather than Apple IDs obviously).


Can anyone help me identify an animated series I remember from the early 90s. Below are few highlights I remember about it:   action took place in space and/or planets (for sure there was some shooting with fancy fighter-ships in space) protagonists were a team of people serving in some kind of (military?) organization (some of them used nicknames at least in the dubbed version), but I don't remember anything more specific antagonists had a mother ship from which they launched their assaults (they also had triangle-shaped fighter-ships from which they launched smaller triangle-shaped ships) graphics similar to "Centurions," so nothing too cartoonish and nothing 3D (and I'm rather sure it wasn't anime)   I remember the series because at that time I was hyped about fighter planes and fighter pilots (regardless if it was in space or not).  It's not "G-force" or "Jayce and the Wheeled Warriors."

I am looking for the name of a sci-fi cartoon. Key plot points  There were Space ships flown by some American voiced crew. They were some kind of rescue squad or maybe space police. In one episode they went to an orange tree farm in a canyon which used mirrors on the canyon walls to direct sunlight to the oranges. They had a force field that protected the canyon but some bad guys came and shot the mirrors. The heroes came back and saved the day. Another episode was set in an underground ancient tomb of some kind that was covered by a sandstorm once they escaped.  Chronology and other relevant information It had kind of 80s or 90s animation. I don't think I ever saw it on TV. I only ever watched the same 3 episodes on VHS.


I made tomato sauce with browned pork roast pieces in it and cooked it for around 6 hours and left overnight by mistake until the next morning. Lots of sodium and water. My apartment a/c is set at 75 degrees C. Can this be safely eaten after reheated to boiling for an hour and then refrigerated before eating for dinner that night?

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


The Lambda (uds) - 1115 MeV The Sigma (uds) - 1192 MeV   Other than the 77 MeV,  why are these 2 different particles?  Is it the spin of 1 quark?  If so, is it possible to determine which one?  If not spin, what could it be?

Title says it all: How can  and  both have $uds$ quark content? Doesn't this make them the same baryon?


I have a JSON-Array and want to loop though it. I know that there is no foreach-loop (like in PHP), but is there a possibility to access the field index of the array?  This is my json:  {     'username': 'Karl',     'email': 'xyz@abc.xx',     'user_id': 5,     ... }   I have some span elements on my page with a data-field attribute. E.g:  xyz   The json-array is the return of an ajax-request. With it, I want to replace every element where the data-field="" matches the array-index.  Right know, I do it this way for each element in the json-array:  $("[data-field='username']").text(data.username); $("[data-field='email']").text(data.email);   But with more and more elements this becomes a little bit ugly^^  Any other possibilties? I read something about transforming the json to an object, but I have no idea how to do.

How do I enumerate the properties of a JavaScript object?  I actually want to list all the defined variables and their values, but I've learned that defining a variable actually creates a property of the window object.


i’m trying to get into film/photography i think just photography right now and then move over to film. anyways i need a camera obviously but i have no idea where to even start. so could someone please send me some camera recommendations? i have another question too! i would like to start editing these pictures but again there’s so many things to choose from i have no idea which would be best so what should i download?? i have a macbook pro

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


Here Explorer sort by Name separates folder and folder shortcuts.     How can I remedy this i.e. get it to sort them together?  EDIT: Clarification: I want the sorting to remain otherwise unchanged, i.e. not to change the sorting of folders with respect to non-folder-shortcut files.

When Windows Explorer sorts files, it first sorts files from directories and only then sorts each group using the sort specified (My default is DateCreated). I don't like this as the default behavior.   I would like it to be a simple sort (without separating files from folders). Is it possible to change, and if so how?


Here's the Node JS I'm running at the beginning of the script to clear the garbage collector and then logging the available space:  global.gc(); var bytes = process.memoryUsage().rss; var GB = (bytes / 1073741824).toFixed(5); g.heapMessage = "MEMORY used in bytes: " + bytes + ", in GB: " + GB + ",  custom message: " + m;   Here's the output to the shell:  JavaScript Extracted  JavaScript Processing MEMORY used in bytes: 27869184, in GB: 0.02596,  custom message: INIT epochProp ^Z [7]+  Stopped                 sudo ./runScript oughtimpliescan1@ubuntu:~$ sudo ./runScript -bash: fork: Cannot allocate memory oughtimpliescan1@ubuntu:~$      As you can see, there's plenty of memory, 0.02596 GB... and yet the shell keeps telling me it cannot allocate memory, I've tried the  of this command:  sync; echo 1 > /proc/sys/vm/drop_caches  and I'm still having this issue, anybody know what's going on?

I’m using Ubuntu 14.04.  Recently, when I login via SSH with my user with sudo privileges, every command I run results in a “Cannot allocate memory” error.  Here are a few I tried at my console  myuser@mymachine:~$ whoami -bash: fork: Cannot allocate memory myuser@mymachine:~$ uname -a -bash: fork: Cannot allocate memory   Even if I try sudo reboot now I get the above error, so I don’t know what else I can try to unlock my instance.  The host is DigitalOcean if that matters.  Edit: Per the answer/suggestion given here is the output of "free"  myuser@mymachine:~$ free -bash: fork: Cannot allocate memory


i have a problem with mycode '=''or'  $connect= mysqli_connect($host, $user, $password, $database);  if (isset($_POST["sub"])){     $userr =$_POST["username"];     $passs =$_POST["password"];     $password = hash('sha256', $passs);     $query="select * from user WHERE username='$userr'AND password='$password'";          $run=mysqli_query($connect,$query);                          if(mysqli_num_rows($run))     {          header("Location: index.php");          $_SESSION['username']=$userr;         exit;     }     else {         $pri ='
 error ';     } } mysqli_close($connect);   so when anyone doing bypass using '=''or' it will go to index.php  I don't know really how to fix it ..

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I am using Ubuntu GNOME 17.04 for the moment and I am asking myself if – through the future upgrade to Ubuntu 17.10 – my Ubuntu GNOME will be exactly the same as the official main flavor, since it will adopt GNOME again, or if there will be two different flavors with GNOME.  What do you think?

^^^^ Will Ubuntu GNOME upgrade to Ubuntu 18.04, or will support discontinue when 18.04 is released?? Just want to know what's better to run right now so I can upgrade and not have to reinstall later(I intend to see this transition through)-- GNOME installed correctly on vanilla Ubuntu, or Ubuntu GNOME?


How Can I test in C# if a node exists in an XML FILE ? I read my xmlfile like these :  XmlDocument docxml = new XmlDocument();  docxml.LoadXml("test.xml");  XmlNode root = docxml.DocumentElement;  And I want to test if a particular node exists in my file. How can I do that ?

How can someone validate that a specific element exists in an XML file? Say I have an ever changing XML file and I need to verify every element exists before reading/parsing it.


How to programmatically determine from a process P, which other process P' has a lock on a file, that prevents P from recreating that file ?  I know there are tools to do that, but how do they achieve that ?  (Context: a batch program that runs overnight fails because of a locked file. Running an admin tool the next day may be too late to get useful information. So it would be nice if the batch program itself was able to determine the culprit.)  EDIT: Added complexity: the file resides on a DFS and P' might not run on the same machine as P (but maybe does). But a solution that works locally would be a good beginning.

I've seen several of answers about using  or , but I would like to be able to find out in my own code (C#) which process is locking a file. I have a nasty feeling that I'm going to have to spelunk around in the win32 API, but if anyone has already done this and can put me on the right track, I'd really appreciate the help. Update Links to similar questions


Me and my wife traveling to Macedonia next week. I am an Indian, holding a Permanent Resident Permit in Germany but my wife still has a one year resident permit. Does she need to apply for visa?

I'm an Indian studying in Germany. I have a residence permit for Germany with which I can travel in the schengen area. Macedonia is not in the schengen area. However people with schengen visa can enter Macedonia for 15 days without visa. Is my German residence permit enough or do I need a seperate visa for Macedonia?


I have proven that the sequence is convergent. Let $x_n=\frac{(2n)!!}{(2n+1)!!}$ $\frac{x_{n+1}}{x_n}$ $=\frac{2n+2}{2n+3}<1$ Therefore the sequence decreases. On the other hand $x_n>0$. Therefore the sequence is bounded below. Since we have a sequence that is bounded below and decreases the sequence must converge. But from here I don’t know how to find the limit. Could you please help me? And could you please say if what I’ve done is necessary or not? Thanks in advance!

Given a sequence $\{x_n\}, \ n\in\Bbb N$: $$ x_n = \frac{(2n)!!}{(2n+1)!!} $$ Show that $x_n$ converges.  I'm wondering why I'm getting a seemingly wrong result (assuming the problem statement asks to prove convergence): $$ \begin{align} x_n &= \frac{(2n)!!}{(2n+1)!!} \\  &= \frac{2\cdot 4\cdot 6\cdots (2n-2)\cdot(2n)}{3\cdot 5\cdot 7\cdots (2n-1)\cdot(2n+1) } \\ &= \frac{2\cdot 4\cdot 6\cdots (2n-2)\cdot(2n)}{3\cdot 5\cdot 7\cdots (2n-1)\cdot(2n+1)} \cdot \frac{2^n\cdot n!}{2^n\cdot n!} \\ &= \frac{4^n (n!)^2}{(2n+1)!} \\  &= \frac{4^n (n!)^2}{(2n+1)\cdot (2n)!} \\ &=\frac{4^n}{2n+1}\cdot \frac{(n!)^2}{(2n)!} \end{align} $$ By Binomial coefficients: $$ {2n\choose n} = \frac{(2n)!}{n!(2n-n)!} = \frac{(2n)!}{(n!)^2}  $$ Thus: $$ x_n = \frac{4^n}{2n+1}\cdot \frac{1}{{2n \choose n}} $$ Doesn't $\frac{4^n}{2n+1}$ grow faster than $\frac{1}{2n\choose n}$ is declining? Shouldn't $x_n$ diverge in that case?


The  is currently showing [closed], [duplicated] and [on hold] questions at the need answer tab. My suggestion is to hide them since they can't be answered.   Sorting by "votes" at SO, we see tons of [duplicated] questions filling almost the entire first page. This way is harder to find good questions (= high upvoted) to answer.

In fact, they appear to all be merged questions.


I want to ask if garbage collector automatically deletes unused objects in a Java program or it should be manually done by assigning an object to null?

Does assigning an unused object reference to null in Java improve the garbage collection process in any measurable way?  My experience with Java (and C#) has taught me that is often counter intuitive to try and outsmart the virtual machine or JIT compiler, but I've seen co-workers use this method and I am curious if this is a good practice to pick up or one of those voodoo programming superstitions?


When I was browsing the internet, a new site opened and it said that I have a virus in my battery and that it will then also infect my sim card and everything else, infected by a recent adoult side that opened while I was watching anime. It was android site so I clicked continue and then it asked for my number so I closed it. I don't know if it's real, and if it is, what should I do?

This keeps coming up on my phone and I have done factory resets thrice already. My phone is only 3 months old, please help me get rid of this and it seems to infect other phones as well.  I think it was this URL:    http://androidmax.mobi/service.customermarket.5206/hwo3ng/back.php?brd=HTC&mod=One%20M9&brw=Chrome%20Mobile&ts=tfx03&var1=68cd67c2-563d-4b02&var2=55b77b9d2a2c4a382546679e&var3=&cs=zno1&voluumdata=vid..00000003-fee6-4323-8000-000000000000__vpid..7b2dc800-430a-11e5-8cee-c3f8afba77aa__caid..d27753a5-480e-4bf9-8fef-29072ffa67a5__rt..R__lid..6056fb29-a6f1-4b3b-82ff-56f1f82adadc__oid1..e43f1ba3-2cda-4f7b-94f8-176b5506c3a3__oid2..10897965-279f-4048-b4e9-d5cec6dc0941__oid3..85de288c-6197-4636-bea1-0dc212cab827__var1..68cd67c2-563d-4b02__var2..55b77b9d2a2c4a382546679e__var8..55599084af7e637526681985__var9..3510__var10..nativeButton__rd..&imp_id=68cd67c2-563d-4b02&app_id=55b77b9d2a2c4a382546679e&idfa=&mac_address=&android_id=&mobile_id=&campaign_id=55599084af7e637526681985&bid=3510&creative_size=nativeButton


For my combinatorics homework I have the following problem: Let $A = \{a_1, a_2, ..., a_m\}$ and $B = \{b_1, b_2, ... , b_n\}$ with $m \geq n$. Show that the amount of surjective functions $f$ from $A$ to $B$ is equal to: \begin{equation}  \sum_{i=0}^n (-1)^i {n \choose i} (n-i)^m \end{equation} My first thought was that, because these functions must be surjective, for every element $b \in B$ there must be a unique $a \in A$ such that $f(a) = b$. Therefore we must choose $n$ elements in $A$ that have a unique image on $B$ and the rest of the elements in $A$ can be sent to a random element in $B$. So i was thinking about: \begin{equation} {m \choose n} \cdot n! \cdot n^{m-n} \end{equation} as the amount of all possible surjective functions $f$ from $A$ to $B$. My second thought was that the combination is unnecessary and therefore the formula must be: \begin{equation} n! \cdot n^{m-n} \end{equation} Is this correct? If so, how can i prove that this is the same as the summation given at the beginning? I hope anybody can help me with this problem. Thanks in advance!

It is quite easy to calculate the total number of functions from a set $X$ with $m$ elements to a set $Y$ with $n$ elements ($n^{m}$), and also the total number of injective functions ($n^{\underline{m}}$, denoting the falling factorial). But I am thinking about how to calculate the total number of surjective functions $f\colon X \twoheadrightarrow Y $.  The way I thought of doing this is as follows: firstly, since all $n$ elements of the codomain $Y$ need to be mapped to, you choose any $n$ elements from the $m$ elements of the set $X$ to be mapped one-to-one with the $n$ elements of $Y$. This results in $n!$ possible pairings. But the number of ways of choosing $n$ elements from $m$ elements is $\frac{m!}{(m-n)!\,n!}$, so the total number of ways of matching $n$ elements in $X$ to be one-to-one with the $n$ elements of $Y$ is $\frac{m!}{(m-n)!\,n!} \times n! = \frac{m!}{(m-n)!}$.  Now we have 'covered' the codomain $Y$ with $n$ elements from $X$, the remaining unpaired $m-n$ elements from $X$ can be mapped to any of the elements of $Y$, so there are $n^{m-n}$ ways of doing this. Therefore I think that the total number of surjective functions should be $\frac{m!}{(m-n)!} \, n^{m-n}$.  Is this anything like correct or have I made a major mistake here?


I want to ask the question that why the value in the map becomes null.  List<Order> insertOrderlist = new List<Order>(); Map<Order,Decimal> OrderPaymentMap = new Map<Order,Decimal>(); For(ObjectName config: [SOQL query]) {       String PaymentTerm = config.value;       Order o =  new Order(fields = values);       insertOrderlist.add(o);       if(!OrderPaymentMap.containsKey(o))           OrderPaymentMap.put(o,Decimal.ValueOf(config.attribute__c)); } For(Order o1: insertOrderlist) {       System.Debug('#####OrderPaymentMap.get(o1): '+OrderPaymentMap.get(o1));   //Debug point 1, the map value is config.attribute__c }  Test.startTest(); System.RunAs(user){       Insert insertOrderlist; } Test.stopTest();  For(Order o2: insertOrderlist) {       System.Debug('#####OrderPaymentMap.get(o2): '+OrderPaymentMap.get(o2));  //Debug point 2, the map value becomes null }   I have the testcase code in a new dev org, it's wired that the map value is changed to null after inserting the Order value. But I have the same code in another sandbox environment, and I don't have this issue.  ====================================  Add a screenshot to show the result in another org:

Are sObjects supported as the keys for ?  I thought they were, but it appears that any subsequent changes to the key sObject break the mapping to the value.  This might be better shown with an anonymous apex example (API v27.0).  Map<OpportunityLineItem, string> testMap = new Map<OpportunityLineItem, string>(); OpportunityLineItem testOli = new OpportunityLineItem(); testOli.Description = 'foo'; testMap.put(testOli, 'bar'); System.assert(testMap.containsKey(testOli)); string mapValue = testMap.get(testOli); System.assertEquals('bar', mapValue);  // After this the OLI will no longer be a key in the map. testOli.OpportunityId = '0064000000RB2eJ';  System.assert(testMap.containsKey(testOli), 'Expected to still contain OLI'); string mapValue2 = testMap.get(testOli); System.assertEquals('bar', mapValue2, 'OLI instance still expected to map to string bar');   This fails for me with:     System.AssertException: Assertion Failed: Expected to still contain OLI   Is this the expected behaviour?


The code seems to show no errors yet when I run it, my ide shows a lang.nullpointerexception. I have no idea what is wrong or how to fix this problem. Thank you so much for taking the time to help me. Much appreciated.   String sql="Select cast(Sum(Copper) as varchar(255)) as sumcu from RawMaterials"; st=conn.prepareStatement(sql); rs=st.executeQuery(); if(rs.next()){ String sum = rs.getString("sumcu"); sum_text.setText(sum);

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


Prove by induction $\forall n\in N, \sum_{k=1}^nk^3=(\sum_{k=1}^nk)^2$  Step 1 of Induction: Prove base case $1^3=1^2$  Since we've proven base case we can assume $\forall n\in N, \sum_{k=1}^nk^3=(\sum_{k=1}^nk)^2$ Is true  Now need to prove $$\sum_{k=1}^{n+1}k^3=(\sum_{k=1}^{n+1}k)^2$$ $$\sum_{k=1}^{n+1}k^3=\sum_{k=1}^nk^3+(n+1)^3$$ This is where I get stuck. $(\sum_{k=1}^{n+1}k)^2$ is kind of tricky to get into an equivalent form. I can see that $(\sum_{k=1}^{n+1}k)^2=(\sum_{k=1}^{n}k+(n+1))^2$, but I don't know how to proceed from here.

How can I prove that     $$1^3+ 2^3 + \cdots + n^3 = \left(\frac{n(n+1)}{2}\right)^2$$    for all $n \in \mathbb{N}$? I am looking for a proof using mathematical induction.  Thanks


We know how to define the , as answered in this question. After watching the Sixty Symbols video about , where the temperature and resulting black body radiation is a crucial element, I wondered how objects made (almost) entirely of neutral particles can radiate electromagnetic waves, since radiation is caused by acceleration of charged particles (at least in classical physics). I can imagine a few possible answers, but I would like the expert's statement:  Neutrons can be excited and radiate when relaxing Neutron stars aren't entirely neutral. The tiny fraction of protons and electrons radiate Neutrons are made up of charged quarks, and the quarks radiate  I believe this question is different from "Are neutron stars transparent" because I'm asking about the generation of black body radiation, not the lack of absorption of any radiation.

Neutrons have no charge so they would not, I think, interact with photons.  Would a neutron star be transparent?


can someone help me with this error in my latex project? I tried different things different times and I cant figure it out   :/

I'm working in a project for university using LaTeX and I'll make a gif explaning the radians of math. And I really don't know how to make this type of line    What I have done so far  \documentclass[border=1cm]{standalone} \usepackage[utf8]{inputenc} \usepackage{tikz} \begin{document}  \begin{tikzpicture}      \begin{scope} \draw (0,0) circle (10cm); \draw[line width=0.15cm, blue] (10,0) arc (0:360:10) ;  \draw[-] (-12,0) -- (12,0) node[right] {$x$}; \draw[-] (0,-12) -- (0,12) node[above] {$y$}; \draw[line width=0.15cm,red] (0,0) -- (10,-0); \node[scale=15.5, red, right, opacity=0.5] at (2,2) {r};  \draw[red][fill] (0,0) circle (0.2cm); \draw[red][fill] (10,-0) circle (0.2cm);     \end{scope}   \end{tikzpicture}  \end{document}


My question is at  Tetsujin closed it pointing to  but just look at the very different O.S.s in the two questions. Also, my question is vastly different in that I have expressly identified that the Case of the Vanishing Disk-Space is solely attributable to Catalina as no such thing was happening in Sierra, and there are also further particulars stated in the question. In one line, What on earth is Catalina doing with and to the disk that other OSXs didn't? With due respect to 'One-Percenters' of apple.stackexchange, please try to read and understand the question and its specifics and don't keep being so trigger-happy in shutting down questions/threads/discussions.

Every few days I get notices on my MacBook that it's running or run out of hard drive space. Curiously, restarting the computer will enable me to recover gigabytes of space (this past time, it was able to recover about 2.2GB). However, I can't identify anything in my personal activity that consumed that space.  It's possible that it's a rogue iTunes podcast or a huge software update that my Mac is automatically downloading - would either of these reclaim the space upon a restart?  One possibility that I can think of is that FileVault has some sort of disk leak, allocating but not freeing files. Does this make sense? Is there a tool that I can run to determine where this space is going? Assuming it is FileVault, should I try to disable it? What's the best way to turn of FileVault on a nearly full computer?


Need to get my wireless network adapter working on Ubuntu 14.1, but when trying to install the required package bcmwl-kernel-source, the "apt-get install bcmwl-kernel-source" installation command hangs on asking repetitively for a Ubuntu cdrom installation disk mount even after one is provided. Here is the exact terminal output that I am receiving:  $ sudo apt-get install bcmwl-kernel-source Reading package lists... Done Building dependency tree        Reading state information... Done The following NEW packages will be installed:   bcmwl-kernel-source dkms 0 upgraded, 2 newly installed, 0 to remove and 12 not upgraded. Need to get 0 B/1,576 kB of archives. After this operation, 8,386 kB of additional disk space will be used. Do you want to continue? [Y/n] y Media change: please insert the disc labeled  'Ubuntu 14.10 _Utopic Unicorn_ - Release amd64 (20141022.1)' in the drive '/media/cdrom/' and press enter  Media change: please insert the disc labeled  'Ubuntu 14.10 _Utopic Unicorn_ - Release amd64 (20141022.1)' in the drive '/media/cdrom/' and press enter   I tried mounting my installation cdrom as requested, but after pressing enter it seems that the installation unmounts the cdrom and loops back to request that I mount it again. Can't get out of this loop. Why does the installation of this package reqest an installation cd? Other packages install fine without requesting this.

I can't update 12.04 LTS. The Update Manager shows this:  CD/DVD 'Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)' is required Please insert the above CD/DVD into the drive '/media/cdrom/' to install software packages from it.   The image I downloaded and burned to CD is from  the PC (Intel x86) desktop CD version. I burned many CDs but the result is the same.


I am again trying to understand what is the best possible option to securely making the apex callouts from a trigger to external application which supports OAuth2. I am not building any application/package here.  I am very new to Salesforce and the integration with external system, so pardon me if I am asking a very lame question. I am kind of stuck not able to understand what is the right choice for my scenario. The end point supports the grant type Client credentials grant_type=client_credentials client_id=clientId client_secret=clientSecret tenant_id=tenant_id resource=resource  As a POC I was able to harcode all the credentials in Apex and I was able to call external system with out any issues. As this not secure I tried exploring the options mentioned   I tried to use the named credentials but found that grant_type client_credentials is not supported as asked in the question  I tried to create the Custom metadata type and stored the credentials like below  but looks like I cannot store the credentials like above as they are not very secure. Read that I could also use a Custom object with the encrypted field also having the FLS to store these credentials and use it APEX Custom settings - I am not sure if I can use the Custom settings as when I tried to create a it I see the warning message where salesforce recommending to use the Custom metadata type   We dont have the platform encryption turned on in our ORg, should we enable that to created the encrypted fields on the Cutom metadta dattype/object/ settings encrypt it and when we reterive in apex should we be decrypting them? Please suggest me what is the best option to use here and also store the access token retrieved so I can use it until it expired.

I doing a Apex Callout to the third party API which uses the OAuth. I am beginner in the integration from Salesforce to external systems. I am successfully able to call the third party API and perform GET/POST methods.  @future (callout=true)     public static void createSegmentD365() {         try{                 String clientId = 'xxxxxxx';                 String clientSecret = 'xxxxxxxx';                 String tenant_id = 'xxxxxxxxxxx';                 String resource = 'xxxxxxxxxxxx';                  String reqbody = 'grant_type=client_credentials&client_id='+clientId+'&client_secret='+clientSecret+'&tenant_id='+tenant_id+'&resource='+resource;                  Http h = new Http();                 HttpRequest req = new HttpRequest();                 req.setBody(reqbody);                 req.setMethod('POST');                 req.setEndpoint('https://login.microsoftonline.com/xxxx/oauth2/token');                 HttpResponse res = h.send(req);                  deserializeResponse resp1 = (deserializeResponse)JSON.deserialize(res.getbody(),deserializeResponse.class);                 String bearerToken = resp1.access_token;                  Http http1 = new Http();                 HttpRequest req1 = new HttpRequest();                 req1.setEndpoint('https://xyz/data/parentAccounts');                        req1.setMethod('GET');                 req1.setHeader('Authorization','Bearer '+bearerToken);                 HttpResponse res1 = http1.send(req1);   The access token I retrieved from the Authorization provider is valid for 1 hour. I am trying to understand is there a way where I can cache the access token, so I can use the cached token instead of calling the authprovider again within the 1 hour for Access Token. we wont be able to use the named credentials and looks like custom settings is deprecated. I started creating a custom metadatatype with the following fields     I am not able follow in any of the article how I store the credentials or how I cache the access token / refresh if the token is expired from the custom metadata. Any help greatly appreciated.


I have a web app say 'App' , and i want to authenticate that with salesforce without connected app using the normal login page.    Can anyone say how to achieve that.

So what I read everywhere is that, in order to connect to Salesforce via the API, you'll have to authenticate using OAuth.  But this involves creating a Connected App, which is 'cumbersome' for normal users. They just want to login and go.   How do e.g. Jitterbit and Mavensmate etc solve this? I don't install Jitterbit/Mavensmate in my org, do I? There's no connected app in my org. Yet, they can access my data when I provide my username and password+token.  How can I connect to Salesforce without running via OAuth and a Connected App or installing something in the org?


I have a iPod 5 touch with the iOs 7.0.4 and I can't get through the Activation Lock and I have no contact with the Apple ID owner. Is there any bypass for this? Please Help

I bought a used iPhone 4.  The previous owner re-set the phone, but did not remove the device from their iCloud.  It is asking me for their iCloud information when I try to set-up the phone.  I don't have contact with the previous owner anymore.  Is there a way to remove the device from their iCloud so I can use a new one?


I can't seem to find a tutorial online that helps me with this tasking. I have some Vigenere ciphertext (LVGPA...). It only says to assume that encrypting the key letter A results in no change, B results in an increment of one, C increments 2, and so forth.  How would I start to find the key?

I'm trying to crack a cypher that I believe is Vigenère encrypted and I'm currently stuck.  I calculated the key length by finding repeated sequences in the cypher and calculating the the common factors.  Word    distance factors agzd    16       2,4,8,16        zna     92       2,4,23,46,92 zdc     54       2,3,6,9,18,27,54 csio    44       2,4,11,22,44 omy     46       2,23,46 zab     5        5   I assume the key-length is 4 as these are the once that are common factors, but from here on trying to map the correct caesar shiffre for each position I'm stuck.  Can somebody confirm that my key-length calculation has no errors which would explain why I can't solve the cypher.  Here is the cypher:  jD 2GSA 7HNA ZNA w.m. V7KXA 36HBM MKE5 /H SGP9 +R GKKJ 2I A4OTC KDBCUR. 19+R 8Y TKJ JG4 IGO6 6U4T OJ hH/BIK. 196 qFKT+9 BNJK ZD6+Q AGZD. kJ'R EaOP6 4NCR ZK 36 / AGZD6C/HOIE2D. x0ZNAC2S8IO8DI HB xX8D4D 0XK O66M 0Y MN62S 8TZABBD2Za8BI. lBJ HA+DF 6UU/ 2J /FOZDC6S8I OJ kDC8G OO 2BLCYZ O66M 0Y G 925F4 UL J2JHCTGH FHH3K


I am an early university student in a math related field and want to practice proofs. In this context I have found  post ("If $D(a)$ is the digit sum of $a$, is there a positive multiple $m$ for every positive integer $n$, such that $D(m)=D(m^2)$") a few hours ago. As I found the proposition interesting I tried to prove this statement. My plan was to proof it by induction:  It is of course true for $a=1$, as $m=1\cdot 1=1$ and such $D(m)=D(1)=D(m^2)=D(1)=1$ Next I assume that the statement hold for all $a$, if it also holds for $a+1$ The last step would be to show it for $a+1$ to prove it for $a$:  So we have $m=(a+1)\cdot b=ab+b, b\in\mathbb{N}$ and $m^2=(a+1)^2\cdot b^2=(a^2+2a+1)\cdot b^2=a^2b^2+2ab^2+b^2$. That must mean that $D(ab+b)=D(a^2b^2+2ab^2+b^2)$ for all $a\in\mathbb{N}$ with some arbitrary $b\in\mathbb{N}$. This is also the part where I fail to make any meaningful progress because I  don't find out when this equality holds even after trying for longer than I probably should have. Because of this I want to ask how I could proceed here, tips should suffice because in the end I want to learn something. Or maybe this idea of proving it by induction is totally off the track...

Let $S(n)$ be the sum of digits of $n$.  Numerically, I've found that for all $n$ where $S(n) = S(n^2)$, $n \equiv 0,1 \bmod 9$.  Why is that? Is there a proof to show that this is always the case?


Nginx keeps logging below message on my error log  [warn] 16387#16387: *1117 an upstream response is buffered to a temporary file /var/cache/nginx/fastcgi_temp/1/32/0000000321 while reading upstream, client: 173.245.54.175, server:  this fills up my log files , i want to disable buffering completely , i've tried turning proxy_buffering proxy_buffering off; but the logs keeps showing that nginx/fastcgi is buffering responses How do i turn off buffering all together ?

I have a rather large and slow (complex data, complex frontend) web application build in RoR and served by Puma with nginx as reverse proxy. Looking at the nginx error log, I see quite a few entries like:  2014/04/08 09:46:08 [warn] 20058#0: *819237 an upstream response is buffered to a temporary file      /var/lib/nginx/proxy/8/47/0000038478 while reading upstream,      client: 5.144.169.242, server: engagement-console.foo.it,      request: "GET /elements/pending?customer_id=2&page=2 HTTP/1.0",      upstream: "http://unix:///home/deployer/apps/conversationflow/shared/sockets/puma.sock:/elements/pending?customer_id=2&page=2",      host: "ec.reputationmonitor.it",      referrer: "http://ec.foo.it/elements/pending?customer_id=2&page=3"   I am rather curious as it's very unlikely that the page remains the same for different users and different user interactions, and I would not think that buffering the response on disk is necessary/useful.  I know about proxy_max_temp_file_size and setting it to 0, but it seems to me a little bit awkward (my proxy tries to buffer but has no file where to buffer to... how can that be faster?).  My questions are:   How can I remove the [warn] and avoid buffering responses? Is it better to turn off proxy_buffering or to set proxy_max_temp_file_size to 0? Why? If nginx buffers a response: When does it serve the buffered response, to whom, and why? Why nginx turns proxy_buffering on by default and then [warn]s you if it actually buffers a response? When does a response trigger that option? When it takes > some seconds (how many?) to serve the response? Is this configurable?   TIA, ngw.


The sub-surf modifier is causing a weird indent around the end of my sleeve right next to where I have the sleeve thicken a little and I was wondering why it was causing that and what I can do to fix it?

I have this model, and when I add the subdivision-modifier:    it seems to be okay, for me (I guess those bumps are there, because of the triangle faces instead of quads):    but when I add the smooth-shading I'm having this:    I think this is something really obvious -- but I just can't figure out the reason..  Thanks in advance,


Let's say I have a class A, which has two methods. I have to test a method, which internally calls the other method.  class A {     private void method1() {         //some steps to be done     }      public void method3() {      //some steps     }      public void method2() {         method1();         if (XUtil.isSupportRequired) {             method3();         }     }  }   So, If I try to test method2, how to mock method1, as it is not public. Any help would be appreciated.  I am using junit and mockito.

I have read  about how to test private methods. I usually do not test them, because I always thought it's faster to test only public methods that will be called from outside the object. Do you test private methods? Should I always test them?


I have a SOT-23 part with part number AEWU9 but couldn't find any datasheet on the net. Where can I search more for this part?

How do I identify the markings on an SMT component and match it up with a part number so I can be a good designer and actually look at a datasheet (and read the whole thing)? Or identify a part to replace an unknown part on a PCB?


I'm trying to solve the following limit.    $$\lim \limits_{x \to 2}{\frac{\sqrt{6-x}-2}{\sqrt{3-x}-1}}$$    Unfortunately, I haven't made any headway.  I tried multiplying by the conjugates of both the numerator and denominator (in 2 different attempts, of course), but ended up with a monster of an expression either time.

You can't use L'Hospital's rule :S  $$\lim_{x\to2} {\sqrt{6-x}-2\over\sqrt{3-x}-1}$$  I've tried to multiply by conjugates but ended up with a so complex equation, please help, anyone? :S


I have a Dell Inspiron laptop with preinstalled Windows 8, upgraded to Windows 8.1 which cannot boot now. I am able to get in recovery screen with an USB installation kit.  In order to get the correct, legal Windows ISO I need to provide my product key. I understand that this is saved and connected to the BIOS/Mainboard/UEFI.  If I access the command prompt from the recovery menu, is there any command which provides me my OEM product key?

I have seen other SuperUser questions on this topic:  |   However, all of the answers assume you have Windows 8 running.  I've already done a clean install of Ubuntu 13.04 on my new laptop, and I'm trying to set up a VM environment for those occasional programs that just absolutely refuse to run even with Wine.  I saw this image on another answer:     So it appears that the key should somehow be available via ACPI. However,  I've tried ls /proc/acpi and that turns up nothing useful as far as I can see, and acpitool isn't helping me at all.  How the heck can I get the product key out?  EDIT: I have tried running RW-Everything via Wine (the  program), but it is unable to 'install its driver'. So no dice there.


I just want to check if the given passwords are not equal to each other. So I had made this:      String password = etPassword.getText().toString().trim();     String confirmPassword = etConfirmPassword.getText().toString().trim();      if (password != confirmPassword) {         Toast.makeText(getApplicationContext(),                 "Passwords do not match", Toast.LENGTH_LONG)                 .show();     }   But somehow it doesn't work. I have logged it when I gave an input value "e" for both passwords.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I know that to show a ring is isomorphic to another ring, I have to find a bijective ring homomorphism between the two rings. Or I could use the F.H.T. but I would also need a function to make that happen (If I'm thinking about it correctly). Do I need to just make up my own function and prove that it is a bijective ring homomorphism? If so, where do I start? Thanks!

Let $R$ be a commutative ring. Prove that $R[x]/(x)$ is isomorphic to $R$.  Should I use the first isomorphism theorem for rings?  Can someone give me a hint on how to approach this problem? Also how would I use the first isomorphism theorem to prove this? I know that the theorem says $R /\ker f$ is isomorphic to image of $f$.


I know that this is convergent. I've proven it with mathematical induction but I want to know what is the exact limit.I have no idea what to do. can anybody help me?             Lim  $1+\frac{1}{4}+\frac{1}{9}\ldots \frac{1}{n^2}$

As I have heard people did not trust Euler when he first discovered the formula (solution of the ) $$\zeta(2)=\sum_{k=1}^\infty \frac{1}{k^2}=\frac{\pi^2}{6}.$$ However, Euler was Euler and he gave other proofs.   I believe many of you know some nice proofs of this, can you please share it with us?


I have a php file for frontend. In this file there are few forms.   <form name="add3" method="post" id="add3" name="add3" action="add_exec.php" role="form"> </form>   now you can see in action add_exec.php. I want this file not to be execute directly.  I don't want to use .htaccess to achieve this.   Is there anything else we can do to prevent direct execution of add_exec.php file.  Thanks  Edit:  I am not looking for htaccess answer. If my file is in form action attribute then it will consider as include or not? If no then how can i prevent the execution.

I have a php file which I will be using as exclusively as an include. Therefore I would like to throw an error instead of executing it when it's accessed directly by typing in the URL instead of being included.  Basically I need to do a check as follows in the php file:  if ( $REQUEST_URL == $URL_OF_CURRENT_PAGE ) die ("Direct access not premitted");   Is there an easy way to do this?


I worked with LaTeX for a short while and now I'd like to create my own templates for e.g. handouts. Here is a example for the beginning of my handout template:  \documentclass[12pt,german,a4paper]{article}  \usepackage[utf8]{inputenc} \usepackage[ngerman]{babel} \usepackage{url} \usepackage{fancyhdr}  \pagestyle{fancy} \fancyhf{} \renewcommand{\headrulewidth}{0pt}  \setlength\parindent{0pt}   All of this templates should be in one folder somewhere on my file system e.g. ~/templates. If I start a specific file I'd like to import one of these files with \input{}. I got the advice to use texmf-local for this because the LaTeX commands doesn't understand environment variables (I use Ubuntu Linux). Unfortunately I don't have any experience with that.  So how can I create a central folder for all my templates and input these files with e.g. \input{handout}? It would be cool if I only have to change one variable after moving the template folder to another place.

I know how to define a package or a class, but how do I make it available (to myself) at all times?  Say I have the package file commonstuff.sty (or myprettyclass.cls), that I want to be able to include in any .tex file I create on my computer. Where do I put it? Do I need to run some installer on it, or is it enough to keep it in a certain folder?  Note: I know I can just place it in the same folder as the .tex file, but that's not what I'm after here. I'm looking for a way to "install" the package centrally on my computer.


Let $a , b, c, d$ be real numbers such that $$ a+b+c+d=6 \\ a^2+b^2+c^2+d^2=12$$  How do we prove that $$ 36 \space \leq\space 4(a^3+b^3+c^3+d^3)-(a^4+b^4+c^4+d^4) \space\leq48\space$$ ?


Can anyone help me with the use of 'that' and the bare form of a verb in the following sentence?   This plan suggested that the supply target for new and renewable energy be increased to 20% by 2020.    Here, I would like to know how the 'be' was used without expressing its tense. I appreciate your help in advance.

We will make the convention that exact categories be skeletally small.   Is this construction (used in a mathematical context) correct? There is something that strikes me as odd in that "be". Should it be "are"? I know I've seen a similar way of using "be" like that, without conjugating the verb, but I'm not completely sure when it should be used.


I use this program in Windows that's one-box and searches all of my drives. By default it lists all files, everywhere, in a single list. Is there a Linux graphical utility that does this?

IMO,  is the best desktop search software on Windows and I wonder if there is an equivalent utility on Ubuntu ?


Can anyone please explain what is meant by this illustration when deriving the formula for the force of surface tension which is $2 L \sigma$, where $\sigma$ is the tension? Where does exactly the factor $2$ come from? Of course, I have read a thousand times that we have to take into consideration the two sides of the sliding blade, but I don't seem to understand how the blade is put relative to the liquid, what two sides, which surface gets bigger? I'm really confused and would be happy to get a detailed and illustrative answer!

According to  on the surface tension of a thin film: $$ \gamma = \frac{1}{2} \frac{F}{L}$$ Where $\gamma$ is the surface tension, $L$ is the length of the movable side and $F$ is the force required to stop it from sliding. (Please refer to the picture of a thin film below, also from Wikipedia)    Why is there a $1/2$ factor included in the equation? Some books said it's because there are two layers of the liquid. But in the case of a thin film, shouldn't there be only one layer? (i.e. one molecule thick). My current understanding is that there are supposedly two layers and each layer exerts an equal amount of force and thus the $1/2$ factor.     EDIT  Here is a picture to clarify what I am thinking (although it doesn't exactly depicts a "thin" film.) It shows a huge magnification of the cross-section around the boundary between the movable rod and the liquid.    $ABCH$ is the cross-section of the movable rod and $DEFG$ is the cross-section of the liquid. The circles in the liquid are liquid molecules, named as lower case letters for the sake of conversation.   Now lets consider molecule $f$ for instance. It stays static because there is a balance of cohesive forces in every direction. Molecules on the liquid surfaces such as $a$ and $d$, however, experience a net downward liquid-cohesive force and therefore must be balanced by the adhesive force from the movable rod, resulting in surface tension. Each line of molecules (along $a$ and $d$) exerts a pulling force of $F=\gamma L$. There are two lines of molecules so $F = 2 \gamma L$.  However, molecules $b$ and $c$ also experience net downward liquid-cohesive force and therefore must be balanced by the adhesive force from the movable rod, resulting in a pulling force exerted by molecules $b$ and $c$ on the movable rod. Therefore $F$ no longer equals $2 \gamma L$ but equals $4 \gamma L$ in this case.


there are some citations with three or more authors in text, I want to collect these citations in a table now. In the text, all author names will be printed when first cited, and only the first author name will be printed from the second citation. It works well in text, but it is not when I put them in a table. The code below shows what I mean (Note: apa style is used):  \documentclass{article}  \usepackage[style=apa,maxcitenames=2,uniquelist=false,     backend=biber]{biblatex}  \usepackage{filecontents}  \begin{filecontents}{\jobname.bib} @misc{ABC:2014,   author = {AuthorA, A. and AuthorB, B. and AuthorC, C},   year = {2014},   title = {Paper1}, } @misc{ABC:2016,   author = {AuthorA, A. and AuthorB, B. and AuthorC, C},   year = {2016},   title = Paper2}, } \end{filecontents}  \addbibresource{\jobname.bib}  \begin{document}  \noindent Some text \autocite{ABC:2014}.\\ Some text \autocite{ABC:2016}.  \noindent Some text \cite{ABC:2014}.\\ Some text \cite{ABC:2016}.  \noindent Some text \textcite{ABC:2014}.\\ Some text \textcite{ABC:2016}.  \begin{table}[htbp] \centering \caption{example} \begin{tabular}{llll}  \hline colum1 & column2 & column3 & \cite{ABC:2014} \\ colum1 & column2 & column3 & \cite{ABC:2016} \\ \hline \end{tabular} \end{table}  %\printbibliography  \end{document}   It will show the result as the attached figure. I suppose the citations in the table will be the form "first author name + et al.", but it is not. The intelligent way I can figure out is use "\cite*{ABC:2014} \citeyear{ABC:2014}" instead of the standard command "\cite" or "\textcite". However, this does not solve my problem well, as I want it show all names if there are two authors. Is there a better way to achieve this? Thanks!

I'd like to use \footcite in a figure environment in a way that acts completely like a \footcite in ordinary text mode. Specifically, I've configured \footcite to print a long citation (i.e. with the author's first name, year of publishing, etc.) on the first reference to a given source, and on subsequent citations, only a short citation should be printed in the footnote.  However, when I use \footcite in the \caption of a figure, I always get a long citation. What can I do to change that behavior?  MWE:  \documentclass[12pt,english,a4paper]{article}  \usepackage[a4paper, total={6in, 4in}]{geometry} \usepackage[english]{babel} \usepackage[backend=biber,     citestyle=verbose,     bibstyle=verbose,     sorting=nyvt]{biblatex} \addbibresource{bibliography.bib} \DeclareNameAlias{sortname}{last-first} \renewbibmacro{in:}{} \usepackage{tikz}  \usepackage{footnote} \makesavenoteenv{figure}  \usepackage{filecontents} \begin{filecontents*}{bibliography.bib} @article{A,   author    = {Alpha, Amber},   title     = {Title},   publisher = {Publisher},   year      = {2014}, } @article{B,   author    = {Beta, Bryan},   title     = {Title2},   publisher = {Publisher2},   year      = {2015}, } \end{filecontents*}   \begin{document}  While some\footcite{A} argue X, Ref. \textcite{B} argues Y. Also, W\footcite{A}.  \begin{figure}[!htbp]     \begin{center}         \begin{tikzpicture}             \draw (0, 0) circle (1);         \end{tikzpicture}     \end{center}     \caption{A circle.\footcite{A}} \end{figure}  \printbibliography  \end{document}     Note how footnote 1 and 2 are long while 3 is short, as I expected them to be. However, I also want 4 to be short, but it isn't.  Thank you in advance!


I have a gas dryer for sale, but do not have a gas line hook-up. Can I use a small propane tank to test the dryer for potential buyers?

I bought a modular home in the woods with no w/d hookup,I want to know if it's safe & OK to hookup a 5 gallon propane tank to a gas dryer, plug it in & dry my clothes?  Do I have to change something in the dryer to run propane from natural gas? Just trying to be safe. I don't want to blow me & my house up! 😳 ANY HELP OUT THERE PLEASE WOULD APPRECIATED!


I'm having problems with my (javascript) API. When I use the coinmarketcap API (). As for "max_supply" for bitcoin, it gives me "16865112.0" in text. This is a problem. I want to automatically put comma's in the number like 16,865,112.0 normally I use toLocaleString() but it is marked as text and it doesnt work.  $.get("https://api.coinmarketcap.com/v1/ticker/", function(data, status) {   for (var i = 0; i < data.length - 1; i++) {     if (data[i].id == "bitcoin") {      $("#total_supply").html(data[i].total_supply.toLocaleString());        }   } });    Any suggestions?

I would like to format a price in JavaScript. I'd like a function which takes a float as an argument and returns a string formatted like this: "$ 2,500.00"  What's the best way to do this?


I was just wondering if FaceTime calls show up on my carrier's (Sprint) bill as a regular call, like the number that was FaceTimed and when and the length of the conversation.

On the newest iPhone, do cell phone carriers have access to FaceTime call data (such as which caller initiated and ended a FaceTime call)?


This issue is really driving me nuts for a while. I have a Mac Book Pro and using a usb C hub with an hdmi port. I am running a HDMI connector to my monitor. Its fairly decent. Acer 27P with 1080 p res and 165Hz refresh rate. The issue is when I drag any window to the monitor screen and try to maximize it, all edges go out of the screen borders. I tried to play with the resolution settings to no avail. Even the menu bar is hidden at the top and I have to carefully move the mouse around to guess where the menu items are. Please help me resolve this. I am hoping to make this a normal 2nd screen where all windows and menu bars are within the screen border and dont extend out of it when made full-screen. Please see the image for an idea. Thanks!

I have a MacBook Pro with Touch Bar. I plugged in my external 1080p display (HP 25bw) in clamshell mode and it almost works great - except the screen is too large for the monitor. My dock is too far down off the edge, and my menu is too far up.  For example, when I took the attached screenshot, the Chrome window fills the entire screen I can see:  I have checked and the display options are using native resolution of the monitor (1920x1080 @60hz).  Does anyone have any suggestions for me? Thanks so much.  Note: For any with this same monitor model in the future, thanks to @bmike I found the steps for disabling overscan for this particular monitor model here:


I want to place the column-spanned figure at the bottom of the page  near to the text  but using \begin{figure*}[b] goes the figure to the end of the document!! Why?  \begin{figure*}[b]     \centering     \includegraphics{fig.eps}     \caption{Something}     \label{f1} \end{figure*}

I'm posting today because I would like to reduce white space in a document I'm writing. The content is two-columns but I have floating tables that span across both columns (table*).   At some point, the text ends in the beginning of the first column of a new page. I would like to include my table on this page since it has a lot of free space below the text, but when I insert the table* right after the text, it goes to the top of the next page instead:    Do you know a way of obtaining the desired behavior?  Minimal working example :  \documentclass{article} \usepackage{lipsum}  \begin{document} \twocolumn  \paragraph{} \lipsum[1]  \begin{table*} \centering \begin{tabular}{|c|c|c|c|} \hline Column 1 & Column 2 & Column 3 & Column 4 \\ \hline Column 1 & Column 2 & Column 3 & Column 4 \\ \hline \end{tabular} \end{table*}%   \end{document}


I keep getting an error:     [2020-01-27 10:37:04] [23000][4025] CONSTRAINT CONSTRAINT_1 failed   When I insert the following row:   '(01)236-4589'   For the following column:  CHECK (phone LIKE '(0[0-9])[0-9][0-9][0-9]-[0-9][0-9][0-9][0-9]')   Please tell me what I'm doing wrong.    Thank you very much for the help.

I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps?


I read  and . From these two SO posts I have a rough idea of what it is. It is an ID for a Serializable class used to check if the sender and receiver are compatible during deserialization. If not a InvalidClassException is thrown.   However I am curious about a few things:   serialVersionUID seems to be divided into 2 "type". 19 numbers followed by L xxxxxxxxxxxxxxxxxxxL or 269L or 1L. These numbers don't seem arbitrarily chosen. If we simply need an ID wouldn't any number work? what is the logic behind this design. For the 20 characters long serialVersionUID it can be positive or negative. What is the difference. Again if serialVersionUID is used for the purpose of identifying, why do we need to have a negative number? We have not used up all the positive numbers yet. In MirroredTypedException.java the serialVersionUID is 269 without the L. It is the only serialVersionUID I found without the L. Why is that? What is the meaning of L?   a snapshot (this snapshot doesn't include all of them)

I'm extending a class (ArrayBlockingQueue) that implements the . Sun's documentation (and my IDE) advises me that I should set this value in order to prevent mischief:     However, it is strongly recommended that all serializable classes explicitly declare serialVersionUID values, since the default serialVersionUID computation is highly sensitive to class details that may vary depending on compiler implementations, and can thus result in unexpected InvalidClassExceptions during deserialization.   Now, I couldn't care less about what value to put in there. Does it matter?


Most of the wide angle lenses are lower focal length and the telephoto lenses are of longer focal length.  Can someone explain (scientifically) to me how shorter focal length of the lenses is help to get a wider angle.  I don't see any relationship between wideness and focal length. Why can't a  telephoto lens have a focal length of 24 mm.

I read on the :     Focal-length determines the angle-of-view seen through a lens for a   given sensor-size. With a full-frame sensor a lens gives the same   angle-of-view as it would on a 35mm film camera. With a smaller   sensor, the angle-of-view becomes smaller. The crop-factor, also   called FLM, is the ratio representing the difference in equivalent   focal-lengths. So a 150mm on a full-frame DSLR such as the Nikon D700   gives the same angle-of-view as a 100mm on a D7000 since its FLM is   1.5X.      Short focal-lengths show a greater angle-of-view compared to longer   ones. [...]   In layman's terms, what is angle-of-view? Is it the same as focal length? If not, how is it different? How is it used? Why do I need to know about it?


Some pollutants heavier than air that are released into the atmosphere include $\text{CO}_2,\text{SO}_2,\text{SO}_3,\text{NO}_2$ etc. Since these gases are heavier than air, Why do they not settle down closer to the surface? By that, I mean why is the concentration of these gases not maximum at sea level?    article has been used as a reference: it is evident that the $\text{CO}_2$ concentration around the 200 HPa band is more than the 800 HPa band in the month of July. Note that this article also does not provide clarity on surface $\text{CO}_2$ levels, it gives data for the 5 km-25 km altitude range.

Air contains about 78% nitrogen and 21% oxygen independent of altitude (up to 100 km). Why is this? Shouldn't the concentration of nitrogen increase with higher altitudes since nitrogen has a lower density than oxygen?


I have a simple bottle with cap. I have exported the mesh with obj file. Importing in After effect with 3d element plugin i get only single mesh. How to have a separate mesh. Any option while exporting.

It is possible to export all object from a scene into different obj files (each object in a obj file separately)?


I will try to keep this short and sweet. I have obtained a German language learning visa in Germany. It expires on September 1st, 2018 (I applied for it in October, so it is an 1-month visa, just in case this information helps). I would like to find a way to stay and do some traveling after my classes end in August since I really haven't had a chance to explore.  I have been reading online that you can deregister the class D visa, fly to the UK and re-enter into France to start a 90-day tourist visa (granted to us Americans by our passport). But I don't know how accurate this information is and I don't want to chance being deported in September if this is not the case. Anyone have experience with this? Or know where I might be able to go to get an accurate answer?  TL;DR Trying to move from study visa to tourist visa by going to the UK and re-entering a Schengen country. Will this work?

I have a 1-year residence permit from one Schengen country that is now expiring. Upon its expiration, I would like to get my 90/180 days validity as a tourist to stay, or return here as soon as possible.  I understand that the tourist short-stay scheme is based on the 90/180 days "counter". But what happens if my previous stay was not tourism but residence (as searching year). Wouldn't that mean that I can quickly exit and re-enter the Schengen area to activate my tourist stay?   Also, is there a way to change this purpose of stay without exiting the Schengen area?


The equivalence principle states that no experiment can determine whether one is being accelerated or if there is gravity present. This is insightful and intuitive.  However, I was sort of surprised. It is commonly stated that a person in free-fall is weightless, however, if a person was just floating around in empty space (free from any other bodies of mass) they would also feel weightless. This is confusing because that means that having gravity accelerating you and having no force at all are the same?   Why is it that one cannot distinguish free fall in a gravitation field from floating? Intuitively they seem to be different things because there is acceleration in free fall.

Note: For the purposes of my question, when I refer to free fall assume it takes place in a vacuum.   From my (admittedly weak) understanding of the equivalence principle, falling in a gravitational field is physically indistinguishable from floating in interstellar space. This would make sense to me if gravity simply caused an object to move at a constant velocity. Moving at a constant speed, or floating in space, are just two different ways of describing an inertial frame, and are fundamentally no different. But free falling in a gravitational field means accelerating continuously, and doesn't an accelerating body experience a force? Then isn't free falling fundamentally different from floating in space?


I need some help with converting the date to dd/mm/YYYY.  I have this code to display my date in a html table from a mysql database  echo "<td>".$zeile['datumFahrt']."</td>";   Can I convert it in this line so the format will be dd/mm/YYYY instead of YYYY/mm/dd?

I have a datetime column in MySQL.   How can I convert it to the display as mm/dd/yy H:M (AM/PM) using PHP?


WordPress or PHP are cutting off the text after saving a post. This happens when there is a special character like ’ or ™.  For example if I enter the following text:  This isn’t working   and then I save the post, the post will be:  This isn   I assume is not MySQL because I entered the same text and it worked. The wp-config.php contains the following:  define('DB_CHARSET', 'utf8'); define('DB_COLLATE', '');   And I have tested it with  define('DB_CHARSET', 'utf8'); define('DB_COLLATE', 'latin1_swedish_ci');   The mysql database has latin1_swedish_ci collation and the tables has utf8_general_ci collation.  I've also tried to change the tables collation but it didn't work. I'm using the latest WordPress version. I don't have experience with collations or encoding. So, my question is: Is there a method to make WordPress save the entirely post without cutting off the content when appears a special character?

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I have a list of contacts that was generated generically in code. At the end of the class I need to send email to a user.  Email should include the list of contacts. (I'm using email tamplate).  How can I add this list of contacts to email before sending it?

I've stumbled upon a problem at the final stage of a new feature I was building (as always)   I need to pass in a custom string into a salesforce template, however there doesnt seem to be a way of doing this through the standard methods.   I'm passing in a contact ID, to email the correct user and name to personailse the email. But I need a string to be passed to the template which is completely unrelated to the contact record, and need to be dynamic. So I cant just put it in the template.   Is there a way? I know i cant pass in a custom object as it needs to be a contact, user or lead id to email a user.   Can you help?   Here is the code if you need to see it:  public static void sendSingleMail(id objId, ID templateId, string fromaddress) {      Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();     mail.setReplyTo(fromaddress);     mail.setTemplateId(templateId);     mail.setTargetObjectId(objId);     mail.saveAsActivity = false;     mail.setReplyTo(fromaddress);     mail.setSenderDisplayName(fromaddress);      ErrLogger.logger('Email being sent to :');     ErrLogger.logger('objId found:  ' + objId);     ErrLogger.logger('templateId found:  ' + templateId);     ErrLogger.logger('fromaddress found:  ' + fromaddress);      Messaging.sendEmail(new Messaging.SingleEmailmessage[] {mail}); }


I need to move/edit few labels in a job. How can I work on it?  I am using QGIS 1.7.4 and the label option in the toolbar (not the layer options)

I'm trying to manually move labels but having some trouble. I'm trying to move the labels while in edit mode. I've added fields for x coordinate (all null), y coordinate (all null), rotation (all =0), and font-size (all =10). This makes the "move label" and "rotate label" buttons active, but when I click on the labels, no box around the label appears and it's impossible to move the label. What am I doing wrong?


What's the best way to inject html template (which also contains  tags) with JavaScript? What I intend to do is for the user to add a line of code like this:

 and then a  tag that populates the div with the html. And how could I inject

I'm looking for a way to insert a "; document.body.appendChild(divNode);   This works in Firefox, Opera and Internet Explorer but not in Google Chrome. Also it's a bit ugly with the
 in front for IE.  Does anyone know of a way to create a


I read this story/novel in the 1970s.  My recollections are : A man wakes up thousands of years in the future, on a planet which turns out to be Earth (maybe).  The man had been somehow petrified, and awakened, due to electricity or lightening. The planet has beings which are feline-like and also canine-like (and I think the two species were in conflict with each other). The man has a romantic situation with one of the cat-ladies. There is some influence of a giant intelligent tree which governs and permeates the planet. The man was considered a deity because he awoke from stone (not sure about that part though). Thanks for any help finding if this was a real book or my imagination.

Trying to identify a book I read years ago. It had one male human that was (petrified?) for thousands of years. The world had ridiculously huge trees and catlike people. The only bit of steel to be found was his switchblade. Think it was published in the 70s.


On Ubuntu 12.04 I can't play DVDs in VLC, the native DVD player, or Parole media play. I must be missing something.  What libraries/codecs do I need etc.? Where do I get them? Where do I find out where to get them?

My machine can't play encrypted DVDs on a fresh install.  How do I add this capability?  Another useful bit of information would be what programs are best for playing DVDs, once I'm able to do so.  See the .  Will I be able to play DVD movies from ?


I did $y=(1+1/n)^n)$ so $ln(y)=n*ln(1+1/n)$ so then $ln(y)=Ln(1+1/n)/(1/n)$ which sith l'hospitals rule becomes $ln(y)=(-1/(n^2 + n))/(-1/n^2)$ which simplifies to $n/(n+1)$ which using l'hospitals rule is $1$ so the answer is e. how do you solve this without l'hospitals rule

I was wondering if it is possible to get a link to a rigorous proof that  $$\displaystyle \lim_{n\to\infty} \left(1+\frac {x}{n}\right)^n=\exp x$$


Good night, someone could help me with some interesting applications of this important theorem and also I could say how I draw a dense subset in the complete space used in the theorem. Thanks for your help

I think I remember reading somewhere that the Baire Category Theorem is supposedly quite powerful. Whether that is true or not, it's my favourite theorem (so far) and I'd love to see some applications that confirm its neatness and/or power.  Here's the theorem (with proof) and two applications:    (Baire) A non-empty complete metric space $X$ is not a countable union of nowhere dense sets.  Proof: Let $X = \bigcup U_i$ where $\mathring{\overline{U_i}} = \varnothing$. We construct a Cauchy sequence as follows: Let $x_1$ be any point in $(\overline{U_1})^c$. We can find such a point because $(\overline{U_1})^c \subset X$ and $X$ contains at least one non-empty open set (if nothing else, itself) but $\mathring{\overline{U_1}} = \varnothing$ which is the same as saying that $\overline{U_1}$ does not contain any open sets hence the open set contained in $X$ is contained in $\overline{U_1}^c$. Hence we can pick $x_1$ and $\varepsilon_1 > 0$ such that $B(x_1, \varepsilon_1) \subset (\overline{U_1})^c \subset U_1^c$.   Next we make a similar observation about $U_2$ so that we can find $x_2$ and $\varepsilon_2 > 0$ such that $B(x_2, \varepsilon_2) \subset \overline{U_2}^c \cap B(x_1, \frac{\varepsilon_1}{2})$. We repeat this process to get a sequence of balls such that $B_{k+1} \subset B_k$ and a sequence $(x_k)$ that is Cauchy. By completeness of $X$, $\lim x_k =: x$ is in $X$. But $x$ is in $B_k$ for every $k$ hence not in any of the $U_i$ and hence not in $\bigcup U_i = X$. Contradiction. $\Box$    Here is one application (taken from ):  Claim: $[0,1]$ contains uncountably many elements.  Proof: Assume that it contains countably many. Then $[0,1] = \bigcup_{x \in (0,1)} \{x\}$ and since $\{x\}$ are nowhere dense sets, $X$ is a countable union of nowhere dense sets. But $[0,1]$ is complete, so we have a contradiction. Hence $X$ has to be uncountable.     And here is another one (taken from ):  Claim: The linear space of all polynomials in one variable is not a Banach space in any norm.  Proof: "The subspace of polynomials of degree $\leq n$ is closed in any norm because it is finite-dimensional. Hence the space of all polynomials can be written as countable union of closed nowhere dense sets. If there were a complete norm this would contradict the Baire Category Theorem."


I am new to this java Selenium. I have 2 classes. 1 parent and 1 child. I have some methods in the parent class. I pass 2 of them to the child class. The problem is only 1 method (from the parent) executes and the 2nd failed. can you help me to understand why I am getting the error and how to resolve it please  : "java.lang.NullPointerException" Parent class : public class SignUp {  public WebDriver driver;      public void go(WebDriver driver)     {     driver.findElement(By.id("id_sign_up")).click();     }         @Test         public void signup(WebDriver driver)                  {             driver.findElement(By.linkText("I’m an advertiser")).click();         }                       public void FormSign (WebDriver driver)                          {                 driver.findElement(By.xpath("//span[@css='1']")).sendKeys("Miron");             }            } Child class : public class OpenBrowser extends SignUp{   @Test public void Start() throws InterruptedException {             System.setProperty("webdriver.chrome.driver", "C:\\Program Files\\Selenium\\chromedriver.exe");     WebDriver driver = new ChromeDriver();     driver.get("https://account.admitad.com/en/sign_in/");     SignUp sg = new SignUp();     sg.go(driver);     //sg.signup(driver);      }  @Test public void miron () {     SignUp mi = new SignUp();     mi.signup(driver); }  Can someone please help me? Thanks in advance

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


When I click on area, GeoNetwork show the next problem: "No matching records found".    In geoserver, the information if it is shown.   What is the problem?

I hope somebody has already figured this one out. I just installed Geoserver 2.9 on a vanilla Ubuntu 16.04 distro. The Geoserver 2.8 method of enabling CORS with the shanbe.hezoun class does no longer work with Jetty 9.2.13.  There are mentions that CORS support is already packaged with Jetty 9.2.13 in the jetty-servlets.jar.  The Jetty lib which is compiled with Geoserver contains a jetty-servlet-9.2.13.v20150730.jar in geoserver/lib but not jetty-servlets.9.2.13.v20150730.jar. Are these supposed to be the same jar with a different name?  It should be possible to enable CORS either in geoserver/etc/webdefault.xml or in geoserver/webapps/geoserver/WEB-INF/web.xml.  My understanding is that the webdefault.xml is applied first and the web.xml thereafter.  I have tried following filter in both xml. I haven't got as far as adding a filter mapping. Adding the filter alone will cause the Geoserver/Jetty service to not start proper.  <filter>     <filter-name>cross-origin</filter-name>     <filter-class>org.eclipse.jetty.servlets.CrossOriginFilter</filter-class> </filter>


My brother accidentally deleted his character. Is he able to get back his stuff by backing up his whole iPod?

I was playing terraria today, and my friend came and deleted the my world.  Is there a way for me to recover my world?


$$\lim_{k\rightarrow\infty}(k!)^{\frac{1}{k}}$$ I want to determine the limit as formal as possible, that is, to prove, for example $$\lim_{k\rightarrow\infty}\frac{\ln(k!)}{k}$$ I had the intention of using the L'Hopital rule and I do not know that it does exist, despite only representing a number. But it is not very justified.  Can you use sanduche theorem? Can I limit?

How do I prove that $ \displaystyle\lim_{n \to{+}\infty}{\sqrt[n]{n!}}$ is infinite?


I find some opinions about the rules for ellipses are conflicting. Here are some conflicting issues:  Q1: Are the spaces between the dots in a ellipsis necessary, i.e. dot-space-dot-space-dot?   (Yes.)      . . . for everyday purposes, it's fine to use regular spaces between the ellipsis points. Type period-space-period-space-period. Just make sure your dots don’t end up on two different lines.  (No.)      Bringhurst writes that a full space between each dot is "another Victorian eccentricity. In most contexts, the Chicago ellipsis is much too wide"—he recommends using flush dots, or thin-spaced dots (up to one-fifth of an em), or the prefabricated ellipsis character.  (No.) My personal habit. I think typing dot-dot-dot is more convenient; though I find it looks better to use the dot-space-dot-space-dot style on this page :)   Q2: Normally an ellipsis should be spaced fore-and-aft to separate it from the text. So, when should the fore space or the aft space disappear?        Ellipses at the beginning and end of quotations    Aardvark said, “. . . Squiggly never caught a fish.”    Ellipses with question marks and exclamation points   “Where did he go? . . .  Why did he go out again?” [Material is removed between the two sentences]    “Where did he go . . . ? Why did he go out again?” [Material is removed before the first question mark. Note the space between the last ellipsis point and the question mark.]   Ellipses with commas and semicolons    “Aardvark went home, . . .  and Squiggly decided to meet him later.”    “Aardvark went home . . . ; Squiggly would meet him later.” [Note the space between the ellipsis and the semicolon.]       . . . when it combines with other punctuation, the leading space disappears and the other punctuation follows.         i … j i-(space)-(ellipsis)-(space)-j, the normal case.   k…. k-(ellipsis)-(dot)   l…, l l-(ellipsis)-(comma)-(space)-l   l, … l l-(comma)-(space)-(ellipsis)-(space)-l   m…? m-(ellipsis)-(question mark)   n…! n-(ellipsis)-(exclamation mark)     Katherine Fry & Rowena Kirton's grammar book: Grammar for Grown-Ups     . . . The only time there isn't a final space is when the ellipsis comes before a closing quote mark -- then the quote mark comes directly after dot 3, 'like . . .' this, 'not . . . ' this.    How numerous the conflicting rules are! I'm totally confused.  EDIT To state my question more clearly -- I need to write some software manuals in plain ASCII text. Can I just type ellipses choosing any style because there's no strict rule about that?

Possible Duplicate:    Should there be a space before three dots? Examples:  I don't know if this is good... I don't know if this is good ...  Also, as a status message intended for a software user: Writing results... Done.  or Writing results ... Done.


What is the reason for the British accents in Game Of Thrones?  Specifically in the North and South, not in what is considered foreign lands like Qarth and Meereen. Although George R. R. Martin is American and the show is directed towards American audiences, everyone in Game of Thrones speaks in some sort of British accent.   Going through some of the characters with accents:   Ned Stark has a northern accent (actually Sheffield). Robb Stark has a northern accent (actually Scottish). Jon Snow and Theon Greyjoy are non-northern actors with northern accents. Arya Stark has a slight West Country accent. Catelyn Stark speaks with a slight southern English accent. King Robert Baratheon has a northern accent. Some of the knights in the Vale speak with Welsh accents Jorah Mormont has a Northern accent (actually Scottish in real life) Davos Seaworth has a Northern accent (actually Irish) Tyrion Lannister umm, .   Anyway, you get the point that the English accent is the theme here. Obviously there are many more characters that speak with British accents, so what was the reason for the British accent?

Okay, I was thinking about the series of Game of Thrones and all the battles and stuff, and I thought why aren't there any characters beside White/English characters that have main/important roles? Can you name any that are alive that are anything else beside White/English?   This is a short list of some of the main characters (all White/English):   Cersei - Queen and important political Lannister. Jaime - Guy who is father to the late king and is King slayer. Tyrion - Short guy in politics who is currently on the run(that's what the wikia told me). Daenerys - Queen who is freeing people and dragon owner.   And the list goes on and on, why aren't there any characters other than Caucasian characters that are in the series?  I've read a lot of articles on the internet about this after Googling around, and none of the articles I read had any scientific evidence or research - it was just conjecture.  So, are there any actors/characters from racially diverse backgrounds? I'm hoping for canon evidence (pictures, links, quotes) from the book and/or TV show. In the case of actors, can you also list their role?    This is not intended as a racist question. I just want to know why, since the story takes place over a large area, there doesn't seem to be any diversity.


I'm new to C# and .net and the question might be silly, but bear with me... Any help or pointer in the right direction (if any) would be appreciated! Let's say I have a C# console application. I would like to be able to set (and read) a permanent parameter from cmd. ex. $ myApp.exe --setName="Bob"  $ myApp.exe --getName > Bob  I would also like to be able to use the parameter in code. Console.WriteLine(name);  should print out "Bob". Note The parameter being permanent means I want to set in once, not every time the app is launched. So this doesn't work in my case  Is there a way to achieve this? If so, can you link some docs if not give a solution? Thank you!

In C# the Main class has string[] args parameter.  What is that for and where does it get used?


Find value of $$I=\int_{0}^{\frac{\pi}{2}} \log ^2(\sin x)dx \tag{1}$$  I tried using property $\int_{a}^{b} f(x)dx=\int_{a}^{b}f(a+b-x)dx$ we get  $$I=\int_{0}^{\frac{\pi}{2}}\log^2(\cos x)dx \tag{2}$$  Adding $(1)$ and $(2)$ we get  $$2I=\int_{0}^{\frac{\pi}{2}}\left(\log(\sin x)+\log(\cos x)\right)^2-2 \log(\sin x)\log(\cos x)dx$$  any clue here?

$\displaystyle \int_{0}^{\frac{\pi}{2}} \ln(\sin(x))dx=-\frac{\pi}{2}\ln(2)$ is an integral that is common.  But, how can we show $\displaystyle\int_{0}^{\frac{\pi}{2}}\ln^{2}(\sin(x))dx=\frac{{\pi}^{3}}{24}+\frac{\pi}{2}\ln^{2}(2)$?.  Does anyone have any ideas on how to approach $\displaystyle\int_{0}^{\frac{\pi}{2}}\ln^{2}(\sin(x))dx$?.  Thank you very much.


Hi I'm looking for a series (at least 2) of fantasy novels I read in the early to mid 90's. I can't remember the author or titles, though I can remember some parts of the books.   The main character isn't a very good wizard When taking a wizarding test he must extinguish a flame and does it the most difficult way, sucking the heat out of the flame.  He gets attacked by a teacher(?) who wields a sword at him and he grabs the blade with his hand, cutting his palm deeply.  The same teacher(?) wants to take over the school using an evil artifact (a statue).  The main character is friends with another student who is extremely gifted with magic, but ultimately quits the school for a normal life and dies later.  I think it starts off the hero is a keep boy and a traveling wizard conjures a tree that grows, wilts and dies. Later the hero tries scrying and knocks himself out.

When I was younger (11-12 years old, so the early 2000s) I once read a story where a young boy, who may have been either a young prince or a squire of some sort, is recruited by a wizard and taken to a city to train as a mage.  I seem to remember him living in dorms with the other children at this school, until he gets into difficulty with another of the boys in the dorm. He is kicked out of the dorms and ends up living above a blacksmith shop (I think).  I remember it being the first book in a series of books of which there were about 3 out at the time. I think one of the stories was about the boy going to a tower to do something or other.  Does anyone have any idea what this book series is? I haven't been able to find it for years now but it was a story I really loved.


Is there a way to automatically split the output into different PDF files?  The reason is that I want to generate a document "paper.pdf" and a different document "supplementarymaterial.pdf", with shared macros, cross references, and even having some theorems from "paper.pdf" restated (using the restatable package) in the supplementarymaterial.pdf file.  The other immediate option (using different source files) has these pros/cons:   shared macros is easy (common \input file with macro definitions) cross references is a pain (xr package, never used it) restating theorems across different source files seems impossible   Basically I am looking for a latex-native alternative to Acrobat->Tools->split document (or wherever that option is)

I'd like to be able to create a TeX file that will output multiple PDF files with one compilation.  I'm not even sure if this is possible.  Here is the setup:  I am writing dozens of cover letters for job applications, and wish for them to all look "personalized".  So I defined a function which calls multiple variables, such as the address, name of the institution, open position, etc., and outputs a "personalized" cover letter for each function call.  The problem is that compilation of the TeX file outputs just one file.  Since I will be submitting all of these files online eventually, I would like each letter to be in its own file.  Is there a way to do this at the TeX level?


I am running Xenial Ubuntu in Windows 10 subsystem linux system. I need to install xvfb-run but I can not because it is not in the repo. I guess I need to upgrade Ubuntu, but do-release-upgrade finds no new versions.   How can I get xvfb-run running on my Xenial Ubuntu in WSL?

I searched around, and currently there are two methods suggested; installing an enhancement for Windows Subsystem for Linux and installing an XServer.  I want to know which method is the most hassle-free (easy to install AND to use), and which one is less memory-heavy.  I just want Synaptic and CMake. Why couldn't that be a builtin feature?


I am trying to find the arc length for the lemniscate $r^2 = a^2cos(2x)$ using the equation $$\int \sqrt{r^2 + (\frac{dr}{d\theta})^2} \, d\theta$$  However, I end up with the integration of $\sqrt{sec(x)}$ which is too difficult to integrate. Is there any different path that I can following using the same formula to find the length of the curve? Is there a way to make this easier?   Any suggestion would be appreciated.

I have to find the arc length of a lemniscate with polar equation $r=2(\cos(2\theta))^{1/2}$.  So far I got like $\sqrt{4\cos(2\theta)+\left(-2\frac{\sin(2\theta)}{\sqrt{\cos(2\theta)}}\right)}$.  I don't know how to proceed, I can't seem to figure out how to approach this.


I was wondering about the hypothetical - and apparently improbable -  when I stumbled upon this seeming contradiction.  A certain volume of space with a uniform distribution of particles has maximum entropy.  However, the action of gravity would condense these particles, decreasing the entropy of the system, which would violate the second law of thermodynamics.  My question is simply: what am I missing here?  What is the solution to this contradiction?

Please forgive: I am a layman when it comes to physics and cosmology, and have tried finding an answer to this that I can understand, with no luck.  As I understand it, the solar system evolved from a massive molecular cloud. To me, this seems to break the second law of thermodynamics, as I think it suggests order from disorder.  I know there must be something wrong with my logic, but am really stuck.  Can anyone explain this one in layman's terms?  (Posting to both "Astronomy" and "Physics", as it seems to overlap these subjects)


How would you word it properly?  Could you hang a bag of IV fluid for Patient 123?  Could you hang a bag of IV fluid on Patient 123?  Could you hang a bag of IV fluid to Patient 123?  Which one is correct? If there's none then how would you word it?  This is an extension to the previous post "Put up an IV fluid". Would it matter if I used hang instead of put up? Thanks.

Back where I come from, we would usually say 'I started the patient on a drip'. But for the 'word' put up ... I only find it natural to say 'I put the fluid up just an hour ago'. What would happen if I were to include a patient in my sentence:   'I put the fluid up (in/on/for) the patient just an hour ago.'  Are all of the options unusual?


In the space between galaxies in the absence of matter, would time run faster than inside a galaxy? A black hole can slow time. Is there a cosmic opposite of that effect on time? Like the following question:   If time stood still at the event horizon of a black hole (wrt an inertial observer), is there a place where time would speed up in absence of mass (again, wrt an inertial observer)? If yes, What is the fastest time can get?

I understand that time is relative for all but as I understand it, time flows at a slower rate for objects that are either moving faster or objects that are near larger masses than for those that are slower or further from mass.  So, the illustrative example I always see is that if I were to leave earth and fly around at near light speed for a while or go into orbit around a black hole the time I experience would be substantially shorter than for those I left behind at home on earth and I'd come back to find that I've only aged however long I felt I was gone by my own clock but that on Earth substantially more time would have elapsed.  Following through on this model, the stars in orbit around the black hole at the center of the Milky Way are aging much much slower (relative to us), right?  So does it not follow that the center of the galaxy is some appreciable (I have no idea how to go about putting this in an equation so will avoid guessing at the difference) amount "younger" than the stuff further away from the center?   If this is not true, could someone please explain why not, and if it is true, can someone please point me to where I can calculate the age of the center of the galaxy :-)  And to be clear... what I'm asking is... if there was an atomic clock that appeared at the center of the galaxy when the center was first formed, and we brought it through a worm hole to earth today - how much time would have elapsed on that clock vs. the age we recon the galaxy currently is? (13.2 billion years)


I want to get a Boltzmann distribution of the $v_x$, $v_y$ and $v_z$ velocity components (please, notice that the distribution is one-dimensional). To do so, I need the cumulative distribution function $F(v_x)$. I can get a random number and set it as $F(v_x)$. After that, how can I get $v_x$ with this information? Is there any other way to get $v_x$ using both, the $F(v_x)$ and the Boltzmann distribution itself?

I have a volume with $N$ molecules; I need to assign to each particle a velocity vector: $$|\mathbf{v}_{i}|=[v_{x}, v_{y}, v_{z}]^{T}$$ for the $i$-th molecule; the velocities must follow the Maxwell-Boltzmann distribution; here is the question: I know the definition of the M.B. distribution, how do I extract the velocities that I have to assign to each molecule? Basically what I want to know is how to calculate $$v_{x}=?$$ $$v_{y}=?$$ $$v_{z}=?$$ for each molecule.


I have upgraded my laptop from Mojave to Catalina. I do not use my laptop with any of the Apache Services. My current version of Apache httpd is: Apache/2.4.41 My security team told me that I need to update to Apache/2.4.42 or later. Again, I am not using the Apache Server, I am not trying to update any path and at the same time I can not install Brew on my mac. I simply need to update this Apache httpd version that come by default in my MacOS. How do I do that? Can I run a simple command line that update the Apache httpd version to 2.4.42 or later. Thank you for your help.

A DHS sweep of the network showed that one of the researchers Macs is running a non-safe version of Apache (2.4.25) and they would like him to update to at least 2.4.27.  He is having difficulty getting MacOS to use the new version of Apache rather than the one installed by default with Sierra. His issues are:  Mac OS X 10.12.6 Sierra   I have installed httpd 2.4.27 . . .  /usr/local/apache2/bin/ but the default httpd running is located at /usr/sbin/ I cannot install a new httpd into /usr/sbin/  - no write persmissions for sudo I made a root user active - but "root" does not have write permissions for /usr/sbin/ either   I cannot find any source on the web that describes how to change the httpd path from the default system version (/usr/sbin/httpd) to a new USER installed version, like /usr/local/apache2/bin/httpd  What steps am I missing?


I have a problem for texstudio software. When I write a very basic format, it always goes wrong. The error presents as "Error: Could not start the command: pdflatex.exe -synctex=1 -interaction=nonstopmode "First year Ro.".tex".  How to fix it? Many thanks.

I just downloaded and installed Texmaker. I've never used any (La)TeX before.  When I click the Run button with an arrow next to "Quick build" I get an error saying "Could not start the command". Why? What do I need to do?


In C++ we pass a subarray to a recursive function and after making changes to the subarray in the recursive function, the changes reflect in the original array. How do I achieve the same in Java as it does not support pointers? E.g., // C++ function  void function(int arr, int n){      if(arr[0]==arr[1]){           //shift arr[1]--arr[n-1] to arr[0]--arr[n-2]                      function(arr+1, n-1); // this is the line which i need help for.      } }

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


Today I installed xubuntu 13.04 and I can't update it to ver. 14.04. I can't install any apps from software center too. When i click "find best server for your location" I can't find any server. But my internet is working. what's wrong? p.s. Sorry for my english.

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


Im trying to use jq to alter a json file via a script.  in my terminal im trying to run this, but getting a permission denied error. Im able to change it using a sudo nano manually.  sudo jq -c  '.interpreterSettings."2ANGGHHMQ"."properties"."zeppelin.pyspark.python" = "python3"' interpreter.json > tmp.$$.json && mv tmp.$$.json interpreter.json   Any ideas on why?  Thanks, Tim

I've been given sudo access on one of our development RedHat linux boxes, and I seem to find myself quite often needing to redirect output to a location I don't normally have write access to.  The trouble is, this contrived example doesn't work:  sudo ls -hal /root/ > /root/test.out   I just receive the response:  -bash: /root/test.out: Permission denied   How can I get this to work?


I have a Python function which converts Eastings and Northings to Latitude and Longitude if line_count == 0:                     keys = row                     print('keys', keys)                     line_count += 1                 else:                     inProj = Proj(init='epsg:27700') # British National Grid                     outProj = Proj(init='epsg:4326') # WGS84                     x1, y1 = row[1], row[2]  # easting, northing                     x2, y2 = transform(inProj, outProj, x1, y1)                     row[1], row[2] = y2, x2                                          json_doc = {}  At the moment it converts from epsg:27700 (British National Grid) to WGS84, however there is a possibility I will get TM75 Irish Grid too. Is there any way I can get Python to recognised which CRS is applicable for the conversion?

I have a Shapefile but its coordinate system is Unknown, and there is no *.prj file.   How can I identify it now?


This is also a TOEFL listening question.  An outside class student is taking a game creation class ( computer programming ) and in order for him to pass the class, he has to demonstrate his own project.  Here is the conversation between a professor and the student.  Professor     Alright, that sounds like it would consititute an appropriate amount of work on your part. Now, the project also incorporates a presentation where the students demonstrate their prototype.   Student     Yeah, I was figuring I'd present my project as if it was a pitch to a company. I figure it would be boring if I went through the whole design document in front of the class, so I'd create a slideshow and present it as if I was looking for investors or a publisher.   Could this mean, possibly, something like a submitting a resume to a company??

The man awkwardly starts his pitch before Jordan takes the pen away.   What does mean by "start his pitch" means ?


I am traveling from the US to the UK and then to Portugal. Round trip. I have a laptop without a battery, so I am hesitant to bring it as carry-on in the plane because I had troubles already with a laptop not turning on through security.   Is there any problem with sending the laptop in the checked-in luggage? If they open my luggage and they find it, would that be a problem? Could they take it away?

According to some reports, your electronic devices are checked whether they turn on before you can get on a US bound flight. What if I carry around a laptop without a battery?


I have a file with these lines:  abcd hfd ktr hfk itor fld fjkdf name fkld ew wew name   It is necessary to change the characters in the lines that satisfy the pattern (contain the word 'name') as follows: a-> b, b-> c, c-> d ... z-> a, and apply these changes to the file. resulting in:  abcd hfd ktr hfk itor fld gkleg obnf glmf fx xfx obnf

I need to replace single quotes with double quotes AND double quotes with single quotes in over 600 files. I've been reading various topics most of the day. I am hampered by only knowing some basic shell scripting commands and an unfamiliarity with regexp.   Below is a sample file I've made a bit generic.     some text KEYWORD_1 table name column = "string" AND column = "string"     Additional text           .           .           .    some text KEYWORD_2 text 'text in quote' etc.    I only want to change the quotes on the 2 lines with KEYWORDs. I can't guarantee the keywords are always going to be first line and last line. I need my solution to find the keyword and change all the quotes on that line only.   I tried some things I found in sort of similar questions on this forum, including a meta on SED. I tried to figure out how to use this command: sed -i 's/foo\(.*baz\)/bar\1/' file. According to that topic the command, "Replaces foo with bar only if there is a baz later on the same line." My keyword is not later on the same line its at the beginning and I couldn't make it work for me.   I also tried ex -sc 'g/DEL/s/ALF/BRA/g' -cx file that didn't do anything. I'm assuming it can't be executed from the command line. I really don't want to open each of 600 files.  At one point I tried, grep KEYWORD_1 file | sed -i "s/'/\"/g" file Of course, that changed all the quotes in the file not just the one line.   I'm betting the solution is simple and I just can't see it. How can I do this?     As requested my desired output is:  some text KEYWORD_1 table name column = 'string' AND column = 'string'     Additional text           .            .           . some text KEYWORD_2 text "text in quote" etc.


Can we define an ordered pair as $(a,b)=\{a,\{b\}\}$? It seems like a good definition to me. It fits, $$(a_1,b_1)=(a_2,b_2)\iff (a_1=a_2 )\wedge(b_1=b_2)  $$

It is to my knowledge that any definition of an ordered pair, (a, b), must satisfy this condition: $\quad (a,b) = (c, d) \iff a = c \land b = d$ However, I chanced upon this definition of an ordered pair: $\quad (a, b) = \{a, \{b\}\}$ which I know does not satisfy the condition. However, how do I prove this formally?


I'm reading  and on page 183 they made this claim:    I think it must be "when its determinant is $0$" instead of "when its determinant is different from $0$". Am I right?

Where can I find a list of typos for Linear Algebra, 2nd Edition, by Hoffman and Kunze? I searched on Google, but to no avail.


Why does an unfocused lens still give a focused view with a longer exposure? For example, I took an out-of-focus photo with a ¹⁄₁₀th second exposure (at f/7.1), but when I change to 10 seconds (at f/22), it seems to be in focus.  Why is this?

How does aperture affect my photographs?  Why should I care about the aperture with which a photo was taken?