Testing for difference between two percentages (using confidence intervals)

I wish to test for whether the difference between 2 percentages is significantly different. For each percentage there are associated confidence intervals, which I need to incorporate into the test (CI reflect the accuracy of the estimated percentage).


Show that there exists a self-complementry graph of order $ n $ if and only if $ n = 0$  or $ 1 \ (\mbox{mod } 4) $.   My thoughts so far:  I've proven the 'only if' direction.   For the 'if' direction, I need to show that if $ n = 0$  or $ 1 \ (\mbox{mod } 4) $ then I can construct a self-complementary graph. I've started by focusing on the case $ n = 0 \ (\mbox{mod } 4) $; in particular, I've drawn such a graph in the case n = 4 (a Z shape). But I'm struggling to generalise my method to n = 8 and higher (in fact, I haven't successfully constructed a self-complementary graph of order 8). I'm not really sure how to think about this; I'm new to Graph Theory and so haven't had much practice yet.  EDIT: I've had a further thought. The graph I construct must have exactly $ \frac{n(n-1)}{4} $ edges.  I'd prefer hints to full answers, at least until I can reach the answer myself. Thanks for your help!


Is it illegal to transfer money to people in foreign countries?

A friend keeps sending money to foreign countries to guys she calls friends and recently began asking me to do it for her through Western Union.  Can I get in trouble for this?


Sorry if it's a stupid question. I would like to free up some space and /var/log is full of logs. I do not intend to use any of the log files, so I don't care if they get deleted or not. But I afraid that it may affect the functionality of the services that produce logs. I understand that it may depend on the program that produces the logs. but Do you think it would be safe to remove regular services and system log such as:  alternatives.log auth.log boot.log                  mail.log      syslog dmesg dpkg faillog fontconfig.log kern.log wtmp nginx/* apt/* btmp


I am working about task for custom GIS application (about 70 users). It must show a map of region with custom objects from database (they will be triangles, lines, and icons with coordinates) . Users can add objects to the map by clicking the mouse. I am reading now about OSM, tiles servers and other information. But I don't know how to start creating the architecture of an application. Could you give some advices or examples of such applications (I think somebody has done such projects). Will I need ArcGIS and what plan? Or can I use only OSM with Leaflet?


How to recover a message mistakenly identified as spam by Inbox?

I found a non-spam message that was automatically placed in spam folder (a false positive). In the Gmail interface, I would click "Not spam" to remove the message from spam folder. But I could not find any such action in the Inbox interface.   How can I tell Inbox that this message (a) was not spam, and (b) should not be deleted in 30 days?


Why does Internet Explorer identify itself as Mozilla?

My version of Internet Explorer uses the following user agent:  User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; blah blah blah   Why does it do this? Theoretically, can Mozilla Foundation sue Microsoft for use of their trademark?


Convert unsigned char array to base64 string

I have an unsigned char array that represent an image, and I want to show it in a web page.  I get the array from ActiveX Control, and I want to show it in my web page using JavaScript, so I have to convert it to "base64 string", so my question is  how to convert unsigned char array to base64 string in c++?


Android "Taking Photos Simply" tutorial does not work for me

So, I am trying to implement taking of photos in my app.  I am following the official "Taking Photos Simply" tutorial, but it just gives me errors.  The only thing I am doing differently, it that I am using a popup dialog fragment.  Below is the error I get:  java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=131073, result=-1, data=null} to activity {com.myapp.demo/com.myapp.demo.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null object reference         at android.app.ActivityThread.deliverResults(ActivityThread.java:3605)         at android.app.ActivityThread.handleSendResult(ActivityThread.java:3648)         at android.app.ActivityThread.access$1400(ActivityThread.java:154)         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1370)         at android.os.Handler.dispatchMessage(Handler.java:102)         at android.os.Looper.loop(Looper.java:135)         at android.app.ActivityThread.main(ActivityThread.java:5289)         at java.lang.reflect.Method.invoke(Native Method)         at java.lang.reflect.Method.invoke(Method.java:372)         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null object reference         at com.paulcanning.mote.NoteDialogFragment.onActivityResult(NoteDialogFragment.java:179)         at android.support.v4.app.FragmentActivity.onActivityResult(FragmentActivity.java:153)         at android.app.Activity.dispatchActivityResult(Activity.java:6192)         at android.app.ActivityThread.deliverResults(ActivityThread.java:3601)             at android.app.ActivityThread.handleSendResult(ActivityThread.java:3648)             at android.app.ActivityThread.access$1400(ActivityThread.java:154)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1370)             at android.os.Handler.dispatchMessage(Handler.java:102)             at android.os.Looper.loop(Looper.java:135)             at android.app.ActivityThread.main(ActivityThread.java:5289)             at java.lang.reflect.Method.invoke(Native Method)             at java.lang.reflect.Method.invoke(Method.java:372)             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)   Button click listener  takePhoto.setOnClickListener(new View.OnClickListener() {          @Override         public void onClick(View v) {             Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);             if (takePictureIntent.resolveActivity(getContext().getPackageManager()) != null) {                 //startActivityForResult(takePictureIntent, 1);                  File photoFile = null;                 try {                     photoFile = createImageFile();                 } catch (IOException ex) {                     // Error occurred while creating the File                 }                 // Continue only if the File was successfully created                 if (photoFile != null) {                     takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,                             Uri.fromFile(photoFile));                     startActivityForResult(takePictureIntent, 1);                 }             }         }      });   onActivityResult (note, it wouldn't let me use protected)  @Override public void onActivityResult(int requestCode, int resultCode, Intent data) {     if (requestCode == 1 && resultCode == getActivity().RESULT_OK) {         Bundle extras = data.getExtras();         Bitmap imageBitmap = (Bitmap) extras.get("data");         imageView.setImageBitmap(imageBitmap);     } }


PHP output showing little black diamonds with a question mark

I'm writing a php program that pulls from a database source. Some of the varchars have quotes that are displaying as black diamonds with a question mark in them (�, , I assume from Microsoft Word text).  How can I use php to strip these characters out?


There is a song at The Queen's Gambit episode Adjournment (S1E6), at the bar scene:                                A woman sings a song like "I remember when it rains...". I was not able to find it on the web and it makes me crazy. If you know the name please let me know. Lyrics (credit to user Daphne):  I remember springtime, I remember when it rained I remember night-time, the happiness and pain I remember you, but I can't remember love, when I do when I do I remember nature, and many other things I remember Big Joe Turner, what he sounds like when he sings I remember you, but I can't remember love


Why "think bright" is used with adjective instead of adverb (think brightly)?

I find "think bright" is much more common usage, but why? In my opinion, "Think" is a verb, so it is reasonable to use adverb to describe it.  Examples:      THINK BRIGHT!      The National University of Science and Technology MISIS   ()


How can I make a click event for a dynamically generated button?

I want to create an click event for a dynamically generated button. How can I do that?  I thought that this code will work, but it doesn't. How can I add the function?    $(document).ready(function() {     $("#keyword_1").click(function() {       var keyword_js = document.getElementById("keyword_1").value;       $.ajax({           url: "list",           type: "POST",           async: false,           data: {             keyword: keyword_js.toString()           },           dataType: "json",           success: function(data) {             //button           }         }       },       error: function(request, status, error) {         alert("code:" + request.status + "\n" + "message:" + request.responseText + "\n" + "error:" + error);       },       complete: function() {         // call back method       }     });   }); });  function insRow() {   var keyword_js = document.getElementById("keyword_en").value;   oTbl = document.getElementById("addTable");   var oRow = oTbl.insertRow();   oRow.onmouseover = function() {     oTbl.clickedRowIndex = this.rowIndex   }; //clickedRowIndex   var oCell = oRow.insertCell();    //Form Tag   var frmTag = "<input type=button value=" + keyword_js + " id='keyword_1'>";   frmTag += "<input type=button value=‘del’ onClick='removeRow()' style='cursor:hand;'>";   oCell.innerHTML = frmTag; }


I am new to Salesforce and trying to understand the concept of Delegated Gateway URL of Single Sign On. I understand that Salesforce will enable this feature after submitting the case and I have to configure in profile level "Is Single sign on" equals true. But under single sign on setting page -- Delegated Authentication section -- when and how to use these two settings:   Delegated Gateway URL    Force Delegated Authentication Callout   Thank you very much in advance and it will be great help if there is any small example you can share.


Is the title attribute (not tag) important to SEO?

The title attribute is an HTML standard element available across most tags.  e.g.
by Function
   I've used this attribute on some sites for usability;  many browsers pop up a "tooltip" over the link with the more detailed description of what is on the other side.  I've been wondering if doing so is having a negative effect on my rankings (hidden text?) or if it has any effect at all on onsite or offsite keyword relevance calculations.  Does anyone know of any research done on this?


Is the C# static constructor thread safe?

In other words, is this Singleton implementation thread safe:  public class Singleton {     private static Singleton instance;      private Singleton() { }      static Singleton()     {         instance = new Singleton();     }      public static Singleton Instance     {         get { return instance; }     } }


How to edit pdf metadata from command line?

I need a command line tool for editing metadata of pdf-files.   I'm using a Aiptek MyNote Premium tablet for writing my notes and minutes on this device, import them later and convert them to pdf automatically with a simple script using inkscape and ghostscript.  Is there any command line tool to add some categories to the pdf's metadata, so i can find the pdf later (e.g. with gnome-do) by categories?  Update: I tried the solution with pdftk and it works, but it seems that gnome-do doesn't take care of pdf-metadata. Is there a way to get gnome-do to do that?


Is the kernel of a map from a $\mathbb{Z}$-free module to an abelian group $\mathbb{Z}$-free? It seems like the answer should be yes as the kernel is contained inside the free $\mathbb{Z}$-module but I can't quite put my finger on the precise reason why.


Very often, we use data which are derived from some measurements. These measurements usually have a confidence measure associated which tells how reliable the measure is, or how confident we are about the measure. For example, we often see some confidence intervals associated with various polls.  I was wondering if there is a theory or algebra about combining multiple measurements and the resulting confidence measure of the aggregate. For example, if I measure $X$ with a confidence interval $\pm x\%$, $Y$ with confidence interval $\pm y\%$, what can I say about the confidence interval of $X+Y$? Similarly, what can we say about the confidence intervals for other operators?  Is there an algebra for this?


Removing constant from the regression model

I am trying to calibrate two variables $(X,Y)$ of different measuring techniques from two instruments, the result of the linear regression analysis appears as shown in the image. The result shows the regression constant is not statistically significant but the model is significant. I have tried to remove the regression constant (it is a very small value close to zero) and $R$ of the new model is raised to 90%. Is it correct to remove the regression constant?


Is there a way to exclude games from Steam Shared Library?

I know there is a list of games that are excluded when you share a library on steam, but I was wondering if there is also a way to exclude some additional games?


Why do we need to specify which environment we end?

Whenever we start an environment we have a \begin{environment}, and when we want to end an environment we write \end{environment} but shouldn't just \end be enough?  As far as I'm aware, the following is impossible:  \begin{coolstuff} \begin{boringstuff} \end{coolstuff} \end{boringstuff}   And the following would be correct:  \begin{coolstuff} \begin{boringstuff} \end{boringstuff} \end{coolstuff}   So why not just write:  \begin{coolstuff} \begin{boringstuff} \end \end   ??


$A,B \in M_n(\mathbb{R})$ are similar over $\mathbb{R}$ if they are similar over $\mathbb{C}$

I want to prove the following statement:     Assume that $A,B \in M_n(\mathbb{R})$ and there is an invertible matrix $P \in M_n(\mathbb{C})$ that $PAP^{-1}=B$.   Prove that there is an invertible matrix $Q\in M_n(\mathbb{R})$ that $QAQ^{-1}=B$   I know that there are some similar questions asked here and I've read all of them. But the point is that I don't want to use determinant approach. All the proofs that one can find here or on the internet are similar to the one you can find in the following link:   all of them use this reality that because $P=C+Di$ for some $C,D \in M_n(\mathbb{R})$ and $det(C+Di) \neq 0$ so there exists a $t\in \mathbb{R}$ that $det(C+Dt)\neq0$ and so on.   I don't want to use this approach. Instead of using determinant, I want to use this theorem that a matrix $M$ is invertible if and only if the only answer for the system $MX=0$ is $X=0$.  Now, because the hypothesis says that $P$ is invertible we can say that the only answer for the system $PX=0$ or equivalently $(C+Di)X=0$ is $X=0$. We have:  $$(C+Di)X=0 \Rightarrow CX=0 , DX=0$$ Now, if we can prove that the only answer for the system $CX=0$ or $DX=0$ is $X=0$ then it means that $C$ or $D$ are invertible. Then we can write   $$PAP^{-1}=B \Rightarrow PA=BP$$ $$P=C+Di \Rightarrow CA+DAi=BC+BDi$$ $$CA=BC , DA=BD$$ Then we can conduce that $B=CAC^{-1}$ or $B=DAD^{-1}$ and the problem is solved. But $C$ and $D$ are not necessarily invertible. How can we construct a new real matrix, say $Q$ that $QAQ^-{1}=B$ by using the theorem that I've mentioned above(or some similar theorems) and not using determinant approach?


On which Stack Exchange site can I ask customer service questions about product X or company Y?

On which Stack Exchange site can I ask questions like        When will [some new feature] for [some product] be released?   Where can I download an update for [some product]?   I'm getting errors when accessing the customer portal for [some company] – how can I fix this?   Why was I banned for doing [some action] on [some platform]?   Why is [some company] discontinuing [some product]?   Why is [some company] giving away [some product] for free?   What's the price for [some product]?      or any other product support/customer service questions?  It's not a product related to programming (or I've read  on Meta Stack Overflow) so I know Stack Overflow isn't the right place. Which other site in the network will take these kind of questions?


Generating a catcode table in Latex (with \typeout to terminal)?

I often need to look up a catcode table, and quick searches on the web are rarely satisfying.   So I thought, it must be (in the long term) easier to use a Latex function of sorts, to loop through all 8-bit sequences (that is, ASCII characters), and print out:   [ASCII code] - [ASCII character] - [catcode] - [catcode meaning]   A "reverse indexing" would be nice as well - where catcodes are output, and then which ASCII chars belong to them, e.g:  [catcode] - [catcode meaning]:      [ASCII code1] - [ASCII character1]     [ASCII code2] - [ASCII character2]     ....   Just wanted to note - I'd like such a table to be \typeouted to the terminal (not typeset in a PDF).   In , a \printcatcode exercise is mentioned, that answers the mapping from ASCII character to a verbose catcode meaning...   So I guess, one would just have to make a loop from 0 to 255 (maybe something similar to approaches in ), and apply all such relevant transformations - unfortunately, I'm not mastering tex core on a level where I can come up with that code off the top of my head. But maybe a function for something like this already exists?   Any suggestions for code that I could use in this context?


How do I get my code to slice a list after asking for user input?

I'm trying to get my list to slice the first 3 items off. I interactively ask for 7 names and output the original list first. When I ask the code to slice the list, it seems to have no knowledge of names inside the list. #Example names for testing: #Liam Noah Eli Logan Mason James Aiden names=[input("Please enter 7 names: ")] for a in names:     print(a) for b in names:     print(b[3:])


What's the difference between "the seat in front of you" and "the seat in front of yours"?

I came across an airline announcement and the following question arose. Which would you say it is THE correct sentence, and why?   For your comfort and safety, please stow the luggage labelled with the red tag and other small items under the seat in front of yours, except for the emergency exists and the first rows. For your comfort and safety, please stow the luggage labelled with the red tag and other small items under the seat in front of you, except for the emergency exists and the first rows.


Can I take a 330g tin of Fois Gras Poitiers in my 10 kg cabin bag with Ryanair?

Can I take a 330g tin of Fois Gras Poitiers in my 10 kg cabin bag from France to London Stansted with Ryanair?


Can You Swap Two Capacitors With Different Ratings?

I've bought a broken receiver recently and I need to swap out a few of the capacitors.  the original capacitor is rated at 100v and 0.01uf. The local electronic store sells 100v 3.3uf capacitors. Would I be able to swap these two, or would the different in uf make them not work with the rest of the system?


Why placing a "?" in front of "FROM" does not work, while in other places it works?    query = "SELECT nome_cliente           FROM ?          ORDER BY nome_cliente";  $rows = $this->db->prepare($query); $rows->execute([$id]);   The error it gives is this:    SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '? ORDER BY nome_cliente' at line 1


Possible Duplicate:          If referring to a Users Group (meaning a group made up of multiple individual users who have some control of the group itself), would you use:    A: User’s  B: Users’ C: Users   I have read the post on the  but in this case, plural is appropriate since the group does not belong to one individual.  Wikipedia suggests Users’ (or Users) and in my domain, a leading stats software company has a , though they then use user’s group as part of the description.  What do you think —  A, B, or C?


What are the sim card options in Belarus for a tourist?

I'm traveling to Minsk and would like to get a local sim while I'm there (only for data). What are my options? Can I buy a sim card at Minsk airport?


I have a set of two rims which have an inner width of 24mm, both of them are  hooked. It is unclear after looking around various sources if Continental Grand Prix 5000 in 32-622 might fit or may have problems. The pamphlet it came with doesn't specify the maximum/minimum tyre width.   (This rim width marked here is 24mm)  Are they a security hazard or will they be fine?


I'm trying to get size of an array in c and for some reason I'm getting a wrong answer for this popular method.      int innerprod(int *v, int *u) {    int n = sizeof(v)/sizeof(v[0]); printf("%d\n",n);             // ouptut here is giving me '2' for a '3' size array           double result = 0.0; for (int i = 0; i < n; i++) {     result += v[i]*u[i];     printf("%d\n",v[i]*u[i]); }     return result; }  int main() { int V[3] = {3,4,-1};   //a 3 size array int W[3] = {7,-2,3}; int x = innerprod(&V,&W); printf("%d\n",x); }


Relations between diffeomorphism symmetry theories and invariant $SU(N), N \rightarrow \infty$ theories

Is it possible to have, an exhaustive panorama (as much as possible), about the relations between theories having a diffeomorphism symmetry, and theories having a $SU(N), N\rightarrow\infty$  invariance ?


Upgrade from 8.04 to 10.04, "no release found"

I've run the following commands as root:  apt-get update apt-get upgrade apt-get dist-upgrade   all work fine, but then i run  do-release-upgrade   and it says "no new release".  This makes no sense as I've upgraded a clone of this machine in the past and it went straight to 10.04.  I can get out to the internet fine.  Any ideas why this might be?


How to move windows that open up offscreen?

I have a dual monitor setup, and I recently played around with the positioning settings, and some of my single window applications do the favour of preserving where they were last closed, and opening in the same position later. Unfortunately, that now places them out of the viewable area of my screens!  Is there some way to force a particular window into the viewable area?


Why do my extruded faces look curved and disconnected when using a subsurf modifier?

I haven't used blender for 2 years and I forgot almost everything. I would like to ask why the faces looks like this? I extruded them from the cylinder's face (the main body) and then the result looks like this.   I'm confused, and yeah I use the subdivision modifier. Tried merge but nothing happens.


Internet speed really slow in linux but not in Windows

On windows downloading a 100 MB file takes less than a minute while on Linux it is taking me 1 hour.  Why is there such a big difference and what do I do to speed it up?   I am using a wireless network adapter made by belkin and since it is working fine on windows I suspect its some driver issue or something.   I will edit this post with outputs of a command if desired!  --- Output of lsusb ---  Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 003: ID 046d:0990 Logitech, Inc. QuickCam Pro 9000 Bus 003 Device 002: ID 04d9:fa50 Holtek Semiconductor, Inc.  Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 003: ID 050d:2103 Belkin Components F7D2102 802.11n N300 Micro Wireless Adapter v3000 [Realtek RTL8192CU] Bus 001 Device 002: ID 413c:2003 Dell Computer Corp. Keyboard Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub   --- Output of lsmod | grep rtl ---  rtl8xxxu              122880  0 rtl8192cu              65536  0 rtl_usb                20480  1 rtl8192cu rtl8192c_common        53248  1 rtl8192cu rtlwifi                77824  3 rtl_usb,rtl8192c_common,rtl8192cu mac80211              761856  4 rtl_usb,rtlwifi,rtl8192cu,rtl8xxxu cfg80211              581632  2 mac80211,rtlwifi


I heard that linked lists are much better than arrays. But why are arrays used at all then?


I'm having a hard time understanding how the Magic Initiate feat works;  does it require spell slots? The feat doesn't say the spell cast is free; it only says you can cast it at its lowest level once per long rest. -when you cast it can't cast again - and casting spells normally requires spell slots. The  (PHB, p. 80-81) is an exception because it doesn't say you "can cast" the spell, but rather that you spend ki points "to cast" the spell:  You can spend 5 ki points to cast stoneskin, targeting yourself.  You pay ki instead of spell slots. And  are another exception. For instance, the 's Spirit Seeker and Spirit Walker features (PHB, p. 50) let them cast those spells regardless, because rituals don't expend spell slots but need to pay with 10 min of casting. The description of  says (PHB, p. 201):  When a character casts a spell, he or she expends a slot of that spell’s level or higher, effectively “filling” a slot with the spell  The description of the  feat says (PHB, p. 168):  Choose a class: bard, cleric, druid, sorcerer, warlock, or wizard. You learn two cantrips of your choice from that class’s spell list. In addition, choose one 1st-level spell from that same list. You learn that spell and can cast it at its lowest level. Once you cast it, you must finish a long rest before you can cast it again. Your spellcasting ability for these spells depends on the class you chose: Charisma for bard, sorcerer, or warlock; Wisdom for cleric or druid: or Intelligence for wizard.  Spell slot can cast (PHB, p. 164):  Class Features>Spellcasting>Spell Slots. You can use the spell slots of those levels to cast the spells you do know  if i'm correct you need to know spell,(to prepare, if you need it), to spend slots to cast, so if you Learn you know or can have prepared? considering on the , you can't spend spell slots to cast spells from another class. For instance, the sorcerer errata.  Spell Slots (p. 101). In the first sentence, “your spells” is now “your sorcerer spells.”  but you can cast rituals and spells from your own class, The feat doesn't say the spell cast is free; it only says you can cast it at its lowest level once per long rest. so i can't spend spell slots to cast spells from another class but can chose it, i can cast rituals because dosen't need spend slots and spells from your own class (if they have) because i can spend it slots, but if i choose nonritual spell from another class i can cast it, but can't spend spell slots and if i can't spend spell slots, virtualy i can't cast it, The feat doesn't say the spell cast is free - requires spell slots.; it only says you can cast it at its lowest level once per long rest. - when you cast it can't cast again but this statement seems contradictory, observing the fact exists a ritual caster feat, i think miss something. Does the 1st-level spell you can cast using the Magic Initiate feat need spell slots? Or can you cast it for "free"? What in the text indicates the answer to this question? Please cite only the rules and those rules only of the PHB to support your answer.


Is that possible to transfer rating from my old account to a new one on SO?

How can I do this? I have migrated from one Gmail account to another and now have two accounts. It would be nice to sum ratings from both and migrate to one of accounts that is newer.


Running After Being Knocked Off Feet in the NFL

In what year(s) in the NFL was the runner allowed to get up and run after being knocked off his feet, as long as they weren't tackled and held down? From memory, it only lasted 1 or 2 years because it caused lots of injuries. I think it was in the 50s but could have been in the early 60s also.


SQL turn multiple results into one column

I have a SQL query that returns a list of GUIDs like this:  92bca6ba-0174-4d80-b701-8bed4b2673e0 917399f2-05d7-42ff-b84e-5f8395c8e8fd   What I need the results to be is one string of text:  '92bca6ba-0174-4d80-b701-8bed4b2673e0', '917399f2-05d7-42ff-b84e-5f8395c8e8fd'   I've looked into several options but can't seem to get it to work.


I was reading the code for the Arrays.hashCode provided below,   public static int hashCode(Object a[]) {         if (a == null)             return 0;          int result = 1;          for (Object element : a)             result = 31 * result + (element == null ? 0 : element.hashCode());          return result;     }   I find it's not as clear as for why 31 is chosen for the hashing.   Secondly, the element.hashCode() send me to the Object class that defines it:  @HotSpotIntrinsicCandidate public native int hashCode();   How the element.hashCode() is calculaed for the each iteration?  Thank you.


What software do you use to keep up to date on literature, and if Google Scholar, how do you avoid information overload?

I see a lot of people use Google Scholar and ResearchGate alerts, but I find those alert systems too overwhelming to the point I get inundated and treat them like spam. Perhaps I'm not using them effectively, though (e.g., too many AND operators in my searches). Any tips to improve my experience? Any alternatives that you might suggest? I'm intrigued by ReadCube Papers for its capabilities to integrate searches for papers, citations, and annotations (which is something I've also struggled to do, having used three different pieces of software for those functions), but I'd prefer something that doesn't have a subscription payment structure, at the very least.


I was wondering how to print the contents of a file above the occurrence of a pattern in another file. I know that using  sed -n '/^PATTERN/i\\ INSERTING' filename would insert above the pattern but can i display the contents of a file instead? This command got close  sed '/^Stephen/r siid' addrfile  but i want the file to be displayed before the occurrence of the pattern


How do you create an alternating series with the sign being the same twice in a row?

I am working on a Taylor series question and I have created a series which alternates however, it does so in doubles. in other words it follows the following pattern: $x$, $x$, $-x$, $-x$, $x$, $x$,...   My goal is to write this series using summation notation.  I know that to produce a normal alternative series I simply use $(-1)^n$. However, I've found this significantly harder to create in summation notation because any manipulation to the $(-1)^n$ part of the sum only moves the position where the alternating series starts. Any suggestions are appreciated!  edit: please note that in my example, "$x$" is just an arbitrary function and each other $x$ does not equal the other $x$'s.


Install Ubuntu 12.10 instead of Windows 8

I have a laptop (4 GB RAM, 500 GB HDD, Intel core i3 2.4 GHz) with 2 Partitions: one For data and one for windows 8 x64.  Actually, I want to install Ubuntu 12.10 instead of Windows 8 but keeping Data partition.   So, my question is: There is no matter to use ubuntu with NTFS Windows Partition. Or i should use ext4 partition for good result? Otherwise what you think about multiple partitions for ubuntu installation?  / /home /etc  ...   Any suggestion will be very appreciated


What quality to choose when converting to JPG?

When you export a picture to JPG you can normally choose its quality in a 1-100 scale. I like to keep a good quality but it wouldn't make sense to keep a JPG that will be almost as big as the original RAW, so is there any guideline to select a particular JPG quality for particular uses? I am mostly interested in Internet sharing and ordering prints online.


Why are closed questions shown an option to protect?

When we reach a reputation of 15k, we are able to protect a question. Intention behind this privilege is preventing questions from getting non spam answers and low quality answers when the question is too popular.   But when a question is closed (not put on-hold) and there's no possibility of getting answered.         What is the point of adding an option to protect a closed question? Is it a feature intended as a preventive measure so that it will be protected even if a question is later reopened after some modifications?,


How do I make Bash my default shell on Ubuntu?

I have a .bash_profile in my home directory, but it isn't getting run on login. If I do the following, then things seem to be as I expect:  ssh myhost bash source ~/.bash_profile   But normally that all happens on login. Thoughts?


How long can I leave kefir and oatmeal at the room temperature?

Thinking of making oatmeal kefir overnight and bringing it for lunch in school. Will it be safe to leave this inside my bag for 5-6 hours?


The Problem  Writing a bounty comment will, after a text exceeds a certain length and passes down to the next line, reformat the frame and the first characters of the next lines thereafter will be wrong.  The Tools  Windows XP SP2, Mozilla Firefox 23.0.1  The Steps   Start a Bounty   Select the Draw Attention button, then press Next   The beginning frame   The problem is at the left. As seen, the entrybox is stretched to the left, and the two first characters of each line are now "seemingly randomly" displayed.


How to automatically mount 2nd internal Hard Drive

(Just upgraded to 16.04; still getting things working...)  Right now, I have two hard drives.   I have the 2nd internal hard drive mount location symbolically linked, and I don't really want to change anything at this point.   The only problem is, it does not mount until I click on the hard drive icon in the unity launcher.  Only after I click it do the symbolic links start working.    How do I make it automatically do whatever it is going to do when I click it...on start up?


Proving/Disproving set identity $(A\cap B)\cup C= A\cap (B\cup C)$

For any sets $A$, $B$, $C$; $(A\cap B)\cup C= A\cap (B\cup C)$     I understand that this means that (A and B) or C = A and (B or C), but how would you prove or disprove these set identities. Any help would be appreciated, Thanks


This started happening today for absolutely no reason. Worked perfectly last week. I didn't touch the machine.  I have an issue described  and need to downgrade in order to be able to upgrade. Currently I'm not able to enter the shell as it exits with error #4   need to upgrade database admin with pdfile version 4.22, new version: 4.5  If I run it with --upgrade I get:  ERROR: error: exception cloning object in admin.system.users system.users entry must have either a 'pwd' field or a 'userSource' field, but not both obj:{ _id: "nod$ exception in initAndListen: 2 system.users entry must have either a 'pwd' field or a 'userSource' field, but not both, terminating   I'm trying sudo apt-get install mongodb-10gen=2.2.10but it doesn't work.  Can anyone direct me to a command I can use to install version 2.2.10?


How could the baddies build such a large fleet in isolation to the galactic economy?

I watched the film 'The Rise of Skywalker' in cinema. Our heroes spent most the film searching for a super secret planet. It turns out the only way to reach the planet is with the help of a extremely rare special navigation device.  When they arrive, the planet itself is uninhabited except for one lonely man. However in orbit is a huge fleet (the biggest ever seen?) of hundreds/thousands of new star destroyers, all with new super powerful weapons and crewed for combat. This is a surprise to the goodies.  How did the baddies build so many ships in secret and in isolation to the galactic economy? Did they import the raw materials? Where did the crews come from?


How does friction help the car to move forward?

Below is the extract from my book.     There is a car with four wheel drive system and during acceleration, the engine causes the tires to push backward on the road surface. This push produces frictional forces $\vec{f}$ that act on each tire in the forward direction. The net external force $\vec{F}$ from the road, which is the sum of these frictional forces accelerates the car, increasing its kinetic energy.   Here the author says frictional force produce acceleration. How can a frictional force produce acceleration in the car?  The only possible explanation I can think that cause the car to moves forward in this case is when the tire pushes the road in backward direction and the friction force is the reaction force acting as mentioned in Newton's Third law.


Which of these is correct or more natural?        One of my greatest strengths is critically analyzing.      One of my greatest strengths is critical analyzing.     One of my greatest strengths is critical analysis.


How to calculate the optimal number of bins for severly skewed data

I have a data set with a sample size over three million numeric values. Close to 20% are either 0 or 1, with the maximum being nearly 18500. So the data is clearly quite heavily positively skewed.  I am trying to categorize some of this data by putting it into bins of equal width, to use the Chi-sqaure test and Cramers V to look for associations between this variable and a categorical one, so I decided to try and find the optimal number of bins. Using the Freedman-Diaconis rule it gave me a value of 126044.0262335108, this is clearly a ridiculously large number of bins for the data.   Breaking the set into the Inter-decile range also proved fruitless giving me [0, 1, 1, 2, 3, 5, 8, 17, 47]  Reading elsewhere the square root of the sample size was suggested, this gave 1732.05081 which is more reasonable. However the method is quite crude.  I also looking into Doane's formula given . But reading up on this method it seems to have been based on an incorrect .  How should I deal with this level of skew in the data?  What is the best way to categorize this data?


How do I prevent condensation on my balcony windows?

On the street, temperatures at night are about -5 °С and about 8 °C during the day. In the apartment it is about 25 °C. So, there is condensation on the windows and I don't want to wipe the windows every time.  How do I prevent condensation on the balcony windows?


Summation of series $\sum_{k=0}^\infty 2^k/\binom{2k+1}{k}$

How to find the sum of this series?  $$\sum_{k=0}^{\infty}\cfrac{{2}^{k}}{\binom{2k+1}{k}}$$  It seems very easy. But I still can not work it out, can anyone help?


How do I create multiple files names from list.txt in bash?

I want to create multiple files at a time using names from a file list.txt, how can I do it?  Sample list.txt:  EOG090W002U EOG090W00C1 EOG090W00DC EOG090W00DE EOG090W00E5 EOG090W00HR EOG090W00MH EOG090W00MS EOG090W00PB EOG090W00U4 EOG090W00UK EOG090W00WM EOG090W00WR   Suppose I have this list.txt containing some id-numbers. Now I want to make separate files using these ids as the name (e.g. EOG090W002U_M0.ctl, EOG090W00C1_M0.ctl, EOG090W00DC_M0.ctl). Also, the contents of the files need to be change accordingly. For example the content of EOG090W002U_M0.ctl, EOG090W00C1_M0.ctl file will be   seqfile = EOG090W002U_p.phy treefile = Constant.txt outfile = EOG090W002U_M0_mlc   or  seqfile = EOG090W00C1_p.phy treefile = Constant.txt outfile = EOG090W00C1_M0_mlc   where *.phy and Constant.txt will be provided in the same folder.


How to logout from iCloud without password? and without resetting

I have an iPhone 6 Plus, and the previous owner forgot to sign out his iCloud account. What should I do? Can I reset this? It may upgrade into the latest ios which will make the phone crash, and I am afraid it might downgrade to iOS 9.


apt upgrade hanging on "linux-headers-4.4.0-146-generic (4.4.0-146.172)"

apt upgrade has been stuck at the following for a day or two now:      Q1: What is the best practice for solving this issue?  I've tried Ctrl+C, as recommended here for "gracefully" terminating the process, but it hasn't worked:    Do I follow the second answer instead?    Q2: How can I avoid this in future?  It looks like it's been reported as a bug here:    So how likely is this to happen again?    Edit: Seems like it could be linked to this    although AFAIK I've had Secure Boot disabled for ages  Could an update have re-enabled Secure Boot somehow?


How do I list what dns servers are being searched for things that need to do dns searches?  It doesn't seem like what I have in resolv.conf is being used, So i want to troubleshoot and step one of that would be to have the system print out what servers it is using.  Everything I found so far assumes I have network manager installed, but I do not, and so nmcli or other such commands would not work.  Linux linuxtest 3.16.0-4-amd64 #1 SMP Debian 3.16.43-2+deb8u2 (2017-06-26) x86_64 GNU/Linux


Serial voting reversed and recidivism prevention

I recently seen a message called serial voting reversed.    In my "reputation" in my user profile on Mi Yodeia,  there was 62 downvotes canceled and 5 of my downvote canceled. There was also 8 upvotes on answer reversed and one upvote on question.   My question is if there is someone who likes downvoting my answers in a serial way, the statistical correction of stack exchange is retroactive only or is there a preventive measure against recidivism.   I searched and did not find an answer. Please help me to know.  I have a high presumption, based on the fact that the last downvote was on an answer in which the same user wrote a comment on an other answer to the same question at the same time. An additional reason is that the difficulty to lose a compulsory activity is great.  In the past it was very hard for me to be taken seriously by moderators. I feel that somewhat is not clear for me how can I require to get advocacy. I feel that for a lengt time  moderators refuted to help me. Is there something non appropriate in the moderation system?


How can I testfor only one player in a specific place?

I am making a map and I need to testfor the last player alive in the arena. I tried with selectors, but I am not really into this. Can someone help me out?


According to newton's third law "for every force there is an equal and opposite reaction" then explain how our our arms move?

My biceps muscles are attached to my arms bone/bones through a tendon/tendons, if my biceps pulls my arms bone/bones with a force of 100N upwards then my arms bone/bones pushes back downwards with a force of -100N,therefore fnet should be 0 and there should be no movement, however in reality our arm moves upwards, why?


creating a method that can return multiple objects in Java

In java i would like to create a method that can return multiple objects like a couple of int values,  strings, float , double etc. what is the way to do this?


Can someone with only a bachelor's degree teach at a community college?

Can someone with a bachelor's degree teach at a community college, or are they required to have something more?


three men drop their hats off at the cloakroom when entering a restaurant and choose at random when taking out 1 of the 3 hats.  Calculating the probability that none of the 3 men take their own hats.   The total outcomes are 3! = 6  There are favorable outcomes: those that have neither 1 in the first position, nor 2 in second, nor 3 in third.  With manual counting, there are then 2 favorable outcomes.  The probability is, therefore 2/6  All is good, but how can I find the number of favorable outcomes when 50 drop their hats off at the cloakroom?     Edit:   After research, the precise answer is the nearest integer to n!/e, 50!/e in my case.


Spatial adjustment of vector data in QGIS?

Is there any plugin or code reference available to spatially adjust vector data based on points selection like in the Spatial Adjustment tool of ArcGIS Desktop?  I am trying to develop spatial adjustment tool plugin in QGIS.


How to rewrite my two methods so I do not get a NullPointerException?

So, I was given the task of writing two simple methods for an array: the first method, double the size of the array; the second method, find the index of the first duplicate string in the array. The main method was written by my professor and is not to be altered. My problem is that I continue to get a NullPointerException when running my code. I believe it has to do with Arrays.sort() or my teacher's code in main, but I was instructed to: only use arrays (no other data structure), use Arrays.sort() in finding the index of the dupe, and not to modify anything else in the program...is there any way I can rewrite my methods keeping to these instructions?   Full code:  import java.io.*; import java.util.*;  public class Practice {     static final int CAPACITY = 10;     static final int NOT_FOUND = -1;     public static void main (String[] args) throws Exception     {         if (args.length < 1 )         {             System.out.println("\nusage: C:\\> java Practice <words filename>\n\n"); // i.e. C:\> java Lab2 10Kints.txt 172822words.txt             System.exit(0);         }       String[] wordList = new String[CAPACITY];     int wordCount = 0;     BufferedReader wordFile = new BufferedReader( new FileReader(args[0]) );      while ( wordFile.ready() ) // i.e. while there is another line (word) in the file     {   if ( wordCount == wordList.length )              wordList = upSizeArr( wordList );         wordList[wordCount++] = wordFile.readLine();     } //END WHILE wordFile     wordFile.close();      System.out.format( "%s loaded into word array. size=%d, count=%d\n",args[0],wordList.length,wordCount );     int dupeIndex = indexOfFirstDupe( wordList, wordCount );     if ( dupeIndex == NOT_FOUND )         System.out.format("No duplicate values found in wordList\n");     else         System.out.format("First duplicate value in wordList found at index %d\n",dupeIndex);  } // END OF MAIN  // TWO METHODS   static String[] upSizeArr( String[] fullArr ) {      int size = fullArr.length; //find the length of the arrays     String[] newSizeArr = new String[(2 * size)]; // creates new array, doubled in size     for (int a = 0; a < size; a++) {         newSizeArr[a] = fullArr[a];     }     return newSizeArr;  } static int indexOfFirstDupe( String[] arr, int count ) {            Arrays.sort(arr);     int size = arr.length;     int index = NOT_FOUND;      for (int x = 0; x < size; x++) {         for (int y = x + 1; y < size; y++) {             if (arr[x].equals(arr[y])) {                 index = x;                 break;             }         }     }     return index; } } // END OF PROGRAM   Location of the NullPointerException:    Edit: This question addresses an NPE in library code, not my own code.


How to UV unwrap a car model using standard perspectives?

I made a low poly car model (772 tris, game asset) but I'd like to unwrap it so that I can use a single texture like this .  Doing multiple "project from view" unwraps doesn't work since it deletes the last one. So what can I do with Blender?


At what scale to plot variables in different units?

I have 4 series/variables over time. They are in totally different units (monetary, quantities, elasticities, and percentages). I want to make a line plot for each of them. I know it makes no sense to put in the same graph, not even when using different axes, as they are messy.   What troubles me the most is the selection of the scale of the y-axis (x-axis is time). You can zoom in or out and get visually different degrees of apparent variability of the series (and careless readers might be fooled by this).  Of course, that's why we care about the standard deviation. But still, I want to make a graph of the series alone that are somewhat informative.  My question is: is there some logical scale at which the y-axis is to be presented? For example, do I select the mean and then select the y-axis to cover 2 standard deviations up and down from that mean? Is there some standard here?   PS: I've seen , , and  question, but I find no answer to mine there. For instance, the last one, suggested by Nick Cox, has all variables in exactly the same units. In my case, they have for different units. The suggestion of percentage change is not helpful either, because some variables are known to vary much more than others. Ideally, I want to plot the series themselves, and not the changes.


I'm trying to figure out an easy query I can do to test if a large table has a list of entries that has at least ONE blank (NULL / empty) value in ANY column.  I need something like  SELECT * FROM table AS t WHERE ANY(t.* IS NULL)   I don't want to have to do  SELECT * FROM table AS t WHERE t.c1 = NULL OR t.c2 = NULL OR t.c3 = NULL   This would be a HUGE query.


Can relative clauses be combined with adverbial clauses other than if-clauses?

The following is from Michael Swan's Practical English Usage:  Relative clauses can also be combined with if-clauses in sentences like the following. I am enclosing an application form, which I should be grateful if you would sign and return.  Then, can relative clauses also be combined with other kinds of adverbial clauses, for example since-clauses in sentences like the following?  It seems something is wrong with this PC, which barely a month has passed since I bought.


how do I remove ubuntu and grub from my vista system and regain access to my second hard disk where ubuntu is installed. There doesn't appear to be an uninstall option on the install disk, so I tried the install disk again. What resulted was 2 installations and about 6 partitions on my second hard disk.


How to get to the GRUB menu at boot-time?

My system is not dual-boot, I run a standard Ubuntu desktop system "on the metal" (I think running it in a VM is the same).  Pressing c while booting does not cause the GRUB menu to appear (which I believe it does for a dual-boot system).  How can I get the GRUB-menu to present itself on a single-boot system?


Does Ubuntu work on ASRock H170M-ITX/DL motherboard?

Can Ubuntu be installed on ASRock H170M-ITX/DL motherboard? If so, do you know of a good guide to use?  Im looking to create a bootable usb from on a mac of the latest Ubuntu that would work with ASRock H170M-ITX/DL .  Please advise. Thank you


Why total RES doesn't match used memory in top command?

This is a 32 GB memory machine and the following top/free command says 30.5 GB memory is used, but the total RES is actually much less than 30.5 GB. Why?  top - 21:54:46 up 20 days,  1:46,  4 users,  load average: 0.59, 0.43, 0.34 Tasks: 238 total,   2 running, 233 sleeping,   0 stopped,   3 zombie %Cpu(s):  3.8 us,  0.7 sy,  0.1 ni, 94.0 id,  1.5 wa,  0.0 hi,  0.0 si,  0.0 st GiB Mem:    31.523 total,   30.609 used,    0.913 free,    0.456 buffers GiB Swap:    4.000 total,    0.134 used,    3.866 free.   22.733 cached Mem     PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND  2600 xxxxxxx   20   0 12.048g 2.002g 0.034g S   0.3  6.4  14:24.92 xxxxxx  1443 xxxxx     20   0  1.302g 0.837g 0.019g S   0.3  2.7 102:19.93 xxxxxx  9782 xxxxxxx   20   0  1.942g 0.573g 0.043g S  17.0  1.8 164:53.02 cinnamon 20730 xxxxx     20   0  0.619g 0.289g 0.055g S   0.3  0.9 102:19.50 xxxxxx 29920 xxx       20   0  0.787g 0.189g 0.020g S   0.3  0.6  60:42.72 xxxxxx 31377 xxxxxxx   20   0  3.390g 0.169g 0.006g S   0.0  0.5  38:45.66 xxxxxx  9497 xxxxxxx   20   0  0.367g 0.168g 0.036g S   1.3  0.5  16:00.60 xxxxxx  1402 root      20   0  1.010g 0.154g 0.024g S   0.3  0.5  54:30.61 xxxxxx 14176 root      39  19  0.306g 0.118g 0.011g S   0.0  0.4   4:32.76 xxxxxx   903 xxxxxxx   20   0  0.383g 0.101g 0.034g S   0.3  0.3   0:43.40 xxxxxx               total       used       free     shared    buffers     cached Mem:            32         31          1          0          0         23 -/+ buffers/cache:          8         24 Swap:            3          0          3   The following ps command calculates total RSS, which is 7 GB, but top/free command returns 30.5 GB used. Why?  ps -e --format rss  | awk 'BEGIN{c=0} {c+=$1} END{print c/1024}'   My big mistake is this machine is actually 32 GB memory, not 64 GB.


What would you call "the other party" in a conversation in which you are participating?

The ideal word would be "conversee" but that obviously isn't correct. "Recipient" doesn't feel right either. I suppose "interlocutor" is somewhat better, but that doesn't refer to the "other", in this context and feels very formal.


We know that Stack Overflow has a suggested edit queue, visible to the users who have the  privilege. Someone said the queue has a fixed size.  What's the fixed size of the suggested edit queue?  Is it often that the queue gets filled up and users can no longer suggest edits?


"java.lang.OutOfMemoryError: Java heap space" occurred while reading image of size 330MB

I'm using following code to read image file of size 330MB  BufferedImage img=ImageIO.read("test.png");   How to resolve this?


Weird behavior in these two ways to create a multi-dimension list


A linear time, constant space algorithm for finding an element with 1 occurrence in a list

Given a list of n integers, where every integer in the list exists twice, except for one element, which exist once in the list. For example,  [1 3 3 6 2 7 1 2 7]   I need to find a linear time O(n), and a constant space O(1) algorithm that returns the element which exists once in the list. In the above example, the algorithm should return 6. Note that the list is not provided by any certain order. (The order of the elements in the list is random).  I could solve this problem in O(n) linear time using a dictionary but unfortunately the dictionary requires O(n) space. Any ideas?


Proving that a polynomial is bounded on bounded domains

Definition: A real function $f:X\to\mathbb{R}$ is said to be bounded if there exists a $k>0$ such that $|f(x)|\le k$      Definition: A subset $X$ of a metric space $(M, d)$ is said to be bounded if $d(x,y)\le c$ for all $x,y\in X$.   Let $p:\mathbb{R}\to \mathbb{R}$ a real polynomial function of degree $n>0$ given by $$ p(t) = a_0 + a_1t+ \cdots + a_nt^n $$ Show that $p$ is not bounded. Moreover, show that for every bounded subset $X\subset\mathbb{R}$, the restriction $s:X\to \mathbb{R}, s(t) = p(t)$ is bounded.


Is the "expansion of space" limited to intersteller space only?

Does the expansion of space (that started from BigBang) limited to expansion of intersteller space only (as observed by Hubble) or does it happen even in the local observable universe?   Specifically, does the space between two stars in our own galaxy is also expanding? Does the molecular space in an ordinary everyday object expanding as well (even if it is very very tiny)?


Show that the plane $\{su+tv|s,t \in\Bbb R\}$ in $\Bbb R^3$ is equal to the null space of some element of $(\Bbb R^3)^{*}$.

Let $\{u,v\}$ be a linearly independent set in $\Bbb R^3$.  Show that the plane $\{su+tv|s,t \in\Bbb R\}$ through the origin in $\Bbb R^3$ is equal to the null space of some element of $(\Bbb R^3)^{*}$.   Attempt: We are supposed to prove that $su+tv=ker(g)=0$ for some $g \in (R^3)^{*}$. And I am stuck now.   I want to argue algebraically. I know that $g= g(s) g_1+ g(t) g_2 $for $g_1, g_2$ being basis for g.  Then from definition of kernel we have   $g(s)=g(s) g_1 (s) +g(s) g_2 (s)=0 \rightarrow g(s)=0$  and $g(t)=g(s) g_1 (t) +g(s) g_2 (t)=0 \rightarrow g(t)=0$  So we have $su+tv=0=g(s)=g(t)$  I am not sure if that makes sense.


Higher order derivative of a composition of vector valued multivariate functions

I have this composition of twice differentiable functions : $$ \Bbb R ^m \overset{f}{\longrightarrow} \Bbb R^n \overset{g}{\longrightarrow} \Bbb R^k$$ And I'm trying to get this result from a book : $$ (g \circ f)''(x) (h,k) = (g''\circ f')(x)\big(f'(x)h,f'(x)k\big) + (g'\circ f)(x)\big(f''(x)(h,k)\big) $$ A poor attempt : $$  \begin{align} (g \circ f)^{\prime\prime}(x) (h,k)   & = \bigg(\big((g' \circ f)(x) f'(x)\big)(h)\bigg)'(k) \\   & = \big((g' \circ f)(x)\big)'(k) f'(x)(h) + (g' \circ f)(x)\big(f''(x)(h,k)\big) \\   & = (g'' \circ f)(x)f'(x)(k) f'(x)(h) + (g' \circ f)(x)\big(f''(x)(h,k)\big) \\ & = (g''\circ f \space)(x)\big(f'(x)k,f'(x)h\big) + (g' \circ f)(x)\big(f''(x)(h,k)\big) \\  (?) & = (g''\circ f')(x)\big(f'(x)h,f'(x)k\big) + (g'\circ f)(x)\big(f''(x)(h,k)\big) \end{align}$$ So It feels like it follows the rules of bilinear differentiation but then $h$ and $k$ should swap places and there's that extra $f'$. What am I doing wrong.


How do I simplify the following series $$1 + \frac{1}{1+2}+ \frac{1}{1+2+3}+ \frac{1}{1+2+3+4} + \frac{1}{1+2+3+4+5} + \cdot\cdot\cdot + \frac{1}{1+2+3+\cdot\cdot\cdot+n}$$  From what I see, each term is the inverse of the sum of $n$ natural numbers. Assuming there are $N$ terms in the given series, $$a_N = \frac{1}{\sum\limits_{n = 1}^{N} n} = \frac{2}{n(n+1)}$$ $$\Rightarrow \sum\limits_{n=1}^{N} a_N = \sum\limits_{n=1}^{N} \frac{2}{n(n+1)}$$ ... and I'm stuck.  I've never actually done this kind of problem before (am new to sequences & series).  So, a clear and detailed explanation of how to go about it would be most appreciated.  PS- I do not know how to do a telescoping series!!


I have an angular component that needs to cycle through an array. Below, I have an array and a global variable called currentAlbum which will hold the value of the album currently being viewed. The below works, but with some odd behaviour. Question 1 Firstly, even though it cycles through correctly, i added console logs to make sure the if statement worked correctly and that it'll begin from the beginning again after reaching the end. The 'currentAlbum' console log will always be one behind of where it appears on screen. Any obvious reason for that? For example, on screen album 3 will be present, the console log will say album 2. Question 2 I also have 5 buttons on the screen, each one, when clicked will show the selected album. This is a simple this.currentAlbum = selectedValue(selectedValue being received from the HTML click). However, when doing this, the timer continues to run. If the timer is five seconds and I click a carousel button at 4 seconds, the new album will show for 1 second before changing to the next. Is there a way to reset this value? (I've also read that setTimeout is a better approach...?)   currentAlbum: number = 1;    albumsArray = [     { title: "Album 1", index: 1 },     { title: "Album 2", index: 2 },     { title: "Album 3", index: 3 },     { title: "Album 4", index: 4 },     { title: "Album 5", index: 5 },   ]    ---------    ngOnInit() {      this.theCarousel();   }      theCarousel() {     setInterval(() => {       if (this.albums == 5){         this.currentAlbum = 1;         console.log('this is album 5)       } else {         this.currentAlbum++;         console.log('this is not album 5)       }     }, 2000);   }


primes whose difference is a multiple of $n$

Hello everyone this is my first question here so if there are any suggested edits  feel free to participate! Is it true that for every $n$ there two prime numbers $p$ and $q$ with $n\mid p-q$? I have verified this empirically but  am not sure if there is a proof for this


I'm trying to run an .mkv video, I even installed the codecs from this page:   But still keep getting this error on VLC player:  No suitable decoder module: VLC does not support the audio or video format "hevc". Unfortunately there is no way for you to fix this.  It plays only the audio.  Help please?


Vertically center a div inside another div

I'm trying to vertical-align: middle a div inside another div, but for some reason it's not working properly. What am I doing wrong?    #wrapper { border: 1px solid red; width: 500px; height: 500px; } #block { border: 1px solid blue; width: 500px; height: 250px; vertical-align: middle; }

 I'm Block

      PS:  This is just an example, so no, I don't actually know the actual width and height of the divs, as they are dynamic, according to their contents, so please no margin-top: 125px, or padding-top: 125px answers, or answers like that.


What to do when 18 month old doesn't want her dinner?

It's becoming more frequent that my 18 month old daughter has started refusing the dinner we give her without trying it. Our best guess at why, is because it contains green things.   We always check the food and it is damn tasty, and she does like it if she tries it, but obviously explaining this to an 18 month old is difficult.  We know she is hungry, because in the past we have given her a replacement of something like toast and she'll gobble that down.  What is the best way to handle this? We don't want her to think that she can always swap her healthy dinner for toast, so the method we have currently been using is, if after 15 minutes she is still not eating, we'll get her down and say something like "You haven't eaten your dinner, you must not be hungry". If, later she decides she does want the food, we'll put here back on her chair and let her eat.  Is this a good way to handle it? Would there be a better method? We don't want her to grow up having "food issues"


Should I use "moving in to" or "moving into" for this sentence?

While writing a sentence like this one, should I use "moving in to" or "moving into"? Since "move in" seems to be a phrasal verb, is it safe to assume that the right choice would be "moving in to"?  They invited all their friends to celebrate their moving in to Crimson Park.


Why does Penicillin only affect bacterial cell walls

I was quite fascinated by the feature  in this month's Wired magazine.  They explain that Penicillin is effective at killing bacteria because it interferes with the growth of bacterial cell walls.  How does Penicillin do that exactly? And why does it not dissolve human cells as well?


The quotient of an ideal generated by idempotents of a prime ideal does not contain any idempotents

Let P be a prime ideal in a ring R (commutative with identity) and I be the ideal generated by the idempotents of R, contained in P. Show that R/I contain no idempotents other than 0 and 1.  An approach suggested is to show that for $x$ being one said idempotent in R/I, Then $x(x-1)$ belongs to I.If we then take X ∈ P , then one way suggested in the hint is to show that ∃ y ∈ I and y^2=y such that $yx(x-1)$=$x(x-1)$. I am unable to find this and then show (1-y)x is idempotent which implies x is idempotent


I made a mistake on Windows with "aux" files

Anyone who knows their way around a Windows machine knows about naming items aux, con, nul, etc etc. Its impossible unless you use third party software or command line.  Long story short: I made a batch file that makes a couple hundred files per second, all of which are named "aux.txt%random%...".   So now I have 600+ files I can't delete. At all. My laptop is dual booted with Linux, but Windows 10 makes the C: drive read only so that won't help.  I'm at a complete loss! I know it was stupid to even try doing this, and that I should've used a VM, but I was just in the moment of testing the lengths of Windows. I must delete these files because they are taking up too much space!!  An example file name is "aux.txt29582001129920227490210248486001047729"


Why do prisms work (why is refraction frequency dependent)?

It is well known that a  can "split light" by separating different frequencies of light:    Many sources state that the reason this happens is that the  is different for different frequencies.  This is known as .  My question is about why dispersion exists.  Is frequency dependence for refraction a property fundamental to all waves?  Is the effect the result of some sort of non-linearity in response by the refracting material to electromagnetic fields?  Are there (theoretically) any materials that have an essentially constant, non-unity index of refraction (at least for the visible spectrum)?


I want to develop BirthDay CountDown calculator in PHP  User input the date DD-MM-YYYY  I have a days differnce calculator, but it calculates the days from between two specified years.  $daysfrom = $_POST['daysfrom']; $daysto = $_POST['daysto']; echo 'Difference of days B.W ' . $daysfrom . '-'.$daysto.' are';     $daysto = strtotime($daysto);     $daysfrom = strtotime($daysfrom);     $datediff = $daysto - $daysfrom;     echo floor($datediff / (60 * 60 * 24));   And I have tried this calculate days between birthday.(I know this is not right)  User will input MM-DD-YYYY and it should calculate days between months.  Ex: - Input: 13-03-1993       Output: (Assume todays date is 10-03-2014), it should display 03 Days left   if (isset($_POST['daysto'])) {        $daysto = $_POST['daysto'];        echo 'Your birthday comes within ';        $daysto = strtotime($daysto);        $now = strtotime(date('d-m'));        $datediff = $daysto - $now;        echo $datediff / 60 / 60 / 24;      }


Replacing '+' with ', ' for labels in QGIS?

I want to replace a '+' with ', ' to label an attribute looking like "ZT10+ZT20+ZT30" to get "ZT10, ZT20, ZT30" using   regexp_replace("zone_nr", '+', ', ')   but I get an Eval Error: Invalid regular expression '+': quantifier does not follow a repeatable item.


I created a custom theme (a sub-theme of  base theme).   I am loading a custom Javascript file (radix_sub.script.js) using the module libraries.yaml file like below:  style:   version: VERSION   css:     theme:       assets/css/radix_sub.style.css: {}   js:     '//cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js': { type: external }     '//stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js': { type: external }     assets/js/radix_sub.script.js: {}   dependencies:     - core/drupal     - core/jquery     - core/jquery.once     - core/drupalSettings   In that file, I want to register some JavaScript events (Bootstrap modal).  (function ($, Drupal) {    Drupal.behaviors.portfolio = {      attach: function (context) {        console.log('CONTEXT', context);        $('#portfolioModal', context).once('bootstrap-modal-shown', console.log('*** REGISTER SHOWN.BS.MODAL')).each(function () {         $(this).on('shown.bs.modal', function () {           console.log('SHOWN BS MODAL EVENT TRIGGERED');         });       });        $('#portfolioModal', context).once('bootstrap-modal-hidden', console.log('*** REGISTER HIDDEN.BS.MODAL')).each(function () {         $(this).on('hidden.bs.modal', function () {           console.log('HIDDEN BS MODAL EVENT TRIGGERED');         });       });     }   } }(jQuery, Drupal));   It works. I see both SHOWN BS MODAL EVENT TRIGGERED and HIDDEN BS MODAL EVENT TRIGGERED logs when I show/hide the modal.  First, am I doing that the correct way?  This is what my developer console looks like when I load my page.        This happens only when I am logged in (as admin). When I am anon, I see the REGISTER logs only once but here my code seems to be executed 11 times.  Is this normal behavior? And/or why is it doing that?


Is there an Eclipse plugin available for JavaScript that allows for syntax checking and autosuggestions for .js files in Eclipse?


How to attach onclick event to an element dinamically created

I'm trying to trigger an event attached to a html  tag  This table is builded insde a function       function detail(id){       console.log(id)     }  function search(data){                 $.post(url, {valorBusqueda: textoBusqueda}, function(data) {                      data = JSON.parse(data);                          $.each(data, function(i, val){                                  id = val.id;                                   html += '<tr onclick="detail('+id+')">';                                 html += '<tr>';                             }                         });                         });  }   But when I click the  element I get this err:   Uncaught ReferenceError: detallePaciente is not defined  when is actually defined in my file  any idea how could I solve this?


I have problem in running Bibtex first I have to know if i have Pine et al,(1999) in tex, is it correct to write \cite{Pine1999} or I have to write \cite{Pine,Winn,Wrigh1999} which one is correct?  Second, in first running of Bibtex I have some empty spaces, then I removed them, but after saving and running again I still receive the same error   Third, I have all cites in my Mendeley and I run the bib file first but receive the blew warning saying that the  database entry for some cite did not find? I am a student and this is my first experience with LaTeX please kindly help me. many thanks here it is the error and warning:  I'm skipping whatever remains of this command  White space in argument---line 70 of file elsarticle-template-last SMR..aux  : \citation{Saeednia,Goodarzi  :                             2013}  I'm skipping whatever remains of this command Illegal, another \bibstyle command---line 102 of file elsarticle-template-last SMR..aux  : \bibstyle  :          {model1-num-names}  I'm skipping whatever remains of this command Illegal, another \bibstyle command---line 103 of file elsarticle-template-last SMR..aux  : \bibstyle  :          {model1a-num-names}  I'm skipping whatever remains of this command Illegal, another \bibstyle command---line 104 of file elsarticle-template-last SMR..aux  : \bibstyle  :          {model2-names.bst}  I'm skipping whatever remains of this command Illegal, another \bibstyle command---line 105 of file elsarticle-template-last SMR..aux  : \bibstyle  :          {agsm}  I'm skipping whatever remains of this command I couldn't open database file figure/bib.bib ---line 106 of file elsarticle-template-last SMR..aux  : \bibdata{figure/bib  :                    } I'm skipping whatever remains of this command  I found no database files---while reading file elsarticle-template-last SMR..aux  Warning--I didn't find a database entry for "Tsaur"  Warning--I didn't find a database entry for "Chiu"  Warning--I didn't find a database entry for "Wang2006"  Warning--I didn't find a database entry for "Solomon2016"  Warning--I didn't find a database entry for "Schmitt1999"  Warning--I didn't find a database entry for "liou2011" Warning--I didn't find a database entry for "lee"  Warning--I didn't find a database entry for "chang2012"  Warning--I didn't find a database entry for "chao2015"  Warning--I didn't find a database entry for "smilanski2009"  Warning--I didn't find a database entry for "Guest1994"  Warning--I didn't find a database entry for "Guest1995"  Warning--I didn't find a database entry for "Oliver1980" Warning--I didn't find a database entry for "Dick"  Warning--I didn't find a database entry for "Basue1994"  Warning--I didn't find a database entry for "Lora"


How to run 32-bit programs on a 64-bit system

Recently I upgraded my netbook to Ubuntu 13.04 64-bit from Ubuntu 13.04 beta 2 32-bit.  I want to be able to run 32-bit programs (such as WPS, which is a clone of MS Office 2012) on my PC.  How do I do it? Is there an easy way of doing it via the terminal?


Where's the foolish part ? Prove that 0/0 = 2

I've been across this on the web:  \begin{align} \frac{0}{0} & = \frac{100-100}{100-100} \\ & = \frac{10^2-10^2}{10(10-10)} \\ & = \frac{(10-10)(10+10)}{(10)(10-10)} \\ & = \frac{(10+10)}{10} \\ & = \frac{2}{1} \\ & = 2 \end{align}    Of course this is wrong but I can't tell where exactly since there is no obvious (to me at least) atrocity... Is this in the first line $ \frac{0}{0} = \frac{100-100}{100-100}$ ?


Mismatch between image quality on viewer and actual phtoto

I am using a Nikon D3200 and I think there is a mismatch between the image seen on the view-finder and the image which appears on the CCD array. I have never been able to achieve the sharp focus as one would expect. The image on the screen is sharp but the actual photos are poor. Any reason for this problem?


I am doing self-study to learn Data Science (software developer by profession) and needed to read and understand  but this book requires Linear Regression as prerequisite. I  and got good books for Linear Regression and I can order one by Draper and Smit from . This is the only one which I can afford buying, rest all are imported and out of my budget.   I only know Algebra and some Calculus which I learned in last 2 months from MOOCs and Khan Academy and lot of search  but I got no background either in Probability or Statistics.  Can I got straight to learning Linear Regression from the book ?   NOTE: I am not looking to learn Statistics or Math and I do not want to learn any theory either.  I just want to understand Linear Regression so that I can do my Data Science work.


Are there any rules about when to say exist and when to say exists in mathematics? For example, both these sentences appear in a book of mine:  There exist αi in I such that xn = Σ αi xi. There exists s'' in S such that s''(s'm – sm') = 0.  I'm a bit confused about when to use exist and when exists.


Let $S$ be open subset of $R^2$ and let $f$ be twice differentiable real valued function on $S$. Suppose that there exists $(a,b) \in S$ such that $f(x,y) \leq f(a,b)$ on $S$, then show that $(\Delta f)  (a,b) \leq 0$ where $\Delta f = f_{xx} + f_{yy}$  I have proved a similar result for functions define on $R$. If $g$ is a function defined on an open interval $I$ such that $a\in I$ and $g(x) \leq g(a) $ on $I$, then $g''(a) \leq 0$ I proved the above using the fact that $g''(a) =\lim_{h\to 0} \frac{g(a+h) + g(a-h) - 2g(a)}{h^2}$ and by observing that $g(a+h) + g(a-h) - 2g(a) \leq 0$ Can I use this somehow to arrive at the required result?


I just want to know, can we somehow derive an expression for the splash distance of water (horizontally) if we drop a ball in to a pool of water and aim to measure the maximum distance the water has splashed by?  I feel like the vertical distance of splash height there might be some connection with energy conservation or conservation of momentum to find the height ( i have found good information here infact ) , but I am not sure if we can mathematically find the distance of the distance stashed horizontally?  I appreciate the help.


Keyboard language layout switching interferes with global system hotkeys

I have installed Kubuntu 18.04 with KDE on my home machine.  I usually use Ctrl + Shift for switching keyboard language layout, but that setting breaks Ctrl + Shift + ← and Ctrl + Shift + → selecting by word behavior (or any other hotkey containing Ctrl + Shift) — instead of selecting text by word it switches keyboard layout. I have switched to using Alt + Shift for language layout switching, but that interferes with JetBrains' IDE hotkey Alt + Shift + L (or any other hotkey containing Alt + Shift) — instead of intended action in IDE it simply switches keyboard layout.  On another machine with Ubuntu 16.04 LTS I successfully use both layout switching hotkeys without any issues, so there must be something I'm missing in keyboard configuration. The question is: why regular keyboard layout switching hotkey interferes with global system hotkeys effectively overriding and breaking them? How to fix that behavior?


What is the formula for following sequence?  $$\frac12 + \frac12 \cdot \frac34 + \frac12 \cdot \frac34 \cdot \frac56 + ... + \frac12 \cdot \frac34 \cdot \frac56 ... \frac{2n - 1}{2n}$$  This is a question from my Calculus class about sequences.


how can i delete my hard drive and format to NTFS

How can I format my disk to NTFS I need to delete everything so I can buy Windows XP and reinstall thanks Barara


Schengen Business visa without a business invitation letter

To apply for a Schengen business visa, you need a letter from the company in the Member state inviting you. My company is based in the UK, owns properties in Schengen countries, and I have to inspect their condition.  What letter do I get?


Formatting and alignment of authors in \maketitle

I am in the process of creating a LaTeX template for a conference submission, and up until now I've been working only with the anonymous submissions. Now I need to create the "camera-ready" version, which means I need to add authors to the document.   The template is based on article.cls, with some tweaks to meet the font and formatting specifications. The following image contains the examples from the Word template for the conference:    Basically, I need to be able to bold the author's name (which could I suppose be done manually in the document rather than in the template) and more importantly: divide the authors into two columns, with an optional centered last column with an odd number of authors. The font size of the author block corresponds to my \LARGE defined in the class file.  Are there any packages that facilitate this type of conditional formatting, either in a document, or in a .cls file? How can I use those packages to achieve the formatting I require?


How can I let a footnote continue on the next page?

I have a rather long footnote which breaks a listing in two parts, unnecessarily.  Since the listing is more important then the footnote I'd rather lake to have the footnote split.   Can I customize (one or all) footnotes to have a maximal length before they are continued on the next page? Or can I manually split a footnote in two to get the effect?


Can we distinguish $\aleph_0$ from $\aleph_1$ in Nature?

Can we even find examples of infinity in nature?


Running Windows 10 on laptop dedicated GPU

I have an older laptop with Intel HD Graphics 4000 and nVidia GeForce GT650M. I bought a monitor that supports Quad HD, but the Intel HD Graphics 4000 does not support it. So I would like to disable it completely and use only the dedicated GPU. Is this possible? I am aware of the ability to switch the GPU for rendering during playing games etc. But I have not been able to find a mention of forcing its usage to allow the use of higher resolutions on a monitor. In the NVIDIA Control Panel, I found a diagram that seems to indicate, that the dedicated GPU has no physical outputs.  Does this mean there is no way to use the GPU to get to QuadHD?


Placing figures side by side with independent captions

I am trying to place two figures from .pgf file input side-by-side. I want them to have independent captions (so no subfigures). I have tried using the minipage way as follows:  \documentclass{article} \usepackage{pgf}  \begin{document}  Some words.. \begin{figure}     \begin{minipage}[t]{0.5\linewidth}         \centering         \input{figure1.pgf}         \label{Figure1}         \caption{This is caption for Figure 1.}     \end{minipage} \end{figure} \begin{figure}     \begin{minipage}[t]{0.5\linewidth}         \centering         \input{figure2.pgf}         \label{Figure2}         \caption{This is caption for Figure 2.}     \end{minipage} \end{figure}  \end{document}   But instead of getting them side by side, I get them one below the other, like the attached picture. Tried using \scalebox{0.6} before \input the pgf but still the same behavior.. I have tried many different combinations and I can't find a way to make this work...  EDIT: This is not a . I am importing .pgf files. My latex code is identical to the above answer but it doesn't work. pgf files are  if someone needs to test.


Google not indexing product pages of my website

After many months and many changes to sitemaps/pages trying to solve the problem, Google still is not indexing the product pages of this site (link removed). Here's the sitemap i'm using (link removed) , use view source to see it better. The pages i'm having problems with are the ones with the product IDs. Like /wp/product-en/?ID=14 and /wp/product-it/?ID=14. I've added the ID parameter to the URL parameter section in the Google Search Console with settings:  "Yes: changes,reorder or narrow page content" ; "Select"; "Let google bot decide" (i've also tried with "Every URL" but it doesn't make a difference);  Now, if i search the URL in the Google Search Console i get different results, for example:  /wp/product-en/?ID=21 says "Discovered – currently not indexed"; The /wp/product-it/?ID=21 version says "URL is unknown to Google" even if it's in the sitemap; The google explanation says "Discovered - currently not indexed: The page was found by Google, but     not crawled yet. Typically, Google tried to crawl the URL but the site was overloaded; therefore Google had to reschedule the crawl. This is why the last crawl date is empty on the report."  But honestly it's odd to think that's the problem for every single product page. The ID is used to select the image and description of the specific product from the DB. Any ideas why the product pages are not indexing? Thanks in advance.


I need an intuitive explanation of eigenvalues and eigenvectors

Been browsing around here for quite a while, and finally took the plunge and signed up.   I've started my mathematics major, and am taking a course in Linear Algebra. While I seem to be doing rather well in all the topics covered, such as vectors and matrix manipulation, I am having some trouble understanding the meaning of eigenvalues and eigenvectors.  For the life of me, I just cannot wrap my head around any textbook explanation (and I've tried three!), and Google so far just hasn't helped me at all. All I see are problem questions, but no real explanation (and even then most of those are hard to grasp).  Could someone be so kind and provide a layman explanation of these terms, and work me through an example? Nothing too hard, seeing as I'm a first year student.  Thank you, and I look forward to spending even more time on here!


I want to prove that $\lambda$ is an eigenvalue of $A$ if and only if $\lambda$ is an eigenvalue of $A^T$. We know that $\det(A)=\det(A^T)$, but how can I apply it to $\det(A-\lambda I)$? Thanks a lot!


How to spend the coins in your "piggy bank"?

I have saved a full piggy bank of coins and I never bothered to count them. I understand that there are money counting machines that usually charges about 10% of the value to convert them into paper money, but I do not want to lose 10% of the value in my piggy bank. So what are some recommended ways to spend the coins there? For example, is it proper to use the coins to:   pay tips? make a contribution to a local church on Sundays? pay for small item at convenience stores? give to homeless people who asks for money?   Will a bank (in the US) usually count the coins and add value to my bank account without a fee?  I am confident that most vending machines will take the coins, but I do not buy products from vending machines often as they are usually dearer than the products in supermarkets.


Why did Dumbledore make it less difficult to get to the Sorcerer's Stone?

The Sorcerer's/Philosopher's Stone was removed from Gringotts to be placed under the most impenetrable of protections at Hogwarts under Dumbledore's custody. But it seems clear Dumbledore took protections which could have been impenetrable, and deliberately made them less so, such that at best they would only slightly slow down anybody trying to access the Stone, rather than just plain block them.  For example, after the Devil's Snare, you have a locked door enchanted such that it cannot be opened by any charm or other means except its own assigned key. That's a great protection, potentially an impassable barrier if the key is not available.  But the key is then left right there in front of the door in the same room.  At least the key is flying around the ceiling. But there are broomsticks right there in the same room, too.  The room with the fires front and back—that could also have been a solid defense—deadly fires that cannot be passed through unless you drink very specific potions tailored to each particular fire's properties.  Except that those potions providing safety are put right there in the same room.  At least, perhaps, they're surrounded by other bottles, some of which contain poison. With no way to know which bottle is safe, that could still almost be a solid protection.  Except that a piece of paper with a logic puzzle detailing exactly which bottles are which is put on the table with them.  Dumbledore always had reasons, and those reasons were always virtuous. What was he up to, deliberately weakening the protections in this way?


Are third party DSLR batteries significantly less reliable than the official ones?

The official Canon battery for my camera (LP-E17) costs around $55 while third party batteries sell for about $20. Are Canon's official batteries really worth the price or would I be okay getting an aftermarket product?


I am currently studying probability and am having difficulty understanding this question: Prove that $$\binom{2n}{n} = \sum_{k=0}^n\binom{n}{k}^2$$ from Jim Pitman's Probability (Appendix I, question vi). So far I have tried writing the right hand side in different ways: expressing it in its factorial form and have tried to implement the identity $$\binom{n}{k} = \binom{n-1}{k-1}+\binom{n-1}{k}$$ but have not gained any new ground. If any one has an algebraic proof, or even a simple combinatorics proof that is intuitive and used with an example that would be preferable. Thanks!


Difference between $\mathbb{Z}/p^e\mathbb{Z}$ and the finite field $\mathbb{F}_{p^e}$?

Q: Let $p$ be a prime and let $e \ge 2$. The quotient ring $\mathbb{Z}/p^e\mathbb{Z}$ and the finite field $\mathbb{F}_{p^e}$ are both rings and have the same number of elements. Describe some ways in which they are intrinsically different.  My textbook confirms my understanding that $\mathbb{Z}/p\mathbb{Z}$ and $\mathbb{F}_{p}$? are the same thing.  With $\mathbb{Z}/p^e\mathbb{Z}$, there will be elements that don't have multiplicative inverses, so it is not a field. What is $\mathbb{F}_{p^e}$ if it's not the same as $\mathbb{Z}/p^e\mathbb{Z}$?


Birthday Problem: Expected Number of people with common birthday

This might be a different variant of the typical birthday problem. Given a room of $n$ people, let $N$ be a random variable representing the number of people who have a birthday common with at least one other person. I will start by writing $$N = P_1 + P_2 + \cdots + P_n$$ where $P_i$ is an indicator random variable which is $1$ when person i's birthday is common with at least one other person in the room. So we have by symmetry \begin{align*}  E[N] &= n E[P_1]  \end{align*} Now I note that person $1$'s birthday $D_1$ is a uniform random variable taking values in $\{1,2, ..., 365 \}$. Same for other people. Hence, by total expectation theorem \begin{align*}  E[N] &= n E[P_1]\\ &= n \sum_{k = 1}^{365} P(D_1 = k) E[P_1 | D_1 = k]\\ &= n \sum_{k = 1}^{365} \frac{1}{365} E[P_1 | D_1 = k]\\ &= n \sum_{k = 1}^{365} \frac{1}{365} \left(1 - \left(\frac{364}{365}\right)^{n-1} \right)\\ &= n\left(1 - \left(\frac{364}{365}\right)^{n-1} \right) \end{align*} Is this right? If not, help me correct my argument. Thanks.


Can you verify my proof if it is right?  Let A and B be sets. (a) Show that A is a subset of B if and only if for any set C, one has A U C is a subset of B U C. (b) Show that A is a subset of B if and only if for any set C, one has A intersect C is a subset of B intersect C.  (a)   To prove (=>) Given A is a subset of B, this implies A U B = B. Given a set C, A U B U C = B U C. Since A is a subset of B, this implies A U C is a subset of B U C. To prove (<=) Solution 1 Given A U C is a subset of B U C , For A U C , x is a member of A U C . For B U C, x is a member of B U C. Suppose x is a member of A but not a member of B, meaning A is not a subset of B. Therefore , A U C is not a subset of B U C. Hence, A must be a subset of B. To prove (<=) Solution 2 Given A U C is a subset of B U C, For A U C, x is a member of A U C and for B U C, x is a member of B U C. Suppose C is a disjoint set. Since A U C is a subset of B U C, it follows that A is a subset of B.   (b)    To prove (=>) Since A is a subset of B , it follows that A U B = B. A intersect C is a subset of A by definition of intersection. B intersect C is a subset of B by definition of intersection. Let x be member of A and member of C. Since A intersect C is a subset of A, x must be in A. Let x be a member of B and member of C. Since B intersect C is a subset of B, x must be in B. Therefore, A intersect C is a subset of B intersect C. To prove (<=) Since A intersect C is a subset of B intersect C, suppose we let Set C be a subset of B and a subset of A as well.  C is a subset of A implies A intersect C is equals to C. C is a subset of B implies B intersect C is equals to C as well. Since A intersect C is equals to B intersect C, A is a subset of B.


Are there reasons to use olive oil when roasting food at high temperatures?

I see many times chefs choosing olive oil as the fat for cooking recipes that undergo heats of 400f+ (very much above the smoking point of refined olive oil) for 30 minutes, and its virgin olive oil many of the times! But isn't olive oil supposed to smoke at those temperatures? Does cooking past the smoke point not cause smoking and undesirable flavors or other issues? Does any flavor benefit from the oil actually remain?


Using Recursion to Solve Coupon Collector

I read a  on one of the questions  and I was wondering how I could use it to solve a coupon collectors problem.  The problem is : There are coupons labelled 1,2,3...,10 how many coupons do I need to collect in order to have one of each labels. I know that the answer is $\displaystyle \sum_{i=1}^{10} \dfrac{10}{i}$  Here is my attempt : Let $X_i$  be the random variable corresponding to the number of coupons needed to be collected to have exactly $i$ unique labels.  \begin{align} E(X_1)&=1\\ E(X_2|X_1)&=\dfrac{9}{10}.(X_1+1)+\dfrac{1}{10}.(E(X_2))\\ \implies E(X_2)&=\dfrac{9}{10}.(E(X_1)+1)+\dfrac{1}{10}.(E(X_2))\\ \text{Similarly,}\\ E(X_3)&=\dfrac{8}{10}.(E(X_2)+1)+\dfrac{2}{10}.(E(X_3))\\ \vdots \end{align} But this gives me the wrong answer. I know that there is a problem in my second equation but don't know why. My logic was as follows: Assuming I know how much it takes to get 1 coupon $(E(X_1))$ with probability 9/10 I find 2 in  $E(X_1)+1$ else, I just have $E(X_2)$.  Neither does the formula in the aforementioned question work. Can someone help me set up the recursion equation?  (If possible, please retain my Random Variables. I am more interesting in knowing why my logic is failing in designing the recursion than answering the original question)


Is it possible to have two Win 10 user accounts running simultaneously, with one used locally and one used via RDP?

I need to allow someone to remotely connect to my windows 10 computer, and am wondering if this is possible:  I have two user accounts right now on my computer, one for me to work on and one for my friend remotely. I want to use my user account locally for myself, and I want to allow him to RDP and log into the other account when he needs to work without disturbing my computer experience.   In other words, I don't want to have to stop what I am doing and log off of my user account when he needs to access his account remotely. Can two user accounts run simultaneously in this regard, with one being connected to via RDP?  If so, can you please explain how to set it up properly?  Thanks for your help!


What are the orders of the elements in $\mathbb{Z}_n$? If $n$ is prime then 0 has order 1 and the rest order $n$. If $a|n$ then $a$ has order $n/a$, and if $a$ is prime then it has order $n$. So are the orders of the elements divisors of n? Say, we take $\mathbb{Z}_{120}$. Are the orders appearing the divisors of 120?


Extracting All Picture Files From a Bunch of Folders

So basically I have an external hard drive with a bunch of old pictures on it my goal is to get them all to google photos. Problem is since these photos where managed with the mac photo software there sorted into a whole bunch of different folders depending on year and date(I think there's about 4000 different folders) I could go through and upload the photos by hand but that would take a long time. So I'm looking for a way to grab all the files with a picture extension ex .jpg, .bmp, and etc and move them to a folder. I'm using Ubuntu and am not afraid to write a script to achieve this. Thank you!


How can I include properly javascript files in my wp plugin

I am creating a plugin for wordpress. And I want to know how can I include properly js in my plugin with correct path function.  Thanks


My question may seem to be too silly as I am not quite in touch with these things since long, for which I apologise in advance. How should I proceed to calculate the following? $$\sum_{n=0}^\infty\left(\frac{1}{n+1}\right)^4$$


How do I call a person who's having a 1 on 1 conversation with me

Participant sounds like one of many people in a group conversation. I want to know the equivalent of that word in a 1 on 1 conversation.


Is there one universally agreed-upon definition of a quantile? If not what definitions exist?

I just realized that in R, the quantile function offers different types of quantiles. In my first statistics class, I learned the definition of a quantile being that value below which a given percentage of values fall. Now it seems like there are other definitions. If correct, what do these definitions have in common? Asked differently, abstractly speaking what is a quantile so that all 9 types of quantile algorithms capture that definition? I read  but it doesn't really address the question of a more abstract definition of quantile that encompasses, for example, all 9 types of the R function.


How to find total number of questions closed by each reason?

Is there any way to get a total of all questions on a given site that have been closed for each reason? E.g.,   123 duplicate 456 OT 789 too broad   Bonus points if OT is separated by its reasons.


Solve $y’ = \frac{2-xy^3}{3x^2y^2}$ using Bernoulli form

Solve, by bringing the equation to Bernoulli form: $$ y’ = \frac{2-xy^3}{3x^2y^2} $$  Therefore we want to bring it to a form like: $$ y’ + p(x)y = q(x)y^n $$ So working with the equation i get: $$ y’ - \frac{2}{3x^2y^2} = -\frac{xy^3}{3x^2y^2} = -\frac{y}{3x} $$ I don’t see how to get to Bernoulli equation from here...


Feature Request: Require comment for downvotes if user reaches reputation threshold

So the idea behind this is quite simple, and I have also not seen any similar solution suggested in meta(after a quick search). Succinctly, I have seen both on my answers and questions(as has anyone) that even on topics for which I consider myself an expert and follow guidelines in producing an objectively correct answer(where applicable), there still can be random downvoting with no explanation.  Clearly, reputation is a SE heuristic for expertise or competency in some area of understanding. So in my mind, a simple fix to many downvote issues would be to just force comments if user meets some lower rep bound.  Thoughts? Potential downfalls? Look forward to seeing what the rest of the users think.  Edit: Obviously different than a universal requirement.


Scenario (Ubuntu 16.04):  I compile and run a C program (with -g, I get the traditional Segmentation Fault (core dumped), and then (of course) there is no mythical "core" file to be found. Some digging says to modify /proc/sys/kernel/core_pattern with a command to the effect of: echo '|tee /home/me/my_core_folder/my_core_file' | sudo tee /proc/sys/kernel/core_pattern, and after doing this, I stop getting (core dumped) and start only getting the plain Segmentation Fault. I try things like gdb ./program_object_file.out core.pid which obviously doesn't exist (I was getting desperate), and of course try the plain gdb ./a.out followed by (gdb) core core.pid and variants of the commands where I spam the tab key desperately trying to get auto-completion to get me to where I need to be.  Question:  Is there a generalized way I can get to core dumps? I recognize that every machine that I touch seems to have a Michael Bay's Transformers-esque ability to reconfigure hardware and software such that no device I own can be expected to work normally out-of-the-box. Is there a simple algorithm/recipe I can follow to locate core dumps on my own machine as well as on other peoples' machines? I always find myself tutoring friends on stuff like this after no small amount of  work to get things working for myself and it would be nice to be able to run a command or something to get core files dumped to the directory which the executable was run from... is there any way to do this that should work on most (I would settle for "some") Linux/Unix machines?


I just discovered a bug, and, even though it is of minor importance, I would like to know if anyone knew why it arises.   bin_width=0.005 max_value=0.7 min_value=0. bins_=[] num_step=int((max_value-min_value)/bin_width) for i in range(0,num_step):     print i,i*bin_width     bins_=bins_+[i*bin_width] print bins_   In this code, the value i*bin_width sometimes differs from the one introduce in the array. For example, bins_[41]=0.20500000000000002, whereas 41*0.005=0.205.  Is that a known bug, and why does it occur ?   Thank you


Sitelinks showed for both search keys: with and without space

I noticed that, for some sites, if I look for i.e.: "benny ben", I don't see Sitelinks, instead if I look for "bennyben" (which matches with the domain name) then I see them. How can I make Google showing Sitelinks for both searches?


What is the proper etiquette at Japanese onsen?

Japan is a volcanically active country which means it has a plethora of onsen (hot springs) all around the country.  Visiting these onsen is supposed to be a popular vacation destination for the work-weary Japanese.    I've been told that, as with other things in Japan, there is a rather strict etiquette surrounding the use of the onsen.  In particular, the two things I've read about so far are   Swimming Suits are not allowed. It is very important that one bathe immediately before entering the onsen.   Are these true?  Are there any other taboos that a naive American should be aware of?


AVG using specific condition for each row

I have a Quotation table with QuotationID, ClientID field. A QuotationDetail table with QuotationID, ProductID A Sales table with Year, ProductID, ClientID and Quantity.  I'm trying to create a view with the following columns: QuotationID | Client Name | Product Name | Quantity2015 | Quantity2016  I am able to join the quotations table with clients and products but can't figure out how to SUM Quantity values for each view row filtering by YEAR (2015 and 2016).  PS: I did not specify but I have the Clients and Products tables with the fields I mentioned.