Motion tracking: object in my scene bonces around

For whatever reason when ever i insert an object into my scene, it bounces around. The markers I have placed, work perfectly, 0.183 solve error, but the object just bounces and moves when I render the video. The object it's self isn't moving, but for some reason the camera sees it that way or something like that. I don't really get it, I'm new to this whole motion tracking thing.


Increase the highlighted button bezel thickness (GNOME)

Is there any way to increase the visibility (e.g. thickness, contrast or colour) of bezel that surrounds the highlighted (aka selected) button in gnome window? TBH sometimes it is barely visible in default version. PS: I am using GNOME 3.28.2.  Here is a screenshot illustrating the issue (from a link posted in a comment):


How do I add SSH Keys to authorized_keys file?

I have an Ubuntu server on Amazon EC2, that I use for development, and today I stupidly cleared everything out of my ~/.ssh/authorized_keys file.  Luckily I have an SSH open, so I am still connected, and can fix the file, but when I try to put my key file back, it doesn't work.  I still get permission denied from the server on my local machine.    authorized_keys has the permissions 600. I have tried appending my SSH key with ssh-rsa and leaving the ssh-rsa off.  I also tried making the SSH key all one line, but that didn't work either.  Is there something else that I have to do like reload the file some how?


The  asserts that our system of Arabic numerals is a geometric design where the number of corners corresponds to the number represented:    My question is: Is our Arabic number system based on a geometric design counting corners?


Can I use a single wire and run two jumpers to two gcfi outlets and on the other side run two wires off the single wire to two gcfi circuit breakers?

Situation: Have a jetted bathtub that requires 2 15A gfci outlets each to its own breaker. Problem only have one wire running into tub area (would have to tear up.newly installed floor to run another. Is it possible to use that single wire and connect two wires and run to the outlets and connect two wires to the other end of the wire (wire is approx 8 ft) and run those to the breaker box and attach to two gcfi breakers


The difference between 'I don't know nothing else' and 'I know nothing else'

What is the difference between the following?  I don't know nothing else  and  I know nothing else  There's a don't in the first sentence, however both sentences translated the same in google translator. So, are they used interchangeably?


Appropriate preposition to go with "outside their comfort zone"

Is the preposition "of" necessary in the phrase "outside their comfort zone"?


I was able to review after failing an audit, but later got blocked from reviewing

I might be just me, but it's not the first time this happens. I failed an audit yesterday (can't remember in which category) and I got the Stop, look and listen message.  I have no excuse whatsoever for failing the review, but I was able afterwards to continue reviewing because I have passed the previous 20-30 tests and made at least 100 previous reviews correct. I even got another "test" afterwards in First posts and passed it. Nevertheless, I saw this morning that I got blocked from reviewing for almost a month (minus 2 days).  I feel that this is strange, in the sense that I don't know exactly for which review I got blocked, but I'm guessing it because it is the only one failed recently. But if so, has anyone else encountered this "delay"?   Edit: I just looked over my activity and saw that I made 10 more reviews after failing. Furthermore, at least 6 hours passed until I got blocked from reviewing


Restarting with new account on iOS/GameCenter

I downloaded Clash of Clans to my iPad (iOS 7) this past weekend and started playing.    Of course, after a couple of hours I realized I made some newbie mistakes that are fatal to my future success.  I wanted to restart, but it seems the only way to do so is to reset the device which I really would like to avoid.  After some Googling I tried the option of logging out of Game Center and logging in with a different Apple ID.  But, sadly, CoC re-launched back into the existing game.  Is there any way I can start over? Or at least start a new game under a different account on the same device?


How to show hidden files and folders in Finder?

I have a folder that starts with a dot . but am unable to display it in Finder. How can I say that for folder x, Finder should also display hidden files/folders?


Given a program that has both 32 and 64bit variant, how do I put them both in my PATH with different names?

Take WinDbg for example. By default it installs into C:\Program Files (x86)\Windows Kits\10\Debuggers\x86\windbg.exe (and x64), which means there are two executables with the same name.  How can I put both of those in my path under different names, so that I can pick which one I'm launching?


What is this insect found commonly in coastal India?

I have lived in two cities on the western coast of India and I have seen quite a few of these insects(?) in both places.  It basically has an outer cocoon of sorts, which looks a lot like dirty lint. The actual insect is a small wormlike creature at the top of the cocoon. It almost always tries to keep climbing up walls and when it dies, it remains stuck to the wall from its topmost point. The overall length of it, including the linty cocoon is about half a centimeter. Can someone tell me what these are and if I need to actively avoid them or prevent their appearance in my closet?


I've been brought up believing that most of the words that have suffix with '-ize' or '-ized' is the American English form and the British English forms use (most of the time) '-ise' or '-ised' as the equivalent.   Two questions:  1) What is the rule, if any, around exception cases, i.e. choice of one or the other in a single form (dialect?) of English?  2) I have read recently, on Wikipedia admittedly, that the etymology of these terms is such that the correct form anyway, for all English from Greek roots, is '-ized' using the 'z'. This contradicts what I see, and what I've been brought up to know. But is that correct - it was from this site:    and the Wikipedia page.  I am not saying it is wrong, but I wanted to verify if this is the case...as I say, it runs contrary to what I know, but came across it by chance and it is a  very difficult habit to get out of. I don't want to do it (as a British person, using '-ise' all the time) to the American English version, when actually it would be wrong.  On a more pragmatic matter, I wonder if doing this is a bad idea anyway in the UK, since most people are told the 's' version is correct.  Finally, etymologically, what is the reason for this shift across, whatever the reason is? And is it something that is 'wrong' or more 'the development of language over time'.   I don't understand why America would revert to 'z' after the development of English in Britain towards 's', given that Greek is the origin. I understood British people discovered America and brought British English over there. Unless, and probably quite likely, I haven't got a clue re the history between the two nations (and this is not meant to offend, I just have a confused understanding - sorry if it does).


I am java programmer. There is concept of HashSet in Java that don't add duplicate elements in a Set. What is the similar concept in iPhone that do same ?  Please hint.  Thanks in advance.


How big can I print a JPEG photo that measures 5120 x 2880 pixels?

I have made a collage with 5120 x 2880 px size using picasa.  Now I want to order a print of it.  What would be the best option to make a canvas print or a poster print?  I want the best size and picture quality.  And what can be the max size of my print in inches, considering the aspect ratio is intact... I dont want any cropping of my lovely collage. :)  Second question... the collage is composed of many pictures of people on it.  So what would be more suitable, a print on canvas or on poster?  I think a canvas is a cloth and poster is paper? Am I correct? and that canvas would give   a rough finish and poster a glossy one?


Does there exist a nontrivial abelian group $A$ such that $\mathrm{Aut}(A) \cong A$?

Does there exist a nontrivial abelian group $A$, such that $\mathrm{Aut}(A) \cong A$? Here $\mathrm{Aut}$ stands for the automorphism group.  What do I currently know:     If such $A$ exists, it has infinite exponent.   It follows from the first Prüfer theorem, that every bounded exponent noncyclic abelian group has non-abelian automorphism group. A cyclic group is isomorphic to its automorphism group iff it is trivial.     If such $A$ exists, it is infinitely generated.   It follows from the classification of finitely-generated abelian groups, that every finitely generated noncyclic abelian group has non-abelian automorphism group. A cyclic group is isomorphic to its automorphism group iff it is trivial.


How to define a skewed distribution using mode and two inflection points?

I want to define a skewed distribution function and plot it in python using the mode and inflection points parameter values instead of using the mean and standard deviation. For example, I have mode=110 and inflection points = (40, 160) for asymmetrical points. Or mode=100 and inflection points = (50,150) for symmetrical points we can define gaussian normal distribution in this case. I tried with this code below for gaussian function, but I don't how I can add the second point to the formula which is returned by the function? Since I have two points, and I don't know how to define a skewed function that depends on two points and mode. import numpy as np import matplotlib.pyplot as plt    def distribution(x, mode, inf_point):     return 1/(np.sqrt(2*np.pi)*inf_point)*np.exp(-np.power((x - mode)/inf_point, 2)/2) x = np.linspace(0,256) plt.plot(x, distribution(x, mode, inf_point))


Could a negatively charged nucleus have caused the results in the Rutherford scattering experiment?

Struggling to understand the answer to this question.     When alpha particles are directed at a thin gold foil it is found that most of the alpha   particles go straight through undeflected. However a very small number are scattered   through angles greater than 90°.      Which of the following is not a valid conclusion?         The atom is mainly empty space.   The nucleus must be positively charged.   The nucleus must contain most of the mass of the atom.   There is a large charge concentration in the centre of the atom.      The answer is 2. I assumed that a negative nucleus would not scatter alpha particles in this way. Could it?


I opened a blend file and the far right properties panel is completely gone.  The only way I an access it is to change either the top or bottom info bar to the properties but I want it to the generic way, where I have all three panels on my screen. There's no other option to add a side panel that I can find and I'm getting extremely frustrated because when I open a new file, all my windows are there, but this one file just won't open with the freaking side panel!


After using absorb elements, will melee spell attacks grant the extra damage from absorb elements?


Handling key-press events (F1-F12) using JavaScript and jQuery, cross-browser

I want to handle F1-F12 keys using JavaScript and jQuery.  I am not sure what pitfalls there are to avoid, and I am not currently able to test implementations in any other browsers than Internet Explorer 8, Google Chrome and Mozilla FireFox 3.  Any suggestions to a full cross-browser solution? Something like a well-tested jQuery library or maybe just vanilla jQuery/JavaScript?


I can't make uppercase of turkish characters like Giriş Tex converts it to GIRIş instead of GİRİŞ.. It's making me crazy.  %this is mwe i guess \documentclass[12pt,a4paper]{article}  \usepackage[utf8]{inputenc} \usepackage{titlesec}  \usepackage[T1]{fontenc} \usepackage[turkish]{babel} \usepackage{pslatex} \begin{document} \uppercase{Giriş} \end{document}


Time series data and Wilcoxon's test. Is it appropriate?

Background   My friend did an observational experiment. She observed several colonies of animals for six months (one time per month) in the year 2014 and 2015. Some treatment to the environments of those animals were made in the year 2014 and in the year 2015, the environment was kept as natural as possible. She wants to test if there is a statistically significant difference between the sizes of colonies comparing the year 2014 and 2015.  The situation  The friend wants to use Wilcoxson's test for paired data to compare if differences in colony size among the year 2014 and 2015 are statistically significant. Each observation is the size of the colony in each month. In my opinion, the test is not appropriate as data is time series.  The plots of the results    The question   Is Wilcoxon's test appropriate for this problem?    If not, could you advise what are the appropriate methods (if possible, an example in R would be appreciated)?      Are any methods of inferential statistics appropriate at all?   The data and R code for plots  library(data.table) library(ggplot2)  col1 <- fread(" colony_size  year   month  637          y2014  01     609          y2014  02 582          y2014  03 902          y2014  04 945          y2014  05 954          y2014  06 640          y2015  01 615          y2015  02 585          y2015  03 922          y2015  04 1040         y2015  05 1097         y2015  06 ")    ggplot(col1, aes(month, colony_size, color = year)) +     geom_line()  + geom_point() + theme_bw() + ggtitle("Colony 1")


I have been looking at divergent series on wikipedia and other sources and it seems people give finite "values" to specific ones. I understand that these values sometimes reflect the algebraic properties of the series in question, but do not actually represent what the series converges to, which is infinity. Why is it usefull to assign values to divergent series?  The only theory I could come up with, is this:  Say you have 2 divergent series, series' A and B, and you assign each a value,   Series ($A= \sum_{n=0}^\infty a_n$), which I assigned the value Q  and series ($B= \sum_{n=0}^\infty b_n$ ), which I assigned the value P  But it just so happens that series $C=A-B= \sum_{n=0}^\infty (a_n-b_n)$ converges. Could that imply that the actual value of series $C$ is the difference of the two assigned values to $A$ and $B$, that is $\sum_{n=0}^\infty (a_n-b_n)=Q-P$ ?  If so, then that would make some sense to me, as to why people sometimes assign values to divergent series.


cd into all directories, execute command on files in that directory, and return to previous current directory

I'm attempting to write a script that will be run in a given directory with many single level sub directories. The script will cd into each of the sub directories, execute a command on the files in the directory, and cd out to continue onto the next directory. What is the best way to do this?


Got a bunch of .mp4 videos (info shows H.264 Video + AAC Audio) that are chapters of a larger video.  I'd like to merge them, but not sure which is the best way.  I don't have Quicktime Pro, but I'll get it if that's the best way to do this.  Edit: Just to clariify this is Mac OSX 10.6 I'm on.


I have 2 points in 3d space ,point A= <5,3,6> and B=<8,2,3>  I want to rotate "point B" by 30 degree from point A.  how do I solve this question using quaternion.  Plz, explain the steps....


The bottom part of site logo for localized SO is obscured on user profile page when not logged

E.g.  page on ruSO.  When not logged (just open on private mode):        All is good when logged:        All localized SO are affected.  Related report on ruSO.Meta:


Finding the error in this induction proof

Claim: If $n$ belongs to $\mathbb{N}$, and $p$ and $q$ are natural numbers with maximum $n$, then $p=q$.   Let $S$ be the subset of the natural numbers for which the claim is true. $1$ belongs to $S$, since if $p$ and $q$ belong to $N$ and their maximum is $1$, then $p=q=1$. Now assume $k$ belongs to $S$, and that the maximum of $p$ and $q$ is $k+1$. Then the maximum of $p-1$, $q-1$ is $k$. But $k$ is in $S$, so $p-1=q-1$, thus $p=q$ and $k+1$ is in $S$, so the assertion is true for all $n$ in $N$.


If a function is holomorphic in a certain domain, does it mean it necessarily has an antiderivative

Say I have a holomrphic function $f(z)$ in domain $D$, say $|z|>4$ and my function is not holomorphic for $|z|\le4$ - it has some poles there. Does it mean there is necessarily an antiderivative for $f(z)$? I know I can use  and calculate all the residues inside $|z|\le4$ and check if their sum is zero. However what seemed more intuitive to me is to prove that since $\int_{\gamma}f(z)dz$ for every $\mathbb{\gamma}$ contained in $D$, depends only on the start and end points, there exists an antiderivative for $f(z)$. Is my prof correct? Can I conclude that in general, a holomorphic function in a domain $D$ not only has infinitely many derivatives in $D$, but it has also infinitely many antiderivatives there?


If $[a],[b] \in \mathbb{Z}_n^* $ then $[ab] \in \mathbb{Z}_n^*$: a doubt about equivalence classes.

If $n$ is a positive number, let $\mathbb{Z}_n^*$ be the subset of class representatives in $\{1,..., n-1\}$ which are relatively prime to $n$. Show that if $[a],[b] \in \mathbb{Z}_n^* $ then $[ab] \in \mathbb{Z}_n^*$. I think $[a]$ is an equivalence class. But what does it represent? If $a = 1$, what does $[1]$ imply? Update: this is what I understand so far. For example, let n = 5, a = 2. Then relatively primes of n is {1,2,3,4}, and [a] = {2,4} because it's only 2 in {1,2,3,4} that has residual when divided by n = 5. Is this correct? Update: My thought on proving the problem. Let [a] = {a + kn | k $\in \mathbb{Z}_n^*$},  [b] = {b + ln | l $\in \mathbb{Z}_n^*$}. Pick an a' from [a] and b' from [b]. I can say a' = a + kn, b' = b +ln. Then a'*b' = ab + n(ak + bk + $nk^2$). This is congruent to ab mod n. Therefore [ab] $\in \mathbb{Z}_n^*$. Would this be an appropriate proof?


How does a photon decide what to hit along it's path?

In general, let us have a light emitting point A and two light absorbing points B and C, such that the three points fall on a straight line and B is somewhere between A and C. For simplicity, let us consider all photons emitting from A to travel along this same line in the direction of the points B and C. Also, let the distance from A to B be AB and the distance from A to C be AC.   For the photon, special relativity states that there should be maximum space contraction along it's direction of motion. That means that, for the photon, A, B and C are all at the same point in space. This results in the photon effectively "reaching" B and C at the same time. How then does the photon "decide" that it must be absorbed by point B and not C, so as to be consistent with what an outside observer would see (point B "casting a shadow" on point C)?


How to show accidentally hidden menu bar?

Here is the blender window I have:    As you see, it doesn't have the menu that is usually displayed at the top of the screen.  How can I get the menu back?


How to replace my disk without having to rebuild my Ubuntu install?

I'd like to buy a new 1TB disk to replace my old 150GB disk. Is there an easy way to copy my Ubuntu installation with   my home folder content,  system settings,  applications,  and so on...   so at the end I can just unplug my old disk and plug the new one without having to re-install everything?


I want to create the process of uploading an image with jquery ajax. here's my code :  <form action="" method="post" name="formPicture" enctype="multipart/form-data">
         <input type="file" name="picture" class="form-control" />

     <button class="btn btn-default" data-dismiss="modal" aria-hidden="true">Cancel</button>     <input type="submit" value="Save" id="btn-saving" class="btn btn-primary" /> </form>    upload_picture.php  <?php $path = $_FILES['picture']['tmp_name']; $file_name   = $_FILES['picture']['name']; $newPath     = "upload/"; move_uploaded_file($lokasi_file,$newPath.$file_name); $insert="INSERT INTO `picture`(`picture`)                          VALUES ('$file_name')"; $query=mysql_query($insert); if($query){     echo '{"status":"success"}';     exit; }else{     echo '{"status":"error"}';     exit; } ?>   but the error said "Notice:  Undefined index: picture on line 4"; there's something wrong with my code ? Thanks..


How to prove there are no more positive integers that are products of 2 and 3 consecutive numbers?

$6$ and $210$ share the property that both are the products of both two and three consecutive numbers. $6$ is $2\times3$ and $1\times2\times3$ and $210$ is $14\times15$ and $5\times6\times7$. It was easy enough to write a program to search for more numbers with this property, I found that there were no more up to at least $1{,}000{,}000{,}000{,}000$ ($1$ Trillion). But it is beyond me to prove that there are either no more numbers like this or to find the next one. Any ideas?


Prevent events from refreshing parts of dom using only frontend options (asp.net)

DISCLOSURE:  Until this project, I hadn't coded anything since 2000.  While I am a quick study, a lot has changed.  So, go easy on me?   I'm working on tweaking the UI for my web store.  On both the cart page and on the item pages there are events (i.e.: change of quantity and add to favorites) that have to refresh elements of the DOM, like the total price.  The issue is that when it refreshes that, there are other elements like the action button or a couple of the DIV containers like the table that the quantities are in get refreshed too.   I'm using CSS and JQuery to tweak the UI since I only have front-end access to editing anything.  If I edit things through CSS I'm fine, but any JS work is thrown out.  I'm adding classes to existing elements and removing the ones I don't want.  When they are refreshed, the original classes come back and mine are gone.  For example, here's a link to the page:   the button is pink at first, but if you click on a radio button to change the quantity or click the heart at the top to add/remove from favorites the button will change to the default Bootstrap version.  I don't want that to happen.  Any ideas on what to even research to find a workaround?  Feels like if I could mark certain elements to be isolated from the refresh life would be easier.  Thanks in advance!


I had used this in a question:  cellNum = [VLOOKUP("string", '2012'!A:M, 13, FALSE)]   The light grey syntax color started at the single quote but then continued until the end of the line. Should it not have stopped at the next single quote?  [EDIT] No highlighting here? In that case, you can view it here:


Example of a ring without unity that has a subring with unity?

I can't think of a ring without unity that has a subring with unity. There must be some element in the parent ring that doesn't work with the subring's identity, but I'm struggling to see how that would be possible. Any suggestions?


Safest way to transport a laptop during flight

I flew a long range flight carrying my laptop, a quite heavy one, inside a neoprene briefcase in the passenger cabin. The recommendation by the aircrew was to place it in the overhead compartment or under the seat in front of me. However, during take-off and landing, the vibrations on the plane are quite strong and, as a result, it received minor damage.   Placing them in the overhead compartment might be equivalent to placing it on the floor under the seat, with the added issue of additional luggage in the compartment shifting.  I considered the alternative of holding the laptop by the handle while sitting, so it won't be any contact with the aircraft's floor. This is impracticable during cruise, but I thought it could be better during the take-off and landing segments. Another option I considered is to wrap it with completely with bubble wrap before boarding the plane.   Which is the safest way to transport a laptop during flight?


We want to knock the kitchen and dining room into 1 room and I am hoping someone can help tell me if the highlighted wall is non load bearing The house is a bungalow


What is the role of "systems" in a component-based entity architecture?

I've been reading a lot about entity components and systems and have thought that the idea of an entity just being an ID is quite interesting.   However I don't know how this completely works with the components aspect or the systems aspect. A component is just a data object managed by some relevant system. A collision system uses some BoundsComponent together with a spatial data structure to determine if collisions have happened.   All good so far, but what if multiple systems need access to the same component? Where should the data live? An input system could modify an entities BoundsComponent, but the physics system(s) need access to the same component as does some rendering system.   Also, how are entities constructed? One of the advantages I've read so much about is flexibility in entity construction. Are systems intrinsically tied to a component? If I want to introduce some new component, do I also have to introduce a new system or modify an existing one?  Another thing that I've read often is that the 'type' of an entity is inferred by what components it has. If my entity is just an id how can I know that my robot entity needs to be moved or rendered and thus modified by some system?  Sorry for the long post (or at least it seems so from my phone screen)!


Copy permissions to identical tree on linux / unix

i have a  tree of files with correct permission. then i have a (filewise) identical tree (with different file contents tough) with wrong permissions.  how can i transfer the permissions layout from one tree to another?


bmatrix brackets too tall when using package setspacing and setting \doublespacing

Is there a way to get the brackets of the matrices to ignore the spacing that I set up for the paper? There is just a little too much space at the top of each matrix when using \doublespacing. I would like to keep the double spacing everywhere else as it makes the text nice and readable.


It seems that on Windows 10 I cannot add new items to the "All apps" part of the Start Menu. I tried moving a shortcut to C:\ProgramData\Microsoft\Windows\Start Menu\Programs, but the program did not show up anywhere under the All apps view. Looking for the cause, I tried changing the name of one of the files already present in the aforementioned folder. To my surprise, the shortcut I renamed no longer shows up on the All apps view at all. Renaming it back to its original name did not bring it back. What could be causing this problem?  Update: Since I posted this question, I have noticed that the "Most used" applications are no longer updating.  Update 2: Since my last update, the issue seems to have somehow been resolved. I will look into possible causes for the resolution.


Syntax to initialize array functionally in C#, similar to python

Python offers the following syntax to initialize a python List functionally:  mylist = [item for item in iterable]   Is there a similar syntax in C# for initializing a C# List?  EDIT:  I guess I should be more specific. I'm trying to emulate the following syntax:  mylist = [operation(item) for item in iterable]


Software installation through command line from download folder

I have just installed ubuntu 16 along with window 7 and also new for ubuntu. I have downloaded some software with .zip, .tar and .exe format which are in downloads folder. Kindly suggest me how to install them from command line.


How to write a base class whose child classes depend on each other?

I'm trying to write a mathematical set class. My idea was to make an base class which is called Set. Then i wrote two child classes of the Set class. Namely the FiniteSet class and the CountableSet class (which can deal with infinite Sets). My problem is now that those child classes depend on each other and I cannot solve this. I will also appreciate completely different solutions to this problem.   //-------------------------------------------------------- //Set class //-------------------------------------------------------- class Set { public:     //some virtual functions  protected:     //some attributes  };  //-------------------------------------------------------- //FiniteSet class //-------------------------------------------------------- class FiniteSet : public Set { public:     //implements all virtual functions       //function which needs to know CountableSet:     Set unionWith(Set* otherSet)     {         if(typeid(CountableSet) != typeid(*otherSet))         {             //the other set is finite. We can simply add all                                      //elements from otherSet to this set.         }         else         {             //create a CountableSet and return it         }     }  private:     //some attributes }  //-------------------------------------------------------- //CountableSet class //-------------------------------------------------------- class CountableSet : public Set { public:     //implements all virtual functions       //function which needs to know FiniteSets     Set intersectWith(Set* otherSet)     {         if(typeid(FiniteSet) == typeid(*otherSet))         {             //do something and return FiniteSet         }         else         {             //do something and return occasionally CountableSet         }     }  private:     //some attributes }


I'm trying to parse a Time field from my lightning component to my apex controller by using JSON and deserializing it in apex into an existing Object. But unfortunately I'm always getting the error  Cannot deserialize instance of time from VALUE_STRING value 10:30:00.000Z  I already tried different Time formats and with/without quotes "" in my JSON  10:30 10:30:00 10:30:00.000 10:30:00.000Z T10:00:00.000Z 2018-06-07T10:00:00.000Z  But nothing works.  My Org is on Spring 18 API Version 42 I have an SObject (Event__c) with a Time Field  The problem is reproducable in anonymous apex with following code Event__c workingObject = new Event__c(); workingObject.Name = 'Lorem'; workingObject.Public_Start_Time__c = Time.newInstance(10,10,10,10);  String serializedObject = JSON.serialize(workingObject); String mixedObject = '{"Public_Start_Time__c": "' + workingObject.Public_Start_Time__c + '", "name": "Ipsum"}'; String manualObject = '{"Public_Start_Time__c": "2018-06-07T10:00:00.000Z", "name": "Dolor"}'; try {    Event__c banana = (Event__c)JSON.deserialize(serializedObject, Event__c.class); } catch(Exception ex) {     System.debug(ex.getMessage()); }  try {    Event__c banana = (Event__c)JSON.deserialize(mixedObject, Event__c.class); } catch(Exception ex) {     System.debug(ex.getMessage()); }  try {    Event__c banana = (Event__c)JSON.deserialize(manualObject, Event__c.class); } catch(Exception ex) {     System.debug(ex.getMessage()); }  which results in the 3 following messages  Cannot deserialize instance of time from VALUE_STRING value 10:10:10.010Z or request may be missing a required field Cannot deserialize instance of time from VALUE_STRING value 10:10:10.010Z or request may be missing a required field Cannot deserialize instance of time from VALUE_STRING value 2018-06-07T10:00:00.000Z or request may be missing a required field  Everything I found so far was for dates or datetimes but not time only.


Can I include alll .bib file entries into text, even if references are missing from main text?

I have written my thesis using Overleaf and managed references using biblatex - all worked fine.  Now I have to make a 15-20 page-long "executive summary" with virtually no equations nor references in this second text. At the end of this "executive summary", I have to provide a "List of main literature used in the thesis".   Is there a way to do this automatically from my original .bib file, using some arguments to the  \usepackage[backend=biber,style=numeric]{biblatex} or  \printbibliography commands?   I am aware of the "manual" option available through \begin{thebibliography} \end{thebibliography} but I hope there is a simpler way.   I have already searched this site and biblatex package reference pdf, with no success.  Thanks for any suggestions.


Is there any difference between accepting date and First Online date? For example in the journal  , I see this  Received, Revised, First Online   03 April 2014, 17 February 2015, 04 October 2018  from    and there is no information about accepting date. I would like to know what is the difference between them and when papers are accepted in this journal.   the journal Applications of Mathematics only shows the  Received, First Online date and not the revised date.  thanks


qgis - slope from DEM - errors due to projection and oversimplified 'z factor'

I'm trying to generate a slope raster from a DEM raster.  It seems there is a pretty significant error due to the 'z-factor' option.  I'm fairly new to this, but some other posts and responses indicate a general workflow:  1) obtain a DEM.  The ones I got (NED) are unprojected: horizontal coords are lat-lon, and vertical coords are meters.  Two possible branches here, A or B:  A2) project the DEM to UTM so that horizontal and vertical coords are in the same units A3) then do slope analysis on the UTM-projected DEM, using z-factor = 1.0  OR  B2) do slope analysis on the unprojected DEM, using z-factor = 111120 (which has been suggested in some posts as a number of meters per degree - see error discussion below) B3) then project the raster to UTM  Problem with option A: the projection process introduces gridded artifacts, and these get amplified in the slope raster:  Original DEM (NAD83, unprojected; zoomed in to one peak; min/max set to show high contrast here):    DEM projected to NAD83 UTM zone 10, note gridded artifacts:    slope analysis output from NAD83-UTMz10-projected DEM, note the same artifacts:    Problem with option B: 111120 seems vastly oversimplified and produces significant errors, see error table below - though, gridded artifacts are greatly reduced since they don't exist in the DEM that you run slope analysis on.  First, number of meters per degree of latitude is not the same at all latitudes, due to the earth not being a perfect sphere.  Second, and more obvious, number of meters per degree of longitude is a function of latitude, varying from ~111km at the equator to 0 at the poles.  For our area (Nevada County, California) here are some numbers from an online calculator, referenced in other places as a trusted source (but feel free to verify these):  Nevada County S extent ~ 39.0deg (WGS84) Nevada County N extent ~ 39.5deg (WGS84) Nevada City ~ 39.25deg (WGS84)  39.0 deg: 1 deg lat = 111015.45 meters 1 deg lon = 86626.37 meters  39.25 deg: 1 deg lat = 111020.23 meters 1 deg lon = 86320.71 meters  39.5 deg: 1 deg lat = 111025.01 meters  (about 9.5 meters longer than at S extent of Nevada County) 1 deg lon = 86013.39 meters (about 613 meters shorter than at S extent of Nevada County)  (at equator, for reference:) 0.0 deg: 1 deg lat = 110574.27 meters 1 deg lon = 111319.46 meters  So, making some straightforward assumptions about how qgis uses the 'Z Factor' argument, here are some resulting errors (note this is in Nevada County but not the same location as the above images), along with Range-Bearing Line from Terrain Navigator Pro which is treated as gospel in this case; also note that this is just for one sample set of from/to; error would vary by compass direction of the from-to line also:    (z-factor is entered by hand for each row; all the other columns are calculated from it)  So, any ideas?  Am I calculating something wrong, or is there a better workflow, or is there just no really good way to get around the error?


How to show $ \sin x \geq \frac{2x}{\pi}, x \in [0, \frac{\pi}{2}]$?

I have tried the following: $$ f(x) = \sin x-\frac{2x}{\pi} \\ f'(x)= \cos x-\frac{2}{\pi} \\ f''(x) = -\sin x \leq 0 $$ But this doesn't seem to be heading in the right direction as it would appear $f'(x)$ is decreasing and has a zero within the domain, so I'm not sure how this might be used to prove the inequality.


Why is the circle homeomorphic to $\mathbb{R/Z}$

How to see that the circle $\mathbb{S}^1:=\{x \in \mathbb{R}^2 \mid x^2+y^2=1\}$ is homeomorphic to the quotient space $\mathbb{R/Z}$ that is given by $x \sim y : \Leftrightarrow x-y \in \mathbb{Z}$?


I am following some basic tutorials of smoke simulations. And I always can't find the settings tab "smoke" under the smoke domain settings. I jumped through some tutorials to see if I am just using another blender version (2.92) but I always have the same problem. Also, the smoke sim looks a behaves different. It feels like they have different preset settings, but the most looks the same. I am also using mantaflow as everyone else. I am very new to smoke sims but have a good understanding of blender. I hope someone can explain. Thank you in advance Here is a picture of the smoke sim of my desktop: ´ And here is an example of a tutorial file:


admin no longer has access to shared folder

So over the weekend I arrive to work, boot my PC and run the virtualbox session of Ubuntu but now I get the message:     The folder contents could not be displayed   You do not have the permissions necessary to view the contents of "sf_virtual"   I don't understand what could have happened?  I did install an update and read an article to re-install Guest Additions and it still doesn't allow access in /media.  When I do gksudo nautilus and then sudo ls -al /media/sf_virtual it will display all the files in virtual as -rwxrwx--- 1 root vboxsf numbers month date time filename.  When I am under name in the terminal ls /media/sf_virtual it returns Permission denied. Any ideas on how to get access back?   I have removed the shared folders and added new ones but it still doesn't work.


Determinant of a matrix that is its own inverse

I need help in showing that when computing the determinant the inverse   of an $n \times n$ matrix with the property    $$M=M^{-1}$$  that is  $$M^2 = I$$   the determinant is either $1$ or $-1$.  I've tried showing it in a couple ways and the way I'm trying to show it has me stuck  $$K^2 = I$$  $$K^2 - I = 0$$  $$\det(K^2 - I) = 0$$  $$\det(I - I) = 0$$  I get here and I am hopelessly stuck. Could I go on to prove it this way? Is there any  elementary way to prove this?


Physics Animation Sequence with Transparent Plane

I would like to save my physics animation in a PNG sequence with the landing plane transparent.  I have an object that is landing on a plane.  This plane needs to be transparent in the PNG animation sequence.  I've seen posts with the "Film" tab, but I don't seem to have this in verion 2.79a.  How do I do this?  Thank you.


How to use 3 external monitors on 15" late 2013 MacBook Pro Retina?

Several people have posted about how they use 3 external monitors with their MacBook Pro Retina. see:        However, when I attempt to do this on my 15" late 2013 MacBook Pro Retina, I can only run 2. Either, 2 thunderbolt, or 1 thunderbolt and 1 HDMI. When I plug in all 3, only 2 of them work.  Apple tech says     Yep. You can only have 2 external monitors (unless you want to add a usb monitor).   Is there some trick I am missing? Some setting to tweak? I have 3 monitors just waiting for the solution. One of my monitors feels quite left out...


Possible usage of Fubini-Tonelli when measures aren't $\sigma$-finite?

Let $(X,\mathcal{A},\mu)$ and $(Y,\mathcal{B}, \nu)$ be measure spaces such that $\mu(X)>0$ and $\nu(Y)>0$. Let $f:X \rightarrow \mathbb{R}$ and $g:Y \rightarrow \mathbb{R}$ be measurable functions (with respect to $\mathcal{A}$ and $\mathcal{B}$ respectively) such that $$f(x)=g(y) \text{   $\mu\times\nu$-almost everywhere on $X\times Y$}$$ Show that there exists a constant $\lambda$ such that $f(x)=\lambda$ for $\mu$-a.e. $x$ and $g(y)=\lambda$ for $\nu$-a.e. $y$.  Here is what I was working on: Consider $E = \{ (x,y) : f(x)=g(y) \}$. Then, $\mu \otimes \nu (E^c)=0$. Thus, $$ 0 = \iint_{X \times Y} 1_{E^c} \, d\mu \otimes d\nu = \int_Y \int_X 1_{E^c} \, d\mu \, d\nu,$$ by using Fubini (since $1_{E^c}$ is integrable) or Tonneli (since $1_{E^c}$ is nonnegative). Now, this yields that $\int_X 1_{E^c} \, d\mu = 0$ $\nu$-a.e. Hence, we can pick $y \in Y$ such that $f(x)=g(y)=:\lambda$ $\mu$-a.e. You can do a similar argument to show that $g(y) = \lambda$ $\nu$-a.e.  Now, I realize that I cannot use Fubini or Tonneli unless the measures are $\sigma$-finite, and I haven't used the fact that $\mu(X)>0$ or $\nu(Y)>0$. What am I missing?


INNER JOIN works as SELECT but not as DELETE

Why does this have a syntax error   DELETE FROM `print_mailing_request` pmr INNER JOIN `person` p   ON p.id = pmr.person AND p.email LIKE '%@TEST.COM' WHERE  pmr.sent_to_fulfiller != 'y'   when this works correctly without error?  SELECT * FROM `print_mailing_request` pmr INNER JOIN `person` p   ON p.id = pmr.person AND p.email LIKE '%@TEST.COM' WHERE  pmr.sent_to_fulfiller != 'y'


I need to find out the arrival to Miami, USA of TAM Flight #8090, from Brasil on July 17 2015.


Coefficients of characteristic polynomial of a matrix

For a given $n \times n$-matrix $A$, and $J\subseteq\{1,...,n\}$ let us denote by $A[J]$ its principal minor formed by the columns and rows with indices from $J$.  If the characteristic polynomial of $A$ is $x^n+a_{n-1}x^{n-1}+\cdots+a_1x+a_0$, then why $$a_k=(-1)^{n-k}\sum_{|J|=n-k}A[J],$$ that is, why is each coefficient the sum of the appropriately sized principal minors of $A$?


What's happened with the user name and why does this user have two 'Code Golf' accounts?

There is a user on ru.SO named Danis. Today, his chat messages have been renamed as if they belonged to someone named "a25bedc5-3d09-41b8-82fb-ea6c353d75ae". If I click on the user's link "a25bedc5-3d09-41b8-82fb-ea6c353d75ae", I see two linked  accounts with Danis code and "a25bedc5-3d09-41b8-82fb-ea6c353d75ae". What it is???    Link:


Rename "Favorite" vote type to "Bookmark" in VoteTypes table SEDE

Over at , in  query, it shows the vote type (or what should be the vote type) "bookmark" as "favorite":  Can we update that to say "bookmark", since ?


Find the probability of rolling ten different, standard 6-sided dice simultaneously and obtaining a sum of 30?  I started to answer this question by setting up an equation like this:  x1+x2+...+x10=30 with 0 less than or equal to xi less than or equal to 6 But we know the die will have values 1-6 so we have y=x+1 so that y1+y2+...+y10=20 Now I know we can have at most 4 6's, 5 5's, 6 4's, 10 3's, 10 2's, 10 1's.  I was not sure if I am heading in the right direction or should I just find all possible outcomes of the die and use the inclusion-exclusion method to find all the permutations in which the sum will be 30?


Disable power LED blinks during Vista hybrid sleep?

Does anyone know how to disable the blinking power LED when Vista enters hybrid sleep mode?  My case has a very bright blue LED that is rather distracting.  I'd rather not disable hybrid sleep, as it works perfectly and allows for much faster resumes than restoring from a hibernated state.


I'd like to find a single noun that relates to me and which corresponds to the list of people including me and each of my ancestors.  I've already rejected the following words:   genealogy : means a work, not a list of people. ancestry : seems to exclude me.


How many people actually participated in the original Voldemort conflict?

From GoF scene where Death Eaters are returning after Voldemort's return, there seems to be VERY few of them (don't recall exact # but my impression was between a dozen and two dozen).   Also, Order of Phoenix seems to have fairly few members as well.  These are probably the "officer/elite corps" of the bigger fight. Is there any estimate of how many actual participating fighters were there on both sides in the original conflict? I'm fine with either human-only totals, or overall (e.g. count giants on Voldemort's side).  On the Death Eater side, you can count/not count Imperioused people if any info like that is available.


How to unzip .tgz file using the terminal?

I've downloaded mongodb-linux-x86_64-2.6.3.tgz file using windows 7 and kept it on D:\Amra\Software\Developing Soft location.  When I right click this .tgz file using Ubuntu  and see property it shows Location:  /media/towhid/Amra/Software/Developing Soft. Now how will I unzip this .tgz file using tar command from terminal?


How to show textures in the 3D View editor?

I have added some textures to objects in blender but the textures don't show up until I render the file. it can be difficult to know what the objects look like without rendering it. is there a way to have textures show in the editor even if they are at a lower res?  In editor:    Rendered:


Can an abstract class have a constructor?  If so, how can it be used and for what purposes?


Move all files from subdirectories to parent directory

I have a directory structure like this:  ├── Tom │   └── c │       └── 2 │           ├── file.jpg │           └── text.txt └── Sam     ├── 1     │   └── c     │       └── music.aac     ├── E     │   └── 9     │       └── pic.jpg     └── b         ├── 9         │   └── sound.aac         └── d             └── book.doc   I'd like to move all files from the various subfolders to the main parent folders (Tom, Sam, etc.) with a single command, and then deleting all the empty subfolders. How can I do that?  Thank you


ls -l /bin/true shows it being 27168 bytes in size, whereas a c program that just returns 0 is . Also, running objdump -d /bin/true gives a huge assembly program with many system calls. Why is all this needed for a program that just "does nothing successfully"?


Passive voice in academic writing; why is it not recommended?

When writing academic papers in English I use three different spelling and proofreading tools: Word, Grammarly, and Ginger. In the settings of all these tools, I specify that the document is an academic article, where possible.  Before I posted this question, I had a look at the question «», but there they discuss more general cases, regular texts, while I'm interested in a subject «the passive voice in academic writing», which usually has different rules and recommendation, comparing to general essays.  What is strange for me, why do all these instruments mark the usage of passive voice as a style error? What's wrong with the passive voice in terms of academic writing? I know, that passive voice is not optimal for regular texts and difficult to understand, comparing to the active voice, but I always assumed that for the academic writing passive voice suits well, isn't it?


This is my first post here so please let me know if I'm doing this wrong...  I'm looking to take the last day of each month for the last 60 months, from a reference date.  For example, if the reference date is today (Aug 21 2014), then the last end of month is July 31st, 2014, and the one before that is June 30th, 2014...  Does anyone know how to do this in python?  Thanks!


Explain Principal Wood's reaction after looking at Spike in the mirror

In the Buffy Season 7 episode First Date, Principle Wood is driving Buffy (passenger seat) and Spike (rear seat) in his car. He asks Buffy how she knows Spike and looks at him in his rear-view mirror. At this point he doesn't know that Spike is a vampire (he finds out 10 minutes later).   If he did see Spike, how? since vampires can't be seen in mirrors      even vampires with souls, such as Angel  If he didn't see Spike, why didn't he react?


Files list file for package missing -- dpkg warning

I want to install Open JDK or Oracle JDK to my machine but I got an error during installation. The error is:  Selecting previously unselected package oracle-java8-installer. dpkg: warning: files list file for package 'unity-scope-gourmet' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'unity-scope-guayadeque' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'unity-scope-gmusicbrowser' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'unity-scope-manpages' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'unity-scope-firefoxbookmarks' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'unity-scope-gdrive' missing; assuming package has no files currently installed dpkg: warning: files list file for package 'unity-scope-home' missing; assuming package has no files currently installed E: Sub-process /usr/bin/dpkg returned an error code (2)   I searched on Google and try to something for install/reinstall this packages. Finally i try to remove Unity. I faced this error for my every tries. I am using Xmonad. How can I fix this issue?


Best Defensive Barracks Troops In Clash of Clans

Several members of my clan have been asking for "Defensive Troops". Which got me thinking what are some good defensive troops that are readily available at the Barracks? Troops that Most members will have access to. So lets try to cap this at nothing better than healers.  So of barbarians, archers, goblins, giants, wall breakers, balloons, wizards and healers which are the very best at defense? By best I mean likely to save you the most money. Whether they kill the enemy before they can do damage or draw enemy fire works. Longevity of troops is also an important element to consider.  I am aware that what the enemy attacks you with will have some impact on this, so let's limit this to which troops are best most of the time.


Using Alpha Textures doesn't work properly

I'm trying to mix to shaders with the use of an alpha texture. I UV unwrapped the cube and adjusted the mapping but it still doesn't work. On the top of the cube there should be a P with the Glossy Shader.


Copyright year of Android App out of date

Should be 2016, not 2014-2015.       App Version: 1.0.85   Device Manufacturer: samsung   Device Model: GT-N8000   OS Version: 4.1.2 (N8000XXCMJ2)


I have a dispute with my partner. He comes from a financial software background but I do not. He recommends that our web app should expire user's passwords after 6 months (and it has to be unique each time). However, our target audience will be in construction. I think it will annoy the users and not provide enough security to justify the annoyance.  Do you think passwords should expire?


Bijection map from a set of subgroup to another set of subgroup under some condition.

Let $G$ be a finite group. Let $N \trianglelefteq G$ and $U \leq G$ such that $G = NU$. Then there exists a bijection, preserving inclusion, from the set of subgroups $X$ satisfying $U ≤ X ≤ G$ to the set of $U-$invariant subgroups $Y$ satisfying $U \cap N ≤ Y ≤ N$.  This is a problem from Kurzweil-Stellmacher book. I dont know how to do it. Thanks for any help.


I just rebooted and noticed the dock was missing. I was messing with the auto-hide functionality earlier, but decided to leave it on. As previously mentioned, now it's gone, though I can see it again by using the super key to open the launcher. As you can see in the screenshot, everything is there but the Dock option.     Any ideas how to get it back?


Derive squared exponential covariance function

In Gaussian Processes, SVMs, kernels are used (as to my understanding) as similarity measure. However, they have the constraint that any kernel has to be represented as a dot product. i.e. $k(x_1,x_2)=\langle f(x_1), f(x_2)\rangle$. Note that $f(x)$ could map x to a higher dimension e.g. $f(x)=[x^2\,\,\,\, \sqrt{2}x]^T$  My question is how can you derive the square exponential function $k_{SE}=\exp(-(x_1-x_2)^2)$ as a dot product.


installing 32-bit version of Skype on Ubuntu 16.04

I'm having trouble installing Skype. I have Canonical Partners enabled in Synaptic Package Manager, but skype is not showing in the search. If I try to install via:  sudo apt install skype   I get:   E: Unable to locate package skype   I went to the Skype web site and it offered a .deb file only in 64 bit.


How to set parent form to a form which opened from class in C#?

I have a parent form AddEmployee which call a class Worker and class opens another(child) form InformationFetching. I want to set AddEmployee as parent form of InformationFetching but I am getting error of Cross-Thread.   //Parent Form public partial class AddNewAccount : DevExpress.XtraEditors.XtraForm {     Thread thrd;     private void brnContinue_Click(object sender, EventArgs e)     {         Worker workerObject = new Worker(this);         //ThreadStart ts = new ThreadStart(workerObject.DoWork);         //thrd = new Thread(ts);          Thread thrd = new Thread(() =>         {            //workerObject.DoWork();  // CrossThreadException            Invoke(new MethodInvoker(workerObject.DoWork));  // OK         });          //some code here         addNewAccount();         }      private void addNewAccount()     {         //parameter define here and pass in verifyDetails         thrd.Start();            validatorClass objClass = new validatorClass();         Bool isSuccess = false;         isSuccess = objClass.verifyDetails(parameters); //it will verify all the details. May take upto a 30 seconds     } }  //worker class public class Worker {     Form parentForm     InformationFetching frmChild;     Bool isTestCall = false;1     public Worker(Form prntForm)     {         // TODO: Complete member initialization         parentForm = prntForm;     }     public void DoWork()     {         //child form         if(isTestCall)             InformationFetching frmChild = new InformationFetching(0)          else             InformationFetching frmChild = new InformationFetching(1) //1 is when small verification         //getting error of cross-thread         frmChild.MdiParent = parentForm;         frmChild.StartPosition = FormStartPosition.CenterParent;         frmChild.ShowDialog();     } }  //validator class public class validatorClass {     // verify all the details one by one and fetch in InformationFetching form     internal void verifyDetails()     {         //phase-1 verification         AccountSyncform().showInfo("Information");          //phase-2 verification         AccountSyncform().showInfo("Information");          //phase-3 verification         AccountSyncform().showInfo("Information");          //phase-4 verification         AccountSyncform().showInfo("Information");          //phase-5 verification         AccountSyncform().showInfo("Information");     }      public InformationFetching AccountSyncform()     {         InformationFetching mForm = null;         try         {             foreach (System.Windows.Forms.Form f in System.Windows.Forms.Application.OpenForms)                 if (f.Name == "InformationFetching")                 { mForm = (InformationFetching)f; break; }         }         catch (Exception ex)         {             MainTainErrorLog.addGeneralErrorToLog(ex.Message);         }         return mForm;     } }   Can anybody please suggest me what I am missing here?


Number of ways to distribute 5 distinguishable balls between 3 kids such that each of them gets at least one ball

How many ways are there to distribute 5 distinguishable balls between 3 kids such that each of them gets at least one ball?   My approach is $ \binom{5}{3} 3! $ + $ \binom{2}{2} \binom{3}{2}2!$ which is equal to $66$?


How do I install Ubuntu on a new drive with a downloaded version 13.10 on a dvd? The file is a zip, do I unzip it the the dvd? I have been able to install Ubuntu on a pc with an OS but having trouble with a new hard drive.


Which is responsible for electric shocks: voltage or current?

What is really responsible for the feel of electric shocks? Is it voltage or current or both  ? explain me in detail


Are there any other real life languages in Star Wars?

As  established, the Hindi language does actually exist in the Star Wars universe, likely as the Sriluurian language. Of course there is also the fact that almost everyone speaks Basic, which is equivalent to English. So my question is, are then any other examples of a real life language being spoken/used in Star Wars, or is it just basic and the occasional Hindi?  Legends and canon are both acceptable.


Is there a Pythonic way to create a list of cloned items?

Consider the following code:  class SomeClass:     def __init__(self):         self.foo = None  some_list = [SomeClass()] * 5   The problem with this code is that all 5 items of some_list refer to the same instance of SomeClass. If I do some_list[0].foo = 7, then I get some_list[1].foo equal to 7, etc.  So how to instantiate N different SomeClass instances in a list?


Problems in the relation $a=v\frac{\mathrm{d}v}{\mathrm{d}x}$

We all know $a = \frac{\mathrm{d}v}{\mathrm{d}t}$. A little application of the chain rule leads to the relation $$a=v\frac{\mathrm{d}v}{\mathrm{d}x}$$ But the above equation shows that $a=0$ whenever $v=0$. And this must be wrong, as when we throw something vertically from the earth surface it stops and then returns due to gravity. There is always an acceleration in the downward direction.  I have come up with two possible ways to solve this problem:   We know that $v = \frac{\mathrm{d}x}{\mathrm{d}t}$, so whenever $v=0$ then $\mathrm{d}x=0$ (i.e. no displacement in that infinitely small time). Also, $$a = \frac{\mathrm{d}v}{\mathrm{d}t} = \frac{\mathrm{d}v}{\mathrm{d}x}\frac{\mathrm{d}x}{\mathrm{d}t}$$ only if $\mathrm{d}x$ is not equal to $0$, as multiplying both numerator and denominator with $0$ will make it $0/0$ (undefined). Or multiplying by $0/0$ is not equivalent to multiplying by $1$.  Now since $\mathrm{d}x=0$ whenever $v=0$, therefore we can not write $a = v\frac{\mathrm{d}v}{\mathrm{d}x}$ when $v=0$. If we plot a $v$-$x$ curve for the motion, whenever $v=0$, as explained, $\mathrm{d}x=0$. Therefore, at that instant $\frac{\mathrm{d}v}{\mathrm{d}x}$ (the slope of the $v$-$x$ curve) will be not defined (as $\mathrm{d}x=0$), therefore the equation $a = v\frac{\mathrm{d}v}{\mathrm{d}x}$ will be undefined and we cannot determine acceleration at that instant with the $v$-$x$ curve.   Now that actually means that by plotting $v$-$x$ curve we lose information about acceleration of the particle when $v=0$.   I want a method to find the acceleration at that point using $v$-$x$ curve. Also a explanation for this defect of the $v$-$x$ curve.  Also I would like to add that so far no physics book (that I had read) has explained this before writing this relation. Also they do not mention that this will not work for $v=0$.     I would like to add the situation where I observed this: when you throw something vertically upward with velocity such that it reaches to a height 10 then the v-x curve will be-   the slope of above curve is clearly not defined at x=10(or the instant where velocity is 0) But we know that there was a constant acceleration throughout the flight. Then how can we find acceleration at that instant??? Also assume that we only have v-x curve. Or if we cannot then why??


Prove that $8(5)^n + 6(3)^{2n} - 80n - 14$ is divisible by $512$ for all $n \in \mathbb{N}$ by induction.

Note: question was updated to correct the constant term $-14$ (vs. $-40$). We need to prove that $8(5)^n + 6(3)^{2n} - 80n - 14$ is divisible by $512$ for all $n \in \mathbb{N}$. I started by taking $n = 1$, then for $n = k$ and then for $n = k+1$. I am stuck here. Not able to solve further but still trying. What to do next? Thanks for your time.


When should one use \begingroup instead of \bgroup?

Is there ever a case when the use of \begingroup is preferred to \bgroup? Obviously, \bgroup is necessary in cases where you need to have balanced braces and thus cannot use {, but when is it necessary to use \begingroup?  A related question would be: What's the difference between a simple group and a semi-simple group?


change current keyboard layout via a .bat file

I got a windows 10 with 2 keyboard layout. I would like to switch progrmatically the current used keyboard via a bat file. Does anyone know what command does it?  to make it clear, I do not want to install a new language pack, I would like to change the input keyboard without making the user press alt+shift  edit: this is not a dup! the question which linked in the header asks about adding new language ,not changing existing lang pack!


I have read that for a given finitely generated module $M$ over a ring $R$ and a multiplicative set $S$ in $R$, $\mathrm{Ann}(S^{-1}M)=S^{-1}\mathrm{Ann}(M)$ as ideals in $S^{-1}R. $ Is it also true for an infinitely generated module? If not, what is a counterexample? Here, $\mathrm{Ann}(M)=\{r\in R:rm=0 \ \forall \ m\in M\}$ and similarly $\mathrm{Ann}(S^{-1}M)$ is defined.


Why can't I modify a variable in Java but an array?

I don't know why can't I modify a variable in Java, take my code, please help me public class Main {     public static void main(String[] args){         int number = 1;         change(number);         System.out.println(number); // it should print 100     }      public static void change(int number){         number = number * 100;     } }  Now, why when I use an array it does work? public class Main {     public static void main(String[] args) {         int[] numbers = {1, 2, 3};          // prints 100, 200, 300         for(int i = 0; i < numbers.length; i++){             System.out.println(numbers[i]);         }     }      public static void change(int[] numbers) {         for(int i = 0; i < numbers.length; i++){             numbers[i] = numbers[i] * 100;         }     } }


Associativity of symmetric difference of sets

By $A\oplus B$ we denote the symmectric difference of two sets. The definition is $A\oplus B =(A\setminus B) \cup (B\setminus A)$. Now I hope to show that $A\oplus (B\oplus C) = (A\oplus B)\oplus C$. I remember that there's an elegant proof, but I forget its detail. (The first step is to show $A\oplus (A\oplus B) = B$, and maybe applying this formula, we can obtain associativity.)


How to sync or share a text to google doc

Ha ii,I am doing a Bible application,my requirement is the user write a note or copy some contents in Bible have to sync or share with google doc.Is there any API available for this ?like sharing to Facebook or twitter. How to do this? Thanks in advance.


Install Teamviewer on Ubuntu 17.04 with 64-bits architecture

Trying to install the .deb package from Teamviewer's website gives unmet dependencies on 64-bit architecture, because the downloaded file is for 32-bit architecture.


it is possible get Salesforce ChangeSet components throw API or Apex?

I just wondering about the way to retrieve information from a changeset, I want to use it for source control proposes. Someone know a way to do this?


I am new to android development. Trying to create app with 3 activity. Error message: Exception raised during rendering

java.lang.NullPointerException     at android.content.res.Resources_Delegate.getDrawable(Resources_Delegate.java:189)     at android.content.res.Resources.getDrawable(Resources.java:845)     at android.content.Context.getDrawable(Context.java:687)     at androidx.core.content.ContextCompat.getDrawable(ContextCompat.java:454)     at androidx.appcompat.widget.ResourceManagerInternal.getDrawable(ResourceManagerInternal.java:144)     at androidx.appcompat.widget.ResourceManagerInternal.getDrawable(ResourceManagerInternal.java:132)     at androidx.appcompat.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:406)     at androidx.appcompat.widget.AppCompatTextHelper.loadFromAttributes(AppCompatTextHelper.java:283)     at androidx.appcompat.widget.AppCompatTextView.(AppCompatTextView.java:105)     at androidx.appcompat.widget.AppCompatTextView.(AppCompatTextView.java:95)     at androidx.appcompat.app.AppCompatViewInflater.createTextView(AppCompatViewInflater.java:182)     at androidx.appcompat.app.AppCompatViewInflater.createView(AppCompatViewInflater.java:103)     at sun.reflect.GeneratedMethodAccessor841.invoke(Unknown Source)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)     at java.lang.reflect.Method.invoke(Method.java:498)     at android.view.BridgeInflater.lambda$createViewFromCustomInflater$0(BridgeInflater.java:259)     at android.view.BridgeInflater.createViewFromCustomInflater(BridgeInflater.java:285)     at android.view.BridgeInflater.onCreateView(BridgeInflater.java:122)     at android.view.LayoutInflater.onCreateView(LayoutInflater.java:930)     at android.view.LayoutInflater.onCreateView(LayoutInflater.java:950)     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:1004)     at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:309)     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961)     at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1123)     at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)     at android.view.LayoutInflater.rInflate(LayoutInflater.java:1097)     at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)     at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1126)     at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)     at android.view.LayoutInflater.rInflate(LayoutInflater.java:1097)     at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)     at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1126)     at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)     at android.view.LayoutInflater.rInflate(LayoutInflater.java:1097)     at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)     at android.view.LayoutInflater.inflate(LayoutInflater.java:682)     at android.view.LayoutInflater.inflate(LayoutInflater.java:501)     at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:328)     at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:396)     at com.android.tools.idea.layoutlib.LayoutLibrary.createSession(LayoutLibrary.java:209)     at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:608)     at com.android.tools.idea.rendering.RenderTask.lambda$inflate$6(RenderTask.java:734)     at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)     at java.lang.Thread.run(Thread.java:748)


Listing layers from .mxd file using ArcPy for ArcGIS Pro?

I am looking for a way to access a .mxd file's layer names and data sources.  In ArcGIS Desktop, I could do:  def print_layer_info(mxd_path):     print(mxd_path + ":")     mxd = arcpy.mapping.MapDocument(mxd_path)      for df in arcpy.mapping.ListDataFrames(mxd, "*"):         lyr = arcpy.mapping.ListLayers(mxd, "", df)[0]         if lyr.supports("dataSource"):             print "\t" + lyr.name             print "\t\t" + lyr.dataSource     del mxd   According to , I could do:  p = arcpy.mp.ArcGISProject("file.mxd")   But that doesn't work. When I do that I get a OSError.  Since the arcpy.mapping.MapDocument is gone in ArcPy for ArcGIS Pro, what is the equivalent way of reading layer name and datasource of an .mxd file?


Integrating R into ArcGIS Desktop (ArcMap)?

Does anyone have any insight into using R with ArcGIS Desktop?   I do not have any R experience, I mainly use SAS to do my data handling before I move into Arc. I currently run a geocoding and enriching process about eight times a year on data that's anywhere from 2 to 5 million records. Right now, I take the raw files for those and process in SAS and then move into ArcGIS Desktop to do the geocoding and enriching, and then export back out to dbf or text just to import back into SAS to finalize the output.  What I am seeking to understand is whether I can/should replace SAS in my processing method, with something like R which I can integrate into ArcGIS. To optimize my processing, I'd prefer to have everything in one application, instead of the various importing/exporting.  In my mind, I'm hoping to learn R and create a script to do my preprocessing and then have a Python script to run inside of ArcGIS that calls the R script, and then it will do the geocoding/enriching process as well.  Can someone tell me if this loose idea is possible with desktop ArcGIS?


What is the title of a story about a elevator through time and the smallest possible change

Many years ago I read a story about a guy working for an organisation that would influence time-lines by traveling through time using a sort of elevator. The objective of the operators was to influence the time-line by making the smallest change possible. Can anyone identify the name and author of the story?


Run bash script in a separated process (dettached from SSH/Putty)

I'm accessing Ubuntu Server from a putty terminal and then I run this test.sh script from that terminal: $ bash test.sh & (note the &) #!/bin/bash while true do      node myscript.js      wait $!     sleep 5  done  Which is supposed to keep that node script running "forever". The issue is that when I close the SSH session/remote terminal (Putty) the script is also terminated. How do I keep that script running after closing that SSH session?


Is it okay to bring up a discussion that happened long ago?

I have seen some pretty popular discussions that happened long ago, and some of them seem pretty good, despite being declined. Some of them are declined because of some circumstances that existed long ago, but no longer do today. In such case, can such a discussion be brought up again?


Graph of Dependencies (like Numerical Recipes)

I'd like to build a graph of dependencies as they do in the index of the Numerical Recipes book. I want something straight-forward and plain like this:    What has been suggested in the question in  is to use some chart offered in . However, I don't want a visual graph since I have many dependencies. How would I best be able to compile a latex document with this type of chart?


I am planning to apply to Masters/PhD program in economics but my grades in first and second year are terrible?

I am planning to apply to some North American Masters and PhD econ programs this upcoming fall. While I meet all the minimum requirements to be eligible for admission into all the programs, I am pretty nervous about my first and second-year grades: they are horrific. Now, I know that a lot of people say that freshman performance doesn't really count, but my situation is a bit different from the rest.   When I was first enrolled in an undergraduate program at the university, I studied business. Like many other freshmen out of high school, I didn't care about grades. All I wanted to do was pass my courses and get the degree. In my first year, I did pass all my courses, but my average was below the honors program requirement and the academic office issued me a probation warning. Probation warning caused me to panic a little bit, but it still was not enough to make me a better student. In my second year, I failed a couple of core business courses and I was put on probation as a result. Over the course of two years, I did not meet the class average in any of my classes. The University allowed me to come back into the program after I would have taken the year off, but I decided to withdraw from the institution and reapply into a different program at another university.  Fortunately, I was offered admission into one of the English programs at the university in the town where my parents reside. Since I earned some credits from the previous institution, I was registered as a second-year student. This time I performed much better. My average improved drastically, it increased from mid/high 50% to 79%. I scored above class average in every single course with the exception of one. This was also the year, I was taking a calculus course which pushed me to switch from Honors English program to Double Major in Economics and English after an excellent performance. In the previous academic year (2017-2018), I obtained an 87% average (for that year alone) in English and Economics courses. Right now, I am taking math courses in the summer and some advanced ones in the upcoming graduate year.   Based on my recent performance at my current undergraduate university, I think I have decent chances to be accepted into at least one of the graduate problems. But as I mentioned earlier, my performance at my first university is terrible. How much of a problem do you think my two years in business would cause me if at all?   Thanks


My laptop (Ubuntu 14.04) is taking too long showing a message "Waiting 60 more seconds for network configuration"


2010 Designer Workflows Not Compiling in SharePoint Online

We have workflows built on the 2010 platform that are currently working in SharePoint Online.  If we save/republish them we now get the following error: Workflow Error:  Errors were found when compiling the workflow.  The workflow files were saved but cannot be run.    Unexpected error on server associating the workflow.  If we check for errors none are found.  So far the only luck we've had is to delete the workflows and rebuild them using the 2013 platform.  This just started happening to multiple users 3 days ago. Examples of workflow changes include adding people to email distribution list or changing a hard coded link to one that uses workflowcontext.  I even tried compiling a workflow without making any changes and get the same error.  Can someone provide any suggestions of things we can try to resolve this?  Surely we shouldn't have to rebuild every workflow as changes are needed, right?


Does the universe have an edge/boundary/barrier? If yes, what is at the edge?

My question related kind of to asking what the shape of the universe is. Say a hypothetical alien civilization built an faster-than-light spaceship. If they keep flying would they end up where they began? ie space itself is curved...or would they hit some invisible barrier?


What's the difference between LAY and LIE?

This has been confusing for me.  Some say:     "I'm laying on/in my bed."   Others say:     "I'm lying on/in my bed."     Which is correct? Do the sentences have any difference?  I'm not sure which preposition to use either. Can ON and IN be used with these verbs?


C# Directory.GetFolder Order Folders And Set Them To List Without Losing Memory And Doing Additional Sort Operations

just want know how to Order folders like they looking in my Explorer folder Sorted by name .. It's looks like :::  So i tried use this :::  DirectoryInfo sourcreInfo = new DirectoryInfo(SourcePath);                 DirectoryInfo[] sourceFolders = sourcreInfo.GetDirectories().OrderBy(p => p.Name).ToArray();  but for sure it's not working ... not sorting and in addition it needs addition memmory ... imagine i have in my folder 1000 reports ... soo ... here how i worked with this sourceFolders:: reportDir is just List   foreach (DirectoryInfo report in sourceFolders)                 {                   reportDir.Add(Path.GetFileNameWithoutExtension(report.Name)).ToString()));                       }  Guys waiting for any proposition how to get Ordered by Name Directories ... To make this operation correctly .. :) Really what in result i getting using DirectoryInfo ::::  I expected :: report1, report2 , report3 , report4 , report5 .... by numbers, like shows in explorer picture


Is it safe to install Ubuntu 16.04 beside WIndows 10 with UEFI?

So I am kinda worried about installing Ubuntu on my main PC, since I love it.  But the problem is, my motherboard is UEFI. Its a gigabyte h81m-hd3.  Would it be safe to dual boot Windows and Linux on this? Also, is the installation as easy as installing it on a PC that has BIOS? (I have Ubuntu on my laptop)  Also, last question, let's say I installed Ubuntu and Windows, and Windows gets an update, can the update break the Grub2 bootloader?  Thanks for your help, if I am able to install Ubuntu 16.04 on my custom build PC I'd be happy as hell.


What is the analog to the $DISPLAY variable to trigger launch of the GUI apps via SSH?

On Linux you can login via SSH or a tty and trigger a launch of a GUI application in completely different graphical session:  DISPLAY=:0 my-application   How to do it on Mac?


Advantages of bisexual reproduction over asexual one toward species promotion?

Are there any advantages of bisexual reproduction over asexual one towards species conservation and promotion? Do animals that have two or more sexes have more chances to reproduce? Does anybody had a quantitative account of this fact?


I am a newbie in Ubuntu. I'm trying to install Texmaker, but can't solve some issues of missing dependencies.  I tried to install one of them: libqt5core5a:  The following packages have unmet dependencies:  libqt5core5a : Depends: libdouble-conversion1 (>= 2.0.0) but it is not going to be installed                 Recommends: qttranslations5-l10n but it is not going to be installed  texmaker : Depends: libqt5gui5 (>= 5.8.0) but it is not going to be installed             Depends: libqt5network5 (>= 5.0.2) but it is not going to be installed             Depends: libqt5printsupport5 (>= 5.0.2) but it is not going to be installed             Depends: libqt5script5 (>= 5.6.0~beta) but it is not going to be installed             Depends: libqt5widgets5 (>= 5.7.0) but it is not going to be installed             Depends: libqt5xml5 (>= 5.0.2) but it is not going to be installed E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).   Try to fix it:  sudo apt-get -f install   Got Error 404  Err:1 http://security.ubuntu.com/ubuntu bionic-security/main amd64 libqt5core5a amd64 5.9.5+dfsg-0ubuntu2.1 Err:404  Not Found [IP: ]   I tried to fix it with the information I found in forums but I didn't work.  Please if you could give some help.  Thanks.


I would like to use  with a video.  With ffmpeg I can export some (.jpeg) images from a video. Can I convert a .jpeg into a valid .tiff or export directly .tiff images from the video with ffmpeg?


Short  definition of :     Can a set of weak learners create a single strong learner? A weak   learner is defined to be a classifier which is only slightly   correlated with the true classification (it can label examples better   than random guessing).   Short definition of :     Random Forests grows many classification trees. To classify a new   object from an input vector, put the input vector down each of the   trees in the forest. Each tree gives a classification, and we say the   tree "votes" for that class. The forest chooses the classification   having the most votes (over all the trees in the forest).   Another short definition of :     A random forest is a meta estimator that fits a number of decision   tree classifiers on various sub-samples of the dataset and use   averaging to improve the predictive accuracy and control over-fitting.   As I understand Random Forest is an boosting algorithm which uses trees as its weak classifiers. I know that it also uses other techniques and improves upon them. Somebody corrected me that Random Forest is not a boosting algorithm?  Can someone elaborate upon this, why Random Forest is not a boosting algorithm?


Ubuntu 18.04 gets always abort when I type y,Y,yes

Hello I use VPS hosting on Ubuntu 18.04 I want to installation things.  When it ask me to continue I type Y,y,yes,-y but it returns always abort:   what can I do?


show that an entire function with the nth derivative zero is polynomial of degree at most n-1

f is an entire function with $f^n=0$ for some $n \in \mathbb{N}$. I need to show that f is polynomial of degree at most n-1.   I know that this question was asked before. But I need another approach to solve it. I don't want to use the taylor expansion or the gauchy integral. I need the most basic approach (using only the differentiability of f).


Make the message shown to registered users without enough reputation to vote less confusing

Currently, when a user with less than the required reputation needed to cast a vote on a post attempts to do so, they are shown this message:     Thanks for the feedback! Votes cast by users with less than [x] reputation are recorded, but do not change the publicly displayed score.   While it is technically correct in that their attempted vote is recorded as feedback, it's rather confusing. It implies that the vote is still recorded as...a vote, not as feedback. This can mislead users into thinking that  (also see its duplicates here as well as ), or that such "votes"  (i.e. still a normal vote with the sole exception that it doesn't change the score).  Can we please change this message so that it no longer implies that an actual vote is recorded?  Examples:     Thanks for the feedback! You need at least [x] reputation to [up/down]vote this post.   or:     Thanks for the feedback! You need at least [x] reputation to cast a vote, but your feedback has been recorded.   In my opinion, the "Thanks for the feedback!" text implies to me that the feedback has been submitted and recorded; there's no need to point that out explicitly.


Why does water pouring from a glass sometimes travel down the side of the glass?

If you have a glass of water, say, three quarters full and you pour it at an angle of say, $45^{\circ}$ with respect to the the table, the water comes out of the glass and goes directly down towards the floor.  However, when the glass is more full, or even three quarters full and the 'angle of pouring' is far less with respect the table, when the water comes out of the glass, rather than going straight down it kind of stays stuck to the glass and travels down the outside of it.  Why does this happen? (I'm sure many of you have observed it yourself by accident and ended up making a mess).


set onclick listener not working in android for moving from one fragment to another activity

My App gets crashed when I have set intent to go from one fragment to another activity. I have set onClickListener on it. and It shows me no error what is the problem. Here is the code for it. Whenever a user clicks on an image he is taken to another activity this is what I am trying to do.       public class HomeFragment extends Fragment  {       private ImageView images;       public HomeFragment() {      // Required empty public constructor      }      @Override      public View onCreateView(LayoutInflater inflater, ViewGroup container,                          Bundle savedInstanceState) {      View view = inflater.inflate(R.layout.fragment_home, container, false);     images = (ImageView) view.findViewById(R.id.complaint_posted);       images.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View v) {         Intent intent=new Intent(getActivity(), DetailPost.class);         startActivity(intent);         }     });     return view; }   ` This is my logcat


More Complex ORDER BY (alpha first, then treat number as a whole number)

So I have a bunch of varchars that I need to sort in a certain way, first be alpha, and then treat the following number as a whole number (i.e. A2 would be before A10). That's the main problem, and then I have some with 'sub' letters after like A1M. Don't want to have to add a new column just for sorting, so I wanted to see if a more complex ORDER BY statement might be able to handle something like this.  They should be sorted like this:  A1 A1M A2 A6 A6B A9 A10 A15 A16 AS10   But it currently sorts like this (standard ORDER BY):  A1 A10 A15 A16 A1M A2 A6 A6B A9 AS10


What's the best way to build a string of delimited items in Java?

While working in a Java app, I recently needed to assemble a comma-delimited list of values to pass to another web service without knowing how many elements there would be in advance. The best I could come up with off the top of my head was something like this:  public String appendWithDelimiter( String original, String addition, String delimiter ) {     if ( original.equals( "" ) ) {         return addition;     } else {         return original + delimiter + addition;     } }  String parameterString = ""; if ( condition ) parameterString = appendWithDelimiter( parameterString, "elementName", "," ); if ( anotherCondition ) parameterString = appendWithDelimiter( parameterString, "anotherElementName", "," );   I realize this isn't particularly efficient, since there are strings being created all over the place, but I was going for clarity more than optimization.  In Ruby, I can do something like this instead, which feels much more elegant:  parameterArray = []; parameterArray << "elementName" if condition; parameterArray << "anotherElementName" if anotherCondition; parameterString = parameterArray.join(",");   But since Java lacks a join command, I couldn't figure out anything equivalent.  So, what's the best way to do this in Java?


Black text not showing on model (transparent PNG)

This is probably a noob question.   I want to add a text texture to a model. I've made the image in GIMP, if I use WHITE for the text color, it appears properly, but if  I change the color of the text to black, it doesnt show up. Everything in the PNG image is transparent except for the text. (Also, I need to give the model a specific color, as in different colors for the buttons)  I'm using Blender 2.80 Beta with EEVEE as renderer. (version date is 2019-04-09)


Do there exist any odd prime powers that can be represented as $n^4+4^n$?

Well, I wrote up a solution on it, but according to the place I found the problem, it isn't quite correct. Ah, I'm simply hoping someone will point out where I got wrong.  Now, let, $n^4+4^n = p^k$, where $p$ is an odd prime and $k$ is a positive integer.  Further, $p^k \equiv 1 \pmod 2$. Therefore, $n^4 + 4^n \equiv n^4 \equiv 1 \pmod 2$, and so $n \equiv 1 \pmod 2$. $n$ must be odd.  Okay, now let, $n = 2m +1$. Substituting it in $n^4+4^n$ and using the Sophie Germain inequality, we have,  $$n^4+4\cdot4^{2m} = n^4 + 4(2^m)^4 = (n^2 + 2^n+2^{m+1}\,n)(n^2 + 2^n-2^{m+1}\,n) = p^k$$  Now, as $p^k$ can only be factorized into smaller powers of $p$, let $n^2 + 2^n+2^{m+1}\,n = p^i$, and let $n^2 + 2^n-2^{m+1}\,n = p^j$ where $i+j= k$, obviously, and $i>j$.  Now consider this:  $$\begin{align} p^i - p^j & \equiv 0\\ 2\cdot2^{m+1}\,n = 2^{m+2}\,n &\equiv 0 \pmod p \end{align}$$  But, as $p$ is odd, $\gcd(p, 2) = 1$, so $n \equiv 0 \pmod p$.  Now look at this:  $$\begin{align} p^i + p^j &\equiv 0 \\ 2(n^2 + 2^n) &\equiv 0 \\ n^2 + 2^n &\equiv 0 \pmod p \end{align}$$  But we just established that $n \equiv 0 \pmod p$, so $2^n \equiv 0 \pmod p$.  Therefore, let $2^n = jp$ for some integer $j$.  Now, $2^n$ is its own prime factorization, which is unique according to the Fundamental Theorem of Arithmetic and does not include $p$. Therefore, the above statement is an impossibility! There exist no such $p$ and $n$, and no odd prime powers can be written as $n^4+4^n$.  Ah, well, that's it. Sorry for the tediousness of it. I've still no clue how to use $\LaTeX$.  Thank you everybody,  Cheers.


(combinatorics) prove that on average, n-permutations have Hn cycles without mathematical induction.

Prove that on average, n-permutations have $H_n$  cycles, where $H_n=1+1/2+1/3+...+1/n$  without mathematical induction.   I think that on average, the number of cycles of length i (1≤i≤n) should be 1/i to prove but, I don't know how to show this. Some books proved this using an indicator function. Do I have to use that?


Especially while talking about FPS, the term "gib" is quite common. While I get it's related to a sudden and gruesome death, I'd like to know its actual meaning and where it comes from.


Let $V$ be a finite dimensional real Euclidean space and $C$ be an open convex cone in $V$. I need to prove that $C = int(\overline{C})$. I proved that $C \subseteq int(\overline{C})$. I have difficulty in proving $int(\overline{C}) \subseteq  C$. I tried to prove it as follows.   Let $x \in int(\overline{C})$. Suppose $x \in \overline{C}-C$(that is in the boundary of $C$). Then for every $r>0$, $B(x,r)\cap C$ is non-empty. Now by convexity of $C$,  $tx +(1-t)y \in C$ for $t \in (0,1)$ and for any $y \in B(x,r) \cap C$ where $r>0$ . Since $C$ is a cone, we have $x+y\in C$ for any $y \in B(x,r) \cap C$ where $r>0$ .  I don't know how to proceed further. I'm not sure whether the approach is correct or not. I also saw in Wikipedia(Symmetric cone) "An open convex cone coincides with the interior of its closure, since any interior point in the closure must lie in the interior of some polytope in the original cone" which I don't understand.   Please help me to solve it!!


Every continuous homomorphism $S^1 \rightarrow S^1$ is of the form $x \mapsto x^n$ for $n \in \mathbb Z$

I wanted to ask if anyone knew of a simple way to prove this.  The proof I know: Identify any such character with a continuous, periodic homomorphism $f: \mathbb R \rightarrow S^1 \subset \mathbb C^{\ast}$.  Then $f$ has a Fourier expansion $$f(x) = \sum\limits_n c_n e^{2\pi i nx}$$  with  $$c_n = \int\limits_{\mathbb R/\mathbb Z} f(x)e^{-2\pi i nx}dx = \begin{cases} 1 & \textrm{if $f(x) = e^{2\pi i nx}$} \\ 0 &\textrm{else} \end{cases}$$  This shows that if $f$ is not any of the $e^{2\pi i nx}$, it is zero.  $\blacksquare$  This proof could be considered circular, because the Fourier expansion of $f$ is essentially using the Peter-Weyl theorem, which says that the characters of a compact topological group form an orthonormal basis for the $L^2$ space.  So we are essentially already assuming that $f$ is one of the $e^{2\pi inx}$.  How can this be proved without using Fourier series/circular reasoning?


When asking questions on Math.SE, the "MathJax help »" link on the sidebar points to , which in my opinion is very friendly to users who have never heard about MathJax before.  However, on many other sites, the help link points to , which seems to be too complete for new users.  Due to its brevity and helpfulness, I think we should use  as a crash course on all SE sites, maybe after immigrating this post to Meta Stack Exchange if necessary.    Actually, I've found , but after nearly 2 years, it received 0 answers and even 0 comments. Also, that post consider this problem a "bug", but I think it should be a "feature request". This is why I'm posting my own question now.


PostgreSQL execute a default query when no row are returned

I need to calculate the average score of a list of userId.  I have a table user_place_score:  (user_id, place_id, score)   Sometimes I do not have the score (no row for (user_id,place_id) in the table) so I need to fetch a "default" score from the table default_place_score:  (place_id, score)   Is is possible in PostgreSQL to do this in one query? For a given list of users and one place_id, select all their scores in the user_place_score and if no row is found then take the score found if the default_place_score table?  Basically I want to avoid doing this kind of stuff:  for (Integer userId : userIds) {   score = (query to fetch the score for this userId)   if (score == null)     defaultScore = (query to fetch the default score for this PlaceId)    total = total + defaultScore }  //return the average return total/numberOfUser


Please help me apply my logo to this tennis ball! (I am so close, I know its something small and basic i'm missing)

I unwrapped the ball, and placed the .png file in position in the uv editor. Then, I added a material, and applied the uv map to the image texture as shown below:     it shows up in the material panel, but not on the ball!   Thanks,


Is it possible for simple RNN to learn infinite sin wave?

I wrote a simple RNN program to create function which fits y = sin(x). I trained the network by giving 0 < x < 2*pi and y = sin(x) data. And then I checked the wave generated by the trained network. Seeing what wave trained network generate, while x is 0 < x < 2*pi, the shape of the wave seems like sin wave, but if x is x > 2*pi, the wave doesn't looks sin wave, it's like tanh wave. I expected simple RNN program like this has an ability to create sin wave of infinite length, but I couldn't make it. Is there any way to make simple RNN program fits sin wave of infinite length? Any help would be appreciated.  Overview of the program:     Simple RNN program:  import tensorflow as tf import numpy as np import random from matplotlib import pyplot as plt  # Create graph # inputs x = tf.placeholder(tf.float32, []) t = tf.placeholder(tf.float32, []) y_prev = tf.Variable(0.0)  # weights ws = [tf.Variable(random.random()*2 - 1) for _ in range(6)]  # Here is the trained weights # ws = [tf.Variable(w) for w in (-0.20203453, -0.9639475, -0.66465586, 0.5334513, -1.0572276, 0.55196327)]  # biases bs = [tf.Variable(random.random()*2 - 1) for _ in range(3)]  # Here is the trained biases # bs = [tf.Variable(b) for b in (0.17080691, 1.4228324, -0.26205453)]  # Calc outputs of hidden 1,2 neuron h1 = tf.tanh(ws[0]*x + ws[1]*y_prev + bs[0]) h2 = tf.tanh(ws[2]*x + ws[3]*y_prev + bs[1])  # Calc y y = ws[4]*h1 + ws[5]*h2 + bs[2]  # Calc loss loss = tf.square(t - y)  # Define Update y_prev operation update_val = tf.placeholder(tf.float32, []) update_y_prev_op = tf.assign(y_prev, y)  # Define Initialize y_prev operation init_y_prev_op = tf.assign(y_prev, 0.0)  train_step = tf.train.GradientDescentOptimizer(0.03).minimize(loss, var_list=ws+bs)  initializer = tf.global_variables_initializer()  sess = tf.Session()  sess.run(initializer)  train_x_lst = np.linspace(0, 2*np.pi, 50) train_y_lst = np.sin(train_x_lst)  sess.run(init_y_prev_op) for epoch_n in range(100):     for x_value, y_value in zip(train_x_lst, train_y_lst):         sess.run(train_step, feed_dict={x:x_value, t:y_value})         sess.run(update_y_prev_op, feed_dict={x:x_value})     sess.run(init_y_prev_op)  # validation predict_x = np.linspace(0,2*np.pi,50) predict_y = []  sess.run(init_y_prev_op) for x_value in predict_x:     predict_y.append(sess.run(y, feed_dict={x:x_value}))  #plt.plot(train_x_lst, train_y_lst) plt.plot(predict_x, predict_y) plt.show()  print("ws:", [sess.run(var) for var in ws]) print("bs:", [sess.run(var) for var in bs])  sess.close()   Trained RNN prediction(0 < x < 2*pi):    Trained RNN Prediction(0 < x < 4*pi):


I realize that the point of the Schroder-Bernstein theorem is to not use the axiom of choice (AC), but I keep reading that the theorem is trivial if one assumes AC. And since much of set theory is performed with AC, I would like to prove the theorem with AC just for the fun of it. So, is the following proof valid?  Assume AC, and $\vert x \vert \le \vert y \vert$ and $\vert y \vert \le \vert x \vert$. Then $\vert x \vert = \vert y \vert$  By hypothesis we are given one-to-one functions $f : x \to y$ and $g : y \to x$. By AC there are bijections $s : \alpha \to x$ and $t : \beta \to y$ for ordinals $\alpha$ and $\beta$. We can therefore write $x = \{x_\delta \vert \delta < \alpha \}$ where $x_\delta = s(\delta)$ and $y = \{y_\gamma \vert \gamma < \beta \}$ where $y_\gamma = t(\gamma)$. If we can show $\vert \alpha \vert = \vert \beta \vert$, then the map $x_\delta \mapsto y_\delta$ is a bijection from $x$ to $y$. Since $f$ is one-to-one and since $f[x] \subseteq y$, we have $\vert \alpha \vert \le \vert \beta \vert$. This conclusion doesn't follow unless $f$ is one-to-one. Similarly for $g$, we can show that $\vert \beta \vert \le \vert \alpha \vert$. Therefore $\vert \beta \vert = \vert \alpha \vert$.


Is every quotient of a finite abelian group $G$ isomorphic to some subgroup of $G$?

I'm having difficulty with exercise 1.43 of Lang's Algebra. The question states     Let $H$ be a subgroup of a finite abelian group $G$. Show that $G$ has a subgroup that is isomorphic to $G/H$.   Thinking about this for a bit, the only reasonable approach I could think of was to construct some surjective homomorphism $\phi\colon G\to K$ for $K\leq G$, and $\ker\phi=H$, and then just use the isomorphism theorems to get the result.  After a while of trying, I've failed to come up with a good map, since $H$ seems so arbitrary. I'm curious, how can one construct the desired homomorphism? This is just the approach I thought of, if there's a better one, I wouldn't mind seeing that either/instead. Thank you.


Can there be two winners at the same time in Catan?

Imagine the following setup:    Player A has 6 points, including the Longest Road. Player B has 8 points with an equally long road. Player C has 9 points with a shorter road.    Now what would happen if Player C places a village, breaking Player A's road chain? At that moment Player A would have 4 points, while both Player B and Player C would have 10.   In this case, who would be declared the victor?


Allow user to customize (or even suppress) reputation indicator

Currently, users with an account get informed of upvotes to their answers via a small green rectangle reporting the number of such upvotes in the topbar. Clicking on it displays a pop-up window with links to the upvoted answers. The only way I know of to clear the upvote indicator is to click on it.  This makes for an interface which forces certain moves on the user.  Could there be a configuration in the user profile to allow the user to completely suppress this indicator of reputation points upvotes?  Also the pop-up window would serve rather to indicate which questions (among those to which the user contributed either by asking or by answering or possibly commenting) received new activity: activity such as an edit of the question, or a new answer, or an edit to an old answer, or perhaps even new comments to the question or the answers.  The reported information would become completely independent of the upvotes.  The user would go click there only as way to keep track of changes to what he/she contributed to.  The only testimony to reputation points changes would be in the total reputation points the user sees underneath his/her account name. Next time I will ask a way to suppress that too ;-)    As per request in comments:   The benefit to the user was already clearly expressed above: stop being forced to be informed of upvotes. The benefit to the site would be to create a more adult and saner relationship with its contributors.   Also moved from comments:  The upvote indicator could display the green rectangle only on hover event.