Derivation of the polar form of an ellipse from first principles

I am trying a derivation of the polar form of an ellipse using vector notation. Beginning with a definition of an ellipse as the set of points in $\vec{R}^2$ for which the sum of the distances from two points is constant, I have $|\vec{r_1}|+|\vec{r_2}| = c$  Thus, $|\vec{r_1}|^2+|\vec{r_1}||\vec{r_2}|=c|\vec{r_1}|$    Choosing a coordinate system (similar to the one in the diagram), such that $\vec{r_1}=\vec{r}=x\vec{i}+y\vec{j}$, and $\vec{r_2}=\vec{F_2 P}=(x-a)\vec{i}+y\vec{j}$  Noticing that $|\vec{r_1}||\vec{r_2}|=\frac{\vec{r_1}\cdot\vec{r_2}}{\cos(\theta)}=\frac{x^2-ax+y^2}{\cos(\theta)}=\frac{r^2-ax}{\cos(\theta)}$  and using $x=r\cos(\theta)$, we get  $r^2+\frac{r^2}{\cos(\theta)}-ar=cr$, thus I get a polar equation for an ellipse of $r=\frac{a+c}{1+\sec(\theta)}$  whereas I expect $r=\frac{a(1-e^2)}{1+e\cos(\theta)}$. Please tell me where this argument takes the wrong turn!


WinApi - ToUnicode function throws an access violation?

LPWSTR data[256]; ToUnicode(vk_code, 0, 0, *data, 256, 0);   This code throws the following exception:  Access violation writing location 0xCCCCCCCC.  The vk_code value seemed to be perfectly normal at the breakpoint, and I checked with msdn to make sure my arguments were valid. What could I be doing wrong?


I need help with proving / disproving something:     Look at the map      $$\Phi: (C([0,1], \mathbb R), ||\cdot||_{\infty}) \to (\mathbb R, |\cdot|); \,\,\,\,\,\,\Phi(u) := \int_0^1 u²(t) dt$$      a) Is it continuous?   b) Is uniformly continuus?   c) Can one find a non-empty subset of $C([0,1],\mathbb R)$ in which $\Phi$ is Lipschitz-continuous?   Can you help me with this?


Screenshot does not include cursor 18.04

I'm using default gnome-screenshot and I enabled include pointer in dconf Editor /org/gnome/gnome-screenshot/delay and cursor nowhere to be seen.  I used the terminal to set it and still nothing happened.  gsettings set org.gnome.gnome-screenshot include-pointer true   Checked if it worked  gsettings get org.gnome.gnome-screenshot include-pointer true


Why isn't light scattered uniformly in every direction?

Light which reflects off a diffuse reflector is scattered preferentially in certain directions, as can be seen in the following image:    Why isn't light scattered uniformly in every direction by a diffuse reflector?


I understand that the code is convert miliseconds to seconds, mins and hours, but I dont understand what the " % " does ...  int seconds = (int) (milliseconds / 1000) % 60 ;  can someone explain please?  can I do the same action in C++ ?  thanks !!               milliseconds = ((System.currentTimeMillis()) - (startTime));             int seconds = (int) (milliseconds / 1000) % 60 ;             int minutes = (int) ((milliseconds / (1000*60)) % 60);             int hours   = (int) ((milliseconds / (1000*60*60)) % 24);


I was refused a visitors visa recently and want to reapply. We find this reason quite intangible in the sense that   I was invited for an assessment and on the letter it states that I should be in the Uk a minimum of 1 week to acclimatize with the weather so I chose 1 month 10 days as my duration.   The reason for refusal as said earlier isn't tangible. In my application i stated I'm the supervisor for a family business and I receive such amount as salary. I added the business registration certificate and his bank account.  The case worker claims he/she doesnt know the source of cash deposits which comes clearly from daily sales.    In my application i stated My dad is supporting me with the stated amount yet it was interpreted as it coming from my personal income and savings and i never said i support the family financially or anyway it's a job I help.    All documents submitted are true and authentic. What's the way forward as i want to reapply   Also I have been employed recently in a government institution. How do I state that in my next application without any conflict as I used to be a supervisor and now with a different institution now?     What do I do next when I reapply ? Should I still state I'm with the family business? Or use my new job role?  How do we explain deposits in my dad's account. My assessment date has now been changed to November meaning i can reapply.   Kindly help me to reapply for my visa


If A Very Distant Galaxy Has Never Been Observable By Us, Then It Never Will Be?

I understand that distant galaxies that are currently inside our particle horizon will, sometime in the future, not be observable by us anymore because they are receding faster than the particle horizon is expanding. I guess, put another way, if a distant galaxy, that we can see today (is currently inside of our particle horizon), has been outside of our event horizon since time $t$, then we will stop seeing that galaxy (it will be outside of our particle horizon) once all the light it emitted before $t$ arrives here.   Does that mean that if a galaxy in our universe has never been observable by us (i.e., none of the light that it emitted, at anytime in the past, has ever reached us), then none of the light that it emitted, at anytime in the past, will reach us in the future?   A similar question might be: if none of the light that it emitted, at anytime in the past, is reaching us now, then none of the light that it emitted, at anytime in the past, will reach us in the future?   I have not seen another question put quite this way, so I do not think that it is a duplicate, but if it is, I apologize. I did try to research this on this site, before posting.


How do you format a Dates Contraction in LaTex?

I'm writing a paper and I need to include a date, for example 20th January 2011.  How can I make the Contraction smaller and position it correctly as an ascender/superscript?


Bought a ticket with Finnair, didn't enter my middle name

I'm travelling from Amsterdam, to Bangkok, via Helsinki. Bought a ticket with Finnair. I filled in the web form, and as it said "One first name is enough" (as also laid out ), I foolishly didn't fill in my middle name.  My first name and last name are correctly filled in. My passport has both my first name and my middle name under "Given names", which may cause confusion.  Is it OK? Seeing as I have a layover in Helsinki, it'd be even more stupid of me to be able to depart from Amsterdam, but not from Helsinki.  Can a name change occur?


Adding a time stamp when moving a file in bash

#!/bin/bash while read server <&3; do   #read server names into the while loop      if [[ ! $server =~ [^[:space:]] ]] ; then  #empty line exception     continue  fi    echo "Connecting to - $server" #ssh "$server"  #SSH login     while read updatedfile <&3 && read oldfile <&4; do              echo Comparing $updatedfile with $oldfile         if diff "$updatedfile" "$oldfile" >/dev/null ; then             echo The files compared are the same. No changes were made.         else             echo The files compared are different.             # copy the new file and put it in the right location             # make a back up of the old file and put in right location (time stamp)             # rm the old file (not the back up)             #cp -f -v $newfile                  mv $oldfile /home/u0146121/backupfiles/$oldfile_$(date +%F-%T)          fi       done 3</home/u0146121/test/newfiles.txt 4</home/u0146121/test/oldfiles.txt done 3</home/u0146121/test/servers.txt   This is my whole script  mv $oldfile /home/u0146121/backupfiles/$_$(date +%F)   This moves the file correctly but it removes the actualy file name and just adds the date. I want to keep the original file name and add the current date to the file name.


Malformed line error fixed update/ upgrade errors:

I fixed the malformed line error in my sources list, and was able to run the sudo apt-get update and sudo apt-get upgrade. When I ran the update these errors came up:   W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release  Unable to find expected entry 'main/binary-i386/Packages' in Release file (Wrong sources.list entry or malformed file)      W: Failed to fetch http://archive.getdeb.net/ubuntu/dists/trusty-getdeb/apps/binary-amd64/Packages  403  Forbidden      W: Failed to fetch http://archive.getdeb.net/ubuntu/dists/trusty-getdeb/apps/binary-i386/Packages  403  Forbidden      E: Some index files failed to download. They have been ignored, or old ones used instead.   What should I do?  Then, when I ran the upgrade, these errors showed up:  The following packages were automatically installed and are no longer required:   account-plugin-windows-live libnvpair1 libupstart1 libuutil1 libzfs2   libzpool2 thunderbird-locale-en thunderbird-locale-en-gb   thunderbird-locale-en-us Use 'apt-get autoremove' to remove them. The following packages have been kept back:   cups-filters cups-filters-core-drivers grub-common grub-efi-amd64   grub-efi-amd64-bin grub-efi-amd64-signed grub2-common libldb1   liboxideqt-qmlplugin liboxideqtcore0 liboxideqtquick0 libsmbclient   libwbclient0 linux-headers-generic linux-headers-lowlatency   linux-image-lowlatency linux-lowlatency linux-signed-generic   linux-signed-image-generic openjdk-7-jre openjdk-7-jre-headless   oxideqt-codecs-extra python-cupshelpers python-ldb python-samba qpdf samba   samba-common samba-common-bin samba-dsdb-modules samba-libs   samba-vfs-modules shim shim-signed smbclient system-config-printer-gnome   ubuntu-minimal winbind 0 upgraded, 0 newly installed, 0 to remove and 38 not upgraded. W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages) W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages) W: You may want to run apt-get update to correct these problems   What should I do? Thanks!


Why should I use the keyword "final" on a method parameter in Java?

I can't understand where the final keyword is really handy when it is used on method parameters.    If we exclude the usage of anonymous classes, readability and intent declaration then it seems almost worthless to me.   Enforcing that some data remains constant is not as strong as it seems.    If the parameter is a primitive then it will have no effect since the parameter is passed to the method as a value and changing it will have no effect outside the scope.  If we are passing a parameter by reference, then the reference itself is a local variable and if the reference is changed from within the method, that would not have any effect from outside of the method scope.    Consider the simple test example below. This test passes although the method changed the value of the reference given to it, it has no effect.  public void testNullify() {     Collection<Integer> c  = new ArrayList<Integer>();           nullify(c);     assertNotNull(c);            final Collection<Integer> c1 = c;     assertTrue(c1.equals(c));     change(c);     assertTrue(c1.equals(c)); }  private void change(Collection<Integer> c) {     c = new ArrayList<Integer>(); }  public void nullify(Collection<?> t) {     t = null; }


A not-too-old, non-Asimov robot story with robots who are not bound by the Three Laws

This, for a change, is a rather recent (less than 30 years old) short story or novelette. Asimov's Three Laws of Robotics are prominent in it, but it was clearly written long after The Good Doctor's demise. In particular, not all robots are built in conformity with the Three Laws.  The future it describes is also influenced by Orwell's 1984. There are also three belligerent powers, with shifting alliances, but the names are a bit different. I forgot the name of the US block, but it was not Oceania which was at war against the US till shortly before the story itself. Now the US block's enemy is Eurasia, but the latter is Chinese dominated, not Russian/Soviet dominated (so the story is most probably post-1991). There is no mention of East Asia. Essentially it is Eurasia that makes non-three-laws robots.  In this context the main character is a NYPD cop. He is divorced and his wife, a very able robotician, has defected to Eurasia. The story really begins when his daughter is kidnapped and he suspects that Eurasian agents did it, and that his ex-wife is behind that. Which is mostly true      but for the fact it was not really a kidnapping, in fact his ex-wife convinced her daughter to come with her.   He finds Eurasian agents, some of which are non-three-laws robots, as per Eurasian usual standards, and is unable to overcome them. But he also has trouble with US secret agents some of which are also non-three-laws robots which should be illegal by US standard, except that Secret Services seem above the law. Beyond that it becomes so complicated that I have trouble telling what comes next.  I read it in French, but I am not sure whether it is a French original or a translation from English. I don't remember what kind of support that was. I remember there was some non-fiction together with it, about Asimov, his Three Laws of Robotics and their impact on SF, with the story put there as a example. Everything was in French.


Hi i'm making a function that checks if a number is a prime or not but its telling me that 9 is a prime.  def eprimo(num):     if num < 2:         return False     if num == 2:         return True     else:         for div in range(2,num):             if num % div == 0:                 return False             else:                 return True


I'm trying to make a table that is as wide as the textwidth singlespaced with etoolbox's \AtBeginEnvironment but that somehow gets rid of the \noindent that I issued before.    \documentclass{report}  \usepackage{array,setspace,booktabs,tabularx,etoolbox} \AtBeginEnvironment{tabularx}{\singlespacing\renewcommand{\arraystretch}{1.3}} \usepackage{lipsum} \begin{document} \lipsum[1-2] \noindent \begin{tabularx}{\linewidth}{ @{} p{3em} X @{} }  \toprule   Table  & Example \\   Table  & Example \\ \bottomrule \end{tabularx}   Any idea how to fix that?


creating the sequence 000,111,222 ... in c++

I want my std::cout  to print 000111222333 ..., but what i'm getting instead is 0111222333 ..., and i don't know why, here is my code:   int threeCounter =1; int outPut =0; for (int i =0; i<300;i++){      if(threeCounter > 3 ){         outPut++ ;         threeCounter=1;      }      cout << outPut << endl;     threeCounter++;  }   I tried the very same code in matlab, and it's producing the correct sequence:   threeCounter=1; outPut =0; for i =1:300      if(threeCounter >3)          outPut=outPut+1;         threeCounter=1;      end     disp(outPut)     threeCounter=threeCounter+1;  end


Why does mesh behave like mirrored in Edit mode without Mirror modifier?

This is probably a very simple question, but the Mirror modifier keeps mirroring my model though i've applied/deleted it.  I read somewhere that I have to disable symmetry lock, but I'm assuming that only works in Sculpt mode which I'm not using because I'm trying to make a low-poly model. I'm not entirely sure why this is happening because I've done it before and I didn't face any problems.  If i can get some help that would be great!


Why isn't glass transparency part of the exposure calculation?

The F number is a ratio calculated purely from the focal length of the lens and the size of the aperture. Any light meter talks in terms of F, Shutter, and ISO.   Different glass, or just different number of elements, is going to change the number of photons that get though the lens; we compensate for ND filters by adjusting F. What am I missing? Why aren't  part of exposure calculations?  In other words, I know what T numbers are, and how they differ from F-stops. What I don't know is why handheld light meters and related tools have no provision to take T into account, but talk only in terms of F.


Suppose I have a cube such as this:  This is a cube of 10x10x10 cm. I go into Edit Mode to extrude and then:  It says 1.27m but the cube isn't that high even after the extrude it wouldn't be this high. I guessed that maybe this is just 1.27 times the height of the cube but visually it doesn't look like it's 27% taller so I figured that's not the answer. I thus have two/three questions. What are these numbers? It obviously isn't the height of the original cube and it also obviously isn't the height the cube would have AFTER extrusion. How do I extrude to a certain height/depth/width?. Say my cube is 10cm high, then I extrude this straight upwards to 15cm then rotate that top surface by a few degree and extrude at an angle and I want to extrude it to exactly 20cm height (such that the final structure is exactly 20cm tall). How do I extrude to a certain amount in the direction of extrusion? Similar scenario but unlike extruding to exactly 20cm height I want to extrude 5cm into the extrusion direction (in which case the total height would be less than 20cm). I also have a few side questions because I'm a beginner but that are unrelated to the problem I have but why does scale change with dimension? If the cube is 0.1m and the scale is 0.05 then it'd be 5e-3 and not 0.1m?


What part of speech is "rested" in this sentence?

In the sentence, "I was well rested," is rested an adjective or a past participle?  Similarly, in the sentence, "Your room was organized," is organized an adjective or a past participle?


What is the mathematics definition of the F value in the ANOVA table?


After a Taiwanese citizen has visited the U.S. and returned to Taiwan,  how long must they stay in Taiwan before returning to the U.S. again?


I am having no idea how I can solve this problem.  I need help!  Here's the problem  $2x^4+x^3-11x^2+x+2 = 0$  I am learning Quadratic Expressions and this is what I need to solve, and I can't understand how :C


What do you call one who has been challenged?

How should I refer to one who has been challenged?  One who offers a challenge is a "challenger," but what would be the appropriate term for the person who receives the challenge?


Attempt to dereference null object error callout in salesforce

I am  getting attempt to de-reference null object error the below callouts.  class1:   public class ProcessImgCallout {      @future (callout=true)      public static void SendImage(ID id) {         system.debug('hello Mahesh '+id);          String endPointURL = 'https://cloud.ocrsdk.com/processBusinessCard?exportformat=xml';         String userName = '';// i removed username for security puropse         String password = '';//i removed password for security puropse         ContentVersion co = [Select id,pathOnClient,title,versionData  from ContentVersion where id =:id];         Blob img =co.versionData;          Blob headerValue = Blob.valueOf(userName + ':' + password);         String authorizationHeader = 'BASIC ' +            EncodingUtil.base64Encode(headerValue);         Httprequest request = new HttpRequest();         Http http = new Http();          request.setMethod('POST');         request.setEndpoint(endPointURL);         request.setHeader('Authorization', authorizationHeader);         request.setHeader('Content-Type', 'image/jpeg');         request.setTimeout(2 * 60 * 1000);          request.setBodyAsBlob(img);                    HttpResponse res = http.send(request);            System.debug('responseBody: '+res.getBody());          Dom.Document docx = new Dom.Document();         //docx.load(responseUrl2);         system.debug('@@@'+res.getbody());         docx.load(res.getbody());          //system.debug('$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ '+doc);         String taskId = docx.getRootElement().getChildElement('task', null).getAttribute('id', null);         system.debug(taskId);         gettaskStatus.GetStatus(taskId);     } }   Class2:  public class gettaskStatus {      public static void GetStatus(String id){         system.debug('hello mahesh i am with task id to get status'+id);         //String taskid=id;           String endPointURL = 'http://cloud.ocrsdk.com/getTaskStatus?taskId='+id;         system.debug(endPointURL);         String userName = '';//i removed username for security puropse         String password = '';//i removed password for security puropse         Blob headerValue = Blob.valueOf(userName + ':' + password);         String authorizationHeader = 'BASIC ' +             EncodingUtil.base64Encode(headerValue);         Httprequest req = new HttpRequest();         Http ht = new Http();          req.setMethod('GET');         req.setEndpoint(endPointURL);         req.setHeader('Authorization', authorizationHeader);         req.setTimeout(2 * 60 * 1000);         //req.setHeader('Content-Type', 'image/jpeg');            HttpResponse resp = ht.send(req);            System.debug('responseBody: to download url '+resp.getBody());          Dom.Document doc = new Dom.Document();         //docx.load(responseUrl2);         system.debug('@@@'+resp.getbody());         doc.load(resp.getbody());          //system.debug('$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ '+doc);         String resulturl = doc.getRootElement().getChildElement('task', null).getAttribute('resultUrl', null);         system.debug(resulturl);         GetLeadfromUrl.GetDownloadUrl(resulturl);      }  }   I am getting attempt to de-reference null object error in the second class can anyone please help me , how to fix this?  public class GetLeadfromUrl {     public static void GetDownloadUrl(String url) {          String ROOT_TAG = 'ocrsdk.com/schema/recognizedBusinessCard-1.0.xsd';;          // system.debug(url);         String downloadurl=url;         String newUrl=downloadurl.remove('amp;');         system.debug(newUrl);          String endPointURL =newUrl;           // ??     } }


I hate narrator. I realize it can be helpful for people that can't see well but I don't have that problem. I keep accidentally pressing whatever keys open it (I still haven't found out what it is) and losing focus on whatever program I had open. Is it possible to remove narrator from my computer forever?


How'd they do it: Millions of tiles in Terraria

I've been working up a game engine similar to , mostly as a challenge, and while I've figured out most of it, I can't really seem to wrap my head around how they handle the millions of interactable/harvestable tiles the game has at one time. Creating around 500.000 tiles, that is 1/20th of what's possible in , in my engine causes the frame-rate to drop from 60 to around 20, even tho I'm still only rendering the tiles in view. Mind you, I'm not doing anything with the tiles, only keeping them in memory.  Update: Code added to show how I do things.  This is part of a class, which handles the tiles and draws them. I'm guessing the culprit is the "foreach" part, which iterates everything, even empty indexes.  ...     public void Draw(SpriteBatch spriteBatch, GameTime gameTime)     {         foreach (Tile tile in this.Tiles)         {             if (tile != null)             {                 if (tile.Position.X < -this.Offset.X + 32)                     continue;                 if (tile.Position.X > -this.Offset.X + 1024 - 48)                     continue;                 if (tile.Position.Y < -this.Offset.Y + 32)                     continue;                 if (tile.Position.Y > -this.Offset.Y + 768 - 48)                     continue;                 tile.Draw(spriteBatch, gameTime);             }         }     } ...   Also here is the Tile.Draw method, which could also do with an update, as each Tile uses four calls to the SpriteBatch.Draw method. This is part of my autotiling system, which means drawing each corner depending on neighboring tiles. texture_* are Rectangles, are set once at level creation, not each update.  ...     public virtual void Draw(SpriteBatch spriteBatch, GameTime gameTime)     {         if (this.type == TileType.TileSet)         {             spriteBatch.Draw(this.texture, this.realm.Offset + this.Position, texture_tl, this.BlendColor);             spriteBatch.Draw(this.texture, this.realm.Offset + this.Position + new Vector2(8, 0), texture_tr, this.BlendColor);             spriteBatch.Draw(this.texture, this.realm.Offset + this.Position + new Vector2(0, 8), texture_bl, this.BlendColor);             spriteBatch.Draw(this.texture, this.realm.Offset + this.Position + new Vector2(8, 8), texture_br, this.BlendColor);         }     } ...   Any critique or suggestions to my code is welcome.  Update: Solution added.  Here's the final Level.Draw method. The Level.TileAt method simply checks the inputted values, to avoid OutOfRange exceptions.  ...     public void Draw(SpriteBatch spriteBatch, GameTime gameTime)     {         Int32 startx = (Int32)Math.Floor((-this.Offset.X - 32) / 16);         Int32 endx = (Int32)Math.Ceiling((-this.Offset.X + 1024 + 32) / 16);         Int32 starty = (Int32)Math.Floor((-this.Offset.Y - 32) / 16);         Int32 endy = (Int32)Math.Ceiling((-this.Offset.Y + 768 + 32) / 16);          for (Int32 x = startx; x < endx; x += 1)         {             for (Int32 y = starty; y < endy; y += 1)             {                 Tile tile = this.TileAt(x, y);                 if (tile != null)                     tile.Draw(spriteBatch, gameTime);              }         }     } ...


Is it possible to make a villager incapable of reusing or adding trades?

Using the Offers:{Recipes:... tag, you're able to /summon a villager with custom trades, and limits on those trades.  Problem is, once you start trading with that villager, he starts adding new trades, or reopening trades that previously ran out. Is there any way to prevent this?  That is to say, if my villager has exactly one trade with one use, for instance, can I prevent him from opening new, non-custom trades - or worse, reopening the custom one that should have had just one use?  I'd prefer to keep him around once his trades run out, and simply be unable to trade with him, but if it comes to /killing all villagers that don't have active trades, so be it.


How can I switch back to Hotmail from Outlook.com

My Hotmail has been switched to Outlook.com automatically and I do not like the Outlook at all. I just need to get my Hotmail back and tried to do the steps mentioned. I can't find the sentence on how to switch back to the old Hotmail?


Possible reasons why status report page is blank

I'm using Drupal 7.23 on my test site and since a couple of days the status report page is completely blank (no theme, no menu, nothing). No info shown at all. Other (report) pages are shown without noticeable issues.  Does anybody have an idea what could cause this? I have a almost similar 7.23 life site that shows this /admin/reports/status report perfectly.   Any log-file to check?


Can I buy a new house before selling my current house?

I am looking to sell and buy a house. But with the current market being as crazy as it is (houses are selling fast for sometimes 150,000 over asking), I'm afraid if we sell first, we could be stuck without a new house. Or stuck settling on or over-paying for something and wishing we never sold at all. I'm wondering if it's possible to buy first. What is the best way to secure my next house before selling my current house without getting locked into a B-lender mortgage or risking too much?  I know there would be some risk putting an offer on a new house without knowing how much the current house will sell for, or the risk we don't sell the current house before the new house closes. I'm also afraid conditional offers will not be considered. Are there any other options?  (We do have a mortgage on the current house, but because the market has gone up so much there is also a good chunk of equity.)


Observer inside event horizon of an extremely large black hole

Imagine a very large black hole, with a mass equal to a large number of galaxies.  Assume a space station is in orbit around the black hole some distance from the event horizon at a point A.  An astronaut in a ship, let's call him observer B, launches from the station toward the black hole.  I have been told (correct me if I'm wrong) that from observer B's point of view, he wouldn’t feel any effects from approaching the event horizon—at least as far as he could determine from inside his spaceship.  In fact, the visible event horizon, from his own point of view, would continually move away from him so that he could never actually reach it.  Is this correct?  If he were to watch the space station out his window, he would see it orbiting faster and faster.  He would see the space stations occupants racing around.  Eventually he would see many generations on the space station be born, live and die.  As he approached the event horizon (as seen by him or the original Schwarzschild radius as seen by A?), he would see stars born and die and eventually galaxies form move out and disappear.  He would see the entire life of the universe in an instant as he got ever closer to the black hole.  Is this correct?  Mathematically, the observer on the space station could calculate these relativistic effects.  In fact, observer A would calculate that on the other side of the event horizon, the space and time axes would actually be swapped relative to his own point of view.  Of course, he cannot see beyond the event horizon, so this would be a strictly mathematical exercise.    Now this is based on my reading of several books on general relativity.  If any of it is wrong, please tell me.  Otherwise, I’m assuming I’ve interpreted things correctly.  My thoughts turn to the following thought experiment.  Now, I do this thought experiment.  I imagine many stars and galaxies moving around inside the event horizon of this black hole (remember it is very large).  And I consider a layer S a fixed distance from the singularity, but located inside the event horizon as observed from some point, say our original station at A.  Let’s assume a person is located at a point P on the surface S.  Nothing between P and the singularity could be seen by this observer P.  Any light between the singularity and P would move inward towards the black hole, so the observer at P would see nothing but blackness if he peered in the direction of the singularity. True?   What I want to know is if observer P peered outward, toward the universe, what would he see?  I’ve been told due to gravitational lensing he would see all the light entering the event horizon concentrated somehow.  I also want to know what the stars and galaxies located inside the event horizon but outside the shell S would look like to the observer at P.  Is it possible that as he looked outward, he would be looking into the past?  Is it possible that he would see all of space limited to his little shell S, and points further out than P would be points in his past?  Is it possible that at the event horizon, he would see his entire shell contract to a point, as if it came from a big bang in his past?  And is it possible that the spacetime he is unable to perceive, between P and the singularity, appears to be in his future?  From his own point of view, he can’t perceive it, because nothing can reach him from that future (from closer to the singularity) without travelling faster than light.  I don’t know if any of this is correct.  Just something I’ve been thinking about and it could be totally out to lunch.


How do I disable keyboard shortcuts that switch tty's (on Ubuntu GNOME)?

I've installed Ubuntu GNOME 16.04, and there's one slight annoyance. When I press Alt+Left I get moved to tty1, and when I press Alt+F4 I get moved to tty4 - which were not what those shortcuts usually do.  I'm guessing that I'm running Wayland now and that that has something to do with it? Is there any way I can disable this?   Please note that I do not want to disable the tty's themselves - I'd like to still be able to reach them using Ctrl+Alt+Fn like before. I merely want to disable these new shortcuts.


Can I publish the games I learnt from tutorials and modified as per my style of game-play?

I am new to the world of making games and all. Well its been a few months or so. There are many tutorials that I have been watching. On the way, I made a few games that I saw and made. I am not asking about those. In fact I don't want to publish those games in my name ever. But then there are some small games that I made which are modified version from what I learnt of those games. Like I changed the game-play style, made it simpler and ignored some features from a game.  Can I publish them in play store? Or this would be any break of law or something? or Something that I should not do?


How the center of a non-cyclic free Group is trivial?

How can I show that "A center of a free group that is non-cyclic is trivial" ?


Antinormal subgroups of symmetric groups

Suppose $G$ is a group. Let’s call a subgroup $H$ of $G$ antinormal if $N_G(H) = H$, where $N$ stands for normaliser.  Any group is an antinormal subgroup of itself. For Dedekind groups this is the only possible antinormal subgroup.  Also a subgroup is antinormal iff the number of distinct subgroups conjugate with it is equal to its index.  A valid example of a proper antinormal subgroup is given by the "reflection subgroups" of odd dihedral groups $\langle b \rangle < \langle a, b| a^{2n + 1}, b^{-1}aba \rangle$.  However, my question is:     Is there some sort of classification of antinormal subgroups of $S_n$ for arbitrary $n$?   The ones that I see are the whole $S_n$ and its subgroups corresponding to the stabilisers of each point (there are $n$ of them, they are all isomorphic to $S_{n - 1}$ and pairwise conjugate; the index of each of them equals $n$). But maybe there is anything else…


How is this 'one colour' design trend referred to in the design community?

I had thought that the current trend towards 'one colour photos' was being called 'monochrome' but can't seem to find any examples.   The attached picture illustrates what I am referring to. The photo has been darkened and edited to match the colour palette of the website.    The technique is referred to in


Zoom in on a photo in Quick Look in macOS Mojave Beta

One invaluable Quick Look feature which I used to use pre-Mojave was pressing the "alt/option" button when using Quick Look to view a photo, which zoom in on the photo to its actual size. However, it seems like on Mojave this changes the orientation of the rotate button on the Quick Look toolbar, a feature I do not expect to use.  Is there an easy shortcut in Quick Look on Mojave, like the alt/option shortcut which existed pre-Mojave, which I can use to get back the old behavior, or has this useful feature been completely removed?


Im starting to learn a bit of xml and xslt, and I read on w3c W3Schools that they recommend you use elements instead of attributes. Whats your practice and why would you not want attributes -  is there any point where you want them really?


Aligning split equations to the left perfectly

Is there a cleaner way to align all equations to the left?  The code below generates this equation:     whose split-equations are not 100% aligned.  \documentclass{article} \usepackage{amsmath} \usepackage{breqn}  \begin{document}  \begin{equation} \begin{split} &\text{minimize \quad} Z(w) \\ &\text{subject to\quad }     f_1(w) \leq a_1\\ &\quad \quad \quad \quad \quad   f_2(w) \leq a_2 \\ &\quad \quad \quad \quad \quad \quad \quad \vdots\\ &\quad \quad \quad \quad \quad   f_m(w) \leq a_m, \end{split} \end{equation}   \end{document}


How do I change the default Chrome tab page?

How do I change the default new tab page in Google Chrome (version 41 on Win 8.1).  I want it to point to an HTML page on my own computer - the same page in fact as I am using for my home page.


Editing Gsettings unsuccesful when initiated from cron

I must have a blind spot, but I cannot find what it is.   I made a small python script that removes VLC from the sound menu. It runs perfectly in any way I run it from the terminal or from a launcher or whatever you can think of.   What the script actually does is nothing more than get the get the current settings:  gsettings get com.canonical.indicator.sound interested-media-players   edit the list, and set the changed list by:  gsettings set com.canonical.indicator.sound interested-media-players "['newlist']"   These commands are executed by a python script,. However, when run from a cronjob (crontab -e) only the gsettings - get - part works, but not the gsettings - set - section. That the get section works fine with cron, I checked by making the script write data (the original as well as the edited) to an external file.  Not a python problem  To see if the problem is related to python code, I created a bash script that applies a changed sound menu items list. The story is the same: the bash script runs fine from the command line or a launcher, not from cron, while any other command in the same script would run fine. Also, if I add any command at the end of the script below, it works fine and it looks like the script is satisfied with its own work.  Why is the gsettings set command not working when initiated from cron?  This is the script:  #!/usr/bin/python3 import subprocess  def read_soundmenu():     # read the current launcher contents     get_menuitems = subprocess.Popen([         "gsettings", "get", "com.canonical.indicator.sound", "interested-media-players"         ], stdout=subprocess.PIPE)     return eval((get_menuitems.communicate()[0].decode("utf-8")))  def set_current_menu(current_list): # this takes no effect from cron     # preparing subprocess command string     current_list = str(current_list).replace(", ", ",")     subprocess.Popen([         "gsettings", "set", "com.canonical.indicator.sound", "interested-media-players",         current_list,         ])  current_list = read_soundmenu() for item in current_list:     if item == "vlc.desktop":         current_list.remove(item) set_current_menu(current_list)


Which one is correct:   A child born today inherits a world vastly different from that of its parent’s generation. A child born today inherits a world vastly different from that of his parent’s generation.   I found the first version of the sentence in a book. But my humble knowledge of English language says it must be written his instead of its.  What do you think and why?  EDIT:  The posts given on  do not answer my question because all the answers refer to rudeness and anger such as in the accepted one: this is something that would be said only in the heat of anger. But the author of the book is not trying to offend anybody.


Yesterday my friends and I were solving this easy-looking question:  A metal cube is placed in an empty vessel. When water is filled in the vessel  so that the cube is completely immersed in the water, the force on the bottom of the vessel in contact with the cube: (A) Will Increase (B) Will Decrease (C) Will remain the same (D) Will become zero  At first we thought the answer to be (B) considering the buoyant force acting opposite to the weight of the cube. But then, a question popped up in my mind: "What causes this buoyant force even if no fluid was actually displaced?" So I referred to the Archimedes' Statement:  Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object. — Archimedes of Syracuse  But according to the question, no such fluid was displaced by the block ! So, here are my questions:  What is the basic reason behind buoyancy? Is it the pressure difference in fluids or the 'liquid-displaced' theory?  What must be the answer to the question (That I was solving) ?  Considering the case that you may say- "The reason behind buoyancy is the pressure difference in the fluids"; Will there be no buoyant force applied to the iron cube as there is no fluid layer present below the cube i.e. no pressure difference?   (Considering the iron cube is VERY dense and thus not allowing any fluid layer to push its way below it)  Or you might add another statement to the above question that-"Yes, buoyant force is applied as there is always a fluid layer present below it..." .Please do explain yourself.  If your answer is according to the Principle given by Archimedes of Syracuse , will there be no buoyant force on the cube as the cube didn't actually displace any fluid? Just like the case where you may consider it to be a part of the vessel itself.


I need some help with starting this problem. I am given that $$C=\left\{\left( \begin{array}{cc} a & b \\ -b & a \\ \end{array} \right): a,b\in\mathbb{R}\right\}$$ is a subring of the ring of all $2\times2$ matrices with real number entries, with respect to usual addition and multiplation of matrices. My task is to show that $C$ is isomorphic to the field $\mathbb{C}$ of complex numbers.


Proof that $\lim_{n\to\infty} n\left(\frac{1}{2}\right)^n = 0$

Please show how to prove that $$\lim_{n\to\infty} n\left(\frac{1}{2}\right)^n = 0$$


What's the easiest way to do a screen recording and get a small file?

I've used  before but for company things it's not appropriate since it becomes public. I need something that lets me record my screen and gives me a small well encoded file that I put into dropbox.  What's my options?


How do I clean up my layers after outlining strokes and dividing?

Hey all. So I'm creating a design in Illustrator. I want all of the shapes to have an even outline, but no stoke. In order to accomplish this I add the stroke and outline the strokes. Afterwards I divide all of the shapes in order to delete any overlapping shapes to create a clean gap in between all of my shapes. Is there an easier way to do this? The end result looks good, but I have to delete a lot of extra shapes in order to keep the design 1-color.  Thanks in advance.


Proof: in $\mathbb{R}$, $((0,1),|\cdot|)$ is not compact.

Let $(M,d)$ be a metric space, and $A\subset M$. By definition, $A$ is said to be compact if every open cover of $A$ contains a finite subcover.  What is wrong with saying that, in $\mathbb{R}$, if $I=(0,1)$, we can choose $G=\{(0,\frac{3}{4}), (\frac{1}{4}, 1)\}$, which satisfies $I \subset \bigcup_{U\in G} U$, but we can't extract a finite subcover, so $I$ is not compact. Is $G$ a finite subcover of $G$, so it is not a valid cover for proving this? I would take $\cup_{n\in\mathbb{N}} (\frac{1}{n},1)$ in order to prove this, can we conclude that every open cover is necessarily a infinite union of open sets $\neq \emptyset$?


Making sense of a bijection between proper classes?

I am trying to solve the following problem in ZF: "Show that the collection $\{\kappa \ | \ \kappa=\aleph_\kappa\}$ is a proper class. My thinking is that in the construction any element of this collection, one takes an arbitrary ordinal $\alpha$, and that therefore one might be able to show it is a proper class by showing that there is a bijection between the class of all ordinals and the class given above, since the class of all ordinals is a proper class.  However, I'm not sure how to fully make sense of the concept of a function between proper classes, since a function is normally defined as being between sets. Is this a valid line of reasoning, and if so, how does one formalise this using the axioms of ZF?


Why do attribute references act like this with Python inheritance?

The following seems strange.. Basically, the somedata attribute seems shared between all the classes that inherited from the_base_class.  class the_base_class:     somedata = {}     somedata['was_false_in_base'] = False   class subclassthing(the_base_class):     def __init__(self):             print self.somedata   first = subclassthing() {'was_false_in_base': False} first.somedata['was_false_in_base'] = True second = subclassthing() {'was_false_in_base': True} >>> del first >>> del second >>> third = subclassthing() {'was_false_in_base': True}   Defining self.somedata in the __init__ function is obviously the correct way to get around this (so each class has it's own somedata dict) - but when is such behavior desirable?


How to find the maximum and minimum value of $\left|(z_1-z_2)^2 + (z_2-z_3)^2 + (z_3-z_1)^2\right|$ (where $|z_1|=|z_2|=|z_3|=1$)?

How to find the maximum and minimum value of $\left|(z_1-z_2)^2 + (z_2-z_3)^2 + (z_3-z_1)^2\right|$ (where $|z_1|=|z_2|=|z_3|=1$ are complex numbers.) ?  My try:  $$\begin{align}\left|(z_1-z_2)^2 + (z_2-z_3)^2 + (z_3-z_1)^2\right| &\leq |z_1-z_2|^2 + |z_2-z_3|^2 + |z_3-z_1|^2 \\ &\leq (|z_1|+|z_2|)^2 + (|z_2|+|z_3|)^2 + (|z_3|+|z_1|)^2 \\ &\leq 2^2+2^2+2^2 \leq 12\end{align}$$  However the answer given is $8$. Where am I going wrong and how to do it correctly?


Geometric intuition about continuous and uniform continuous functions

I'm looking for a geometric way to identify functions that are continuous but not uniformly continuous without using the definition. I can't really put my hands on a concrete difference between the two.


Removing "." from number-strings in dataframe using regex deletes all from it

I have downlaoded data from SAP and trying to do ETL. Data set looks like below.  11.780,00 13.824,00 0,00 33.024,00   I am trying to remove "dot" first and then replace "comma" with dot The following code makes the whole column as blank (everything just vanishes) It's just a simple regex replace statement sales = sales.withColumn('gross', regexp_replace('gross', '.', ''))  Again when I try as below sales = sales.withColumn('gross', regexp_replace('gross', '.', ':')) output looks like below  :::::::::::::  How do I handle this conversion. It's bit weird. Thanks.


Titanium in Body. Should I be careful of anything?

I have an all titanium wire mesh underneath my eye due to a car accident. It is supposed to be MRI and X-Ray safe and I have traveled with it once before. I usually avoid informing security beforehand in order to avoid additional security checks and confusions.   Is there something I should be worried about health-wise at airports or at security checks wherein it would be a better decision to inform them beforehand rather than running into some medical issues?


Forgot to add one year old child's details while booking an Indian Railways ticket

I had booked a ticket for travel through Indian Railways using IRCTC and got a confirmed ticket. While booking, I forgot to mention the details of a one year old child who will also be traveling.     Will it create any problem while boarding the train?


How does one prove by induction that  $n! > n^2$  for $n \geq 4$


Note - To avoid duplication, I have referred the related .  Many a time, it happens that I put milk on the stove and forget about it while doing other work. So, milk always boils over. What can be done to prevent the milk overflowing the pan?


My machine is unable to play any video format. Error is:  Videos requires to install plugins to play files of the followings  types:MPEG-1 Layer 3(MP3) decoders, MPEG-4 Video decoder.


When a metal or rubber is bent and deformed, it heats up. What is the reason for this? I know that when deforming it, work is done on the object. If the object is perfectly elastic, all of the energy is stored as elastic potential energy, which is released when the stress is removed. But if it not perfectly elastic, by energy conservation, some of the energy is dissipated as heat. By what mechanism does the energy stored due to compression/stretching of chemical bonds (e.p.e) end up increasing the temperature (proportional to avg translational k.e of molecules)?


Why is my camera so forgiving for overblown exposure when shooting in RAW?

I've found that my camera (Sony A99) is very forgiving in terms of overexposure when shooting in RAW. By that I mean, I can overexposure by a stop or so and when I get home for the post processing I can underexpose it back and get all the details back.  Of course this wouldn't work in jpeg. There's no data beyond the right most area of the histogram. But not the same with RAW, data magically come back into the histogram. Why? Does the camera reserve an area of the histogram from me in case I make mistaken? If so, doesn't this mean some latitude is lost if I were to shoot correctly (perfectly exposed)?  Also, why is this only available for overexposure? But not underexposure? I don't think I'll be able to pull details out of crushed black areas.


I want to increase the number of vertices in a cylinder I have a version of 2.90 in blender. Does anyone know how to do this?


I have an ETL/database server running on a 16.10 system. I get errors when trying to apt install packages so I’d like to upgrade. Is it safe to do so?  It looks like I need to run commands to edit files.   Database has streaming replication and I rsynced all of my files (I hope) to another system.


Prove that the row-space and column-space of A have that same dimension via the below specific steps

Let A be an mxn matrix with entries from a field.   Our objective is to prove that the row-space and column-space of A have that same dimension i.e. the same rank.  a)   b) As a follow on from part (a) Suppose that A is in reduced echelon form. Use part (a) to show that its row-space and column-space have the same dimension.  c) Show that if A′ is obtained from A by an elementary row operation, then the row-space of A′ is equal to the row-space of A.  d) Give an example showing that if A′ is obtained from A by an elementary row operation, then the column- space of A′ is not necessarily equal to the column-space of A.  e) Suppose that A′ is obtained from A by an elementary row operation. Show that a collection of columns of A is linearly independent if and only if the corresponding collection of columns in A′ is linearly independent. More precisely show that if c1, . . . , cn are the columns of A, c′1, . . . , c′n are the columns of A′ and J ⊆ {1,...,n}, then {ci : i ∈ J} is linearly independent if and only if {c′i : i ∈ J} is linearly independent.  f) Conclude that the row-space and column-space of A have the same dimension.


Confidence interval for the "shift parameter" of a non-central exponential distribution

Suppose that $X_1, X_2, \ldots, X_n$ (with $n > 0$) is a random sample from a non-central exponential distribution with probability density function:  $$f(x | \lambda, k) = \lambda * e^{-\lambda*(x-k)}$$    Both the scale parameter ($\lambda$) and the shift parameter ($k$) are unknown, with: $k < x < \infty$ and $\lambda > 0$ .  For the previously mentioned sample ($X_1, X_2, ... , X_n$) and $k$, the maximum likelihood estimate (MLE) is:  $$K = min_i X_i$$     Question : how would a $95\%$ confidence interval (for the shift parameter, $k$) look like ? I'd imagine it must be something like $[K-\epsilon, K]$, but how can we figure out the value for "$\epsilon$".  Thank you !


How to navigate to C drive in bash on WSL-Ubuntu?

I've installed bash on Ubuntu on Windows feature on Windows 10 and I want to change directory this path on my C:\ drive:  C:/wamp64/www    What should I do ?


Unit $d$-sphere looks locally like $\mathbb R^{d-1}\times\{0\}$ under a suitable diffeomorphism

If $k\le d$, then $M\subseteq\mathbb R^d$ is a $k$-dimensional $C^\alpha$-submanifold iff for all $p\in M$, there is an open neighborhood $U\subseteq\mathbb R^d$ and a $f\in C^1(U,\mathbb R^{d-k}$ with $M\cap U=\{f=0\}$ and such that ${\rm D}f(x)$ has full rank for all $x\in U$. Now there is an equivalent definition which states that $M$ is a $k$-dimensional $C^\alpha$-submanifold iff for all $p\in M$, there is an open neighborhood $U\subseteq\mathbb R^d$ and a $C^\alpha$-diffeomorphism $F:U\to F(U)$ with $F(M\cap U)=V\cap(\mathbb R^k\times\{0\})$. Now consider, for example, the unit sphere $M:=S_{d-1}=\{x\in\mathbb R^d:|x|=1\}$. Considering $$f(x):=|x|^2-1\;\;\;\text{for }x\in\mathbb R^d,$$ it's easy to see that $M$ is a $(d-1)$-dimensional $C^\infty$-submanifold and $f$ is as in the first definition.  How does the corresponding diffeomorphism from the second definition look like?


I have problem with passing values to event listeners inside for loop.  for(var i = 0; i < 5; i++) {     btns[i] = document.getElementById("exercise"+i);     btns[i].addEventListener("click", function(){ alert(i); });  }   Script alerts last 'i' value instead this one inside loop. I think there is easy solution, but somehow I'm stuck and I want to improve my code.


Windows freezes sporadically. Audio plays back after unfreezing

Description:  I have a desktop that I assembled myself about 1.5 years ago. Recently it has started to freeze occasionally. I haven't noticed a particular application that triggers this to happen. I've had it freeze while just running Chrome and also when I'm multitasking and running Starcraft 2.  Symptoms:  System is completely unresponsive. Mouse won't move and Ctrl+alt+del doesn't do anything. After around 3 minutes, system unfreezes. Audio that was playing at the point when my computer froze is now played back. Eg. I was on a Skype call and the computer froze suddenly, cutting off the audio. When it unfroze a couple minutes later, I heard another 5 seconds of audio from the call that was cut off when the computer froze.  The computer seems to work fine after it unfreezes. No error messages and no critical events in the event log.  Computer components:   Gigabit Z77 motherboard Intel I5-2500K CPU Crucial M4 SSD Sapphire HD6770 video card   Running Windows 7 Pro


How to get this bonus 100 XP? NOT excellent throw!

Not first time bonus, not using lucky egg.  It happened to me twice today.  Can anyone tell me how this can happen so I can try to do it to level up faster?


Python 3 - Global Variables with while loops

I have been trying to write a Python script that uses global variables. I am getting what seems to be unexpected results in my code. Instead of dumping all the code here, I have created a small piece of code to show what I'm seeing.  def func1():     global aaa     aaa = 1  def func2():     while aaa < 5:         print(aaa)         aaa += 1  func1() func2()   I am expecting to get,  1 2 3 4   What I get instead is,  Traceback (most recent call last):   File "test2.py", line 11, in <module>     func2()   File "test2.py", line 6, in func2     while aaa < 5: UnboundLocalError: local variable 'aaa' referenced before assignment   If I change func2 to remove the while loop & just print the aaa variable, it works fine, so the global variable is accessible.  def func1():     global aaa     aaa = 1  def func2():     print(aaa)  func1() func2()    Running it produces,  1   If I set the aaa value at the top of func2 it also works.  def func1():     global aaa     aaa = 1  def func2():     aaa = 1     while aaa < 5:         print(aaa)         aaa += 1  func1() func2()   Which results in,  1 2 3 4   I have experience with Perl, but am new to Python. Is there something that I'm missing here?


unzip the latest zipped file from a list of zipped files

I want to write a script which gets the latest file from a list of zipped files and then unzip the file  I have tried ls -t1 |  head -n 1 -exec unzip {} -->  to get the latest zipped file. and unzipping it but it is not working


Don't understand why UnboundLocalError occurs (closure)

What am I doing wrong here?  counter = 0  def increment():   counter += 1  increment()   The above code throws an UnboundLocalError.


What is the order of $g^r$ in terms of order of $g$?

Let $G$ be a finite group. Suppose $g \in G$ has order $o(g)$ and let $r$ be a divisor of $o(g)$, what is the order of $g^r$ ?   I’m able to find answers that give me what I think I need but its difficult for me to decipher all the notation and precisely what the answers are trying to tell me  What I know is:    Order of $g$ is the minimal $m$ such that $g^m=e$. $r|m$ , so there exists a $k \in \Bbb Z$ st $m=kr$ I conclude that $g^{rk}=e$ with $rk=m$, thus $r=m/k$ So the order of $g^r$ is $m/k$   I just doubt every abstract Algebra thought I have, so naturally I feel that this is incorrect.  Any Thoughts? Thanks!


Does someone know if there already is a WhatsApp Version for Ubuntu Phone? I decided to install Ubuntu on my Android, but I don't want to use my phone without WhatsApp.


Ecological tale of a world covered by a forest that is all one organism

Interstellar explorers have discovered what looks like a very suitable planet for human colonization. The climate is good, there are no pathogens, and a beautiful forest grows abundantly. A charming aspect of the flora is that leaves can detach themselves and fly off like flocks of multicolored butterflies. When they land on humans, the fliers take a tiny genetic sample as a sort of hello. Some of the biologists at the research station are disturbed that this idyllic scene will soon be plowed under.   To make the planet ready for settlers, an island has been cleared of native vegetation and inroads are being made on the mainland as well. But the forest that covers the mainland resists mightily, creating solid rings of wood around cleared areas that are planted with terrestrial vegetation. And it's hard to keep an area cleared when the trees can distribute themselves as flying leaves. The woody rings can be blasted open to allow terrestrial plants a foothold, but more rings form, and from the air the scars are very evident.  The forest is really all one organism. Eventually a pair of characters finds it possible to communicate chemically with this world-straddling forest. In the process, they become symbiotic with it.  I probably read (and reread) this story in an English-language anthology during the 70s, a time when ecologic concepts were becoming widespread in science fiction.


Run a Autolaunched Flow with Trigger type Scheduled

I have a flow as described in the title. If I click on the 'Run' button i receive the following error:  The flow failed to start because the provided values were not valid: Scheduled Flow could only be run from a schedule   If i try with the following code:  Map<String, Object> params = new Map<String, Object>(); Flow.Interview.FlowName thisFlow = new Flow.Interview.FlowName(params); thisFlow.start();   I receive the same error (as expected):  System.FlowException: The flow failed to start because the provided values were not valid: Scheduled Flow could only be run from a schedule   I tried also this way:  System.schedule('my flow ' + String.valueOf(Datetime.now()), nextFireTime, thisFlow);   and I receive the following:  Method does not exist or incorrect signature: void schedule(String, String, Flow.Interview.FlowName) from the type System   What's the proper way to run such flows?  EDIT: I tried to run the flow as explained in another question creating this class   public class ChargentRecurringInjector_Scheduler implements Schedulable {      public void execute(SchedulableContext sc) {         Map<String, Object> params = new Map<String, Object>();         Flow.Interview.Chargent_recurring_injector_for_scheduledBatchProcessing thisFlow = new Flow.Interview.Chargent_recurring_injector_for_scheduledBatchProcessing(params);         thisFlow.start();     } }   and executing it via System.schedule(...); but, from my developer logs I still can read the same error : "The flow failed to start because the provided values were not valid: Scheduled Flow could only be run from a schedule"


Why don't players get extra xp for large encounters?

Based on the table Encounter XP Multipliers from the Basic Rules' DM section, Page 57, when you're building encounters in 5E, you include an XP modifier depending on the number of creatures your PCs will be fighting: 1.5x for a pair, 2x for 3-6 and so on. However, the PCs only get the base XP as a reward.     This doesn't change the actual xp reward ... just your calculations of how difficult the encounter is.   Why is this? After acknowledging that battles vs multiple opponents are more difficult, why not reward them as such?


How were the voltages/frequencies of mains defined?

In other words, are there any historical reasons that set mains supply voltage to 120, 127, 220, 240Vrms per phase, and 50/60Hz? These are the most common voltages/frequencies, there are many others, depending on country. Here in Brazil a single phase is always 127Vrms/60Hz.


I just bought a house and want to replace the locks. Unfortunately, on door has what appears to be an older Schlage double cylinder deadbolt that I can't figure out how to remove. I've tried prying faceplates off with no success. Internet searches talk about screw caps but these don't seem to be capping anything and I can't pry them out. I tried going in from the door edge, but the plate there seems to be attached to the inner mechanism and I couldn't get it out. Does anyone know how I can remove this lock with destroying the door? Image of the inside attached. The outside looks the same but without the two depressions on either side of the key.


Cannot start Eclipse from Unity Launcher

I downloaded Eclipse Juno package, and extracted it to /opt directory. For installing it, I followed the steps given in this site -  under the User Installation section. I created the opt_eclipse.desktop file in /usr/share/applications/ directory. Here is the content of my desktop file:  [Desktop Entry] Type=Application Name=Eclipse Comment=Eclipse Integrated Development Environment Icon=eclipse Exec=eclipse42 Terminal=false Categories=Development;IDE;Java; StartupWMClass=Eclipse X-Desktop-File-Install-Version=0.20   Then I installed the desktop file on Unity using the following command, as given in :  sudo desktop-file-install /usr/share/applications/opt_eclipse.desktop   Then I created the symbolic link using the below command:  sudo ln -s /opt/eclipse/eclipse /usr/local/bin/eclipse42   I also moved the icon to the pixmaps folder using the below command:  cp opt/eclipse/icon.xpm /usr/share/pixmaps/eclipse.xpm   Now, when I go to Unity, I can find the Eclipse Icon. But, when I click it, nothing happens. It doesn't get started. I'm completely new to Ubuntu. Did I miss something out there?


As Java intermediate programmer how can i contribute to Ubuntu?

I'm intermediate Java programmer and C at beginner level, I'm willing to contribute to Ubuntu, how can I start and where to start from?   Pls explain me in detail.Interested in small projects.


How to copy all text and exe files in a folder [windows]

Is there any way to copy all .text and exe files in folder?  like,  cp *.[exe|txt] c:\temp


I have a tex-document with some text and a folder with plantuml diagrams.  I need to import diagrams into a document.  I've tried to use plantuml package - . It works pretty well for me. Yet, it works only when I paste uml text inside my document manually.  Is it possible to use that package to import files by path? Or, should I use another package? Or, maybe, should I use Lua for my task?  I'm quite new in TeX %)  My restrictions:   path contains spaces, e.g. "../folder name/file name with spaces.md" plantuml file is a markdown file with injected uml syntax, e.g. (of course, dashes without spaces in original files)   ` ` `plantuml @startuml skinparam BoxPadding 30 ... @enduml ` ` `   Either include or import doesn't help me :/ Maybe, I do smth wrong with TeX.


Getting the correct IDs of the maximum values for each group of rows

From a simple table with three rows (id, status, value), I would like to retrieve the id and the value from the row with the maximum value, for each status group.  The simple query I tried is:  SELECT t1.status, t1.id, MAX(t1.value) FROM t1 GROUP BY t1.status;   The problem is that I do get maximum value for each group, but not the correct id. I get the the id of the first row from each status group... Is there a simple way to get the proper id?  There are many questions about getting the maximum value, but aren't many about the id. Couldn't find an answer for that one..


Verifying no argument and private methods using Mockito

I am new to JUnit & Mockito, the below class is defined with a method execute which needs to be tested, I wonder is it possible to mock this type of class ? Please shed some light and share your thoughts.  public class MyRule implements SuperRule{       private OrderList orderList;   private ScheduleList scheduleList;    public MyRule (OrderList orderList, ScheduleList scheduleList) {     this.orderList = orderList;     this.scheduleList = scheduleList;   }    @Override   public void execute() {     createWeeklyClassificationRule(orderList);           handle(scheduleList);    }         private void createWeeklyClassificationRule(OrderList orderList) {    //......   }         private void handle(ScheduleList scheduleList) {      //......         } }


Is it reasonable to estimate the CDF of a random variable with the help of kernel density estimation?

Given a set $S$ of samples from a random variable $X$ with pdf $f$ and cdf $F$, is it reasonable to estimate $F(x)$ by finding an estimation  $\hat{f}$ of $f$ via kernel density estimation on $S$, and calculating, using an appropriate numerical integration method, $\int_{-\infty}^{x}{\hat{f}(z)}dz$?  What I mean by "reasonable" is this: would there be any sort of general characteristics of $X$ (e.g., a high kurtosis of its pdf) that would ensure this estimate to be better than the one obtained via the empirical distribution of $X$ implied by $S$?


For the equation:  The indefinite integral of $\frac{1}{x^4+1}$ My question is, without partial fractions to turn this into "integrable" form what can I do?   Is it algabraically possible to manipulate this to fit any of the standard integration rules?  Possibly letting $u=x^2$, giving $\frac{1}{u^2+1}$.  Thanks


Does zeroing a drive equivalent to 'Nuke it from orbit'?

Say I have two OS on my computer, one is Windows, and another is Ubuntu.  My Windows apparently has been infected by nasty malware, and it currently making it unusable. However Ubuntu doesn't seem to affected by the occurrence of malware.  People suggest to 'nuke it from orbit'  to banish the malware, I guess this is effective.  If I run dd if=/dev/zero to my main hdd, does that also count as nuke it from orbit?  will that get rid of malware?


Prove that $\forall\alpha\geq\omega$, $|L_\alpha|=|\alpha|$ without AC

Without using Axiom of Choice, prove that $$\forall\alpha\geq\omega,~~|L_\alpha|=|\alpha|,$$  in which $\alpha$ is an ordinals, $\omega$ is the set of natural numbers, $L_\alpha$ is the $\alpha$-th constructiable set, $|x|$ is the cardinals of $x$.  I am learning a set theory, and I have read a proof by using AC. The AC is used only when $\alpha$ is a limit ordinals during the transfinite inductive method for $\alpha$ . I wonder if there is a proof without AC. 　THANKS!


Keep "Employee" on the profile of SE employees on meta

Currently, SE employees are given diamonds wherever they need them. I agree with  on this to some degree, employees shouldn't be treated any different.  But... on meta, employees are different. They have the power to dole out official responses, and thus we should be able to differentiate between an employee and a normal user. Currently, only some employees have a diamond on MSO (see , ). This makes it confusing, especially when you see official-sounding posts like .  Now, giving diamonds to all employees on meta may not be the best solution to this. I don't think all employees want their precious inboxes spammed with all the suspensions that are doled out on meta, and other mod stuff. They won't really need the diamond powers either (though it wouldn't hurt).  So, I propose this:  Similar to how moderators have "Moderator" clearly on their profile    display "employee" on an employee's profile, along with the diamond if they have one. At least on meta.    It would imho be even better to display it on their usercards in some form, but that has already been shot down.  It would be even even better if non-MSO mods had greyed out diamonds, similar to , but that's just me wanting more shiny stuff ;-)


How to get file and upload to server using php jquery without form tag

How to get file and upload to server  folder and filename to database using php jquery without form tag using there id here's the code  <input type="file" name="upload" id="upload">


How to change camera movement speed on Path during animation

Im making a animation in blender that requires the camera to change speeds while moving along a path. I'm using the Curve/Path for the path. I need the camera to move at a certain speed going between 2 places, and then slow down while moving around something its focusing on.


Can you Refreeze baked/cooked chicken? How long can it stay in refrigerator after cooked?

.   Can you Refreeze bake/cooked chicken?   How long is cooked meat good in refrigerator?


If $m^*(E)=0$ show that $m^*(E^2)=0-Satisfactory Answer$.

If $m^*(E)=0$ show that $m^*(E^2)=0$ where $E^2=\{x^2:x\in E\};E\subseteq \Bbb R$.   EDITS(Please  don't close this): I did not get a satisfactory answer.So I posted my approach. Here is my approach:  Since $m^*(E)=0\implies \exists $ a sequence of intervals $\{I_n\}$ such that $E\subset \cup I_n$ and $\sum l(I_n)<\epsilon $ for all $\epsilon>0$.  Now since $E\subset \cup I_n\implies E^2\subset \cup I_n^2$ because let $x^2\in E^2\implies x\in E\implies x\in I_n$ for at least one $n\in \Bbb N\implies x^2\in I_n^2\subset \cup I_n^2$.  Also $l(I_n)<\sum l(I_n)<\epsilon\forall n\in \Bbb N\implies l(I_n^2)<\epsilon^2\implies \sum l(I_n^2)<\epsilon^2\implies m^*(E^2)=0$.  Please help me to check whether it is correct or not .If not where are the loopholes in the proof.Please point them.


The advantages and disadvantages of using Kaiser Rule to select the number of principal components

Is the Kaiser rule (choosing only PCs with eigenvalues >1, ) a reasonable method to select the number of principal components to retain? What are its pros and cons?


Get Millisecond from January 1st 00:00:00:000 with Javascript

How would I get the millisecond from January 1st 00:00:00:000 (of this year) with Javascript? For example, January 1st 00:00:00:000 would give me 0 and December 31st 23:59:59:999 would give me 31536000000.


This might be awkward to ask but just wonder if by any chance one could inform me: I just like very much the font and the text style used in this report here  Could anyone by any chance tell me what usepackages and font need to be used to get this type of output? Thanks so much.


Solving system of linear equations ( 4 variables, 3 equations)

Finding the solution(s) for:  $$ \begin{align*} \begin{cases} 2x_1+x_2+3x_3+2x_4 &=5\\  x_1+x_2+x_3+2x_4&=3\\ -x_2+x_3+6x_4&=3 \end{cases} \end{align*} $$  I tried using elimination to rewrite the system in row echelon form, then back substituting. I have no idea what I did wrong, or if I was doing the elimination process correctly.. but I kept getting stuck. I am confused and not really sure how to proceed, I must be awful because I've been staring at this problem for hours.


Writing an awk script that reads variable from command line

I am trying to write an awk script that can read a users input from command line and store it as a variable.  I know that if I compile from command line and do   ./myawk.awk -v ID=4 text.sql   ID will be a variable set to 4. However, the input test cases I am given for my script are just   ./myawk.awk ID=4 text.sql   The final goal of the script is to take an ID, find any line that begins with   -- ID   and print the following line. What I have so far is   #!/bin/awk -f {   if ($1 ~/--/ && $2 ~/^ID/){     x = NR+1   }   while (NR <= x){     print $0   } }   How  would I able to read the variable ID without altering the line and adding -v before it, as well maybe give me advice on my current awk script.


I've been breeding a lot of Pokemon recently and I've been doing the loop around the Battle Resort, which led to me wondering: what is considered to be a step in the Pokemon breeding world?    Is it now calculated through how long you've been walking or how many steps you've taken? I ask this because on the Battle Resort loop there are three sand pits that hinder how fast you go, does this also hinder my egg hatch time?   Any help is appreciated.


Bug with user removal and going over 200 point per day cap?

I've noticed from time to time that when a user is removed from the system that I'll receive a -10. However if I'm over the 200/day cap and this happens, any further upvotes do not count.                                                 This seems like a bug, where another of the skipped upvotes would now be counted?


Under what conditions are inactive users removed?

Today I noticed on one of the sites that I moderate that a user account was removed due to inactivity. What are the conditions for being removed for inactivity? I was not aware that this was grounds for account deletion, so I was surprised to see this.


I want to reset Ubuntu. I have searched it on Google many times and I am new to Ubuntu so I am wondering how to reset it without too much complication. I have already tried re-installing it but my computer will not boot from the DVD. I am using Ubuntu 14.04.2 LTS.  I want to completely delete everything and have it start like it did when it was originally installed. Completely erase everything and restart, reinstall, and reconfigure Ubuntu.


I am using ubuntu 12.04.presently I am having a booting problem relating busybox v1.18.5 and initramfs prompt

mount: mounting /dev/disk/by-uuid/02bc41cc-1e21-4700-a179-be2805a658c4 on /root failed: Invalid argument mount: mounting /dev on /root/dev failed: No such file or directory mount: mounting /sys on /root/sys failed: No such file or directory mount: mounting /proc on /root/proc failed: No such file or directory Target filesystem doesn't have requested /sbin/init. No init found. Try passing init= bootarg. BusyBox v1.18. (Ubuntu 1:1.18.5-1ubuntu4) built-in shell (ash) Enter 'help' for a list of built-in commands (initramfs)   Please suggest a way out. I am dual booting with windows 7 and I have many photos which I can not afford to lose.


Which user's password does `sudo` asks for?

$ ls -l /usr/bin/sudo -rwsr-xr-x 1 root root 136808 Jul  4  2017 /usr/bin/sudo   so sudo is runnable by any user, and any user who runs sudo will have root as the effective user ID of the process because the set-user-id bit of /usr/bin/sudo is set.  From      the most visible difference between sudo and su is that sudo requires the user's password and su requires root's password.    Which user's password does sudo asks for? Is it the user represented by the real user ID of the process?   If yes, doesn't any user can gain the superuser privilege by running sudo and then providing their own password? Can Linux restrict that on some users? Is it correct thatsudo asks for the password after execve() starts to execute main() of /usr/bin/sudo?  Since the euid of the process has been changed to root (because the set-user-id bit of /usr/bin/sudo is set), what is the point of sudo asking for password later?   Thanks.  I have read , but it doesn't answer the questions above.


How to create a complete directory structure with a single command?  By this question I mean, if I wanted to create a directory structure like below in one go using a command.  /abcd/efgh/ijkl/mnop/qrst/uvwx/yz/   then what command shall I use?


Does Michonne ever reveal who her pet walkers were?

So, Michonne's pet walkers: who were they, and where did they come from? Is it ever revealed?  I guess this question would be directed more towards the comic book fans, since the best answer in the show has been "they deserved what they got, they weren't human to begin with". Other that that she always clams up at the subject.  I have my theories, but because she is so reluctant to reveal anything about herself it's really difficult to put any stock in those theories...


C# .Net Windows Service with Windows Form Application

I'm a fresh novice on C# dev, and I need your knowledge for this case. Let me explain, I have to make running :   A windows service who watching a directory to do some job on files putted inside it A windows application, that expose configuration for this service, and a system tray icon to control this service   So i have these two projects done in the same solution, and I need now to make them work together. What is the way ?  I tried to add reference to the service in application, but it seems to not be the way and it's not working.


How to prepare for driving on the opposite side for the first time, after decades driving on the other side

Lessons-learned are appreciated  I am accustomed to driving on the right side of roads for several decades.  I will be required  drive on the opposite side of the road internationally in two weeks in Jamaica, whose population is characterized as aggressive-reckless drivers.  It is expected that the rental car company provide a car that is designed (right-hand drive) for the country  What can I do to prepare myself (ideally practice), to unlearn decades of reflex and minimize the chance of an accident? If you have gone through this (waited several decades before driving on the opposite side of the road), please indicate this in your response?


I have an iPhone 6s with iOS 10.  In the Photos app, there are Albums and each Album has a cover photo.    How can I change the cover photo of an Album?


How do I recover my old Clash of Clans (COC) game save & base?

I unintentionally and stupidly wiped my Clash of Clans game data. I went to Application Manager on my Android and clicked 'Clear data'. (I used this for fixes before and it never started a new game.)   Now, my level 60 or so base has been wiped as if was to start a new game. Have I doomed myself to starting again or is there a way in which I can retrieve my old game save? Maybe by contacting Supercell? I have a snapshot of my base.


Can a creature take turns as normal if they are inside an Antimagic Field while another creature casts Time Stop?

Time stop is a spell that stops time for other creatures, allowing one creature to take multiple turns in a row. It says:     You briefly stop the flow of time for everyone but yourself. No time passes for other creatures, while you take 1d4 + 1 turns in a row, during which you can use actions and move as normal.   Certainly, this is a magical effect. The spell causes the flow of time to stop for other creatures, and while you are taking multiple turns, no time flows for them. I imagine antimagic field can defeat it. The relevant text says:     Spells. Any active spell or other magical effect on a creature or an object in the sphere is suppressed while the creature or object is in it.   So, imagine combat between Annie, Tim, and Charlie. Ordinarily, initiative might look something like this:     Annie → Charlie → Tim   Suppose Annie casts time stop and rolled a 1 on their d4. Thus, they take 2 turns in a row. Initiative would look like this:     Annie → Annie → Charlie → Tim   Now imagine that Tim cast antimagic field, and following their turn, Annie casts time stop. Suppose they rolled a 1 on their d4 so that they can take 2 turns in a row. What would the initiative order look like?  Here are some possible resolutions I can think of, but none satisfy me totally:   Time stop defeats antimagic field. The initiative order is: Annie → Annie → Charlie → Tim. The reason this is unsatisfactory is that time stop shouldn't seem to prevail because it's a spell, and antimagic field defeats spells. Time stop cannot be cast while there is an active antimagic field, because there exists some creatures you can't stop time for. The reason this is unsatisfactory is there is no rule that prevents these two spells from being active at the same time. Also, since things like beholders exist, it's not unreasonable to say there is almost always an active area of antimagic somewhere in the world, and that means time stop can almost never be used. The caster of time stop and antimagic field take their turns as normal while everyone else is frozen in time. Thematically and narratively, this seems the most logical. So we go through the turn order, treating every turn Alice would have taken as one full round. For this scenario, since Alice takes two turns in a row, then we can imagine two rounds going by. Ordinarily, everyone but Alice takes a turn, but now we unfreeze anyone inside an area of antimagic. So initiative would be: Annie (time stop starts) → Charlie (frozen in time) → Tim (unfrozen) → Annie (time stop ends) → Charlie → Tim. The reason this is unsatisfactory is because we're advancing the "round count" now, which feasibly triggers things like lair actions that activate on a certain initiative count. It does have the side effect of allowing Tim to act normally though, affecting other creatures if he wants, because he isn't bound by time stop and Annie isn't the one doing the violations of the rules of the spell. There is no answer to this question, and this is solidly in the zone of DM adjudication. This is unsatisfactory because, well, all questions answered that way tend to be unsatisfactory.   So which is it? Or is it an option I haven't listed here? Can Tim take turns as normal while inside an antimagic field if Annie casts time stop?


If $G / Z(G)$ nilpotent then G is nilpotent.

Let $G$ be a group. If $G / Z(G)$ nilpotent, then prove that $G$ is nilpotent.   The way I have worked out this question is fairly tedious, and I would be interested if there is a more straightforward approach here.  I solved this problem by showing that if $G / Z(G)$ is of nilpotence class $k$, then $G / Z(G) = Z_{k}(G / Z(G)) = Z_{k+1}(G) / Z(G)$, the latter equality shown using a tedious induction proof. Then the conclusion readily follows.  Is there a different approach to this problem, or is there a short way to prove that $Z_{k}(G / Z(G)) = Z_{k+1}(G) / Z(G)$?


What do green folders mean in Windows 7 Explorer?

I downloaded a ZIP file and dragged the files out of the ZIP into a directory. The subdirectories I copied displayed in Windows Explorer in green instead of the default black.  What does the green folder text mean?    (In case you're wondering, the download was from )


Default gateway is 192.168.1.1 but can't access it with browser

I have a Zyxel P-870H VDSL modem, I"M trying to diagnose internet problems.   I have my computer computer plugged into it via ethernet. I'm able to access the internet, and ipconfig tells me that the default gateway is 192.168.1.1, and I'm able to ping that address,  but when I enter that into the browser, I'm not able to access the modem.   Any ideas?


Dell Latitude E6420 8GB memory showing as 3GB Windows 7

This is what RAMMON is showing; Ram Type    DDR3    Not Populated Maximum Clock Speed (MHz)   666.67 (JEDEC) Maximum Transfer Speed (MHz)    DDR3-1333 Maximum Bandwidth (MB/s)    PC3-42600 Memory Capacity (MB)    8192      This is what I see in Windows 7 task manager; physical memory (mb) total 3241 cached 433 available 498 Free 77  system information; installed memory 4gb (3.17gb usable)  32 bit operating system.  Is this normal? what's going on? Thanks.  Edit: thanks for the reponses. I am more asking about why is it only 3gb usable that I am seeing not the max 4gb for a 32bit OS? And see that it was answered by the first comments, thanks


A word meaning the general belief of a specific time period

I remember learning this in art history class but for the life of me I can't remember. The word is synonymous with common sense. Like the belief or thought was so widely believed that it was believed to be a given fact but only in that time period. For example, it was once common sense for people to have slaves. My searches in the thesaurus return results with words meaning "sound judgement" or of that nature which is what I'm not looking for. Im looking for a word that's more objective, almost clinical?


I want to disable comments on my pages. That means there should be no comment form, no message asking to log in in order to post comments, nothing.  Under Settings > Discussion is the option "Allow people to post comments on new articles." That implies that disabling comments on pages is possible, assuming that "article" means "post or page."  Unfortunately, a comment form still appears despite my unchecking this box. I thought that the option might be overridden on the page itself, but there are no relevant options on the page edit screen.  I really don't want to hack my theme when the facility to disable comments clearly exists already. How can I accomplish this?


I am making sauerkraut, and don't have a handy kitchen scale. What is the approximate volume of 1 lb of cabbage?  Also, any advice on saurkraut making would be appreciated. This is my second batch. The first one turned out very good, but I had to throw away that last of what was in the crock as it had mold on top.  I am using a Harsch Crock.


How can the speed of light be independent of the speed of the observer

First of all, I saw few similar questions here but most of them address the question of why, when I want to address a question of HOW. Also one question is addressing the same problem but I find it's formulation rather complicated and this makes it difficult to understand the question and answers. When the problem can be described and visualized in much simple way:  Let's consider a spaceship floating under the Earth. There is a source of light and at time 0s the light will reach some point on Earth and the end of spaceship:  Then, after 1 second have passed on Earth, we will see the following picture:   As we can see, relatively to the Earth the light have made a distance of 300,000 km in 1 second. But relatively to the spaceship the distance is half of that. When explaining how this can happen, usually they say that clock on the rocket will tick slower so speed calculated by folks on the spaceship is the same.   And it sounds believable until you imagine an other source of the light from an other end of the scene:  In this case by the same time the light from an other source have made a distance of 450,000 km. So if we use the same time as we did in previous case, the speed must be different.  So how can you imagine\describe the same speed for light from both sources and for both reference frames?


How do I make WPF ListView items repeat horizontally, like a horizontal scrollbar?

I have a WPF ListView which repeats the data vertically. I cannot figure out how to make it repeat horizontally, like the slideshow view in Windows Explorer. My current ListView definition is:  <ListView ItemsSource="{StaticResource MyDataList}" ItemTemplate="{StaticResource ListViewTemplate}"> </ListView>   The DataTemplate is (although I believe this should not matter);                                                                                <Rectangle HorizontalAlignment="Stretch" Margin="0,1,0,0" x:Name="rectReflection" Width="Auto" Grid.Row="1" Height="30">                     <Rectangle.Fill>                         <VisualBrush Stretch="None" AlignmentX="Center" AlignmentY="Top" Visual="{Binding ElementName=imgPhoto}">                             <VisualBrush.RelativeTransform>                                 <TransformGroup>                                     <MatrixTransform Matrix="1,0,0,-1,0,0" />                                     <TranslateTransform Y="1" />                                 </TransformGroup>                             </VisualBrush.RelativeTransform>                         </VisualBrush>                     </Rectangle.Fill>                     <Rectangle.OpacityMask>                         <RadialGradientBrush GradientOrigin="0.5,1.041">                             <RadialGradientBrush.RelativeTransform>                                 <TransformGroup>                                     <ScaleTransform CenterX="0.5" CenterY="0.5" ScaleX="1.202" ScaleY="2.865"/>                                     <SkewTransform AngleX="0" AngleY="0" CenterX="0.5" CenterY="0.5"/>                                     <RotateTransform Angle="0" CenterX="0.5" CenterY="0.5"/>                                     <TranslateTransform X="-0.002" Y="-0.491"/>                                 </TransformGroup>                             </RadialGradientBrush.RelativeTransform>                             <GradientStop Color="#D9000000" Offset="0"/>                             <GradientStop Color="#01FFFFFF" Offset="0.8"/>                         </RadialGradientBrush>                     </Rectangle.OpacityMask>                 </Rectangle>             </Grid>         </Border>     </DataTemplate>


What happens if two Divination Wizards try to affect a roll?

Does this interact like Lucky, wherein both Portent rolls cancel each other out and the original, untampered roll is used, or would the diviner that replaces the roll later, override the other that tried to replace the roll earlier?


How do I upgrade from 18.04.1 to 18.04.2

I follow all instructions in , and never see the chance to go to 18.04.2.  The command:  ubuntu-report show    "Install": {   "Media": "Ubuntu 18.04.1 LTS \"Bionic Beaver\" - Release amd64 (20180725)",     The update manager told me about 18.10 because I had changed the option to all updates instead of only LTS.  When I have it set to LTS, it shows nothing is available to update.      31: cat /etc/lsb-release     DISTRIB_ID=Ubuntu     DISTRIB_RELEASE=18.04     DISTRIB_CODENAME=bionic     DISTRIB_DESCRIPTION="Ubuntu 18.04.2 LTS"   As you can see, I do have 18.04.2.  I just can't figure out in the StackExchange UI how to say my problem is solved.  If someone could mark it as such, I'd appreciate it.


Do I cite introductory material in a subject that helped me indirectly?

I am writing my undergrad Bachelor's thesis in computational physics where I do C++ programming. In some C++ books, I read some things that were quite useful during programming, but they do not have a direct connection to the physics.  Since I was proficient with LaTeX before I started the thesis, I do not see a point in adding anything about that in the references. That is rather a skill than specific facts, and I did not really read about it during my research.  Another thing are resources that I consult for an introduction into a topic when I do not understand something in a paper. After reading that introduction material, I often understand the paper to a sufficient extent. When I then write the text, I think I could get by by only referencing the paper since it contains virtually everything needed. But it also seems wrong to omit that I read introduction material.   Should I cite sources like the C++ book? Should I cite introduction material like Wikipedia, websites or easy books?


Can you please refer a source that you consider to contain the most complete list of statements and theorems equivalent to the axiom of choice (over the axioms of ZF)?  I am already aware of most of the equivalent statements listed on the wiki page here:   I am most likely looking for a study or (maybe several) chapters of a book.


What does the expiration date on milk cartons mean?   I have different experiences with the date:    There is still about a week before the expiration date but the milk has gone bad  It is 1-2 days after the expiration date but the milk doesn't smell or taste bad   In both case, the milk was kept in the fridge.


HP Spectre x360 -- How to disable trackpad automatically when going into Tablet Mode?

The HP Spectre x360 is a "convertible" laptop, meaning it is able to bend all the way backwards to become a tablet. Whenever I do this, Ubuntu automatically disables the keyboard, which is nice. However, it fails to disable the trackpad. This can be very annoying. Is there any way I could fix this error?


When is a group isomorphic to a non-trivial quotient group of itself?

This question popped up as an exercise in a mathematics magazine. Thoughts are that we're looking at an infinite group but beyond that I'm stumped.  Any ideas/examples would be fantastic!


When do Commutative Rings with Identity lack the existence of gcd’s?

I’m aware that not all commutative rings guarantee the existence of gcd’s. The only example I have of this currently is the ring of even integers in which 2 has no divisors and therefore no greatest common divisor. I can’t, however, think of a commutative ring with identity in which this is the case. I know that such an example would need to not be a UFD since UFD’s guarantee the existence of gcd’s. Any ideas?


What is the reason for using "to" and "to the" before the word "church" in different parts of this passage?     On Sundays, we always went to church. After breakfast, the carriage took Ambrose and me to the church in the village. All the servants came to church too. On Sunday evenings, we had an early dinner. Usually, some of our neighbours would eat with us.   (, Daphne Du Maurie)


Show that a polynomial $f(x)$ over a field $k$ is irreducible if and only if the polynomial $f(x+1)$ is irreducible

I have literally no idea how to do this. I tried writing out $f(x+1)$ and rewriting it but didn't seem to get anywhere. I suspect I should use the degree of the polynomials but don't know how.


Going into dual space for a vector product

I am a bid confused regarding the notation for tensor products when going into dual-space  If $\left| \Psi \rangle \right. = \left| A \rangle \right. \left| B \rangle \right.$ is $ \left. \langle \Psi \right| = \left. \langle A \right| \left. \langle B \right|$ or $\left. \langle B  \right| \left. \langle A \right|$?  My guess is the last choice, since operators should act on   $\left| 0 \rangle \right. = \left( \begin{matrix}   1 \\   0  \end{matrix} \right) $  $\left| 1 \rangle \right. = \left( \begin{matrix}   0 \\   1  \end{matrix} \right) $  so  $\left| 01 \rangle \right. = \left| 0 \rangle \right. \left| 1 \rangle \right. = \left( \begin{matrix}   0 \\   1 \\   0 \\   0  \end{matrix} \right) $  But then, for me, it should be  $\left( \begin{matrix}   0 & 1 & 0 & 0  \end{matrix} \right) = \left \langle 10 \right|$ But this is not correct if i calculate the tensor product, since   $\left \langle 1 \right| \left \langle 0 \right| = \left( \begin{matrix}   0 & 0 & 1 & 0  \end{matrix} \right)$  For instance, shoulden't it be  $\left| 01 \rangle \right. \left \langle 10 \right| = \left( \begin{matrix}   0 & 0 & 0 & 0\\   0 & 1 & 0 & 0\\   0 & 0 & 0 & 0\\   0 & 0 & 0 & 0\\  \end{matrix} \right) $ ?  I hope I have made my confusion clear


Expand all \newcommand without doing anything else in LaTeX?

Can I expand all \newcommands without doing anything else in LaTeX?  Edited: My true goal is standardizing math papers in plain text so that theorems and definitions can be accurately and easily extracted without losing mathematical symbols.


Armijo rule intuition and implementation

I am minimizing a convex function $f(x,y)$ using the steepest descent method: $$\mathbf{x}_{n+1}=\mathbf{x}_n-\gamma \nabla F(\mathbf{x}_n),\ n \ge 0$$  My function is defined over a specific domain $D = \{(x, y) \in R^2 : 2x^2+y^2 < 10\}$, if my $x_{n+1}$ goes out of bound, my method diverge. I was told to choose $\gamma$ using armijo rule to stay inbound.   Can someone explain to me the method and also describe a pseudo code for implementing it?


I am performing an analysis in which the unit of analysis is a geographical area (more precisely, an ). This is a case when the sample analysed can represent the entire population (all 32000+ LSOAs in England). How do we interpret, in this case, the point and interval estimates of a, say, regression analysis?


Does TeX use Hookean physical springs to represent positive and negative glue?

What does \hskip 60pt plus 100pt minus 100pt mean? I used to think of this as a mechanical spring with natural width and some string constant k. But, I know that it is not exactly so, since the plus and minus need not be exact, and, also, the text box has maximal and minimal width, whereas a Hookean spring has infinite elasticity.  Now, the nice thing about Hookean strings is that they can be . Here are some questions:   Does TeX inner engine rely on this property to model several adjacent boxes as one? Does the physics of spring carry through to TeX? Did Knuth develop the math and physics of glue? Are there any instances in which \hboxes are connected in parallel? If TeX glues are likened to physical springs, what are TeX springs in the physical world?   If you do not like the springs analogy, the questions are then restricted to creatures created by \hbox and glues. Is it the case that the serial concatenation of two of these, cannot be represented with a single box with different glue?  More abstractly, what are the elasticity functions of compound creatures? Is it a  of some kind?


How can I associate Hit Dice with healing?

My first version of D&D was 4th Edition and one of the things that was new to me during the Next playtest period was the inclusion of Hit Dice (which I understand were present in earlier editions). On the surface, they seemed intuitive enough: Hit Dice are tied to how many hit points a character has overall.  However, I always seem to have trouble with Hit Dice in relation to healing. In 4e, healing means you expend a Healing Surge and regain a number of hit points equal to your Healing Surge Value. In Next/5e, the amount you heal is tied to your Hit Dice. While I guess it makes sense that you recover hit points based on your Hit Dice, it seems that I always have a mental disconnect when I want to heal (a positive thing) and I have to think about getting hit (a negative thing). I know it may sound trivial especially if you are one who intuitively gets it, but it has been a problem for me as I often waste 5 seconds or so searching my character sheet for "Heal Dice" or something similar before I remember that I'm looking for "Hit Dice".  To my disappointment, the name has remained Hit Dice through the playtest and into the final version. I've really tried to brute-force memorize this, but for whatever reason I have a hard time associating Hit Dice with Healing. Are there any tips, tricks, mnemonic devices, whatever that can help me and other 4e players remember this?