I am making a scene where I have balls pouring into a invisible container. The problem is these balls pass through each other which makes it unrealistic. I have tried searching for the 'Molecular Addon' by Pyroevil but it seems the website no longer exists. PLease help Thank you very much    to all those suggesting and giving me links to pyroevil I have told you it's not working for me all i see is this.

I have tried everything to fill an invisible container with particles but the particles just seems to sinks to the bottom and they don't fill the container. I am trying to create something like in the video below how balls take the shape and fill up the space i want to create something like this. Please help.  Edit : have also tried the molecular script but that doesn't seem to work as well.


I managed to create a Rest Apex Class that sends an emailmessage, attached to a given case. But unfortunately, the sent email lacks  the tag ref:_00D3X2nqVQ._5003X1tjFN0:ref I guess that's because I need to set a Thread Id, but I don't know how to do it  Manually created / sent eMailMessge do get the ref:_00D3X2nqVQ._5003X1tjFN0:ref appended to the body

There are many posts about creating Case threadIds with Apex, notably   As the posters have noted, the SFDC rules of the threadId are subject to change over time and the only reliable way that I've seen is to do   // To be replaced with a real case Id. Id caseId = '500c0000008kJL5';   List<Messaging.RenderEmailTemplateBodyResult> renderResults =   Messaging.renderEmailTemplate(null, caseId, new List<String>{'{!Case.Thread_Id}'});  System.debug('this is the Case Thread Id: ' + renderResults[0].getMergedBody());   HOWEVER ... The method call Messaging.renderEmailTemplate burns a SOQL ()  So you can't prepopulate your Cases in an afterInsert or beforeUpdate Trigger because a transaction can be up to 2,000 (Platform Events), up to 10,000 (direct Apex DML) or more, typically, 200 rows.  All of these are > 100 SOQL limit.     So, before I go to the trouble of doing this in a chained set of async   tasks; is there more recent thinking on this subject of creating ThreadIds?


I am currently writing a (mathematical) paper, which considers so called paths in graphs. The start of a path is usually denoted by the letter s and the end of the path is denoted by t. The whole path is then called "s-t-path" and my question is about which indefinite article to use with it.  The selected answer in  says to just use 'a' or 'an' according to how you pronounce what follows. This would imply that one should write "a s-t-path", because the s goes with a (a superhero, etc.). When I am actually using the construct in a spoken sentence, however, what I would be saying is "an s-t-path".  There are 39,700 google search results for "an s-t-path" versus 41,900 results for "a s-t-path", which is to show that this topic truly divides the nation ;-)

In the following example, is it appropriate to use a or an as the indefinite article, and why?     He ate __ green apple.   I know that in the case of just "apple", it would be "an apple," but I've heard conflicting answers for "green apple," where the noun is separated from the article by an adjective.  Also, which is more appropriate in this case:     He ate  __ enormous Pop-Tart.


Some questions tackle with this problem for general instances; however, in this case, all I see is just a value returned by a function. See by yourself:  The third line, (void) signal (SIGALRM, myAlarm); is supposed to execute the system call signal, which - if I understood correctly - returns a pointer to a function. Being it the general case, I can see why a function pointer is being cast to void; however, apart from C's implicit casting, that line itself does exactly nothing to the returned value "in memory" as it's simply a value. Am I missing something? Does (void) actually do anything in the third line (and for the rest of the program)? Even if the function pointer were to be of a different type than void, wouldn't the third line act only on the returned value, instead of a (hypothetically) stored one? In a few words, is it necessary or is it a redundancy?

int fn();  void whatever() {     (void) fn(); }   Is there any reason for casting an unused return value to void, or am I right in thinking it's a complete waste of time?  Follow up:   Well that seems pretty comprehensive.  I suppose it's better than commenting an unused return value since self documenting code is better than comments. Personally, I'll turn these warnings off since it's unnecessary noise.    I'll eat my words if a bug escapes because of it...


I build a client/server chat in java  and i want to end the connection if one of the client or the server send a "good buy" message  but that not what happened the connection still a live  The code in the client side:  import java.io.*; import java.net.*;  public class TCPClient {     public static void main(String[] args) throws Exception {         String message;         String recivedMessage = "h";          Socket clientSoc = new Socket("127.0.0.1",9999);          while(recivedMessage != "good buy") {             System.out.print("Client : ");             BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));             DataOutputStream outToServer = new DataOutputStream(clientSoc.getOutputStream());             BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSoc.getInputStream()));              message = inFromUser.readLine();             outToServer.writeBytes(message + '\n');              recivedMessage = inFromServer.readLine();             System.out.println("Server : " + recivedMessage);             if (recivedMessage == "good buy") {                 break;             }         }         if (recivedMessage == "good buy") {             System.out.println("Connection end");             clientSoc.close();         }     } }   The code in the server side:  import java.io.*; import java.net.*;  public class TCPServer {     public static void main(String[] args) throws Exception {         String Message;         String recivedMessage = "h";         ServerSocket welcSoc = new ServerSocket(9999);          while(true){             Socket serverSoc = welcSoc.accept();             while(recivedMessage != "good buy"){                 BufferedReader inFromClient = new BufferedReader(new InputStreamReader(serverSoc.getInputStream()));                 DataOutputStream outToClient = new DataOutputStream(serverSoc.getOutputStream());                 recivedMessage = inFromClient.readLine();                 System.out.println("Client : " + recivedMessage);                  System.out.print("Server : ");                 BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));                 Message = inFromUser.readLine();                 outToClient.writeBytes(Message + '\n');             }             if (recivedMessage == "good buy") {                 break;             }         }         if (recivedMessage == "good buy") {             System.out.println("Connection end");             welcSoc.close();         }     } }

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


I was trying to implement a genetic algorithm for the game 'tic tac toe'. How I am doing it at the moment is the following:   Initiliaze 50 random networks Let each network play against each network. After that, each network will have played 98 games (against each player on each side) the fitness of each network is calculated this way: fitness = wins + draws -loses Apply the genetic algorithm:  5.1. Select the 5 best networks by using their fitness value.  5.2. Copy these 5 networks onto the other 45 networks. (So 10 times the first, 10 times the second...)  5.3. Change p percent of the weights with a random gaussian multiplied with a factor of s.  if(p < Random(0,1)){     weight/bias += Random.gaussian() * s; }   My values that I am using right now is:  p = 0.05 s = 0.05   And my network is making decisions the following way:     I am using a minimax algorithm with a depth of 2 (not a lot, I know).   The evaluation of the board is being done by the network.   My problem right now is that it does not work as expected. When I play against it afterwards, it usually does stupid moves and let's me win or does not win itself when I let it.  I am very happy if someone could help me with this one.  Greetings, Finn

I'm training a neural network but the training loss doesn't decrease. How can I fix this?  I'm not asking about overfitting or regularization. I'm asking about how to solve the problem where my network's performance doesn't improve on the training set.    This question is intentionally general so that other questions about how to train a neural network can be closed as a duplicate of this one, with the attitude that "if you give a man a fish you feed him for a day, but if you teach a man to fish, you can feed him for the rest of his life." See this Meta thread for a discussion:   If your neural network does not generalize well, see:


I have been quite stuck on this problem and with the help of others, I may have solved it. This is what I have to prove.      $$\binom{N}{n+1}=\sum^{N-1}_{k=n} \binom{k}{n}.$$  So far I have this $${N \choose {n+1}}={{N-1}\choose{n+1}}+{{N-1}\choose n}.$$ by Pascals triangle. If I repeat this idea, I believe I end up with: $$={{N-x}\choose{n+1}}+{{N-x}\choose{n}}...+{{{N-1}\choose n}}$$For some $x$ such that $x=n+1$. But lets go one further.  $$={{N-x-1}\choose{n+1}}+{{N-x-1}\choose{n}}...+{{{N-1}\choose n}}.$$ But this reduces to $${{n}\choose{n+1}}+{{n}\choose{n}}...+{{{N-1}\choose n}}.$$ However $${{n}\choose{n+1}}=0$$. Therefore we are just left with: $\sum^{N-1}_{k=n} \binom{k}{n}.$ as desired.

Let $n$ be a nonnegative integer, and $k$ a positive integer. Could someone explain to me why the identity $$ \sum_{i=0}^n\binom{i+k-1}{k-1}=\binom{n+k}{k} $$ holds?


I have figured out how to place a selected item in a chest: /data modify block -255 71 97 Items[{Slot:0b}] set from entity @p SelectedItem  How do I place a selected item in a storage using /data modify storage ... ?

Version 1.14.4: I am trying to make a commands system that forces a player to drop whatever item is in their main hand. Because I can't use commands to make a player press Q and drop the original item, I need to copy the NBT into a new item on the ground and remove the old one from the player. I obviously want any NBT, including enchantments, names, lore, etc. to be copied over exactly.  I know that I can use /data to get the NBT from the SelectedItem of a player, and execute store can put NBT into an entity. However, /data get only returns numeric data, and execute store only allows me to set one NBT path at a time, so my plan of summoning a generic item on the ground and then just copying the NBT over (including the item ID) does not work.  Am I going about this wrong and there is a way to do this, or is this just impossible? My eventual plan is to implement this into a datapack, so if a method requires moving items into tile entities or something similar involving setting aside a space to spawn blocks in I'd rather avoid that. Of course, if you know a method like that by all means put it as an answer because someone else with the same question may find it useful for their situation.


I started studying my PhD with a federal scholarship that was supposed to sustain all my expenses and allow me to study without the need to work. Long story short, between family and mortgage payments money was scarce. My relatives helped with some of the expenses, but after 2.5 years, there were just too many pressure from financial problems, and I was not having a good progress in my investigation, that my advisor and I decided to suspend the PhD and that I should focus on getting a job.  To that extent, is it a good idea to emphasize that I started a PhD but was not able to finish it, or will it create a bad image about me not ending what I start? Should I wait until they ask what I did for those 3 years to tell them I didn't finish it? The PhD is in my CV, as started but not finished. Should I keep it that way or should I erase it?  To note for the possible answers is that I already have a Master degree in the same specialty as the PhD, and this is happening in México.

I am in the process of leaving my PhD programme in life sciences at a top university in the UK. A PhD is simply not for me and I find the work/life balance to be intolerable; in addition, my PhD so far has included an industrial placement at a Fortune 500 company that was very eye opening and enjoyable. I am looking to leave academia permanently and apply for graduate schemes.  My question is whether it is better to leave the fact that I quit a PhD off my CV, or to have the failed PhD / MPhil on there, or to mask it as '18 months of lab experience' or something similar. Is it possible to make the fact I left a PhD sound good?


I just recognised that an accepted answer does not always appear at the top of the other answers (for example ) Sometimes it does, but if I reload the page the two answers change their positions and the accepted answer is at the bottom.

What does it mean to accept an answer? How do I accept an answer, and what are the rules? Can I accept my own self-answer? What are the reputation benefits? Which answer should I accept? Should I upvote the accepted answer? What should I do if none of the answers are suitable?      For more information, see "" in the .


I'm new to C++ and messing around with functions. I have two cpp files and one header. One of my cpp files is main.cpp where the following code is: a->change(42.57);  I then have another cpp where the following code for change is: bool Student::change(float mark)  and then the header where the following code is: bool change(float mark);  When I pass the float in, it is 42.57. However, after it is passed in it suddendly chnages to 42.5699997. Could someone please explain why this happens?

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


If we consider a CNN that takes in $32 \times 32$ grayscale images and has a single convolution layer with 3 different $3 \times 3$ convolution filters (without or with boundary padding). I wonder whether we can treat this CNN as a feed-forward NN with each pixel as input and posting constraints on the weights in the hidden units? If so, what could be the constraints?

I understand that the architecture of Convolutional Neural Networks (CNN) and Feed forward (FNN) are quite different. And that CNNs use pooling and filters of shared weights over a patch of the image. I am not so clear on the core convolution operator (1):   If anyone could link me to an explanation, I have looked at the Colah blog and Nielsen's online book, and I understand what it is doing but don't understand the convolution operator.  Also, it looks quite similar to the the core FNN function is there and difference? (2).  (1) convolution operator is $a^1 = \sigma(b + w*a^0)$ which is equivalent to:  $a^1 = \sigma(b + \sum^4_{l=0}\sum^4_{l=0}w_{l,m}a_{j+l,k+m})$  (2) feed forward operation:  $a^1_i = \sigma(\sum^n_{j=1}w_{ij}x_j +b_i)$  Many thanks  Sources: functions taken from:


I recently upgraded by Windows 7 Home Premium machine to Windows 10 Home. The upgrade went fine and the machine's been running alright, except for one thing: I hibernate it every night when I'm done using it, and Win 7 stayed "off" until I turned it back on again whereas Win 10 seemingly randomly turns back on.  I've disabled Wake-on-LAN as well as wake on keyboard/mouse movement. Windows Update is configured to have me schedule the updates instead of installing them automatically. There doesn't seem to be anything relevant in the Event Viewer, although to be honest I'm not 100% sure what I'd be looking for there.  So what gives? How can I diagnose these random wake-ups and stop them?    I did read through  and checked out my scheduled tasks and maintenance settings. There are four scheduled tasks and none are configured to wake up the system. The automatic maintenance is supposedly configured to run at midnight, but that doesn't seem to be the case. I came home today to find my machine running and the maintenance run date is reported as 4pm:        I also have the following in the Event Viewer:  The system has returned from a low power state.  Sleep Time: 2015-09-23T03:47:52.760473200Z Wake Time: 2015-09-23T19:36:37.370293600Z  Wake Source: Unknown   This 4 p.m. wake-up seems to be consistent with previous wake-ups. WindowsUpdate ran about 3 minutes after the machine reportedly "woke up", so I'm not sure if that's what woke it up or if it just started running since the machine wasn't in use. I did also see , which matches the behaviour I'm seeing, but unfortunately the "turn off automatic updates" solution doesn't apply since that's already off.  Is this a dead end? What else can I look at?

I have an interesting problem. I am using Windows 8.1 on my PC and I have WOL enabled from my BIOS and my LAN card settings and it works just fine.  But, since a couple of weeks back, my computer turns on by itself in the middle of the night.  Two nights ago, after it woke me up because of the noise, I removed the LAN cord and everything was well until the next morning when I powered the PC myself. I also thought it could be a peripheral, so from Device Manager I went through every device there (apart from the LAN card, which I need because of the WOL), disabling Allow device to wake the computer from "Power Management". Also, in the LAN settings, I checked and the network card can be wake the PC up just by using Magic Packet or Pattern Mach.   The problem persisted last night (it woke around 5am).  I started reading forums and saw the idea of looking what last turned on my PC, so I checked with powercfg -lastwake and it returned the following:   Wake History Count - 1 Wake History [0]  Wake Source Count - 0   Because of the answer, I couldn't find a thing, therefore I checked the Windows logs, filtering them by Power Issues. I found the last wake my PC  experienced, and the log was as it follows:   The system has returned from a low power state. Sleep Time: 2014-05-08T23:38:33.848063300Z Wake Time: 2014-05-09T01:56:48.134397800Z     Wake Source: Unknown   This is the reason I have posted the issue here, even though there are many posts about this. I didn't want to repost, but I never found this same problem (with wake source unknown) in any post or forum.  I hope someone has an idea of what may be the problem.


s = 'blah blah blah... _ABC_superman_is_cool_CBA_ ...blah blah blah...'   This is just an example, but I want to match everything between _ABC_ and _CBA_. So 'superman_is_cool'. There may be multiple sections of _ABC_..._CBA_.  re.findall('_ABC_(.*)(?=_CBA_)', s)   I tried this first, but obviously doesn't correctly work at all.

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


twice in the last week all of the light bulbs in my house (those that were turned on) burned out at the same time.  What would cause this and is my house safe to stay in.

I live in Texas.  I ran 300 ft of aluminum electric direct-bury 4-4-2 from the pole on street to my new home. The pole is metered and yes, I had my utility's blessing to do so.  Everything worked perfectly for 6 months, but now suddenly if I plug anything (lamp, heater, charger ) in my lights dim, or sometimes if I plug in elsewhere things get very bright or plug in heaters work better or worse depending.   There’s no rhyme or reason to any of it.    I have undone and redone every receptacle to be sure.  I installed 50 amp breakers in every slot of box on house to try to solve this problem to no avail. (I have never once tripped a breaker ever) I haven’t been able to put up sheetrock because I don’t want to have to remove it.


Imagine a foolish astronaut who travels into a Schwarzschild black hole. It’s thought that there’s nothing special about the geometry he encounters at the Schwarzschild “radius” (OK, maybe some serious tide). But suppose he has a thermometer. What temperature does he measure? You may assume the thermometer is either a radiometer pointed toward the black hole, or a radiometer that averages over all directions.

I try to understand two principles formulated by Leonard Susskind in his book The Black Hole War:  1, To any observer who remains outside a black hole, the stretched horizon appears to be a hot layer of horizon-atoms that absorb, scramble, and eventually emit (in the form of Hawking radiation) every bit of information that falls onto the black hole.  2, To a freely falling observer, the horizon appears to be absolutely empty space. [...]     Now, in reaction to (an unanswered)  by Nathaniel, let us suppose that a distant observer A sees (according to the principle #1) Hawking radiation from a black hole (with Planck spectrum and say measurable temperature). Now suppose there is a freely falling gas somewhere between the event horizon and the observer. According to the principle #2, to the gas (considered an observer B) the horizon is empty space so there is no light coming from it to absorp.  Would the observer A detect absorption lines in the black hole spectrum? How does it change with distance of the gas (or the observer) from the black hole? Will the distant observer see the lines if he is free falling?


I'm a hard mode mobile terraria player. I have 2 amazing worlds(my main ones). But both of them are being over-run by the corruption. I've tried powder, but it always comes back. Is there any way to get rid of it or contain it?

Well, what I tried to do was completely cleanse a Corruption area. I assumed it's all about the grass, since that seems to be how the Corruption spreads, and other biomes (such as the Underground Jungle) work like that.  So, I bought a few stacks of Purification Powder and Sunflowers, and purified every bit of Corrupted grass I could find.  It didn't completely work, however. Slimes/Zombies now spawn, but so do Eaters of Souls, still — and the music hasn't changed.  Is there something else that has to be done to completely eradicate the Corruption? (I've already smashed every single Shadow Orb; I doubled checked using the World Viewer.)


Based on this  which claims almost all integers contain a $3$, I have a few questions on the reasoning behind recurring decimal numbers like $0.9999\ldots =1$  What they have shown is that $$\lim_{n \to + \infty} \frac{10^n-9^n}{10^n} = 1$$  this basically means that probability of eg. a $3$ occurring in a set of numbers like for $1-10, 1-100,$ increases as the upper bound gets large.  So you are more likely to see a $3$ when you take $1-100000$, than $1-10$ as the probability gets higher.  So what I would like to know is as '$n$' approaches $∞$ does probability of seeing a '$3$' equals $0.99999....$?  But since $0.9999... = 1$ wouldn't this not make sense, since there are infinitely many numbers that do not have a '$3$'?  All I need is for an explanation as to why this logic is wrong. Simpler answers are most appreciated.  Note   I am not looking for the reason as to why 0.9999...=1.

I'm told by smart people that $$0.999999999\ldots=1$$ and I believe them, but is there a proof that explains why this is?


I accidentally pressed Ctrl + L in bash (intending to do it in the browser).  This caused the terminal window to scroll so that the history of commands is above the top and everything below the current command is blank.  So I scrolled it back to where the new command would be at the bottom - but as soon as I started typing, it immediately scrolled all the previous lines out of sight again.  Is there a way to undo this so it resumes behaving normally again, leaving the new typing at the bottom?  (Getting a new shell seems to do it, but I don't want to have to exit SSH and reconnect if this happens again.)  Edit: (The  explains what Ctrl + L does, and there are lots of answers for people wanting this effect, but I haven't found anything about reversing it.)  Note: The history is still there for reference, it's just a hassle to have to keep using the scroll bar to get a look at it.

I accidentally typed ctrl + L in terminal and my terminal window jumped one 'screenful' size. I looked at the keyboard shortcuts in "Edit"->"Keyboard shortcuts" and didn't find that shortcut.  What does ctrl + L do and where is it defined?


Prove that if $$f(x)=\sum _1 ^{\infty} a_n \cdot x^n,$$ where $(a_n)$ is the Fibonacci Sequence, and if $|x|<1/2$, then $$(x^2 + x - 1) \cdot f(x) = -x.$$   So far, as an earlier part of this question, I've shown that $a_{k+1}/a_k \le 2$ and that $f(x)$ converges for all $|x|<1/2$.  Although I'm aware that this $f$ converges, I have no method for finding what it converges to!   This question implies that $f(x) = -x/(x^2 +x -1)$ which, for $-1/2 < x < 1/2$ is inside $(-4/10,2)$. I've also tried factoring the $(x^2 + x -1)$ into my series for $f$, but just don't know where to go from here.


So I am trying to make a hash function that put an element k into a 2D array based on it's mod. For this example the size of the outer array is 4. So to start out the hash table I want it to be a 2D array that has the size of the outer array to be 4. Then there will be 4 empty arrays inside the outer array. Like so...  n = 4 A = [[]]* n   Which is [ [], [], [], [] ] So when I use the hash function like this hash(A, 2) it should output this [ [], [], [2], [] ] based on this code below...  def hash(A, k):     idx = k % 4      for i in range(len(A)):         for j in range(len(A[i])):             if i == idx:                 print(A[i][j])                 A[i][j] = A[i][j].append(k)   So the problem is that it outputs this [ [], [], [], [] ] and not this [ [], [], [2], [] ].   I have tried...  def hash(A, k):     idx = k % 4     A[idx].append(k)   but this only outputs [[2], [2], [2], [2]] which is not what I want.   How do I make my hash function give me this output [ [], [], [2], [] ]?  (P.S. I know it's a lot better to simply just make an array of linked lists. I am doing this for a better understanding of hash table if they were implemented with arrays and to get a better understanding of 2D arrays.)

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


iPhone 4S (VZN Model) with IOS 9.3.2 unlocked and works with TMO.  What is the procedure / process to configure it for wifi calling.  As I understand it IOS 8 supports wifi calling.  As Bill Tanner has graciously pointed out, Apple indicates a 5C or newer model is supported.  I suspect that the 4S has the hardware necessary to perform wifi calling.  If this is not the case, I'd like to understand the gap that prevents wifi calling: I have successfully made SIP calls (a form of wifi calling) with the device.      The question is not whether 4S is supported for wifi calling, but what (if any) procedure would be needed to enable wifi calling functionality.  It would not surprise me this feature is feasible with the 4S and that Apple is in a position to easily add it to the list of model that are valid for wifi calling code / instructions  Insight into the procedure to enable wifi calling on the 4S would be appreciated.  Thank you

I have an iPhone 5, and I don't have good reception at home, so I was hoping to use wifi calling after upgrading to ios 8, but I can't find an option to enable it.  BTW I'm with T-Mobile carrier.


Find all the numbers $n$ such that $\frac{6n-8}{2n-5}$ can't be reduced.   Attempt:  It can't be reduced when $\gcd(6n-8,2n-5)=\color{red}1$  $$1 = \gcd(6n-8,2n-5)=\gcd(4n-3,2n-5)=\gcd(2n+2,2n-5)=\gcd(7,2n-5)$$  that's equale to one when $2n-5\not\equiv 0 \pmod 7$ i.e $n\not\equiv 6 \pmod 7$  Is my attempt correct?

Find all the numbers $n$ such that $\frac{4n-5}{60-12n}$ can't be reduced.   Attempt:  $$\gcd(4n-5,60-12n)=(4n-5,-8n+55)=(4n-5,-4n+50)=(4n-5,45)$$  $$n=1: (4-5,45)=1\quad \checkmark\\ n=2: (3,45)=3\quad \times\\ n=3: (7,45)=1\quad \checkmark\\ n=4: (11,45)=1\quad \checkmark\\ n=5: (15,45)=15\quad \times\\ n=6: (19,45)=1\quad \checkmark\\ n=7: (23,45)=1\quad \checkmark\\ n=8: (27,45)=9\quad \times\\ \vdots$$ So the answer is that it can't be reduced for $n=1,3,4,6,7,..$ i.e  $$\bigg\{n\bigg|n\notin \begin{cases}a_1=2\\a_n=a_{n-1}+3\end{cases}\bigg\}$$  I want to verify that my solution is correct


Write a function identity(n) that returns the n identity  matrix. For example: identity(3) outputs [[1,0,0][0,1,0][0,0,1]] I have tried as follow:  def identity(n): matrix=[[0]*n]*n i=0 while i<n:     matrix[i][i]=1     i+=1 return matrix   Also I tried with range but it did'n work like this  def identity(n):     matrix=[[0]*n]*n     k=matrix[:]     i=0     for i in range(1,n):         matrix[i][i]=1         i+=1     return k print(identity(5))   But it output for n = 5:  [[1, 1, 1, 1, 1], [1, 1, 1, 1, 1], [1, 1, 1, 1, 1], [1, 1, 1, 1, 1], [1, 1, 1, 1, 1]]


I have an object (button), which has been rotated and where the rotation has been applied. I want to align this button to a surface (the blue surface of the cube). The black background should sit flat on the blue surface.    I tried "Snap to Face" with "Center" and "Align Rotation to Target". I also tried to use an empty to find the rotation of the button in the 3D space. But nothing worked. Any help is highly appreciated!  This is a link to the example file:

Hi! I'm a beginner learner and I'd like to know how to snap these three objects. I'd like to snap the two cylinders with the different faces of the cube. The short one on the left and the highest cylinder on the top of the cube. I'd like to have the center of the cylinder aligned with the center of the cube (the base of the cylinder inscribed into the face of the cube)  I'm sorry for bad explanation I hope someone can help me  Thanks!   I add a screenshoot in which you can see what I have to do   Thanks again if someone can help me with this!


I am interested in learning how to create documents through LaTeX and was wondering what editors might be good for someone starting out. I currently have windows 8 but am thinking about installing Ubuntu as well. I'm not looking to do too much, just to create a clean, good looking resume. Thanks!

What editors/IDEs are available for easing the process of writing TeX/LaTeX documents? Please state some useful features like code completion, spell checking, building final DVI or PDF files, etc.  This question is undergoing a systematic refurbishment, see  on Meta. If you’d like to see another editor feature covered here or to take care of an editor that’s not covered yet, share your ideas in that meta question.  List of editors Links to answers.


I have deleted the windows efi partition ( not windows ).I have in my system 2 linux distro and 2 efi partitions.  I am trying to fix windows boot following steps like:   and .  The problem is , that when I enter the command:  bootrec /fixboot   it shows :      The system cannot find the file specified   I tried to run :     bootrec /rebuildbcd   ,so it shows:     Successfully scanned Windows    C:\Windows   Add installation to boot list?   I answer "Yes" and then it again throws me the previous message.  What can I do about that?  (The "This question may already have an answer here" doesn't help since the /fixboot doesn't work..)  ---- UPDATE ----   1) I tried to run : bcdboot c:\Windows and it throws:      BSFSVC Error:Failed to create a new system store   2) I typed active  after assign letter  = v: but it shows :      The selected disk is not a fixed MBR disk   3) I saw that in the directory : C:\Windows\Boot\EFI\ it has the files : bootmgr.efi , bootmgfw.efi  Should I try there all the commands:  bootrec /fixboot , fixmbr or I may do things worse?  ------ UPDATE ---------------------  This post is different from the duplicate one , in that  , when I try to run :  bootrec /fixboot , it shows: The system cannot find the file specified  I think I made this clear.Why do you duplicate this post???  --- UPDATE 2 -------------------------  I tried ( i have only 1 disk in my laptop ):  list disk sel disk 0 list partition sel partition 2 ( it is an efi partition I have created when I installed linux ) active -> gives message "The selected disk is not a fixed MBR disk"    I then followed the same procedure:  list vol sel vol 11 assign letter = v: exit   Now , when I try: bootrec /fixboot , it shows me the message "No element found"   ------UPDATE 3-------------------  I upload screenshots  and . Disk 0 is my laptop disk. Disk 1 I don't know Disk 2 is the flash drive from which I am running repair disk.  As for the partitions , the 2 and 10 are EFI partitions I generated from the linux distros. So, the volumes are 11 and 12. I tried both.  ---------- UPDATE 4 ----------------------------------------------------  I tried :   bootsect /nt60 ALL /force   but still nothing. When I enter : bootrec /fixboot ,it shows :      element not found.   Also, after this:  Successfully scanned Windows installations. Total identified Windows installations: 1 [1]  D:\Windows Add installation to boot list? Yes<Y>/No<N>/All<A>:   I enter Y but I am getting a negative answer ( I don't remember what exactly! ).  The good thing though ,is that now (after updating grub) the windows boot option appeared in my grub menu. But when I select it ,it shows:     The boot configuration data file is missing required information.      File :\BCD    Error Code: 0x0000034   I am not sure what to do from now on.  I saw somewhere to try : bcdboot c:\windows  but I don't know how to access 'C' drive. Ok, I am doing:  sel disk 0 list vol   and in volumes I can see 'C' listed . But I don't know beyond this.  Also,I tried renaming the BCD file and then rebuild but still the same.  -----UPDATE 5--------------------------  Volume 10 contains:  Bin Boot Recovery -> empty RicaTools -> bootmgr,bootmgr.efi .... TFR WinRePartition.ini   Volume 11:  EFI-> manjaro -> grubx64.efi       BOOT-> BOOTx64.efi       Microsoft-> Boot -> bootmgfw.efi                           bootmgr.efi                           boot.stl                           MokManager                           BCD                           ...       ->ubuntu-> grubx64.efi,grub.cfg,shimx64.efi   Volume 12:  EFI-> mint ->grubx64.efi       manjaro-> grubx64.efi   ---UPDATE 6------------------  Finally it worked thanks to Christophe!  Just want to note for anyone who has the same problem , that the last command fixboot gave      Element not found   but it didn't matter!  Of course ,finaly,I had to do an update-grub .

I installed Windows 7 and Windows 8 in EFI mode on a hard disk some days ago. Today, the bootloader got missing/corrupted.  I currently have the Windows 8 installer on a flash drive and tried using the Automatic Repair option to repair the bootloader but it didn't do anything. The Startup Repair option is also missing in the Windows 8 installer.  How I can repair/recreate the EFI bootloader from the Command Prompt?  BCDEDIT returns the following message:  The requested system device cannot be found.


In Harry Potter and the Goblet of Fire, when the kids and Arthur get to  The Burrow from Privet Drive and Molly is cooking and raging about Fred and George's shenanigans, the following occurs:     Mrs. Weasley slammed a large copper saucepan down on the kitchen table and began to wave her wand around inside it. A creamy sauce poured from the wand tip as she stirred.   In Deathly Hallows, Hermione says that this is not possible:     “Your mother can’t produce food out of thin air,” said Hermione. “no one can.   Food is the first of the five Principal Exceptions to Gamp’s Law of Elemental   Transfigura—”      “Oh, speak English, can’t you?” Ron said, prising a fish out from between his   teeth.      “It’s impossible to make good food out of nothing! You can Summon it if you   know where it is, you can transform it, you can increase the quantity if you’ve already got some—”   So how was Molly causing sauce to pour from her wand, seemingly out of thin air?

According to Hermione in DH, food is one of the Five Exceptions to Gamp's Law on Transfiguration.  Yet, in CoS, Professor McGonagall is able to give Harry and Ron a plate on which sandwiches appear continously. One can object that some sandwiches cannot be considered as food, but they still are. The same can be said about Molly Weasley making sauce from her wand in GoF while grumbling about how the twins abuse magic.  Is there any canon explanation on how McGonagall and Mrs Weasley created food from nowhere?  By canon, I mean anything coming from the books, Pottermore, or JKR quotes.


I want to travel in Canada on November but I renewed my passport. When I renewed my passport, the machine readable zone in my old passport was cut in order to make it useless. Also my visa is intact.  My question is can I travel in Canada with both my passport although my old passport can not be read with a machine? The Old passport should be intact?

I recently renewed my passport. I also have an expired passport which has my Canada visa (visitor's) valid for another three years. I have already used my Canadian visa which is multiple entry. I am planning to visit Canada this summer.  Since my valid Canadian visa is in my old/expired passport, do I need to renew/transfer my Canada visa or can I simply travel with valid visa in old passport?


Ive got an .indd indesign file that ive created as a template for other users to copy and fill out with images and text.   The issue is that they keep moving and / or resizing the text boxes, not by much but enough to nudge things out of alignment, am i able to lock a text box so that it cant be moved and / or resized, but only typed into ?   We are running indesign CC - latest.

How to lock the position and size of a text-frame in InDesign CS6?  I would like to lock those properties in each page in Indesign. Sometimes the designers get wrong and drag and drop the text frame without noticing.  Then we have to remove the page and create again. If this is not done when I update the master will not update the size and position of the text frame


Good morning,  For a homework I used a support vector machines (classification) with a RBF kernel, k-fold cross validation=10, cost of constraints violation=100, and gamma=0.001.  It works great and my predictions are very good.  However, we didn't see how to formulate the model in mathematical terms (well we are not going to cover svm in the course at all), and I believe it's important.  I reviewed Hastie's and other books, but I still don't know how to formulate this model.  Can somebody point me in the right direction?

How does a  work, and what differentiates it from other linear classifiers, such as the , , or ? *  (* I'm thinking in terms of the underlying motivations for the algorithm, optimisation strategies, generalisation capabilities, and run-time complexity)


I just installed Ubuntu on my old Macbook, and I'm not able to connect to WiFi. Nearby networks do appear, but when I try to connect to any network, I receive the error message "Connection failed -- Activation of network connection failed."  lspci shows:  02:00.0 Network controller [0280]: Broadcom Inc. and subsidiaries BCM4321 802.11a/b/g/n [14e4:4328] (rev 03)  iwconfig shows:  wls4      IEEE 802.11  ESSID:off/any             Mode:Managed  Access Point: Not-Associated              Retry short limit:7   RTS thr:off   Fragment thr:off           Power Management:on  lo        no wireless extensions.  ens5      no wireless extensions.   I followed the instructions here () to uninstall and re-install the bcmwl-kernel-source package without success.   I know this has been asked a lot, but after searching through previous questions/answers, I'm not sure what else to try.  Thank you!  EDIT:  lspci -knn | grep Net -A3; rfkill list shows:  02:00.0 Network controller [0280]: Broadcom Inc. and subsidiaries BCM4321 802.11a/b/g/n [14e4:4328] (rev03)         Subsystem: Apple Inc. AirPort Extreme [106b:0088]         Kernel driver in use: wl         Kernel modules: ssb, wl 0: phy0: Wireless LAN         Soft blocked: no         Hard blocked: no 1: brcmwl-0: Wireless LAN         Soft blocked: no         Hard blocked: no 2: hci0: Bluetooth         Soft blocked: no         Hard blocked: no

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


I have someone's code which sets the name of a new Object.  function setName(human) {      human.name = "Nicholas";     human = new Object();     human.name = "Greg"; };  var newPerson = new Object();  setName(newPerson);  console.log(newPerson.name);   I want to use the value of the property 'name' of the person object.   I was expecting the value to be 'Greg' but I am getting 'Nicholas'.  This is my understanding: 'human' is a pointer to an Object. When the function is called, another pointer to the same Object would be created by the name of newPerson.  The 'name' property of the newPerson Object would be set to 'Nicholas'. Then, another newPerson object is created in the second line of the function. Hence, the first instance should be destroyed. Then, the 'name' property of this new Object would be set to 'Greg'. Where am I going wrong?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


I have setup adb server and client within the Android device and can issue adb commands via terminal emulator.  But I need to have the fastboot in the same way. My requirement is to temporarily boot into TWRP without a PC or another Android device:  # fastboot boot /path/to/twrp.img   I think the Android has fastboot-over-usb.

I want to do the following without a PC, just directly from an Android phone using a script / Android Terminal:     Reboot into bootloader, and then enter a few fastboot commands   Is this possible?


I'm trying to make a circuit (with no programmable circuits, only logic gates, flip flops and latches) that outputs a short impulsion each time it's input toggles from 0 to 1. Do you have any idea of how to do so?

Basically, I want to turn a continuous "1" into a short "1" pulse then "0". I'm new to logic gates, apologies if it's too obvious.


Let $X$ be a random variable. Suppose there exists a constant $c ∈ R$ such that $E(|X − c|^2) < ∞$. Show that the random variable $X$ has finite mean and variance.  And I'm quite confused about the definition about finite mean and variance. I searched on google, but seems there is no explanation in datail. Can anyone help me out? Thanks

It would be appreciated if the following examples could be given:   A distribution with infinite mean and infinite variance. A distribution with infinite mean and finite variance. A distribution with finite mean and infinite variance.  A distribution with finite mean and finite variance.   It comes from me seeing these unfamiliar terms (infinite mean, infinite variance) used in an article I am reading, googling and reading a thread on the , and not finding it a sufficiently clear explanation. I also haven't found any explanations in any of my own textbooks.


I accidentally changed a folder name to be '.., and now whenever I try to delete it, windows is saying it can't find the file or folder specified.  I need to delete it though because it's messing up the git repo

I'm trying to delete a folder in Windows 7 and get a perplexing error message: "Could not find this item:  This is no longer located in G:\Graphics.  Verify the item's location and try again.  I can see the folder -- I can find it.  I just can't delete it.    I also get a second error message (sometimes) when I click on the folder: G:\Graphics 2009-11-17 refers to a location that is unavailable...this information might have been moved to a different location.    I'm using Windows 7; this folder is on an external hard drive.  I've emptied the folder (there were items in it); I've scanned that external hard drive for errors.  Trying to rename the folder yields the same enigmatic error message.    Is there a way to delete this folder?


I'm practising how to model my Kitchen radio. On the top of the model it has many holes, I've used subdivision modifier on my mesh. My first attempt was to deactivate the submodifier and make an array of holes, but once I turned on the subdivision modifier again, it was extremely unclean mesh.   So what would be the best way to achieve the holes on top of the mesh?  Thank you.

How would I be able to create a grill of sorts found on the front of some computer cases such as this one


I already wrote my conference paper in IEEE format and the following code fits well in one column. Now, when I need it in ACM format, it won't fit in one column.   \documentclass[sigconf]{acmart}     \usepackage{booktabs} % For formal tables  % Copyright %\setcopyright{none} %\setcopyright{acmcopyright} %\setcopyright{acmlicensed} \setcopyright{rightsretained} %\setcopyright{usgov} %\setcopyright{usgovmixed} %\setcopyright{cagov} %\setcopyright{cagovmixed}      \usepackage{ctable} \usepackage{multirow} \usepackage{balance} \usepackage[intoc]{nomencl} \usepackage{listings} \usepackage{multicol} \usepackage{amsmath} \usepackage{flushend}  \copyrightyear{}  \acmYear{}  \setcopyright{acmcopyright} \acmConference{}{}} \acmPrice{} \acmDOI{} \acmISBN{}  \begin{document} \title{}  \author{xxxx   xxxx} \affiliation{%   \institution{xx-xx-Institute\\ University of xx, xx} } \email{}  % The default list of authors is too long for headers} \renewcommand{\shortauthors}{ et al.}  \begin{abstract}  \end{abstract}  % % The code below should be generated by the tool at % http://dl.acm.org/ccs.cfm % Please copy and paste the code instead of the example below.  %  \begin{CCSXML} <ccs2012> <concept> <concept_id>10002951.10003227.10003233.10003288</concept_id> <concept_desc>Information systems~Blogs</concept_desc> <concept_significance>300</concept_significance> </concept> </ccs2012> \end{CCSXML}  \ccsdesc[300]{I}  \keywords{}  \maketitle \input{sections/introduction} \input{sections/relatedwork} \input{sections/PredictingAttributes} \input{sections/Classification} \input{sections/PrototypeandImplementation} \input{sections/conclusion}  \bibliographystyle{ACM-Reference-Format} \bibliography{sample-bibliography}   \end{document}  I am using these packages,       \documentclass[sigconf]{acmart}     \usepackage{booktabs}      \setcopyright{rightsretained}     \usepackage{ctable}     \usepackage{multirow}     \usepackage{balance}     \usepackage[intoc]{nomencl}     \usepackage{listings}     \usepackage{multicol}     \usepackage{amsmath}     \usepackage{flushend}

I have a table that I want to insert on a page, but at least one (perhaps both) of the following conditions are met:   The table is too wide to fit within the text block or page. That is, I'm exceeding some horizontal restriction. The table is too tall to fit within the text block or page. That is, I'm exceeding some vertical restriction.   What are my options to make this table fit? If it doesn't fit, regardless of my attempts, what other options exist?


I have been a part of this site for a number of years now and was thinking to myself the other day... Why exactly do I post here? This is not a forum, extended discussions are actively discouraged.   I have spent years adding content to this site with not a hint of any monetary value for all the content I have provided. Moderators don't even get a salary or a stipend for all there efforts, and still there is a company built on the work of other people, who for all there efforts go unpaid?  At least, YouTube has given some content creators money. There is still ways to monetize your YouTube efforts, but here there are none.  Why cannot a couple of dollars be given to good answer / question or some sort of monetary reward for hitting certain reps, the company makes money, why shouldn't we?

If we are effectively generating more traffic to Stack Exchange sites, would it become a better community if users were compensated somehow besides rep points? Even with minuscule alt coins?


Does a shield used as an improvised weapon via Improvised Weapons rules     An improvised weapon includes any object you can wield in one or two   hands... (PHB 147)   count as a melee weapon since it is similar to melee weapons?     In many cases, an improvised weapon is similar to an actual weapon and   can be treated as such. (PHB 147)   If so...  Do you get +2 to AC from a combination of the +1 AC from the Shield and the +1 AC from the first bullet point of the Dual Wielder feat?     You gain a +1 bonus to AC while you are wielding a separate melee   weapon in each hand. (PHB 165)

Let's say I am wielding a dagger and shield, and I am using the shield as an improvised weapon. Would Dual-Wielder Feat and the Dual Wielding fighting style be in effect while I am using these as improvised weapons?


I have the following thoughts so I'd like to hear are there any straightforward implications which might support or undermine them.  You have a class BPP where problems have a TM with bounded two side error and constant ratio of correct leaves in your computational tree.  You have a class NP, which you can think of there is a TM with computational tree which is correct for no instances , but for yes instance $x$ you can have the correct leaves ration as small as $\frac{1}{2^{p(|x|)}}$.  If you kind of combine this you get for no instances all leaves correct for yes instances only the constant ratio, and this is class RP.   So the conjecture is $RP = NP \cap BPP$. What are the important implications? Is there a 1-line proof?  From me, I can add that the widely believed conjecture $BPP = P$ definitely supports the claim.  Thank you.

The reverse inclusion is obvious, as is the fact that any self-reducible NP language in BPP is also in RP. Is this also known to hold for non-self-reducible NP languages?


Are there significantly less features or uses for them? They seem to be quite popular, and being free and open source is definitely a plus as opposed to the Adobe suite.

I know Adobe's solutions are more advanced, but, as professionals, do you think you would survive (against competition) using GIMP and/or Inkscape instead of Photoshop and/or Illustrator for your actual work?  Would it be worth it or would it actually complicate your work?  I am specially interested to see if there is anyone that actually made the switch to the open source solutions and know why you did it.  My question is with regards to the possibility of fully divorcing from Adobe's solutions and still being able to function as a graphic design studio.


We know that for laymen, an STI (sexually transmitted infection) is something that can spread via sexual activities. However, there are some infections that can spread sexually but is not considered STI:s, like cholera. Also, there are a lot of STI:s that can be transmitted via non-sexual means. So it seems like STI means something that it typically spreads via sexual activities.  So my question is, is there any formal definition?

I am very confused as in  to  I agreed with the OP that HIV is an STI.  I have been led to believe the following definitions:  STI  Stands for Sexually Transmitted Infection — an infection caused by bacteria or virus which has been transmitted through sexual contact.  STD  Stands for Sexually Transmitted Disease — a disease caused by the infection of a bacteria or virus transmitted through sexual contact.  With regard to HIV  These definitions class HIV as an infection.  This is a fact to me because:  (bold emphasis mine)     Over time, HIV can destroy so many of these cells that the body can’t fight off [other] infections and disease. These opportunistic infections or cancers take advantage of a very weak immune system and signal that the person has AIDS, the last stage of HIV infection ()** Website managed by the U.S. Department of Health & Human Services and supported by the.   HIV is a retrovirus, which is:     a family of viruses that are grouped together based on how they are structured and how they replicate within a host. Besides human immunodeficiency virus (HIV), the virus that causes AIDS, there a two other retroviruses that can cause human illness. One is called human T-lymphotropic virus type 1 (HTLV-1) and the other is called human T-lymphotropic virus type 2 (HTLV-II) ().   Human T-cell lymphotropic virus type 1 (HTLV-1) is primarily transmitted through sexual intercourse or from mother to child () making HTLV-1 an STI in definitions I have been led to believe, and AIDS is an STD due to the fact that it is caused by HIV infection which in many circumstances is transmitted through sexual contact, although HIV can be transmitted through other means ().  It cannot be an STI as AIDS is not transmitted.  It is a disease as a result of HIV infection.  What creates a confusion?  In the comments to my answer, @Jan stated that HIV is not an STI, but just a virus.  To make matters worse, when trying to confirm or deny his responses I have been trying to look up a definitive definition and found that in the key points of , it states that:     HIV is an STD. Chlamydia, gonorrhea, human papillomavirus (HPV) infection, and syphilis are examples of other STDs. ()   So the question is: What is the difference between STIs, STD and "just a virus transmitted through sexual contact"?  References  HIV.gov (2017) What Are HIV and AIDS?Retrievable from:   Minnesota Department of Health, (n.d.) Other Retroviruses That May Cause Human IllnessRetrievable from:   National Inststutes of Health (n.d.) HIV and Sexually Transmitted DiseasesRetreivable from:   Paiva, A., & Casseb, J. (2014). Sexual transmission of human T-cell lymphotropic virus type 1. Revista da Sociedade Brasileira de Medicina Tropical, 47(3), 265-274.DOI:  PMID:


What is summation of 1/k where n ranges from 1 to n. I need the general formula for the summation.  I know the series tends to infinity when k tends to infinity . But upto n terms there must be a definite sum value. Correct ?

How to find the sum of the following series? $$1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \dots + \frac{1}{n}$$ This is a harmonic progression. So, is the following formula correct? $\frac{(number ~of ~terms)^2}{sum~ of~ all ~the~ denominators}$ $\Rightarrow $ if $\frac{1}{A} + \frac{1}{B} +\frac{1}{C}$ are in H.P. Therefore the sum of the series can be written as : $\Rightarrow \frac{(3)^3}{(A+B+C)}$ Is this correct? Please suggest.


Here goes:    imagine a spacecraft with engines shut off in a free fall towards some celestial body x. let's say the distance to surface is $100 000$ $\text{meters}$.  initial vertical velocity is $500$ $\text{m/s}$.  gravitational pull experienced by the body is obviously given by $F=G \frac {m_1  m_2}{r^2}$. acceleration of said craft is calculated as $a = \frac{F}{m}$.   Given constant $F$ and therefore $a$, impact velocity and time are easy to calculate, but how exactly do I solve this, considering  that gravitational pull and  acceleration are constantly changing as we approach the surface?  Key question in  is "To what value does the velocity v of the particle converge to as x approaches infinity if the particle starts at some point x0?"  The answer by David H involves the following formula $v_f = \sqrt{\frac{2k}{x_0} + v_0^2}$  In my case x goes from 100000 to 0 m (surface), in other words, there is a clearly defined endpoint which is not equal to infinity. Therefore I do not see how David's formula is applicable in my situation.

A particle experiences an acceleration described by  $$ a=kx^{-2} $$ where x is the displacement from the origin and k is an arbitrary constant.  To what value does the velocity v of the particle converge to as x approaches infinity if the particle starts at some point x0?  If I approach this problem with energy, then $$ W = \int F \mathrm{d}x $$ $$  = \int_{x_0}^\infty mkx^{-2} \mathrm{d}x $$ $$  = mk(-\infty^{-1}+{x_0}^{-1}) $$ $$ W = K = mk{x_0}^{-1} $$ $$ \frac{1}{2}mv^2 = mk{x_0}^{-1} $$ $$ v = \sqrt{2k{x_0}^{-1}} $$  How would I solve this problem with pure kinematics? (there appears to be some sort of cyclical dependency where acceleration affects velocity, velocity affects displacement, and displacement affects acceleration)  Likewise, two particles experience accelerations described by $$ a_1=k_1x^{-2} $$ $$and $$ $$ a_2=-k_2x^{-2} $$ where x is the distance between the two particles  What two velocities do the particles reach as x approaches infinity if the two particles are initially separated by some x0?


I'd like to remove the title bars in Gnome Shell. Running Ubuntu 18.04 with Gnome and the Adwaita theme.   Is there a file I can edit to remove the title bars off the windows? It's really wasted space. I use shortcut keys to close windows, press alt if I need menus, and move things around with alt + mouse click. I'd love to give that screen real estate back to my browser or terminal.   Extensions don't seem to work. I want to know where in the code of the theme these title bars are so I can either delete them or change them. I remember doing this in the past, but don't want to hack away at files indiscriminately like last time.

Just moved from Unity to GNOME with the update to Ubuntu 17.10. There is a HUGE amount of wasted space at the top of the screen, when an application is open.  Evolution and Firefox both have four "bars" with 90% of each empty. Unity, to its credit was able to blend / mix these horizontal bars so there was only one / two.      Four is way too much. If this is GNOME I may carry on with Unity for the next six months.  Can anybody suggest a tweak/change/fix for this?


I often use an app to access SE/SO. Sometimes I see some post on Stack Overflow that didn't get much attention, so I want to use my reputation to set the bounties while I am on an app (Android). I couldn't find the bounty button. Where is the bounty button?

(I was surprised I couldn't find this in an existing question, so here goes)    I'd like to add a bounty to a question, but I'm too lazy to go get my computer or a web browser. I like the SE app, and want to use it to do everything. I can't find the button to add a bounty to a question.  Please add this button, I really want to be able to add bounties to questions from the app.


I just upgraded to a 1tb HDD in my MacBook Pro (non-retina) and would like to dual boot from OS X to a linux distro.  I'd like to find out a few things so I can be better prepared and informed for this process.  1) Partitioning...  Should I... a) Use BootCamp to create the second partition? b) Use Disk Utility to resizes and create the second partition? c) Create the partition from within the Linux live USB or DVD?  2) Which distro is recommended?  I've used both Mint and Ubuntu in the past and definitely prefer distros based on Debian that use apt-get as opposed to the others like SUSE.  3) I've heard that it's a pain to get the wifi to work, is that true?  If so, how to I enable the drivers?  Is there an apt-get command I can use in order to do so?  4) Other than the wifi difficulties is there anything else I should be aware of and be prepared for?

I have a Macbook Pro and I am loving it, though I still miss my Linux box, there are many things I need which are not completely compatible with Mac OS X.  I heard many stories about installing Linux on a Mac OS, some say it's not a problem, but some others tend to say differently.   My question is, is it or is not fine to install Linux on a Mac OS machine? What are the pros and cons?  I am very well aware about virtual machines, but let's be honest, they do not run quite as well when running on a physical hardware.


I have written a simple C code in which I have defined two struct datatypes dT0 and dT1. The dT0 datatype has one int elemnt (a) and one double element (r) whereas the datatype dT1 has two int elements (a and b) and a double element (r). Naturally I would think that the memory requirement for dT0 would be less than that of dT1 but to my surprise, when I try to print their sizes in main using sizeof(), I get the same memory requirement for both, that is 16. I was expecting 12 bytes for dT0 (4 for int and 8 for double) and 16 bytes for dT1 (8 for two ints and 8 for double). What am I missing?  #include<stdio.h> #include<stdlib.h>  typedef struct dType0 {   int a;   double r; }dT0;  typedef struct dYype1 {   int a,b;   double r; }dT1;  int main() {   printf("%d %d\n",sizeof(dT0),sizeof(dT1));   return(0); }

Why does the sizeof operator return a size larger for a structure than the total sizes of the structure's members?


Is there a way to do this? I have tried a number of the write ups on this, and it appears that libgdal-mrsid-src no longer exists. Is there any other workaround? USDA NAIP imagery is sent as MrSID.

I need some help importing MrSID Raster files in QGIS. I am running 2.6.0 on Linux Mint 17. After an internet search I have found a couple of resources that are perhaps outdated. The most promising is found here :    However when I attempted to follow the instructions my terminal and I could not find the file "libgdal-mrsid-src" on either the stable or unstable Ubuntu GIS repos. Has anyone had success or could lead me in the right direction?


Is there some way I can fire an event with jQuery when the page scrolls far enough for a div to come into view?

I'm loading elements via AJAX. Some of them are only visible if you scroll down the page. Is there any way I can know if an element is now in the visible part of the page?


I want to prove that the Zariski tangent space at $x\in X$ ($X$ is an affine scheme) is isomorphic to $Hom_K(X,K[\epsilon]/(\epsilon^2))$ (K is the residue field at $x$). I want to say that  $$Hom_K(\mathfrak{m}_{X,x}/\mathfrak{m}_{X,x}^2,K)\simeq Hom_K(\mathcal{O}_{X,x}/\mathfrak{m}_{X,x}^2,K[\epsilon]/(\epsilon^2))$$ so I need splitting $\mathcal{O}_{X,x}$ into $\mathfrak{m}_{X,x}/\mathfrak{m}_{X,x}^2\oplus K$, and I build this splitting using the exact sequence  $$\mathfrak{m}_{X,x}/\mathfrak{m}_{X,x}^2\rightarrow \mathcal{O}_{X,x}/\mathfrak{m}_{X,x}^2\rightarrow K$$ so I need a splitting map $\sigma:K\rightarrow \mathcal{O}_{X,x}/\mathfrak{m}_{X,x}^2$. How can I do to find $\sigma$?

Let $X$ be a scheme over a field $k$, and let $x\in X$ be a rational point, that is, we have $k(x):=\mathcal{O}_x/\mathfrak{m}_x\cong k$.  Let $\alpha:\mathfrak{m}_x/\mathfrak{m}_x^2\rightarrow k$ be an element of $T_x=(\mathfrak{m}_x/\mathfrak{m}_x^2)^*$, the Zariski tangent space to $X$ at $x$.  Using $x$ and $\alpha$, I'd like to define a $k$-morphism of schemes Spec $k[\varepsilon]/\varepsilon^2\rightarrow X$.  In the course of the construction, I need to define a local map of local rings $\mathcal{O}_x\rightarrow k[\varepsilon]/\varepsilon^2$.  Using $\alpha$, what is a natural way to define such a map?  It might be helpful to note that I have an injection $k\hookrightarrow\mathcal{O}_x$ arising from the $k$-scheme structure on $X$.  I think this leads to a decomposition $\mathcal{O}_x/\mathfrak{m}_x^2=k\oplus(\mathfrak{m}_x/\mathfrak{m}_x^2)$ as $k$ vector spaces, from which the desired map would follow, but I can't seem to explicitly see what this decomposition is inside of $\mathcal{O}_x/\mathfrak{m}_x^2$.  This is part of exercise II.2.8 in Hartshorne.


I'm trying to develop a script that will iterate through a list of values within a FBGDB table/field and insert the last non-null value that was found into the ones that are null.    Here's what the table looks like:   This is what I have so far:  import arcpy  updatecursor = arcpy.da.UpdateCursor("D:\Tools\Scripts\insert over null\Testing.gdb\Test_tbl", ["From_Value", "To_Value"])  for row in updatecursor:     if row[0] is None:         print "There are Nulls"         row [1] = row[0]([-1])         print row[1]     else:         row[1] = row[0]         print "Has Value"     updatecursor.updateRow(row) del row, updatecursor   I know my issue is in row[1] = row[0]([-1]) but I can't figure out how to make it read backwards to the last non-null value which in theory would be the previous value in the list (assuming it's populating as it iterates through.

I'm using ArcMap to tidy up some field collected point data. The point data is a sequential track from a handheld device. In the attribute table i have a field with differant activities that separate out each track. However, only  the first occurrence/point of the activity is filled in and the rest below are blank till the next activity. .eg.  running  -  walking  -  Is there a way to filldown the entries to blank fields below? There are hundreds of blank entries for each one with a value, not sure if this makes a difference.


Can someone please tell me how I can display hidden folders with Nautilus?

How do you show a hidden folder (whose name starts with .) in File Manager a.k.a. Nautilus on Ubuntu?  I am somewhat new to Ubuntu and can't seem to find the "view" menu.


I got into console login page by CTRL+ALT+F1 and I don't want to reset the PC.  ESC or ALT+F4 or CTRL+C weren't enough to get back to the desktop environment. How could I get back to the desktop environment?  Thanks,

I tried to install an nvidia driver and there was an error saying I must not be in an X terminal when doing so. So I did a Ctrl+Alt+F1.  The resulting terminal did not allow the nvidia driver to be installed and showed the same error message. How do I revert back to the Unity GUI?


The title says it all; I deleted the ~/.Skype dir, restarted Skype, agreed to the T&Cs and added my sign-in information, yet my chat history still remains whenever I click any contact I have spoken with.  How do I remove chat history?

It seems that in the Window version of Skype, . It is supposed to be Tools > Options > IM & SMS > Clear history button but effectively nothing similar is here:    This option is not present on the version that come with my Ubuntu 13.04. In the privacy settings there is this option:     and somewhere in the Skype forum it is said that changing that to Disable History and then restarting Skype will get rid of the chat history. Tried that, don't work.   Searching a bit I found that you have to ; I did that from the directory I have:  cd $HOME/.Skype/my_skype_name/  rm chat*.dbb user*.dbb    ...still no go. Before I get rid of all the .Skype directory and re-configure all Skype, is there anyone that know how to do it? The content of the directory is:    alert2048.dbb       chatsync             httpfe           msn.db-journal alert4096.dbb       config.lck           keyval.db        msn.lock bistats.db          config.xml           keyval.lock      profile16384.dbb bistats.db-journal  contactgroup256.dbb  main.db          sms512.dbb bistats.lock        dc.db                main.db-journal  transfer256.dbb call256.dbb         eas.db               main.lock        voicemail callmember256.dbb   eas.db-journal       msn.db           voicemail256.dbb   Removing all other *.dbb doesn't work, either.  Lesson: never put sensitive data on a Skype chat.


I am trying to solve the following definite integral:  $$\int_0^\pi \frac{x\sin(x)}{1+\cos^2(x)}dx$$  However, it appears that an elementary antiderivative does not exist for the function. Is there any way to solve the definite integral?

Find the integral  $$ \int_0^{\pi} \frac{x \sin x}{1+(\cos x)^2}$$


EDIT: Added my thoughts about "downvote as quality info"; removed the part about opinions (thank you Manishearth); explained better the proposal.  The question is already in title: do you think that down-voting is really useful for any Stack Echange community?  In my opinion down-voting  misses its primary intention: does not educate the user. I think it's more useful for the user you would down-vote and for the entire community to explain what's wrong in the post with a comment.   (new) As pointed out by Yannis and Manishearth, downvotes are useful to signal bad posts, but you can do the same upvoting good posts. This is even more so for answers, since you can also vote to close them.  Down-voting is like giving a silent slap. Commenting is like admonishing. It's not fair that a questioner and an answerer must explain clearly what they write, while a down-voter can simply click a button. Personally I down-voted only two times, when the post was already commented by me or someone else as not good and the author had not changed it.  Yes, Stack Exchange sites will suggest that you should add a comment, but from my (little) experience people that leave a comment before down-voting are a minority. For example, a question of mine had a bad answer, and I commented it to explain why it is bad; in the meanwhile the answer was down-voted without any comment. After a while the answerer deleted it. I do not think that the down-vote was particularly useful. And if I can be completely honest, I'm a bit angered by the fact that the answerer can think the down-vote was casted by me :D  Furthermore down-voting is particularly misleading for sites like Meta Stack Overflow or Programmers or something, since I noticed that people on these sites tend to down-vote a post because they do not agree with it instead of because the post is badly written.  I think a more useful method would be to allow users to check a "Down-vote if not edited" box. If such a comment is left and the post is not edited after X minutes, a down-vote will be automatically cast. (changed) If the post is edited, the commenter will be informed and can down-vote if (s)he don't like the edit. In my humble opinion a system like this will conjugate the quickness of down-voting with the fairness of commenting.

I'm not a fan of the downvoting feature in general; frankly, I think it should be removed from all of the stackexchange sites.  Negative feedback leads to negative results. I recognize that the intent is not to provide a means of giving negative feedback, but that's what downvoting does. "The community's way of telling peers that their content can be improved" isn't an accurate description of downvoting: people who downvote other people with no explanation as to why (the usual practice) generally consider them not their peers, but their inferiors.   I fear that the downvoting feature panders to the worst aspects of human nature, to an extent that far outweighs any possible benefit that it can provide. I recognize that the intent of downvoting is to make a form of constructive criticism available, but that it fails to do. It simply says "this is bad" without any explanation. If someone really wants to offer constructive criticism, he can do so in the comments, or by closing questions with an explanation of how to bring them up to par. If he does that, it is that that has the value, not a downvote that might or might not go along with it.  I submit that the increasingly negative "elitist" reputation of many of the stackexchange sites (stackoverflow, the "bread and butter" site, in particular) is due more to unexplained downvotes than anything else: downvoting is (much) more often than not a way of telling new people that they aren't welcome in the club. This isn't conducive to growth.  It seems to me that the recently introduced admonishment to "be nice" to new members acknowledges the problem without really doing anything about it. It would be given more teeth if the downvoting feature were removed entirely — people have to give a lot more thought to a comment than a downvote decision. Furthermore, the (apparently many) "serial downvoters" who contribute little if anything else to the site would take themselves elsewhere.   Thoughts? What are the positive contributions (are there any?) that downvoting makes to the stackexchange sites?


Towards the end of 'Endgame', Captain America goes back in time to return all the stones. But instead of returning to the current timeline, he stays back in the earlier timeline and ages naturally.  The question is, how did he end up back in the present timeline? It is already mentioned in the movie that altering the past does not alter the future, it merely creates new timelines. So this Captain that travelled back in time cannot exist in the new timeline.  In the present timeline, the young captain exists. In fact, he existed a couple of minutes before the older one turned up. The existence of the younger Captain cannot be changed in the current timeline. This is what Bruce says - changing the past cannot change the future. There can now only be a new timeline where the older Captain exists but NOT in the 'present' timeline.

If Steve Rogers, as Avengers: Endgame has shown, never went on the ice to go to the future to form the Avengers, then the current timeline doesn't make sense. Also if he went back before he went on the ice, then what happened to the other Captain America in general?  If he went back after the past Cap went on ice then that would mean that there are now inconsistencies with Winter Soldier and Civil War where Peggy is mentioned as to have already lived a life without him.


How do i get the .tga image on the right onto the mesh on the left?    thank you

I want to put a 2D image on a 3D object in Blender. How do I do that?  I have found the "textures" tab in the "properties" window, but I can't figure out what to do with it.  Preferably, I would like to click and drag an image off my desktop right onto the object.


I want to enable or use Backspace to switch back to previous page that I visited previously in the Firefox browser on Ubuntu. For example, if I am using any browser on Windows, I can use Backspace instead of back button in browser to go to previously visited page.

In Firefox on Windows when I press the Backspace key it goes to the previous web page I surfed to.  Why doesn't it work in Ubuntu and what can I change to make it work?


I'm trying to download a torrent, and Transmission bittorrent isn't showing up on the list of programs to run the file with, and I don't know where to locate it.

I went to download a torrent today and Firefox asked me to choose an application to do so (although the bit torrent files normally go to transmission per the permissions I've set in Firefox).  I go to search for transmission and the search function just turns up music files with the letters 'tran' in them. I'm very frustrated.  I literally can't find the path to a file that's on my computer.


I want to add sums while writing tabular (tabularx) lines. For this I have written a command to emit individual lines, but all the \FPxxx commands fail to work from within the tabular environment. I boiled this down to this MRE: \documentclass{article}  \usepackage{fp}  \FPset\x{2} \FPadd\x\x{7}  \begin{document} \Huge  x = \x  \begin{tabular}{l} \FPadd\x\x{100}text \end{tabular}  x = \x\\(should be 109)  \end{document}  This results in the following output:  As you can see, the first \FPadd worked, but the second one inside the environment fails. Why and how can I work around that?

I have this code in my LaTeX:   \FPset{totalHours}{0}  \newcommand{\entry}[5]{     \FPeval{totalHours}{(totalHours)+#5}     #1 & #2 & #3 & #4 & #5 \\ }   Where \entry is meant to be an entry in a time log. The 5th argument is a number representing the number of hours in that entry. I want to keep a running total of the hours in a variable I can print later on, totalHours.   This seems to do the \FPeval but then totalHours gets reset to 0 by the next time I write \entry. What is the correct way to keep a running total? Thanks.


I am trying to take a string in a list of strings and remove all the white space while separating non-space with a comma. For example I have the string:  '        XX       XX          X   XXXXXX   XX               XXXXXXX    XXXXX'   and need to return it as ['XX', 'XX', 'X', 'XXXXXX', 'XX', 'XXXXXXX', 'XXXXX']. Any suggestions?   Note: The amount of space between each segment varies.

What regex pattern would need I to pass to  java.lang.String.split()  to split a String into an Array of substrings using all whitespace characters (' ', '\t', '\n', etc.) as delimiters?


Teferi, Time Raveler's static ability reads:  "Each opponent can cast spells only any time they could cast a sorcery."  Madness rules state (emphasis added):     502.24. Madness      502.24a Madness represents two abilities. The first is a static ability of cards that functions while the card is in a player's hand. The second is a triggered ability that functions whenever the first ability is applied. The phrase "Madness [cost]" means "If a player would discard this card from his or her hand, that player discards it, but may remove it from the game instead of putting it into his or her graveyard," and "Whenever this card is removed from the game this way, until he or she passes next, he or she may play it any time he or she could play an instant as though it were in his or her hand by paying [cost] rather than paying its mana cost. When he or she passes next, he or she puts it into his or her graveyard."   Teferi prevents opposing players from casting spells except when they could cast a sorcery. If someone discards into exile as the result of a spell or triggered/activated ability causing them to discard a card, they cannot cast a sorcery because the stack isn't empty.  Am I correct in understanding that Teferi effectively disables madness for his controller's opponents while he's on the board?

says that enemies can only cast spells at sorcery speed. Does this prevent spells that are getting cast off of Cascade from casting?


I have below list  l1 = [1,2,3,4,5,6,7,8,9]   I want to understand below  result :-  >>> l1 [4:8:-2]   Please explain result of above slicing.

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


I saw an ad on a local site for a Minolta XD11, seemingly body only. The listing claims manual exposure works but battery operation has not been tested. The price is dirt cheap. What do I check for, assuming I meet the seller?

I'm planning to buy a used Nikon F5.   I have no experience with a film camera and I want to know what all should one be careful of before buying a used film camera and more specifically a Nikon F5.


Link2sd not working on my rooted phone please help. trying from 2 weeks. having Android 4.2 jellybean. it says Mount script cannot be created. no such file or directory.

My Link2SD doesn't seem to be fully working. I noticed this when updating the Facebook application. Google Play prompted me of insufficient storage. I first uninstalled some apps but I got curious so I checked Link2SD's storage info, I got this:   (Click image to enlarge)  As you can see, the internal storage only has mere 70mb left. What's peculiar is, these are the only apps I have NOT linked:   (Click image to enlarge)  I tried moving one linked app (Amazing Alex) to the sd card (normal Android way) and sure enough, the free space on my internal storage got bigger by about an additional 20mb-ish.  Why is this happening? Why isn't Link2SD moving the data to my sdext2? How do I solve it?


When I want to emphasize a result or aim, I use a phrase with 'so that'.  Other authors use 'such that'.  I wonder if there are any rules or if both can be used interchangeably.  For example     Experts from different backgrounds are invited so that diverse opinions can be heard.   vs.     Experts from different backgrounds are invited such that diverse opinions can be heard.

Are these the same?  The image will be sheared such that the x-axis goes through (1,1). The image will be sheared so that the x-axis goes through (1,1).  I think I have usually seen the former, I didn't even know that “so that” is allowed in English until I once saw it in a text from a (as I assume) native English speaker. Simon


Forgive me, I am forgetting my basic statistics.

Many studies in the social sciences use Likert scales.  When is it appropriate to use Likert data as ordinal and when is it appropriate to use it as interval data?


I always wondered why the hassle creating the Matrix anyway?  Yes, the machines need energy which can be harvested in the form of biological energy from humans. But why did they not just take animals, e.g. sheep. Since the physiology of animals and humans is very similar, they would likewise be able to generate energy. Advantageous over humans though, it would be possible to hold them captive without creating a Matrix.

The machines are keeping humans alive for their body heat, right? But they also have nuclear fusion reactors, and (while I haven't run the numbers) I'd be willing to bet that a single fusion reactor would generate more net energy in an hour than all the humans on today’s Earth would in a day.  I have one more additional doubt:  Why people, instead of animals that don't need a computer simulation to keep their brains entertained?  Why do the machines keep humans alive if they have nuclear reactors?


I am facing this problem on Ubuntu 20.04:  Err:9 http://ppa.launchpad.net/faux/jailkit/ubuntu focal Release   404  Not Found [IP: 91.189.95.83 80] Ign:7 https://www.tolaris.com//apt precise InRelease Ign:8 https://www.tolaris.com//apt fossal InRelease Err:10 https://www.tolaris.com//apt precise Release   404  Not Found [IP: 35.246.229.84 443] Err:11 https://www.tolaris.com//apt fossal Release   404  Not Found [IP: 35.246.229.84 443]  And I don't know how much this affects the server. Because I install Webmin-Virtualmin and see that it uses apt, too in install modules and update. How can I solve that? I have not seen anything about it in web search and studies.

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


I've enabled logging on my desktop application by configuring app.config  <system.diagnostics>   <trace autoflush="true" indentsize="4">     <listeners>       <add name="myListener" type="System.Diagnostics.TextWriterTraceListener" initializeData="application.log" />       <remove name="Default" />     </listeners>   </trace> </system.diagnostics>     And then I can log on my application with a line like this  System.Diagnostics.Trace.TraceInformation("Start tailing file: {0}", watcher.FileLocation);   Now I want to enable the log file ONLY when I start application on Debug mode, because I don't want to distribute my package with log enabled.  Is there any way to configure it?

I need to use different database connection string and SMTP server address in my ASP.NET application depending on it is run in development or production environment.   The application reads settings from Web.config file via  property.  I use Build/Publish command to deploy the application to production server via FTP and then manually replace remote Web.config with correct one.  Is it possible somehow simplify the process of deployment? Thanks!


Am i able to do something like this: (without defining new environment)  \newcommand{\code}[2] {      \begin{lstlisting}[language=#1]         #2     \end{lstlisting}  }   I don't want to write:  \begin{code}{python}     >>> print "Hello World!" \end{code}   I want to be able to write:  \code{python}{>>> print "Hello World!"}

I'm trying to this:  \newcommand{\code}[1] {\begin{lstlisting} {#1} \end{lstlisting} }   But I keep getting this error:  Package Listings Warning: Text dropped after begin of listing   I'm calling \usepackage and all so, do any of you knows how to solve this?


I've tried a lot with the Euclidean Algorithm, but I still can't figure it out. Do you know how I can use the Euclidean Algorithm to find the inverse of $\overline{x^2 -x}$ in $(\mathbb{R} [x]/(x^4 + 1))^*$? Thanks in advance!

Let $\theta$ be a root of $p(x)=x^3+9x+6$, find the inverse of $1+\theta$ in $\mathbb{Q(\theta)}$.  So problems like this really annoy me but I did crappy on the last homework after making a lot of arithmetic mistakes so I want to run everything by you guys. This one isn't actually for homework it's just a suggested practice problem but okay lets go!!!  So I'm not sure if the method I used to do this was standard or not, I don't remember my professor showing me, but what I did first was used the canonical euclidean algorithm in $\mathbb{Q[x]}$ and wrote:  $x^3+9x+6$  $=(1+x)(x^2-x+10-\frac{4}{x+1})$  $=(1+x)(x^2-x+10)-4$  the reduced modulo  the minimal polynomial of $\theta$ i.e. $x^3+9x+6$ and so  $4=(1+x)(x^2-x+10)$  $\rightarrow$  $1= \frac{1}{4}(1+x)(x^2-x+10)$ and sooo ah $(\theta^2-\theta+10)\frac{1}{4}$ is what I believe is the inverse of $(1+\theta)$ in the quotient field... Like i said I hate these problems but ehh is this correct? On a lighter note it's finally getting cool enough for me to go on proper runs here and so that's pretty bomb!


I am using ubuntu 12.04 with unity 2d. I want to change the wallpaper per workspace, i came across few gconf editor related tutorials but is it possible in any other way? Does unity have it built in or I will have to hack it from these tutorials?  I want it to work on both unity2d and Unity3d.

I normally use 4 different workspaces for different things, and they are always the same. Can I make a different background image for each one of them?   I would like an answer that works for GNOME 3 desktop environment, Unity and the Classic desktop environment.     This question has multiple answers covering different Ubuntu versions:


Suppose a function $f$ continuous on $[0,1]$ and differentiable on $(0,1)$ such that $f(0) = f(1) = 0$ and $x_0 \in (0,1) $. Prove that there exist $c \in (0,1)$ such that $f'(c) = f(x_0)$   My attempt:   Assume $f(x_0)>0$ there exist a $c_1$ such that $f'(c_1) = \frac{f(x_0)-f(0)}{x_0-0} = \frac{f(x_0)}{x_0} > f(x_0)$ as $x_0 <1$ and $c_2$ such that $f'(c_2) = \frac{f(1)-f(0)}{1} = 0 < f(x_0)$ by Mean Value Thereom and by IVT, there exist a  $c$ such that $f'(c) = f(x_0)$ Do the same for $f(x_0)<0$.   However, I realise that $f'$ may not necessarily be continuous which will cause IVT to not hold. What is the approach then?

Let f be a function continuous on [0,1] and differentiable on (0,1)  My attempt:  I have tried solving using Rolle's theorem for f'(c) = 0  I let c<x then by Mean Value Theorem, f'(c) = (f(x)-f(0))/(x-0) = f(x)/x since f'(c) = 0, f(x) = 0 Hence f'(c) = f(x)  Similarly, I let c>x and by Mean Value Theorem again, f'(c) = (f(1)-f(x))/(1-x)       = f(x)/(1-x) since f'(c) = 0, f(x) = 0 Hence f'(c) = f(x)  I feel like this proof is wrong because I don't know how to continue with the case where c=x


I need to change a file that i have already pushed but i don't want to do a new commit, so i tried amend. But when I try to push the changes to the remote branch it gives me an error. Do I need to do a force push or something else ?? I'm the only one working on this project so no one is going to pull this branch(I can use amend).  Thanks.

When I've worked a bit with my source code, I did my usual thing commit and then I pushed to a remote repository. But then I noticed I forgot to organize my imports in the source code. So I do the amend command to replace the previous commit:  > git commit --amend   Unfortunately the commit can't be pushed back to the repository. It is rejected like this:  > git push origin To //my.remote.repo.com/stuff.git/  ! [rejected]        master -> master (non-fast forward) error: failed to push some refs to '//my.remote.repo.com/stuff.git/'   What should I do? (I can access the remote repository.)


How can one prove without using anything but differentiation, that $e^x$ is the only function with $f'=f$? Clearly I can prove that $(e^x)'=e^x$, and $0'=0$, but how can one show that no other functions exist? Thank you.

I was wondering on the following and I probably know the answer already: NO. Is there another number with similar properties as $e$? So that the derivative of $\exp(x)$ is the same as the function itself. I can guess that it's probably not, because otherwise $e$ wouldn't be that special, but is there any proof of it?


I have one lists with many duplicates, for example:  AARC AARC AARC TNGT TNGT TNGT CAAC CAAC   And one list without any duplicates, for example:  AARC TNGT YUGT BATR   etc.   All of the entries in the first list will appear in the second list, but not vice versa.   I want to compare the lists and find out how many entries are in both, however I want to retain and recognize duplicates. For example, the output could either be:  AARC AARC AARC TNGT TNGT TNGT   Or  AARC\tAARC AARC\tAARC AARC\tAARC TNGT\tTNGT TNGT\tTNGT TNGT\tTNGT   The issue I'm having is that comm grabs the first duplicate and moves on, counting subsequent entries as not being shared. Every article I can find online references removing duplicates, not retaining them. There used to be a database I could use for this, but they recently changed their default behavior to removing duplicates, and with thousands of entries I can't do it by hand :/

I have the following code that I run on my Terminal.  LC_ALL=C && grep -F -f  genename2.txt hg38.hgnc.bed > hg38.hgnc.goi.bed   This doesn't give me the common lines between the two files. What am I missing there?


Suppose you have two lists of strings, the first one being the keys for the dictionary, and the second being the values for the keys of corresponding position. So it's something like this:   >>print keys ['key1', 'key2', ..., 'keyN'] >>print values ['value1', 'value2', ..., 'valueN']   with this line of code:   dic = dict.fromkeys(keys)   I've assigned the keys to my dictionary. So my output is something like this now:   >>print dic {'key1': None, 'key2':None, ..., 'keyN': None}   Can I somehow do the same thing I did with the keys, but with the values as well? But only this time store the values one by one to the dictionary? So my targeted output is something like this:  >>print dic {'key1':'value1', 'key2':'value2', ..., 'keyN':'valueN'}

Imagine that you have the following list. keys = ['name', 'age', 'food'] values = ['Monty', 42, 'spam']  What is the simplest way to produce the following dictionary? a_dict = {'name': 'Monty', 'age': 42, 'food': 'spam'}


Being a value semantic language, C++ passes all parameters by value. So when I pass pointer to an object, the object is passed by reference, but the pointer itself is passed by value (although I believe the object is not  passed at all, only the pointer is, and we access the object inside the function by reference. I think this idea  also conform to value semantics, since if I thinks like this, value semantics becomes more meaningful, Nothing is passed except value).  So thinking this way makes sense for pointer, as a pointer to something is itself an object, which has both lvalue and rvalue. While passing a pointer as a parameter, a copy of the rvalue is sent, like any other object (ex. passing an integer).  But what about reference? Theoretically, reference is not any individual object, id does not have any identity, simply an alias to the object it refers to. Common implementation of reference may be on top on pointer, but what about uncommon implementation? Even if implemented in terms of pointer, is it passed by value?

I would like to clarify the differences between by value and by reference.  I drew a picture     So, for passing by value,  a copy of an identical object is created with a different reference, and the local variable is assigned the new reference, so to point to the new copy  How to understand the words: " If the function modifies that value, the modifications appear also within the scope of the calling function for both passing by value and by reference "  Thanks!


Since the price of the Microsoft Surface has dropped significantly, I'm seriously considering getting one. The only problem - I hate Windows. I would really love to install Ubuntu on it - even if I have to run it from a flash drive. I just would like double assurance, and maybe some instruction on how I could do the install! Either way, I think you guy will be able to help me on this one. If I can't, then I'll probably just buy an iPad Mini (which wouldn't be AS cool...) Cheers! - Mike

My family might be buying a Windows Surface tablet with Windows RT (Nvidia)? I was wondering if I can run Ubuntu or WUBI on it for my homework?


I want Skype to open automatically on start-up. So I got the instructions... Start-up Applications > Add. Then I get a window with three fields. In the first I write "Skype".  In the second I cut and paste the code: /usr/bin/skype as instructed.  In the third field I write "Internet Telephony".  I then press Add… and all I get is another box.  The application simply will not load. I have tried every possible permutation of that code, with no result. This has taken months of trying and I still can't get Skype to open on startu-up!

I've installed Skype and it's running all OK but I want it to start automatically when I log with my user.  How can I do that?


I'm study Learnpythonthehardway, in ex40, I met this slice of code.  for sentence in snippet, phrase:     result = sentence[:]   I'm not quite understanding sentence[:] here, especially the [:]  I've tried to figure it out by underlying test code:  sentence = 'sss errf : fe : eee' f = 33 result = sentence[:f] print result   but nothing happens, result is the same as the sentence  So, smart geeks, what does sentence[:] mean here?

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


Is there a way one can combine all textures that are applied to a mesh's faces in a texture atlas in blender and export said atlas as .png alongside an .obj for example?  If not, is there a way one can map textures of a texture atlas to a mesh's faces in blender? (I believe this process might be called 'uv mapping', but how does one apply images to the unwrapped 2d image?)  Here a sample atlas:    Should any of this be possible, do you know of any tutorials that explain the process in detail?

I have a finished model where the UV maps overlap - lots of wood that isn't detailed to be particular to the model.    I'd like to re-map the texture so that specific details can be added. I'd like to rebuild the UV map into non-overlapping islands, without losing the current texture application, and preferably without manually pulling apart the islands.  Is this possible?


I am trying to create a weapons upgrade for my Spaceship, using libGosu and Chingu (in Ruby). This question is about how to deal with this issue specifically in Ruby, and more specifically in libGosu.  In the player class I have tried several variations of the following:  def fire   Bullet.create(:x => @x, :y => @y, :angle => @angle)   Bullet.create(:x => @x + Gosu::offset_x(90, 25), :y => @y + Gosu::offset_y(@angle, 0), :angle => @angle) end   It sort of works, but not exactly how it ideally should. For reference, this is what the Bullet class looks like:  class Bullet < Chingu::GameObject   def initialize(options)     super(options.merge(:image => Gosu::Image["assets/laser.png"]))     @speed = 7     self.velocity_x = Gosu::offset_x(@angle, @speed)     self.velocity_y = Gosu::offset_y(@angle, @speed)   end    def update     @y += self.velocity_y     @x += self.velocity_x   end end   How should I construct "def fire" in order to get the extra bullets to align properly when the spaceship rotates?    In the first image (above) the bullets are separated as intended.    In the second image the bullets are clumping together when the spaceship is rotated.

I try to shoot a bullet toward the mouse position by this code.  float deltaX = mousePosition.x - (aircraft.getPosition().x + aircraft.getLocalBounds().width / 2); float deltaY = mousePosition.y - (aircraft.getPosition().y + aircraft.getLocalBounds().height / 2); float angleRadian = (float)(std::atan2(deltaY, deltaX)); float angleDegree = (float)(angleRadian * 180 / PI);   It works fine with one bullet but when I add another one bullet to shoot together I use this code to specify start shooting point of each bullets.  sf::Vector2f offset1(aircraft.getPosition()); offset1.x += -10;//start shooting point first bullet.  sf::Vector2f offset2(aircraft.getPosition()); offset2.x += 10;//start shooting point second bullet.   this is a picture of this problem.   When I rotate aircraft to picture 2 the bullets are not the same as the first picture.  How can I solve this problem?