I have a Netherlands visa. My plans have changed drastically. I would be staying most number of days in Spain. Can i have my POE in Madrid? Will it be a problem if neither my POE not my maximum number of days are not in the country from where i got my Schengen visa?

In case, if I get a multiple-entry Schengen visa in one of the embassies in Ukraine, Kyiv - should my first trip be to the country which issued the visa?  Any there any requirements of this sort? Does this condition vary depending on embassy which issued the visa?  What are the possible consequences on not visiting that country first? Does it somehow depend on country where the embassy is (i.e. non-Schengen and not EU members)?


As the title, how can the galaxy have instantaneous wireless 3D video communication across arbitrary distance, but the Death Star plans had to be carried in one copy by the space travel equivalent of ?  They seem important enough that the Rebels might be willing to send them to a bunch of different ships in different areas of the galaxy (remember, they can send data instantaneously over any distance, albeit with some difficulty as shown when they had to bounce a signal in Episode I, so perhaps they couldn't send it just anywhere, as noted by Richard) and then immediately have them make the jump to hyperspace with the destination somewhere else, to evade Imperial interception (assuming the signal could be intercepted and traced in the first place).    I do realize that the real answer is that the writers had no idea that FTL communication opens up such a huge can of worms, I'm just interested if it was ever explained in-universe.

Many rebels died to procure the , which were then transmitted to the Tantive IV. As we all know, the Tantive IV was then captured by Vader and the Imperials. Leia stores the plans within the data banks of R2-D2. We're told repeatedly how important R2 is because he must be delivered to the rebels so that they examine the plans to destroy the Death Star.  But why?  Even just within the original trilogy, we're shown examples of long range, interstellar communication.   Why weren't the plans sent directly to the rebels instead of the Tantive IV, or sent directly from the Tantive IV when they first received them?


What is the difference between returning by pointer and returning by reference? In both cases, the address is returned to the caller, am I right?  According to this little program - its obviously the same - it prints the value of an integer.  Are the any limitations concerning returning by reference rather than returning by pointer? My teacher tells us - when you return by reference to a receiver, the receiver "borrows" the object. When you on the other hand return a pointer - you "transfer" the ownership of the object to the receiver.   #include <iostream> using namespace std;  class A {     int x;    public:     A() : x(10) { }      void print() {         cout << "x = : " << x << endl;     }  };  class B {     int y;    public:     B() : y(30) { }      void print() {         cout << "x = : " << y << endl;     }      A& create() {         A* a = new A;         return *a;     } };   Return by pointer, then these parts of the code I changed:  A* create() {    A* a = new A;    return a; }   And in the main:   b.create()->print();

I know references are syntactic sugar, so code is easier to read and write. But what is the difference between a pointer variable and a reference variable?


For example after doing apt-get update, it shows Reading package lists... 82% with the percentage changing in the same line.  How is that achieved? Is it possible to use it in a bash script?

I really like the look of the output of   But that script is only used for Input/Output operations.  How can I use it as a replacement for sleep but with visual feedback?  sleep 10


What is the significance/geometric interpretation of eigen values or eigen vectors in a vector space?

What is the importance of eigenvalues/eigenvectors?


The set {0} with the + and × operations defined as 0+0=0 and 0×0=0 sarisfies the properties to be a field, so a vector space can be constructed over it, with the property $0x = x $ where x is a vector.  In my book it states that the vector $x $ by itself forms a linearly dependent system iff $x=0$.  This seems to lead to a contradiction: if we assume that the vector space is over {0} with the properties said before, then $x =0$ is also linearly independent since the only way to get the null vector from it is multiply it by 0...  So does this mean that it is linearly dependent and independent at same time? Which would mean that lin. dependence is not the negation of lin. independence... Or is the book wrong? Or am I making a mistake?

Consider the set $F$ consisting of the single element $I$.  Define addition and multiplication such that $I+I=I$ and $I \times I=I$ .  This ring satisfies the field axioms:   Closure under addition.  If $x, y \in F$, then $x = y = I$, so $x + y = I + I = I \in F$. Closure under multiplication.  $x \times y = I \times I = I \in F$ Existence of additive identity.  $\forall x \in F$ (i.e., for $x=I$), $x + I = x$, so $I$ is the additive identity. Existence of mulitiplicative identity. $\forall x \in F, x \times I = x$, so $I$ is the multiplicative identity. Additive inverse. $\forall x \in F, \exists y = I \in F: x + y = I$ Multiplicative inverse. $\forall x \in F, \exists y = I \in F: x \times y = I$.  However, because the additive identity need not have a multiplicative inverse, this is a vacuous truth. Commutativity of addition.  $\forall x, y \in F, x + y = I = y + x$ Commutativity of multiplication.  $\forall x, y \in F, x \times y = I = y \times x$ Associativity of addition.  $\forall x, y, z \in F$, $(x + y) + z = I + I = I$ and $x + (y + z) = I + I = I$, so $(x + y) + z = x + (y + z)$ Associativity of multiplication.  $\forall x, y, z \in F$, $(x \times y) \times z = I \times I = I$ and $x \times (y \times z) = I \times I = I$, so $(x \times y) \times z = x \times (y \times z)$ Distributivity of multiplication over addition. $I \times (I + I) = I$ and $I \times I + I \times I = I$, so $\forall x,y,z \in F, x(y+z) = xy+xz$   Based on the above, $\{I\}$ seems to qualify as a field.  If $I$ is assumed to be a real number, then the unique solution of $I + I = I$ and $I \times I = I$ is, of course, $I = 0$.  So, is {0} a field, or is there generally considered to be an additional field axiom which would exclude it?  Specifically, is it required for the multiplicative identity to be distinct from the additive identity?


I am new to Blender and would like som help to extract Blender mesh information, such as faces and vertices so I can use it in my Python project. I have found a video () showing how to create objects in blender from Python code, and this is also the mesh structure I would like to use, e.g.  verts = [(0,0,0), (0,5,0), (5,5,0), (5,0,0), (0,0,5), (0,5,5), (5,5,5), (5,0,5)] faces = [(0,1,2,3), (7,6,5,4), (0,4,5,1), (1,5,6,2), (2,6,7,3), (3,7,4,0)]   However, I would like to do it the other way around. First create a 3D object in blender, and then extract the mesh information to Python.  Can you help me?

I have a  which I import into Blender.    Now what I'm trying to do is to export the coordinates of vertices into a .ply file. When I export these vertices into a .ply file they are not correct. It seems that it only exports the coordinates of the single face which you can see in the picture. How can I export those vertices correctly?  EDIT The .csv structure:  1;2;3\n  4;5;6\n  ... Each column is separated by a semicolon and each row by a new line.


For the symmetric groups $S_n$ there's a quite simple way to find all the conjugacy classes. We find partitions of $n$, that is, we write  $$n = n_1+\cdots+n_k,$$  and then for each such partition there's a conjugacy class which is the set of all permutations of the form  $$\sigma=\sigma_1\cdots\sigma_k,$$  being $\sigma_i$ one $n_i$-cycle.  Now, what about $A_n$, the alternating groups? Is there any systematic way like that to find all the conjugacy classes?

Browsing  I came across this:  The conjugacy class of an element $g\in A_{n}$:  splits if the cycle decomposition of $g\in A_{n}$ comprises cycles of distinct odd length. Note that the fixed points are here treated as cycles of length $1$, so it cannot have more than one fixed point; and does not split if the cycle decomposition of $g$ contains an even cycle or contains two cycles of the same length.   Anybody with a proof?


Iam new to ios, iam an android developer i have code were iam converting image to byte array and sending to server. here is my code in java,  String sResponse = "";                 String url = webpath+"user_upload.php?";                 HttpClient httpClient = new DefaultHttpClient();                 HttpPost httpPost = new HttpPost(url);                 MultipartEntity entity = new MultipartEntity();                 entity.addPart("first_name", new StringBody(f_name));                 entity.addPart("last_name", new StringBody(l_name));                 entity.addPart("user_image_name", new ByteArrayBody(                         image_byte_array, "image/png", ".png"));                  httpPost.setEntity(entity);                 HttpResponse response = httpClient.execute(httpPost);                  BufferedReader reader = new BufferedReader(                         new InputStreamReader(                                 response.getEntity().getContent(), "UTF-8"));   can any one help me implement this in ios, have tried many codes they are not working for me.. here is the code in ios  NSData *bytes= UIImageJPEGRepresentation(profilePicImageView.image,0.0);         NSString *recordPostLength = [NSString stringWithFormat:@"%d", [bytes length]];         NSMutableString *urlstr = [NSMutableString stringWithFormat:@"%@", WEB_URL];         [urlstr appendFormat:@"first_name=%@", firstName];         [urlstr appendFormat:@"&last_name=%@",lastName];         [urlstr appendFormat:@"&user_image_name=%@",recordPostLength];         NSMutableURLRequest *recordRequest = [[NSMutableURLRequest alloc] init] ;         [recordRequest setURL:[NSURL URLWithString:urlstr]];         [recordRequest setHTTPMethod:@"POST"];         [recordRequest setValue:recordPostLength forHTTPHeaderField:@"Content-Length"];         [recordRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];         [recordRequest setHTTPBody:bytes];         NSURLResponse *recordResponse;         NSError *recordError;         NSData *recordResponseData = [NSURLConnection sendSynchronousRequest:recordRequest returningResponse:&recordResponse error:&recordError];         NSString *recordResp = [[NSString alloc]initWithData:recordResponseData encoding:NSUTF8StringEncoding];         NSLog(@"recordResp:%@", recordResp);

I know how delegates work, and I know how I can use them.  But how do I create them?


If you have a TRULY random key (in binary) and you have a text (in binary) that you want to encrypt.  Can you simple XOR the key and the text?  Is that secure?  How secure?

I have heard criticism of various cryptosystems saying that "at their heart, they were just XOR."  Is this just ignorance, or is there something inherently wrong with XOR based ciphers?


during the last month i've dedicated myself to the study of Flask, a python framework for building web application.  Following different tutorials i've found online, I've discovered SQLAlchemy.   To be honest, i find it complicated and not really useful since i have a pretty good knowledge of SQL language.   What i want to understand is if there is any major gain in using ORM like SQLAlchemy that i'm missing (maybe some security issue in using pure sql that i don't know about?).  Also, i would appreciate if you could advice me of what's the best python library for working with pure SQL queries.

For some of the apps I've developed (then proceeded to forget about), I've been writing plain SQL, primarily for MySQL.  Though I have used ORMs in python like , I didn't stick with them for long.  Usually it was either the documentation or complexity (from my point of view) holding me back.  I see it like this: use an ORM for portability, plain SQL if it's just going to be using one type of database. I'm really looking for advice on when to use an ORM or SQL when developing an app that needs database support.  Thinking about it, it would be far better to just use a lightweight wrapper to handle database inconsistencies vs. using an ORM.


I'm looking for a book recommendation for an undergraduate level textbook covering Lagrangian and Hamiltonian Mechanics. I'll be taking the second course on classical mechanics in the upcoming term. Ideally, I'd like a textbook that -- in addition to focusing on the application of the principles to solve physical systems, as mostly done in "$\text{PHY}: 101$" -- focuses on the theoretical aspects as well -- Poisson Brackets etc. Most of the textbooks I have seen seem to focus only on the former.  Since ideas in Hamiltonian and Lagrangian Mechanics pop up everywhere -- from non relativitic QM to QFT -- I'd appreciate if someone can recommend an undergraudate level textbook that caters to both of the aforementioned criteria.

I'm taking a course on  and  Dynamics, and I would like to find a good book/resource with lots of practice questions and answers on either or both topics.  So far at my university library, I have found many books on both subjects, but not ones with good practice questions and answers. I have Schuam's outline of Lagrangian Dynamics, but didn't really find a lot of practice questions.  Any suggestions would be greatly appreciated!


Tanenbaum's Computer Networks says     The IP address 0.0.0.0, the lowest address, is used by hosts when they   are being booted. It means ‘‘this network’’ or ‘‘this host.’’    [::]   is IPv6 version of IPv4's 0.0.0.0.  Questions:  1) When does [::]  or 0.0.0.0 mean this network and when this host?  2) When it means this host, does it mean all the network interfaces on this host, or just one specified network interface on this host?  3) Why does [::]   allow me to access the mysql server from other hosts in the same LAN?   Does it mean this network or this host here? Why is  [::] used by mysql server, although the host is not in the case "when they are being booted"?     $ sudo netstat -ap | grep mysql    tcp6       0      0 [::]:mysql              [::]:*                  LISTEN      23683/mysqld            tcp6       0      0 [::]:33060              [::]:*                  LISTEN      23683/mysqld            unix  2      [ ACC ]     STREAM     LISTENING     1169294  23683/mysqld         /var/run/mysqld/mysqld.sock    unix  2      [ ACC ]     STREAM     LISTENING     1169513  23683/mysqld         /var/run/mysqld/mysqlx.sock    unix  2      [ ]         DGRAM                    1169211  23683/mysqld   Thanks.

We are serving a port on localhost and want to check in another process if the port is available. Due to a bug in our code, it is actually trying to connect to the IP 0.0.0.0:<port>, and for some reason it succeeds -- as strace proves:  [...] connect(3, {sa_family=AF_INET, sin_port=htons(10002), sin_addr=inet_addr("0.0.0.0")}, 16) = 0 [...]   What does it mean? Why does it work?


I set up up a new laptop with Ubuntu 18.04.1 and try to customize it so that it "feels like mine". In addition to the normal system settings, gnome-tweaks already provided some more configuration options, but I miss the option to specify the layout of workspaces. Some versions of Ubuntu by default had the workspaces distributed in a row, others in a grid and in Ubuntu 18.04 they are all in one column. I really prefer the grid, but found no way to configure that. Even the keyboard shortcuts to move windows one workspace to the left/right are gone, but instead there is the option to move them one monitor to the left/right.  Any ideas about how to restore this behaviour?  Thanks, Philipp

I have just upgraded to Ubuntu 17.10 and found out there is no option to have 2 by 2 workspaces. I was able to configure 4 "static" workspaces using , but I would like to have them in 2 rows by 2. Any ideas?


I want to replace &sp; in the string below with Z.  Input text : ABCD&sp;EF&p;GHIJ&bsp;KL  Output text : ABCDZEFZGHIZKL  Can anyone tell me how to replace the every instance of &\D+; using java regular expression?  I am using /(&\D+;)?/ but it doesn't work.

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}?


How will I upgrade Ubuntu 12.04 to 13.1 internally without the iso file . Please help .

I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please?


I am having doubt in following code how const is working. below code runs without error and showing Z is 8 . what my expectation is it should throw refrence error z is already defined . Can anyone explain this     (function() {   {     const z = 4;      if (true) {       const z = 8;       console.log("Z is " + z);     }   } })()

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


How can I use these references in my bibliography? When I create my bibliography, it change the font of special A' or...., how can I fix it?

How to write in bibliography (package natbib) letter "a" with two dots above? Specially, I mean the word Birkhäuser.  Is there a general rule or way how to write such umlauts or other accented letters in bibliographies?


I'm trying to make use of a 3rd javascript library in my LWC. The LWC is on a record page and shows this error when trying to load the page    If I add the component to an app page, it loads without a problem. The component class looks like this  import { LightningElement } from 'lwc'; import chartsJS from '@salesforce/resourceUrl/charts'; import { loadScript } from 'lightning/platformResourceLoader';  export default class Illustration extends LightningElement {     connectedCallback() {         loadScript(this, chartsJS);     } }   Using the debugger I can see the error is coming from the platformResourceLoader because the ownerDocument is undefined  function getDocument(cmp) {   // Detect LWC type via duck-typing.   if (cmp && cmp.template && cmp.template.host && cmp.template.host.ownerDocument) {     const doc = cmp.template.host.ownerDocument;     return doc;   }    throw new TypeError('The first parameter of loadScript() and loadStyle() must be an LWC component.'); }

one of my LWC component failed to work after the summer'19 release because it is unable to load styles not the script from the static resource  I have included the custom lwc inside a lightning record page  Here is the error which I am facing


I live in a flat in the UK and have caught such mites a few times on my skin. I think they are responsible for my bites. On one occasion one mite had one dark spot in the middle instead of two.  Does anyone know what it is?  Regards

I have seen these on my hands recently and I am wondering what they are. Urban Setting. South Central Pennsylvania.


I just did a fresh install from a USB of Ubuntu 14.10, and Firefox was working perfecting find until I executed:  sudo apt-get update && sudo apt-get dist-upgrade   And then restarted.  Now I am unable to launch Firefox (and the only way I managed to get any internet at all was to download the .deb file for another browser on another machine, and then transfer it to my machine using a USB stick), I have tried reinstalling it, but it still refuses to run.  When running it through Terminal using:  firefox   I get this output (<username> replaced with my username):  (process:2192): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed Could not create gnome accelerators directory `/home/<username>/.gnome2/accels': Permission denied   So what is wrong and how do I fix this (it was also working perfectly fine before I did a fresh install - I was previously running Ubuntu 14.10, but had some problems so had to wipe the disk and install it again)?  OS Information:  Description:    Ubuntu 14.10 Release:    14.10   Package Information:  firefox:   Installed: 36.0+build2-0ubuntu0.14.10.4   Candidate: 36.0+build2-0ubuntu0.14.10.4   Version table:  *** 36.0+build2-0ubuntu0.14.10.4 0         500 http://gb.archive.ubuntu.com/ubuntu/ utopic-updates/main amd64 Packages         500 http://security.ubuntu.com/ubuntu/ utopic-security/main amd64 Packages         100 /var/lib/dpkg/status      33.0+build2-0ubuntu0.14.10.1 0         500 http://gb.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages

When I am in my home folder there is a padlock on my Desktop icon. In properties there is written that root is the owner of Desktop and consequently I can't put anything on my Desktop.  I have recently installed this Ubuntu 14.04 and I would like to know why does the desktop icon belong to root while it wasn't so in Ubuntu 12.04 that I used earlier.  I know how to change the owner of a file using the command "chown" (or maybe this won't work for Desktop?) but I am afraid that it could somehow impair my security so first I would like to know the reason of this default setting.


My Ubuntu 18.04 Software Centre isn't showing VLC or other applications I want. If I search for "vlc", there are only a few apps...   What should I do?

I tried to enable additional repositories according to the instructions from , however my Ubuntu Software app is still missing a lot of popular apps. Is there anything I'm missing?  Ubuntu 16.10 Ubuntu Software app 3.20.1


Let $\alpha=\sqrt{2+\sqrt{3}}$.  Let $L=\mathbb{Q}(\alpha)$.      Show that $L$ is a normal extension of $\mathbb{Q}$.   I know that we need to prove that the Galois group for this extension is isomorphic to $\mathbb{Z}_2 \times \mathbb{Z_2}$ (which i dont know how to prove ). An extension is normal if and only if the subgroup of automorphisms which fix each intermediate field is a normal subgroup of the Galois group. When this group is abelian, every subgroup is normal and thus every extension is Galois.  Thanks

Suppose $L=\mathbb{Q}(\sqrt{a+b\sqrt{d}})$,($d$ and $a+b\sqrt{d}$ are square free algebraic integers) when is $L/\mathbb{Q}$ a normal extension? When does $Aut(L/\mathbb{Q})=\mathbb{Z}/4\mathbb{Z}$ or $Aut(L/\mathbb{Q})=\mathbb{Z}/2\mathbb{Z}\times \mathbb{Z}/2\mathbb{Z}$?


I have an ASUS eee pc that I bought second hand. It had the password of the previous owner/administrator, and was running Ubuntu 12.04. I  how to reset the password, and I took what appeared to me the easiest way to reset the password.   I was told to press the left shift key when turning it on. I did this and I then went to recovery mode, as instructed. It asked for the new Linux password. I gladly typed in my name, and it was blank where I was typing. You see, I had no idea it was supposed to be blank.   So, now I have a new dilemma. I have no idea what I typed in for a password, and when I attempt to go to recovery mode to select a new password, it doesn't ask for a Linux password, but instead I see this message:  Give root password for maintenance (or type Control-D to continue)  What can I do to fix this?

I'm working on a Ubuntu system, and my client has completely forgotten his administrative password. He doesn't even remember entering one; however it is there.  I've tried the suggestions on the website, and I have been unsuccessful in deleting the password so that I can download applets required for running some files. Is there a solution?


Given a  problem where the cost function is given by:  $$ J = { \left( x - H \Theta \right) }^{T} {C}^{-1} { \left( x - H \Theta \right) } $$  There is a Sequential Solution for the cases we get a sample by sample of $ \left\{ x \left[ 0 \right], x \left[ 1 \right], \cdots x \left[ N \right] \right\} $  Namely, given $ x \left[ N + 1 \right] $ we can derive $ \hat{\Theta} \left[ N + 1 \right] $ by  $$ \hat{\Theta} \left[ N + 1 \right] = \hat{\Theta} \left[ N \right] + K \left[ N + 1 \right] \left( x \left[ N + 1 \right] - {h}^{T} \left[ n \right] \hat{\Theta} \left[ N \right] \right) $$  With the appropriate choice of $ K \left[ N + 1 \right] $ (Very similar to ).  The question is, can we have a sequential form to a  problem where the cost function is given by:  $$ J = { \left( x - H \Theta \right) }^{T} {C}^{-1} { \left( x - H \Theta \right) } + \lambda {\left \| W \Theta \right \|}^{2}_{2} $$  Is there such form?

Can anyone point me in the direction of an online (recursive) algorithm for Tikhonov Regularisation (regularised least squares)?  In an offline setting, I would calculate $\hat\beta=(X^TX+λI)^{−1}X^TY$ using my original data set where $λ$ is found using n-fold cross validation. A new $y$ value can be predicted for a given $x$ using $y=x^T\hat\beta$.  In an online setting I continually draw new data points. How can I update $\hat\beta$ when I draw new additional data samples without doing a full recalculation on the whole data set (original + new)?


I'm compiling ffmpeg on Centos7, Nvidia driver 384.81, CUDA 9.0. I'm using a Tesla P4.  Here is my config line:  ./configure --enable-cuda --enable-cuvid --enable-nvenc --enable-nonfree --enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64   I get this error:  ERROR: cuvid requested, but not all dependencies are satisfied: cuda   I found some recent info on this issue at:     so I did this:  git clone https://git.videolan.org/git/ffmpeg/nv-codec-headers.git make sudo make install   output looks like this:  sed 's#@@PREFIX@@#/usr/local#' ffnvcodec.pc.in > ffnvcodec.pc install -m 0755 -d '/usr/local/include/ffnvcodec' install -m 0644 include/ffnvcodec/*.h '/usr/local/include/ffnvcodec' install -m 0755 -d '/usr/local/lib/pkgconfig' install -m 0644 ffnvcodec.pc '/usr/local/lib/pkgconfig'   Then I try to configure ffmpeg again and I get the same error.   ERROR: cuvid requested, but not all dependencies are satisfied: cuda   Is this header fix only for cuda 8.0 or should it work with 9.0 also? Does anyone have a way to resolve this?

I am trying to compile FFMPEG with Nvidia Cuda support, on Debian 9.3. Parameters, what I am using:  --enable-cuda --enable-cuvid --enable-nvenc --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64 --enable-gpl --enable-libx264 --disable-x86asm --enable-libx265 --enable-libfdk-aac --enable-nonfree   Nvidia Cuda with drivers are installed. When I try to configure ffmpeg, it says:  ERROR: cuvid requested, but not all dependencies are satisfied: cuda   Newer ffmpeg will show a similar, re-worded message:  ERROR: cuda requested, but not all dependencies are satisfied: ffnvcodec   I absolutely don't know why I'm having this issue, because I am compiling ffmpeg on all of our trans-coding servers.


Iam new to blender. Iam making a dominoes falling animation. I have set start frame 1 and end frame 350 but after 250th frame it stops falling and there is no animation happening

I've set up the physics of a swinging wrecking ball and set the animation to run for 240 frames.  This was not long enough for the entire "swing" of the ball-and-chain.   I'm unable to reset the timeline, but I can set the end frame to (say) 1000 frames, but when I try to play the animation, the animation progress halts at frame 240 and I cannot get it to go any further.   There are no markers or keyframes in the timeline.  What should I do to "force reset" the animation-timeline, to allow changes to the length?


I have a file, called "some.img", created with fallocate, that has a filesystem on it. I can mount the img file using mount -o loop some.img /media/where, and I see the filesystem. When I reboot, however, the file is no longer mounted.  How do I automatically mount this at boot?  Update: SuSE Linux

I created a file   touch /datastore/virtual/pseudoblock   created a loop device with it  sudo losetup /dev/loop0 /datastore/virtual/pseudoblock   (although I got a warning about its size)  and then initialized it with random data  dd if=/dev/urandom of=/dev/loop0 bs=1M count=100   My questions are  a) why is it not displayed yet in my block devices' list?  NAME                     MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT sdb                        8:16   0 489.1G  0 disk   ├─sdb2                     8:18   0   488M  0 part  /boot ├─sdb3                     8:19   0 488.1G  0 part   │ └─sdb3_crypt           253:0    0 488.1G  0 crypt  │   ├─ubuntu--vg-root    253:1    0 472.2G  0 lvm   / │   └─ubuntu--vg-swap_1  253:2    0  15.9G  0 lvm   [SWAP] └─sdb1                     8:17   0   512M  0 part  /boot/efi sda                        8:0    0 931.5G  0 disk   └─sda1                     8:1    0 931.5G  0 part     └─sda1_crypt           253:3    0 931.5G  0 crypt      └─store--vg-store1tb 253:4    0 931.5G  0 lvm   /datastore   b) how can I permanently mount it via /etc/fstab since I cannot get its UUID?  $ blkid /dev/mapper/sdb3_crypt: UUID="fSHjbj-51K2-QfhI-G0Wb-o3lN-4pE1-BB4wCP" TYPE="LVM2_member" /dev/mapper/ubuntu--vg-root: UUID="9e452886-4d8g-fj54-854c-80bc171826e8" TYPE="ext4"   working on   $ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 16.04.5 LTS Release:    16.04 Codename:   xenial   with  $ uname -a Linux pkara-pc01 4.15.0-42-generic #45~16.04.1-Ubuntu SMP Mon Nov 19 13:02:27 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux


I would like to compare two dates in javascript.  I have been doing some research, but all I can find is how to return the current date.  I want to compare 2 separate dates, not related to today.  How do I do that.   var startDate = Date(document.form1.Textbox2);

Can someone suggest a way to compare the values of two dates greater than, less than, and not in the past using JavaScript? The values will be coming from text boxes.


I viewed  to redirect text to file while displaying the output. My question is how can I redirect it while working AND without constant | tee command.  My plan is to use  to identify terminal (Gnome or Guake) and record only Gnome for my Linux commands testing. So I need constant and immediate redirecting of commands and their outputs (with errors) to a file (say cmdlog.log).

How can I run sudo apt-get install by BOTH seeing the process of installation (long in my case) and saving its output into a text file ?


So, as the title says I would like to know if there some way to measure how much computer resources a specific program takes up on a windows OS.  Is there any libraries or default header files that allow this? :)    What I want to be able to do is :   Somehow target a process (by code) and check how much computer resources it takes up.  So, if I target something like let's say... Minecraft for example, it would tell me the resources Minecraft uses up on my system.

I once had the task of determining the following performance parameters from inside a running application:   Total virtual memory available Virtual memory currently used Virtual memory currently used by my process Total RAM available RAM currently used RAM currently used by my process % CPU currently used % CPU currently used by my process   The code had to run on Windows and Linux. Even though this seems to be a standard task, finding the necessary information in the manuals (WIN32 API, GNU docs) as well as on the Internet took me several days, because there's so much incomplete/incorrect/outdated information on this topic to be found out there.  In order to save others from going through the same trouble, I thought it would be a good idea to collect all the scattered information plus what I found by trial and error here in one place.


I wanted to know what would happen if I put regular gas in a 2 stroke engine and 2 stroke mix gas into a 4 stroke.

First off, this is NOT to be confused with the following question:    2 cycle oil is used for my weed eater. There is no way I could use a whole gallon in a year.  Sometimes I run out of gasoline for my 4 cycle lawn mower, and that 2 cycle mix fuel is sitting there getting really old.  If I run that in the lawn mower, am I simply going to create extra pollution or could the 2 cycle fuel cause any damage to the 4 cycle engine?


I found a very informal proof (geometric one, for by taking $\alpha$ as $\beta$ in the x-axis and y-axis and showing rectangle area is smaller than area under the plots).  Is there a proper algebraic proof for the inequality ?  $$ \alpha\beta \leq \frac{\alpha^p}{p} + \frac{\beta^q}{q} $$ where $\alpha, \beta > 0$ $$ \frac{1}{p} + \frac{1}{q} = 1 $$

states that if $a, b \geq 0$, $p, q > 0$, and $\frac{1}{p} + \frac{1}{q} = 1$, then $$ab\leq \frac{a^p}{p} + \frac{b^q}{q}$$ (with equality only when $a^p = b^q$).  Back when I was in my first course in real analysis, I was assigned this as homework, but I couldn't figure it out.  I kept trying to manipulate the expressions algebraically, and I couldn't get anywhere.  But every proof that I've seen since uses calculus in some way to prove this.  For example, a common proof is based on this  and integration.  The proof on Wikipedia uses the fact that $\log$ is concave, which I believe requires the analytic definition of the logarithm to prove (correct me if I'm wrong).  Can this be proven using just algebraic manipulations?  I know that that is a somewhat vague question, because "algebraic" is not well-defined, but I'm not sure how to make it more rigorous. But for example, the proof when $p = q = 2$ is something I would consider to be "purely algebraic":  $$0 \leq (a - b)^2 = a^2 + b^2 - 2ab,$$ so $$ab \leq \frac{a^2}{2} + \frac{b^2}{2}.$$


I'm working with .net core, and I having some issues formatting one number.  I have a decimal like this   decimal d = 362250;   And i want to show it rounded to 4 digits   3623    I was reading both  and  but i wans't be able to do it  I try :  Console.WriteLine($"{d:####}"); //show 362250 Console.WriteLine($"{d:####,}"); //show 362   How can i achieve that?  I know its so simple, but I fighting with it for 2 hours!

If I have a double (234.004223), etc., I would like to round this to x significant digits in C#.  So far I can only find ways to round to x decimal places, but this simply removes the precision if there are any 0s in the number.  For example, 0.086 to one decimal place becomes 0.1, but I would like it to stay at 0.08.


I used command scp text.txt root@*.*.*.*:/~ to move text.txt file to home directory of my server. but it instead make a ~ directory in / of my server I can't either remove or access it because when I run command cd /~ it assume it as cd /home/username.

I managed to make a directory literally named ~.  (Apparently, Python's os.mkdir('~/something') does this.)  How do I remove it without nuking my home?  Also, if it helps, I have my real /home on a separate partition. And the duplicate ~ is located in (the real ) ~.


Summertime, and the livin' is easy   Fish are jumpin' and the cotton is high   Oh, your daddy's rich and your ma is good-lookin'   So hush little baby, Don't you cry   ()   Is "fish are jumping" in the song "Summertime" a correct grammatical construction?  Plural of fish is fishes, right? Or if it's fish as general substance then I would expect "is". Or I missed some subtlety?

Now, I encountered a sentence in a text book, saying     Many fish are specially adapted to live only in certain places.   I know that plural of the word fish can be fish as Merriam says    But wouldn't it someway or somewhat sound unusual or "too unique"?  Is it only to me?


I am trying to call execv() with some arguments, imagePath and outputPath are std::string so I converted those to C strings, then I am converting integers to C strings as well. The error I'm getting is function not viable: no known conversion from 'const char *[6]' to 'char *const *' for 2nd argument int      execv(const char * __path, char * const * __argv) __WATCHOS_PROHIBITED __TVOS_PROHIBITED;  What is the difference between const char *[] and char *const *? void Utility::ExecCrop() {     // convert numbers to strings     const char* x_char = std::to_string(job.x).c_str();     const char* y_char = std::to_string(job.y).c_str();     const char* w_char = std::to_string(job.w).c_str();     const char* h_char = std::to_string(job.h).c_str();          const char* arguments[] = { imagePath.c_str(), outputPath.c_str(), x_char, y_char, w_char, h_char };      execv(execPath.c_str(), arguments); }

I often use the execv() function in C++, but if some of the arguments are in C++ strings, it annoys me that I cannot do this: const char *args[4];  args[0] = "/usr/bin/whatever"; args[1] = filename.c_str(); args[2] = someparameter.c_str(); args[3] = 0;  execv(args[0], args);  This doesn't compile because execv() takes char *const argv[] which is not compatible with const char *, so I have to copy my std::strings to character arrays using strdup(), which is a pain. Does anyone know the reason for this?


Relating to this question;    My query is if this would work in the following order(below) and if so, how would i achieve that?    enum compassDir {     S = 0, SE = 1,     E = 2, NE = 3,     N = 4, NW = 5,     W = 6, SW = 7 };

If you have a 2D vector expressed as x and y, what's a good way of transforming that into the closest compass direction?  e.g.  x:+1,  y:+1 => NE x:0,   y:+3 => N x:+10, y:-2 => E   // closest compass direction


I'm using Microsoft Word 2007. When I insert a picture into a document the default setting has no border for the picture.  I usually want to add a black line border, but this takes up too much time.  I am looking for a way to change the default setting to create a black line border whenever I insert a picture.  Does anyone know how to do this?

The Microsoft Office Ribbon has a convenient gallery of styles to apply to pictures, shown here:    It functions much like the Quick Styles gallery in Word for quickly applying formatting to text. But whereas one can create a new text style and add it to the Quick Styles gallery, I haven't been able to find a way to do the same with the Picture Styles gallery. The default styles aren't what I need, and the styles I do need involve changing multiple settings, so a shortcut would be nice. Am I stuck just using the copy-paste format options?


I know that in English we can sometimes "skip" the Present Perfect and use the Past Simple, like here:     John has won the election. Appropriate sort of the next day of the election night, when the speaker can suppose this is new information to the audience      John won the election. Appropriate in other cases (when this is not new information etc.)      Have you heard me? A more formal way, the result is important (we want to emphasize it), looks like a superior is asking a subordinate etc.      Did you hear me? A more informal way, when the result is not so relevant (we do not want to emphasize it) etc.   Now, the question is:   Do the same rules apply to the past perfect, is one forced to use the Past Perfect in every case, where the action was completed before the reference point?  For instance:     People had had no tooth disease, until they started to eat sugar.      People had no tooth disease, until they started to eat sugar.      I saw the car taxing from the garage, luckily the driver had managed to start the engine      I saw the car taxing from the garage, luckily the driver managed to start the engine   This question is highly related to , and the accepted answer there actually raised my doubts on the matter, because I have never heard that the Past Perfect can be "skipped".  Thank you very much.

I have never had this problem before. But after seeing some questions posted on ELU, I started to doubt. I have been through links1, pages of grammar books2, a lot of questions3 posted here and ELU. I now still can't seem to understand how the past perfect is exactly used. The references sometimes even contradict each other.  What I had understood so far was      The past perfect is not necessary if we are not 'going back' to the earlier past, and simply moving from one event to another.   but I then saw a lot of other 'rules' including      If the sequence is clear, the past perfect is not needed.   which is slightly different, less 'narrow' and can be applied in more situations than the first ruleA, and      The past perfect is optional only when talking about an action at a specific time.   This is confusing. Can anyone here clarify things out please?    A For example, for  Doing the survey [completed] -> Showing the result      We showed the result of the survey we did.      If the second rule is applied, the sentence above is fine (the sequence is clear), but not if the first rule since we are not moving from any event to the next and possibly even going back.    1  and   2 Practical English Usage (2005) by Michael Swan, Collins Cobuild Student's Grammar (1991). Upper-Intermediate Cutting Edge.  3 including , , ,  etc.


Let $S$ be a set of infinite cardinality $\kappa_1$. What is the cardinality $k$ of the set of subsets of $S$ with cardinality $\kappa\le\kappa_0<\kappa_1$? I understand that if $\kappa_0$ is finite, then $k=|S\times S\times\ldots \times S| $ (at most $\kappa_0$ factors), so $k=\kappa_1^{\kappa_0}=\kappa_1$. But does this still hold if $\kappa_0$ is infinite?  Thanks for any help!

Let $\kappa , \lambda$ be cardinals with $\omega \leq \lambda \leq \kappa.$   Prove $\kappa^{\lambda} = |\{X: X \subseteq \kappa, |X|=\lambda\}|$.  i.e could anyone advise me on how to construct a bijection between $\{f \mid \text{$f$ is a function},~{\rm dom}(f) = \lambda,~ {\rm ran}(f) \subseteq \kappa\}$ and $\{X: X \subseteq \kappa, |X|=\lambda\}$?  Thank you.


I am trying to turn a planar grid diagram into a 3D toroidal graph by identifying the top edge with the bottom and the left with the right, i.e:    So the grid below on the left would be transformed into a right-hand trefoil knot on a torus:     I would like to draw a torus which looks like this but with the grid structure (including the grid itself, the o's, the x's, and the red lines). Could I please have some help. Many thanks in advance!   Edit: I have created a 'torus' out of A4 for illustration - would like the x's and o's to be placed in certain unit grids and the red lines to be straight like in the original grid diagram:

I want to use tikz to draw something similar to this:    That is, we tile the tore with squares, we cut it open, twist it and then glue it back again.  The idea would be to draw 4 torii: a simple square-tiled torus, a cut-open torus, this cut-open torus twisted and then this new tore glued back again.  An example of a cut-open torus would be this:    For the basic torus, I drawed the following:  \begin{tikzpicture} \useasboundingbox (-3,-1.5) rectangle (3,1.5); \begin{scope} \fill[ball color=blue, opacity=0.15] (0,0) ellipse (3 and 1.5);   \draw (0,0) ellipse (3 and 1.5);   \clip (0,-1.8) ellipse (3 and 2.5);   \draw(0,2.2) ellipse (3 and 2.5);   \clip (0,2.2) ellipse (3 and 2.5);   \draw (0,-2.2) ellipse (3 and 2.5);   \fill[white] (0,-2.2) ellipse (3 and 2.5); \end{scope} \end{tikzpicture}   However, I dont know how to square-tile it nor do I know how to "cut" it like in the video.  How could I do it? (I think that this could be easier in assymptote than in Tikz but since every other figure I did in this document was based on the torus I drawed in the MWE, I would like to stay in tikz for this drawing.)


This is not a duplicate of , because this reports different things from that question. That question is specifically about the case where the user has run out of daily reviews; this question reports different problems outlined in the below bullets. While this post also formerly covered that, that has since been edited out. The review queues indicator shows all reviews in a queue a user has access to, no matter if that user is able to review them.  As a result, there are various circumstances where the review indicator gives false information:  There are items in a queue which the user does not have the reputation to review. (I only know of this happening in the suggested edits queue, where tag wiki edits land in the same queue as post edits.) This once . The only pending edits in the suggested edits review queue are the user's own tag wiki edits. (Users with 5,000 reputation but less than 20,000 can review tag wiki edits, but can't bindingly edit them.) There is a single pending suggested edit, which is currently being reviewed by someone else and has been "checked out" to that reviewer. The reviewer has already voted on a post in the queue (e.g. flagging a current Low Quality post as NAA or VLQ externally, or externally voting to close or reopen a post currently in one of those queues) The reviewer has skipped reviews The user has reviewed all items in a queue, but they have not left it yet  There have been numerous calls to fix all different aspects of this, as you can see by the links above. However, at heart it is all one problem: the indicator appears for queues when a user can’t review the items in the queue. I suggest solving this problem once and for all, by making sure that users are not notified for reviews they can do nothing about. So here’s my plea: please don’t show us the indicator for reviews we cannot perform!

I have found the  has been helpful in prompting me to review queues.  There should be red when there's red dots against review queues:   image stolen from   However, when I have used all my reviews for some queues:    If those queues are large enough to warrant the red alert, it will still show on my review icon, even though none of the queues I am able to review in are not alerting.     It would be better if it is like this:    Can we have the red alert vanish if the alert is for queues we have finished reviewing for the day please? It's honestly annoying and will eventually degrade the UX for avid reviewers. (imo)


I have a cheatsheet with a table that looks like   \begin{tabular}{l|l} $k > 0$    &  \verb+k > 0+    \\ $k \geq 0$ &  \verb+k \geq 0+ \\ $\sum_l$   &  \verb+\sum_l+   \\ %etc \end{tabular}   There is a lot of redundancy here since the argument to verb is the same as the first entry of the table. I tried to make a macro to remove the duplication  \newcommand\code[1]{$#1$& \verb+#1+\\}   but that gives an error. I also tried using detokenize  \newcommand\code[1]{$#1$&\texttt{\detokenize{#1}}\\}   but that introduces superfluous spaces. How can I define a macro that produces both the formula and its verbatim code?

To write some documentation, I would like the ability to define a command such as  \showcase{x^{y}\in\Omega}   which expands to something roughly equivalent to  \verb|x^{y}\in\Omega| & $x^{y}\in\Omega$ \\   so that I can show what the latex code looks like and how does it show on the document.  Now I now that it isn't really possible to use \verb for this because it's really fragile and you can't pass arguments from a macro to it. But, assuming that I'm not trying to write anything crazy in the argument to \showcase (e.g. braces are always balanced, I don't care much if spaces are collapsed, no %'s inside), is there a way to define such a command?  Update  \detokenize does (almost) exactly what I want. Take the following example  \newcommand\showcase[1]{{\ttfamily\detokenize{#1}} & $#1$} \begin{tabular}{cc|cc} \showcase{x^{y}}      & \showcase{\hat{x}, \bar{x}} \\ \showcase{x_{y}}      & \showcase{f\colon X \to Y} \\ \showcase{x'}         & \showcase{\sqrt{x+2}} \\ \showcase{x''_{2}}    & \showcase{2 < x \leq 4} \\ \showcase{A^{1}_{2}}  & \showcase{\frac{a+b}{c+d}} \\ \showcase{3\pi/4}     & \showcase{\int_{0}^{1} x^{2} \,dx} \\ \showcase{x\in\Omega} & \showcase{A \cup B \subseteq C \cap D} \end{tabular}   Which produces the output:    My minor quibbles are that:   The double '' seems to have been collapsed into a " I find mildly annoying the spaces after control sequences. I know why they are there, but could there be a way to remove the space if it is not followed by a letter or number? (Or, conversely, if followed by { or _)


Let $A\in M^{(2k+1)\times(2k+1)}(\mathbb{R})$ where $k$ is a natural number, and also assume that $A$ is an anti-symmetric, meaning  $$A=−A^{T}$$  Prove that $\det(A)=0$.

I have to prove that determinant of skew- symmetric matrix of odd order is zero and also that its adjoint doesnt exist. I am sorry if the question is duplicate or already exists.I am not getting any start.I study in Class 11 so please give the proof accordingly. Thanks!


This new PC that I have was gifted to me, and I am brand new to Ubuntu, and I would rather use windows because it is something that I am used to because I use it for school 24/7. I have been trying to follow along with tutorials on youtube,but whenever there is a certain command, it says that the file isn't there, and I don't know if I have a dual boot computer or not. And the terminal commands that I have tried are either incredibly long or result in an endless void of language that I don't understand. If there is a simpler way to remove my computer of Ubuntu and replace it with Windows 10, that would be greatly appreciated. Thank you.

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


For a 3D rendering of an organ, I would like to make part of it a transparent wireframe so the contents become visible (similar to this , only I would like to have a much smaller area as the transparent wireframe). Could anyone point me to a tutorial, our explain me a bit how to approach this? Thanks!

I'm trying to fade an object's regular solid surface into its wireframe.  I've got as far as duplicating the object and deleting vertices until I'm left with an area of overlap.    Is it possible to render this in such a way that there is a smooth transition at the area of overlap? Maybe there is a better way to achieve this effect?  Another example:


How do I search in a textfile with grep for the occurrence of a word or another word?  I want to filter the apache log file for all lines including "bot" or "spider"  cat /var/log/apache2/access.log|grep -i spider   shows only the lines including "spider", but how do I add "bot"?

I want to find all lines in several files that match one of two patterns. I tried to find the patterns I'm looking for by typing   grep (foo|bar) *.txt   but the shell interprets the | as a pipe and complains when bar isn't an executable.  How can I grep for multiple patterns in the same set of files?


For some reason, a long press of a letter doesn't bring up the accented letters anymore on the Touch Bar (MacBook Pro 13-inch, 2018, US keyboard). It does bring up the accented character menu, so that you can chose by pressing a number.   I spent couple of hours on the phone with Apple Care folks trying to figure it out but still don't have a solution. I don't have Webroot or any such other program installed...what's really annoying is that I created a second test account, and there it works fine. Has anyone figured out a solution to this???  Edit: This is a different question b/c it's not an issue with Webroot or some other anti-virus software. I don't have those installed.   Also, I tried a PRAM and SMC reset and no help. It doesn't work in safe boot either - not on the main account at least.   Edit 2: Added image. This is what should be happening on the Touch Bar. But it doesn't.

After upgrade to Mojave, a long press of any letter does bring up the accented character menu but not anymore on the Touch Bar (Mac Book Pro 15-inch, 2018 with US keyboard).   Do you have an idea to to get them back on the touchbar ?


I consider myself to be fully bilingual. My mother tongue is Afrikaans and I went to Afrikaans schools, but I learned English as a toddler and was a fluent speaker by the time I went to school. I read my first (abridged) Dickens at age 10. My degree was presented only in English. My husband and I speak mostly English to each other, although I speak Afrikaans to my children. When I speak, read or write English I think in English. I more often have to translate words from English to Afrikaans than the other way around. Can I claim English to be my first language?

Let's say English is not my mother tongue, but I claim in my CV that my English level is "as if" it was my mother tongue? Is natively the word for that? As in:  Languages:  Hebrew: mother-tongue English: natively   P.S. It's quite paradoxical and funny, asking how to say in English "my level of English is like a native speaker"; if my level was really like a native English speaker, I wouldn't have needed to ask.


I see many packages sold online with a camera body and extra lenses.  Are they any good? Since they're bundled, is the price better then buying the "extra" lens later?

If I were buying my first "serious" camera, is there any value in buying a "full beginner's kit" like the below or should I just buy the camera with the kit lens? The full kit costs about $100 (or 10%) more than the camera and kit lens.  Overview of kit [brand names, other than Canon, obscured]


I am trying to install Windows 10 on my laptop into which I just put an SSD. I downloaded the ISO from the official Microsft page and I proceeded to do the installation from a USB drive, but the installation loops and does not let you install.  I leave you that video of reference to the problem that happens to me. I hope you can help me.

I was having a time getting my bootable USB 3, 32GB W10 install USB to be recognized. It recognized one time but I had to restart for something and it never came up again. I eventually removed all other boot up options to make it easier and faster to try again (no F12 needed).  Finally I gave up and tried another drive (16GB this time FWIW) and then it worked.  HOWEVER, it's stuck on a reboot loop now. I can choose to install, then to select the right disk, then it says it's loading file and then next thing I know it's saying do you want to install or upgrade.


As you can see in the picture the black things shows thru the glass but the other glass shape doesnt. The other glass shape is the same distance from the glass so its not just out of range.  The other black things only show through the glass when their materials have "screen space refraction" de-selected  The glass must have "screen space refraction" selected to show objets behind it.   Other objects in same the glass material won't show through this glass.  What could be wrong here? Why are the black things visible but not the other glass shape?  Thanks to anyone who knows anything about this!

I was just testing Eevee and found that you cannot view a glass object through another glass. Is there any workaround? It works fine only If I rotate the glass window or put my camera to the back side of the scene


I am a current chemical engineering student with a 2.8 GPA and two years research experience and one paper in the works of being published. Is being admitted into a chemical engineering or bio-engineering masters program an unattainable goal?

When applying to a PhD program in the US, how does the admissions process work? If an applicant is weak in a particular area, is it possible to offset that by being strong in a different area?  Note that this question originated from this . Please feel free to edit the question to improve it.


Let $a$ , $b$ , $c$ and $d$ satisfy the following equations  $a+7b+3c+5d=0$  $8a+4b+6c+2d=-16$  $2a+6b+4c+8d=16$  $5a+3b+7c+d=-16$  Then $(a+d)(b+c)$ equals?  Options: $16$ , $-16$ , $0$ or none of these  I know it can be solved by adjusting the equations through elimination or substitution to find the four variables. But I was wondering if there is a less tedious method?


I need your help. I am confused about the output of the following code.    a = [] b = []  for j in range(2):     b.append(j) a.append(b) print(b) print(a)  for i in range(2):     b.append(i) print(b) print(a)  a.append(b) print(a)     I thought that the 3rd "print(a)" should give [[0,1],[0, 1, 0, 1], but it actually gives [[0, 1, 0, 1], [0, 1, 0, 1]]. It seems that after the 2nd loop the "a" is automatically updated, sth that is not happening in the following case, for example, where both prints should give 0:    x=0 y=x print(y)   x=9 print(y)     Does anyone know what changes from the 1st "print(a)" to the 2nd and why they give different outputs?  Thanks!

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?


To a mathematician a vector is a geometrical entity in space that can be defined perfectly well without establishing up a set of x,y,z,t axies.  In other words, mathematically we can work with vectors as entities without the need to determine their components in some basis.  My question is, can the laws of physics also be framed in this way? Of course we can write $$\vec{F} = m\vec{a}$$ but how useful is that unless we also talk about inertial frames of reference?  So, can we define frames of reference without  making the coordinates primary to our definition (or establishing basis vectors, which amounts to the same thing)?  [I don't believe this is a duplicate question.  The other fellow was asking for a book recommendation - I am asking about the framework for the laws of physics]

I am a graduate student in mathematics who would like to learn some classical mechanics. However, there is one caveat: I am not interested in the standard coordinate approach. I can't help but think of the fields that arise in physics as sections of vector bundles (or maybe principal bundles) and would love an approach to classical mechanics or what have you that took advantage of this.  Now for the questions:   Is there a text book you would recommend that phrases the constructions in classical mechanics via bundles without an appeal to transition functions?   What are the drawbacks to this approach other than the fact that it makes computations less doable? (if it does that)   Are there benefits to thinking about things this way, ie would it be of benefit to someone attempting to learn this material to do it this way?


Every sauced pasta dish recipe I ever read calls for using the water in which the pasta was cooked for the purpose of thickening the sauce, as the water contains a lot of starch which helps the pasta adhere to the sauce  In  recipe, this step is skipped and the pasta is added without any water/starch  What was the reason for not using the pasta water? Or in other words, when should you not want to add pasta water? (other than in cold pasta dishes like salads)

Since it is starch in hot water in both cases, I wonder why starchy pasta water is so prized over adding (trigger warning for Italians) warm water and cornstarch when tossing pasta.


This question may sound silly. Can we sort the dependent variable Y of a dataset and apply Linear Regression on it. What I think is, it introduces Bias on the model and it will perform poorly on unseen data. Please correct me if I'm wrong. What are all the other reasons on why we should not do it. Explain with an example.  Example: Matching $x_1, x_2, \ldots, x_n$ with $y_{(1)}, y_{(2)},\ldots, y_{(n)}$(sorted asc) where $y_{(j)}$ is the $jth$ smallest value of $y_1,\ldots, y_n$.

Suppose we have data set $(X_i,Y_i)$ with $n$ points. We want to perform a linear regression, but first we sort the $X_i$ values and the $Y_i$ values independently of each other, forming data set $(X_i,Y_j)$. Is there any meaningful interpretation of the regression on the new data set? Does this have a name?  I imagine this is a silly question so I apologize, I'm not formally trained in statistics. In my mind this completely destroys our data and the regression is meaningless. But my manager says he gets "better regressions most of the time" when he does this (here "better" means more predictive). I have a feeling he is deceiving himself.  EDIT: Thank you for all of your nice and patient examples. I showed him the examples by @RUser4512 and @gung and he remains staunch. He's becoming irritated and I'm becoming exhausted. I feel crestfallen. I will probably begin looking for other jobs soon.


I am trying to make a comment section for products. I am setting two primary keys, the CommentID and the ProductID for the Comments table. But what I want to do with the primary keys is as follows: for each ProductID, the CommentID should start counting from the beginning. So for ProductID = 1, the CommentID should start from 1 and be incremented, for ProductID = 2, the CommentID should also start from 1 and be incremented, and so on. Same time the ProductID is the foreign key that points on Product table.  Can someone guide me how to archive that, is it a good practice or does a better workaround exist except making two primary keys?  Thank you!

I need to have one column as the primary key and another to auto increment an order number field. Is this possible?  EDIT: I think I'll just use a composite number as the order number. Thanks anyways.


I submitted a a short note, less than 10 page long, to a very prestious journal in mathematics. It has been about 4 months and I have not heard back. I wonder if that means the note made it pass through the initial assessment and is under review or it simply doesn't mean anything. The status of paper reads: reviewing.  How does the reviewing process differ from lower tier journals to much more selective and reputable( whatever that means)journals?

What steps does a manuscript typically go through from submission to publication (or rejection) in a typical journal? How are these steps referred to, in particular by editorial systems, and how long do they each typically take?  Note that this question is about the typical situation and hence not about:   Journals with an atypical workflow, e.g. those that allow for an instantaneous reviewer–author interaction. Exceptional steps or rare occurrences such as withdrawal or .   This is a canonical question on this topic as per . Due to its nature, it is rather broad and not exemplary for a regular question on this site. Please feel free to improve this question.


I re installed Ubuntu 12.04 from a flash drive, it doesn't boot without the flash drive.   I tried to install the grub in using the command sudo grub-install /dev/sda but it says it cannot find the device for /boot/grub and asks if the device is mounted  I checked with the disk utility program, the disk is there, its name is sda1 and it is mounted.  What could be my next move?

I had Ubuntu 12.04 Beta installed on my computer. When 12.04 was finally released, I made a bootable USB Flash Drive using Startup Disk Creator.  Then I decided to check if this drive works properly and to reinstall the system on my desktop. I must add, my desktop behaves a bit strange when it comes to bootable USB's, it recognizes them as HDD.  In BIOS I changed priority of boot so USB Flash Drive (recognized as HDD) was first. Successfully booted, I installed Ubuntu. Everything worked fine, but...  Now I cannot boot from my real HDD. Every time I want to boot, I put the USB Flash Drive into my computer, boot, safely remove it and everything works.  What do I need to do to repair boot?


This is a problem in " Basic set theory "- S.Shen: prove that if $ [0,1]=A \cup B$ then either $A$ or $B$ has the cardinality of the continuum. (Does this follow from the Cantor-Bernstein theorem?)

$A$ and $B$ are sets. $|A \cup B| = \mathfrak{c}$, prove that $A$ or $B$ has cardinality $\mathfrak{c}$.  This is an exercise problem from my textbook. It's easy if I assume CH to be true. But how can I prove this without it? I don't know how to eliminate the case of $A$ and $B$ both has cardinality larger than that of natural numbers and strictly smaller than that of reals.


My textbook asks me to prove that  when  1>|r|,  $$\sum_{k=1}^∞ k r^{k-1} = \frac{(1)}{(1-r)^2}$$  Does anyone know if this can be proven?  Note: This question has been flagged as duplicate, but before you go on look at other answers, here is how I solved this question:  $\sum_{k=1}^n k r^2 = 1+2r+3r^2+...... $  $S= 1+2r+3r^2+4r^3+.....$  $Sr= r+2r^2+3r^3+4r^4+....$  $S-Sr= 1+r+r^2+r^3+r^4+....$  $S-Sr= \frac{1}{1-r}$  $S(1-r)\frac{1}{(1-r)}=\frac{(1)}{(1-r)(1-r)}$  $S=\frac{(1)}{(1-r)^2}$

How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


Context I have a scenario in which i have to read the file data from Directory (I/O) after 5 minutes and read the content of the file using TPL and after reading it i have to show the file content in a Grid to some Windows form ?  Questions:  I have created the windows service and schedule it to run after every 5 minutes and it reads the files from the specified directory but now the problem is how i will show the data to grid because its a separate application written using WPF. Is there a way to get data from Windows service and show to windows form ?  Thanks

I've never had to do IPC on Windows before. Currently I'm developing a pair of programs, a standard GUI/CLI app and a windows service. The app has to tell the service what to do. So, assuming the communication is local only, what would be the best communication method for these two processes?  Where best is defined as more robust and less error prone, not the most performant nor the easiest to code.  Code examples will be very welcome, but aren't required :-)  Note I'm asking about what to use, a standard TCP socket, named pipes, or some other means of communication only.  Thanks!


I'd like to directly connect (be able to use ping/ssh or other common commands) two local Mac machines as one sometimes is on VPN. The two Mac normally are connected via a wireless router when none of them are on VPN. The VPN does not allow split tunnel. Once a Mac is on VPN, it can not access the other Mac behind the router.  The only solution I can think of is to directly connect them without using the wireless router. I'd prefer not to use a wired connection. However, it seems that this can not be done wirelessly, as via wireless a Mac can either connect to the wireless router or connect to a local network set up by the other Mac but not both.  Could anybody let me know a good way to solve this connection problem when one local Mac is on VPN? Thanks.

I have demo that I want to conduct and it requires two computers, the place where I am doing the demo will not have a router available for said demo.   Is it possible to configure two MacBook Pro's to communicate with each other directly over wifi without having a router involved?


I have exactly the same problem as in  except that my disk has ext4 filesystem. (don't have enough "reputation" to comment there)  To repeat the problem: I can only write as root.  The corresponding line of /etc/fstab is atm  UUID=<long stuff> /mountpoint ext4 defaults,rw,user,auto,exec 0 2  Linked answer doesn't work since mount -t ext4 doesn't have -o uid=<...>,gid=<...> option.

How do I mount an ext4 partition as my user account so I wouldn't require root access to r/w on it? I used -o uid=flint,gid=flint on the mount command but I keep getting   mount: wrong fs type, bad option, bad superblock on /dev/sda7,        missing codepage or helper program, or other error        In some cases useful info is found in syslog - try        dmesg | tail  or so   Another thing, I want avoid using udisks for now as it doesn't let me mount to my specified mount point name.


Even though mm is a shortened form of millimeter, would mm be written as 'an mm' or 'a mm', given that m starts with an 'e' sound.

99% of the time, I'm clear on when I should use "a" versus "an." There's one case, though, where people & references I respect disagree.  Which of the following would you precede with "a" or "an," and why?   FAQ FUBAR SCUBA   [Note: I've read the questions  and , but the rules given there don't necessarily apply here.]    [Edited to add]  Here's a shorter (and hopefully clearer) version of the question…  In written English, which is correct (and why): "a FAQ" or "an FAQ"?  Some references with differing opinions:   an: the  and  a: the Microsoft Manual of Style for Tech Publications, 3e either: the  and


I am an indian citizen working in Amsterdam (Dutch resident permit) and intend to travel to Mumbai. BA offers flight from Amsterdam to London City (LCY) and then a connection from London Heathrow to Mumbai. The same applies for my reverse journey. The questions is do i need to apply for a visa (Tranist/Visit)? I am simply connecting thru different airports in london and dont intend to go sight seeing! My residence permit is valid for my return journey and i dont have a valid schengen visa.  Pls advise. Thanks!

Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.


I am trying to include an image in my document, and I don't know if I am doing it the right way.  What I want is that on a certain page, I place an image in the background (only being in the background on a small part of the page) AND have it not affect the placement of anything else (so removing the image or reintroducing the background image doesn't change the position of the text in the page).  I have so far been using the tikzpicture environment, though I am not convinced this is the best way to do this.  \begin{tikzpicture}[remember picture,overlay]  \node[xshift=10.5cm, yshift=-3.3cm, opacity=0.3, inner sep=0pt] at (current page.north west) {\includegraphics[width=\textwidth,height=2cm]{myimage.png}}; \end{tikzpicture}   After this code, I have included the text for the page normally.  So the page begins with a title like  \begin{center}      \textbf{\Large Some kind of title} \end{center}   etc etc.  This seems to do what I want, but it slightly shifts the text in the page down.  I thought the overlay command was supposed to prevent this.

I am generating one report where I need to use background image. But I found that image always starts leaving some margin space to left side.    \documentclass{article} \usepackage{wallpaper} \usepackage{mdframed} \usepackage[top=2cm, bottom=2cm, outer=0cm, inner=0cm]{geometry} \begin{document}  Some content \ThisLRCornerWallPaper{1.0}{image.jpg} \end{document}    How can I use background image covering whole page?


Is it possible to keep a physical SIM in one of the new iPhones that support dual SIM via eSIM, keeping only the eSIM active for both calls and data?   on the topic is a bit unclear whether only data can be disabled for whichever SIM is chosen as secondary.  I would like to entitely disable my physical SIM while traveling to avoid any incoming call/text charges, and I was wondering whether it was possible to do so without physically removing it.  And is the reverse possible as well? (Disable all eSIM profiles without deleting them, using only the physical SIM)

I'm wondering if there is a way to turn off the Physical sim and use only the eSim on my iPhone XS Max. I travel a lot and I'm loving the use of eSIM.   I understand that I can turn off the eSIM if its required, but I wanted to know if there was any way to turn the Physical Sim off and leave only the eSim ON.  Note - I have an unlocked iPhone XS Max.


I am totally new to linux and am trying to run minecraft on it. i have tried to search the web but unfortunately dont quite understand. can some one please break it down a little simpler. thanks

How to correctly install Minecraft, including setting any needed packages or apps to install it and to troubleshoot the most common problems that Ubuntu users face when trying to use Minecraft.  I am trying to install and run Minecraft without first having to install the Oracle version of Java. I want to use the OpenJDK version that comes with Ubuntu and as a last resort, use the Oracle one.  I also want to know a list of problems related to Minecraft in Ubuntu and the possible solutions to them.  A step by step guide on how to install Minecraft would also help.


I have a long list of vectors written between the signs $ $, the problem is that the list is so long it does not fit the page. I want to make the list break at some point and continue in the following line, how could I do this?   THis is my script.  $G(B)=\left \{ \begin{pmatrix}0 & 4 & -17 & 24 \end{pmatrix}^T,\begin{pmatrix}1 & 0 & -3 & 3 \end{pmatrix}^T,\begin{pmatrix}1 & -4 & 14 & -21 \end{pmatrix}^T, \begin{pmatrix}2 & -4 & 11 & -18 \end{pmatrix}^T, \ \begin{pmatrix}3 & -4 & 8 & -15 \end{pmatrix}^T,\begin{pmatrix}4 & -4 & 5 & -12 \end{pmatrix}^T, \begin{pmatrix}5 & -4 & 2 & -9 \end{pmatrix}^T, \begin{pmatrix}6 & -4 & -1 & -6 \end{pmatrix}^T\right \},   \begin{pmatrix}11 & -8 & 1 & -15 \end{pmatrix}^T, \begin{pmatrix}17 & -12 & 0 & -21 \end{pmatrix}^T, \begin{pmatrix}7 & -4 & -4 & -3 \end{pmatrix}^T,  \begin{pmatrix}8 & -4 & -7 & 0 \end{pmatrix}^T \right \} $   Thanks!

In the inline math mode ($...$), if the formula is too long, LaTeX will try to break it on operators, e.g.  very long text followed by a very long equation like $a+b+c+d+e+f+g+h+i+j+k+l$ etc   may be rendered as  very long text followed by a very long equation like a+b+c+d+e+f+g+h+i+ j+k+l etc   However, the break won't happen if they are separated by commas, e.g.  very long text followed by a very long equation like $a,b,c,d,e,f,g,h,i,j,k,l$ etc   will overflow the page like  very long text followed by a very long equation like a,b,c,d,e,f,g,h,i,j,k,l etc   How to make LaTeX able to insert line breaks after a comma too?


We subscribe to a request for information press service, were they send us 15 / 20 emails a day (each with 20 or so queries in them) which are all request from reporters / journalists, asking for an opinion / quote for an article they are working on.  99% of these queries are irrelevant to us, but we have to sift through them to make sure.   We use gmail / google apps for business for our emails i was wandering is there a way that i can set a custom filter to skim through the content in these email, if the phrase/s we are looking for them are not found then archive them but if the phrases are found then mark it as important.   ie. if phrases 'design, architecture, interior design, furniture' are in the email mark it as important, if not archive email.

I have a couple on-going conversation threads in Gmail with a number of different people. Is there a way to setup a filter so that it will add a label if the body of any new, unread email contains my name? Then remove the label once I've read the email?


I've been having this problem for some time now.  Right now this trigger is sitting on prod, and has recently broke I have tried to rewrite the trigger, re write the test class but I can't figure out how to fix it.  What else should I be looking at/taking into consideration with this trigger.    After doing some research about this topic I found a bunch of posts but none of them help.  Such as adding isActive = true.  The following is my trigger, which I think my logic will work.  Could someone give me some guidance on how to properly test this?  I asked this question recently located , and I was told I can't do it this way but it is all working up to   if(groupMap.containsKey(ld.CreatedById))   After this point it doesn't get into my condition, which is why I need help with my test class.   So in the end Is this possible?  Side note -- No one in my company really knows what a "PowerPartner" even is, and aren't sure who wrote this trigger originally, and im just trying to put out the fire.  I'm only trying to fix it so I can deactivate it through a changeset  Should I be looking at something else besides the trigger.  Trigger  trigger PartnerLeadShare on Lead (after insert,after update) {  if(Trigger.isAfter){ List<LeadShare> leadShareList = new list<LeadShare>();        Set<id>pUserMap=new set<id>();         for(User u: [select id,UserType,isActive from user where UserType = 'PowerPartner' and IsActive = True]){                       {                 pUserMap.add(u.id);                   System.debug('pUserMap ' +pUserMap);         }       }   Map<Id, GroupMember> groupMap = new Map <Id, GroupMember>(); for(GroupMember grp : [select GroupId, UserOrGroupId from GroupMember where UserORGroupID IN:pUserMap]){     groupMap.put(grp.UserOrGroupId, grp);     } System.debug('groupList    '+groupMap );  if(pUserMap != null){     //System.debug('Inside PartUserMap != null');     for(Lead ld: trigger.new){           System.debug('Created BY!!  ' +ld.CreatedById);            if(groupMap.containsKey(ld.CreatedById)){                     System.debug('Inside GroupMap Contains');                           LeadShare ldShare = new LeadShare (LeadId = ld.id, LeadAccessLevel = 'Edit');                    leadShareList.add(ldShare );              }            }  }    Test Class   static testMethod void myUnitTest1() {       Profile p = [SELECT Id FROM Profile WHERE Name='Disti Partner'];    List<Lead> leadList = new List<Lead>(); List<LeadShare> leadShareList = new list<LeadShare>();    for(integer i =0; i<3; i++){  Lead ld = new Lead(); ld.lastName = 'Tester';   ld.Company = 'Debbie TestRep'; ld.Status = 'Open'; ld.Program_EAU__c ='11';  insert ld; system.debug('ld****' +ld);  GroupMember groupMemberStore = [select GroupId,UserOrGroupId from GroupMember limit 1]; LeadShare ls = new LeadShare();  ls.LeadId = ld.id; ls.UserOrGroupId = groupMemberStore.UserOrGroupId ; ls.LeadAccessLevel = 'Edit'; system.debug('ls ++!@+!  '  +ls);  insert ls;

I'm getting an error INACTIVE_OWNER_OR_USER, operation performed with inactive user, and I have been doing a lot of research and the cause that I have found for this is its attempting to assign a my lead to inactive user.  So I understand that part I think the issue is now I don't actually know how to fix it, I didn't write this trigger/test class and I'm not sure how to go forward.  Do I need to create a new Test User?  I've never worked on the Lead object before..  Edit** I added IsActive = True the trigger user query, no luck.  Edit** I just went talking to anyone that might have an idea about UserTypes, and they have no idea what UserType = 'PowerPartner' is.  So I changed it to a different UserType.. didn't work  Edit**  I'm nuking this trigger, I have to re write it..  Test Class  @isTest private class PartnerLeadShare_test { static testMethod void myUnitTest1() { List<Lead> leadList = new List<Lead>(); List<LeadShare> leadShareList = new list<LeadShare>();   Lead ld = new Lead(); ld.lastName = 'Tester';//=/ ld.Company = 'MyCompany'; ld.Status = 'Open'; ld.Program_EAU__c ='11'; insert ld; system.debug('ld****' +ld);  GroupMember groupMemberStore = [select GroupId,UserOrGroupId from GroupMember limit 1];  LeadShare ls = new LeadShare();  ls.LeadId = ld.id; ls.UserOrGroupId = groupMemberStore.UserOrGroupId ; ls.LeadAccessLevel = 'Edit'; leadShareList.add(ls);   if(leadShareList.size()>0){     system.debug('INSIDE LEADSHARE LIST.');      insert leadShareList;  }  } }   Don't know this will help but here is my trigger..  trigger PartnerLeadShare on Lead (after insert,after update) {  Map<id,User>PartnerUsermap = new Map<id,user>([select id,UserType from user where      UserType = 'PowerPartner' and IsActive = True] );    List<GroupMember>GroupMemberList = new List<GroupMember>([select GroupId,UserOrGroupId   from GroupMember]);   System.debug('PartnerUsermap ===  '  +PartnerUsermap); System.debug('GroupMemberList    '+GroupMemberList );  List<LeadShare> leadShareList = new list<LeadShare>();    if(!PartnerUsermap.isEmpty()){ for(Lead ld: trigger.new){      for(GroupMember grpmem : GroupMemberList){         if(grpmem.UserOrGroupId == ld.CreatedById){               LeadShare ldShare = new LeadShare (LeadId = ld.id,UserOrGroupId = grpmem.GroupId,LeadAccessLevel = 'Edit');              leadShareList.add(ldShare );         }     } } } if(!leadShareList.isEmpty()){ Database.SaveResult[] lsr = Database.insert(leadShareList,false);            Integer i=0; for(Database.SaveResult sr : lsr){     if(!sr.isSuccess()){     Database.Error err = sr.getErrors()[0];              if(!(err.getStatusCode() == StatusCode.FIELD_FILTER_VALIDATION_EXCEPTION                                              &&  err.getMessage().contains('AccessLevel'))){                  trigger.newMap.get(leadShareList[i].LeadId).                   addError(                    'Unable to grant sharing access due to following exception: '                    + err.getMessage());             }     }    i++; } }


I followed this  to install Virtualbox, but it failed eventually and I get this error message      Kernel driver not installed (rc=-1908)      The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or   there is a permission problem with /dev/vboxdrv. Please reinstall the   kernel module by executing      '/sbin/vboxconfig'      as root.      where: suplibOsInit what: 3 VERR_VM_DRIVER_NOT_INSTALLED (-1908) - The   support driver is not installed. On linux, open returned ENOENT.   When I ran this command # sudo /sbin/vboxconfig I get this     vboxdrv.sh: Building VirtualBox kernel modules. vboxdrv.sh: Starting   VirtualBox services. vboxdrv.sh: Building VirtualBox kernel modules.   vboxdrv.sh: failed: modprobe vboxdrv failed. Please use 'dmesg' to   find out why.      There were problems setting up VirtualBox.  To re-start the set-up   process, run   /sbin/vboxconfig as root.   and here's the last three lines of dmesg output:  [   44.698246] wlo1: Limiting TX power to 20 (20 - 0) dBm as advertised by 00:18:0a:79:2c:79 [  163.080255] capability: warning: `VirtualBox' uses 32-bit capabilities (legacy support in use) [ 2349.627558] [drm:intel_pipe_update_end [i915_bpo]] *ERROR* Atomic update failure on pipe A (start=142454 end=142455) time 484 us, min 1073, max 1079, scanline start 1061, end 1095   I tried to re-install dkms sudo apt-get install --reinstall virtualbox-dkms I get this error and nothing changes .     vboxpci.ko: Running module version sanity check. Error! Module version   5.0.24_Ubuntu for vboxpci.ko is not newer than what is already found in kernel 4.4.0-47-generic (5.1.10). You may override by specifying   --force.   Any help will be appreciated. Thanks in advance.

Yesterday I received a kernel upgrade and after reboot, VirtualBox stopped working.  Here is my system info (after kernel upgrade):  matteo@workstation:~$ cat /etc/lsb-release  DISTRIB_ID=Ubuntu DISTRIB_RELEASE=16.04 DISTRIB_CODENAME=xenial DISTRIB_DESCRIPTION="Ubuntu 16.04.3 LTS" matteo@workstation:~$ uname -a Linux workstation 4.4.0-116-generic #140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux   I installed VirtualBox long ago with  sudo apt install linux-headers-$(uname -r) sudo apt install virtualbox-dkms virtualbox virtualbox-qt   used on daily basis and never had problems with kernel updates. The error I receive now is   matteo@workstation:~$ sudo modprobe vboxdrv modprobe: ERROR: could not insert 'vboxdrv': Exec format error matteo@workstation:~$ dmesg | tail -n 1 [ 1413.167311] vboxdrv: version magic '4.4.0-116-generic SMP mod_unload modversions ' should be '4.4.0-116-generic SMP mod_unload modversions retpoline '   I found a forum post with this error message  from three days ago, unfortunately without resolution. Therfore I tried to remove the VirtualBox packeges from the Ubuntu repo, and install the latest 5.2 using . However, even after rebooting the machine, the error remains.  What can I do in this case?


Sometimes in mathematics, when defining a function, I see something like  f(x) = 0 if x is even        1 if x is odd   where an open brace is used in front of the values 0 and 1. How can I do that in LaTeX?

I want to write a conditional expression such as the following.    What is the best way to express such conditional expressions in Latex?


I want to have a command block that uses the setblock command (or any command that will work, but I'm new to command blocks and setblock is what  I know) to place another command block that will also setblock a command block with a command that will yet again setblock a command block with a command and so on. In the end I want to setblock 4 command blocks. In my testing this is what I've been doing: Command block 1: /setblock x y z command_block{Command:"setblock x y z command_block{Command:'setblock command_block{Command:setblock x y z command_block{Command:'setblock x y z command_block{Command:time set day'}'}'}'}"} --This is accepted as a valid command Command block 2: setblock x y z command_block{Command:'setblock command_block{Command:setblock x y z command_block{Command:'setblock x y z command_block{Command:time set day'}'}'}'} --This is not accepted as a valid command, and thus the setblock chain ends there. What am I doing wrong? Is what I'm attempting even possible?

I need help with a specific command that I am using in a new game that I am creating inside of Minecraft. The command is:  /give @p sign 1 0 {BlockEntityTag:{Text1:"{"text":" [MF2]","color":"gold","clickEvent": {"action":"run_command","value":"tellraw @a [""{"text":"[MF2]  ","color":"gold"},{"selector":"@p","color":"dark_aqua"},{"text":" is now an admin of the server!","color":"white"}]"}}",Text3:"{"text":"Click to join Admin","color":"dark_aqua","clickEvent": {"action":"run_command","value":"scoreboard teams join admin @p"}}"},display: {Name:"Custom Sign"}}   If I take out the /tellraw command then the command works fine, but I need the command in there to announce to the game that a new admin has joined.  With the tellraw command, the error message is the following:  Data tag parsing failed: Unexpected token 't' at: text":" [MF2]","color":"gold","clickEvent":{"action":"run_command","value":"tellraw @a [""{"text":"[MF2] ","color":"gold"}, {"selector":"@p","color":"dark_aqua"},{"text":" is now an admin  of the server!","color":"white"}]"}}",Text3:"{"text":"Click to join Admin","color":"dark_aqua","clickEvent": {"action":"run_command","value":"scoreboard teams join admin @p"}}"   If anyone knows how to fix this, please let me know.


I've opened 21st port, but still can't connect to any ftp server using ftp command.     limmy@Limmy-U:~$ ftp ftp.gnu.org ftp: connect to address 208.118.235.20: Connection timed out Trying 2001:4830:134:3::b... ftp: connect: Network is unreachable   What the reason of it? Thanks      limmy@Limmy-U:~$ sudo iptables -L [sudo] пароль для limmy:  Chain INPUT (policy ACCEPT) target     prot opt source               destination          ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:ftp  Chain FORWARD (policy ACCEPT) target     prot opt source               destination           Chain OUTPUT (policy ACCEPT) target     prot opt source               destination          limmy@Limmy-U:~$ ftp ftp.gnu.org ftp: connect to address 208.118.235.20: Connection timed out Trying 2001:4830:134:3::b... ftp: connect: Network is unreachable ftp> exit

When I attempt to ping google's dns or any outside the network I get  connect: Network is unreachable?  I can't update either which I put down to this  I am new to networking... And Ubuntu. But these are results of some commands I thought might help  $ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo     inet6 ::1/128 scope host         valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000     link/ether 00:0e:7f:a9:10:54 brd ff:ff:ff:ff:ff:ff     inet 192.168.0.5/24 brd 192.168.0.255 scope global eth0     inet6 fe80::20e:7fff:fea9:1054/64 scope link         valid_lft forever preferred_lft forever 3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN      link/ether 86:0b:cb:43:63:a5 brd ff:ff:ff:ff:ff:ff     inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0 mcserver@helloworld:~$   $ vi /etc/resolv.conf: # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 192.168.0.5 nameserver 8.8.8.8  $ vi /etc/network/interfaces # The loopback network interface auto lo iface lo inet loopback  # The primary network interface auto eth0 iface eth0 inet static         address 192.168.0.5         netmask 255.255.255.0         network 192.168.1.0         broadcast 192.168.0.255         post-up iptables-restore < /etc/iptables.up.rules         dns-nameservers 192.168.0.5 8.8.8.


I´ve just installed Xubuntu and installed java on it and I can't play minecraft and have no idea how to install it! Could anyone help me!


Coming from Python land, one of the best tools is  which automatically tweak the layout and spacing of your programs to fit the  code style guide.   My basic question is: are there any similar tools/standards for LaTeX or similar functionalities in various IDEs that can automatically standardise my source-formatting and slap me around when I screw it up?

I'm looking for a LaTeX code sniffer and/or code beautifier, because I'm creating a CI server for my LaTeX books and I wanted a few things. :D


I'm trying to figure out how I can render values from nested Paragraphs. Basically I have field/values from a Paragraph within a Paragraph I have tried experimenting and searching for answers but I can't seem display the values from the nested Paragraphs to the twig template.         Here is the sample of the code below that I have been working on     First Paragraph      {% for paragraph in node.field_sidebar_area %}
{{ paragraph.entity.field_label.value }}

          {% for block_query in paragraph.entity.field_block_query  %}              {{ block_query.entity.body.value | raw }}          {% endfor %}

          {% for link in paragraph.entity.field_link_item %}
{{ link.url }}

{{ link.title }}
           {% endfor %}
      Second Paragraph     {% for object in paragraph.node.field_sidebar_content %}          {{ object.entity.field_label.value }}      {% endfor }  {% endfor %}

I have a content type, basic, where i have added a Paragraph field field_pr that has two fields: field_text, field_color. I have a twig template node--basic--full.html.twig where I want to print the value of the paragraph field node.field_pr.   node.field_pr can have between one and ten paragraph values.   When I print the array for content.field_pr, I get a huge array. However, I only want the values from the field_pr.field_text and field_pr.field_color. How would I be able to do this from the node twig template?   I have tried the following but cannot seem to access the values. What am I missing?  {% for field in content.field_pr %}    {{ field[loop.index0].entity.field_text.value }}    {{ field[loop.index0].entity.field_color.value }} {% endfor %}  {% for field in content.field_pr %}    {{ field[loop.index0]['#paragraph'].field_text.value }}    {{ field[loop.index0]['#paragraph'].field_color.value }} {% endfor %}   Here is an image of the array that is printed for the node.field_pr field.


Given is the matrix $A=\begin{pmatrix} a & b\\  c & d \end{pmatrix}$.   Derive a (necessary and sufficient) condition (equation or inequation in the coefficients $a,b,c,d$) such that $A$ is regular   and determine $A^{-1}$.   I'm not quite sure how such a condition is supposed to look like with these mentioned coefficients.  So I know that $\det(A) = 0$ is a necessary and sufficient condition for a matrix to be not invertible e.g. not regular. (Wikipedia)  From this it follows that $\det(A) \neq 0$ is a necessary and sufficient condition for a matrix to be invertible e.g. regular.  How do we achieve that?   If $a=0$ and/or $d=0$, then $c,b \neq 0$ If $c=0$ and/or $b=0$, then $a,d \neq 0$ $a \cdot d \neq c \cdot b$   So this would be a necessary and sufficient condition? Not really, in my opinion.. :(  The two sentences at the beginning seemed better but I didn't use any coefficients there as mentioned in the example task.  How do you do this correctly? I'm really scared of such a task in a test..

I am looking for a derivation for the inverse of a 2x2 matrix. I am also wondering why the determinant is involved in the expression. I am familiar with high school maths and linear algebra. If there is an intuitive reason for expression i would also be interested in that.


In  at page 20, one can read $M(t)$ as being defined as the expected value of $N_t$ where $N_t$ is the number of occurence of an event at time=t. As demonstration of the result, the author says: $$E[N_t] = \sum_{n=0}^{\infty}{P(N_t>n)}$$ I don't understand where it comes from. The expected value should be $$E[N_t] = \sum_{n=0}^{\infty}{n P(N_t=n)}$$ How do you obtain the author's expression?

Is there a formula like  $$ EX=\sum_{i=1}^{\infty}P\left(X\geq i\right) $$  (which can be found on   and holds for positive $X$) for $EX^{n}$ ?  And I don't mean this one,   $$ EX^{n}=\sum_{i=1}^{\infty}P\left(X\geq\sqrt[n]{i}\right), $$  which is immediate, if we take $Y=X^{n}$ and use the above formula for $Y$. I mean a "more elegant" one - if there is one.


I have applied for a France shengen visa but am not able to go in France. Instead am going to Italy and Austria and then London. so will there be any problem at immigration due to France Schengen visa or while departing outside of the Schengen area?

In case, if I get a multiple-entry Schengen visa in one of the embassies in Ukraine, Kyiv - should my first trip be to the country which issued the visa?  Any there any requirements of this sort? Does this condition vary depending on embassy which issued the visa?  What are the possible consequences on not visiting that country first? Does it somehow depend on country where the embassy is (i.e. non-Schengen and not EU members)?


I am trying to add an elementaryOS repository on ubuntu 20.04 to install Pantheon but this is what it says: sudo apt-add-repository ppa:elementary-os/stable  E: The repository 'http://ppa.launchpad.net/elementary-os/stable/ubuntu focal Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.

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 saw a problem online asking to show that $52$ has an inverse in the multiplicative group modulo $109$. I don't really know how to do this without using brute force.   The solution is "apply the Euclidean algorithm to find $c=65$." But I don't see what they're talking about. I used the Euclidean algorithm to show that $21\times 109-44\times 52=1$, but how does that help get the $65$?

Isn't finding the inverse of $a$, that is, $a'$ in $aa'\equiv1\pmod{m}$ equivalent to solving the diophantine equation $aa'-mb=1$, where the unknowns are $a'$ and $b$? I have seem some answers on this site (where the extended Euclidean Algorithm is mentioned mainly) as well as looked up some books but there is no mention of this. Am I going wrong somewhere or is this a correct method of finding modular inverses? Also can't we find the Bézout's coefficients by solving the corresponding diophantine equation instead of using the extended Euclidean Algorithm?


I'm trying to make a basic "20 questions" type of thing to learn how to use if statements with boolean comparators like && in them. However, my "if" statements are not, uh, "doing" (sorry) even though their criteria are being satisfied (as far as I can tell).   When I compile, no matter what "answers" I input, the only output I get is "I'd ask you if I'm right..." ALA:   Think of an object, and I'll try to  guess it! 1. Is it an animal, vegetable, or mineral?vegetable Is it bigger than a breadbox?yes I'd ask you if I'm right, but I don't really care   I tried googling and searching but I feel like I'm missing out on something so basic that I'm just not seeing it.  Here's the code:  Scanner keyboard = new Scanner(System.in);     String response1, response2;      System.out.println("Think of an object, and I'll try to "             + " guess it!");     System.out.print("1. Is it an animal, vegetable, or mineral?");     response1 = keyboard.next();      System.out.print("Is it bigger than a breadbox?");     response2 = keyboard.next();      if(response1 == "animal" && response2 == "yes")     {         System.out.println("You're thinking of a moose");     }     if(response1 == "animal" && response2 == "no")     {         System.out.println("You're thinking of a squirrel");     }     if(response1 == "vegetable" && response2 == "yes")     {         System.out.println("You're thinking of a watermelon");     }     if(response1 == "vegetable" && response2 == "no")     {         System.out.println("You're thinking of a carrot");     }     if(response1 == "mineral" && response2 == "yes")     {         System.out.println("You're thinking of a Camaro");     }     if(response1 == "mineral" && response2 == "no")     {         System.out.println("You're thinking of a paper clip");     }      System.out.println("I'd ask you if I'm right, but I don't really care");   Thanks in advance to any respondents!

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?