I am fairly new to programming, and I am using postgres 12.2.  I am having a lot of trouble even setting up postgres. When I try to connect to a database, such as using   psql -U postgres -d demo  which is the first command in the list of commands , I get prompted for a password, which I have never set.   As far as I can tell, postgres should be a "super-user" that does not have a password. Through using resources online, I have used the command initdb to make an initial database cluster (though I do not know how to use this cluster) and I have set the bin file to be in the path system variable, something which I do not understand the purpose of.  Here is an example:  C:\>psql -U postgres -d C:\usr\local\pgsql\data\base\1   Password for user postgres: psql: error: could not connect to server: FATAL:  password authentication failed for user "postgres"

When I set the password to blank, it didn't give any warnings. Now when I try to log in with a blank password, it gives me an error "fe_sendauth: no password supplied". So now I can't log in - any ideas how I can get access to the db again?


Houses have historically only offered AC power throughout, but I'm wondering if that makes any sense anymore.  If I were building a large addition, or even building a new home from scratch, would it make sense to build with only AC power?  Let's think about the main things we have in the house that use power.   LED lights: the bulbs have to convert the AC to DC.  Why not just use DC to begin with?  Of course this means buying new bulbs, which may be expensive, or altering the existing ones, which may be time-consuming... Laptops, phones, tablets: again, they have to convert to DC power, which seems silly and inefficient.  Of course I'd need DC cords for all laptops... Refrigerators: I don't know what form of power they actually use, but I've seen DC versions available at a much higher price, so this may be one reason to at least not get rid of AC completely.  Maybe.   Those seem to be the main things.  I don't need hair dryers or toasters, and can use gas for most other major appliances.  Now let's say I'm going to try to power the addition (or new house) completely with solar panels.  Suddenly any difference in efficiency has a much more noticeable effect on what I'm paying for the panels.  Would it make sense in this case to use DC for almost everything, if not everything, even if it didn't make sense previously?     * UPDATE *  While at first glance this may appear the same as , anyone who takes the time to actually read both of them can see that they are very different.  That other question is looking toward the past and asking why things came to be the way they are.  My question is looking toward the future and asking if it makes sense to change.  In that sense they are the opposite.  Therefore this question should be reopened.

I'm not sure if there's a better place to ask this or not.   Why, at least here in America, is the standard electrical system set up for alternating current (AC) rather than direct current (DC)? I'm just completing a long-distance move and realizing how many DC adapters I have and how many of my devices require DC power:   All of my guitar pedals. My alarm clock. My external hard disks. My USB car HDD dock.   ... and the list goes on. If we're almost constantly having to use DC adapters to convert AC into DC, why isn't the standard DC, other than because people resist change?


I have a requirement where a user browse through JFileChooser and selects a folder.  But while doing this selection the user should not be allowed to select root drive. By "Root Drive" I mean C: or D: etc. in Windows and / in UNIX/Linux.  I think here I can not use filters for JFileChooser as its job is to browse through the files and hence it does not make any sense to filter the drive itself.  Please suggest a proper solution which may work on all Windows/Linux file System.

I want to limit my users to a directory and its sub directories but the "Parent Directory" button allows them to browse to an arbitrary directory.  How should I go about doing that?


By default, most titles in a KOMA Script article (scrartcl) are set in bold (bx) weight. For a particular document, I use a special font via  \usepackage{fontspec} \setsansfont{MySpecialFont}   (this is with lualatex) and would like to have all titles in normal (m) weight. That is for the document title, paragraph titles, section titles etc.  How can that be achieved?

Is there a possibility to change the font-style in the table of contents? Everything I wrote down in my document was written with Times. However, the ToC does not have the same font family. Is there a way to change the font of the ToC to Times New Roman? Thank you : )    \documentclass[a4paper, fontsize=11pt]{scrbook} \usepackage{geometry} \geometry{a4paper, top=25mm, left=25mm, right=25mm, bottom=20mm, headsep=10mm, footskip=12mm}  \usepackage[ngerman]{babel}  \usepackage[T1]{fontenc}        \usepackage[latin1]{inputenc} \usepackage{acronym}      \usepackage{anyfontsize}  \begin{document}  \tableofcontents  \chapter{Test} Is there a possibility to change the font-style in the table of contents? Everthing I wrote down in my document was written with Times. However, the ToC does not have the same font family. Is there a way to change the font of the ToC to Times New Roman?  \end{document}


I met a very weird situation in JavaScript, which is that  9007199254740992 + 1 = 9007199254740992 9007199254740992 + 3 = 9007199254740996   Does anyone know the reason for this? Thanks a lot in advance!

Is this defined by the language? Is there a defined maximum? Is it different in different browsers?


(Using Blender 2.76) I have some object groups from one file (source) linked as dupligroups in another file (target). I had to change the name of the subdirectory containing the source file, and the name of the source file itself, so the links in the target file broke (as expected; even relative file paths wouldn't have helped with the renamed file/directory). So now when I open the target I get the error messages stating missing data, and all the dupligroups are just empties (empty empties that is) showing no mesh that they did before the name changes.  I think it will be easier to split this into two questions:   How do you fix a broken dupligroup link when the path to the source file (directory name/s) has changed? Like this: //directoryA/source.blend changed to //directoryB/source.blend How do you fix a broken dupligroup link when filename of the source .blend file has changed? Like this //directoryA/oldSource.blend changed to //directoryA/newSource.blend   But of course I have to fix both of these things.  The reason I split that into two questions is because I did some tests and had different results depending on whether the intermediate directories names had changed (changed path) or whether the actual source filename had changed (changed filename). I had two ideas that both failed:  Idea 1 (failed):   Go to file/External Data Find Missing Files   Changed Path: For the changed path this got the error message about missing data to stop displaying upon .blend file opening and when using File/External Data/Report Missing Files, but the dupligroups were still empty!  Changed Filename: For the changed source filename this did not get rid of the error messages or fix the dupligroups.  Idea 2 (failed):   Go to the outliner Select "Datablocks" in the pulldown Expand the "Libraries/lib" item Change the "File Path" field to reflect the new subdirectory/filename (For this selecting the file path input box in the menu does not open a file selector or anything, so I just typed in the new path/filename manually and hit enter. Maybe I'm doing that wrong?)   Changed Path/Changed Filename: It failed for both. The dupligroups were still empty. I did try restarting the file to see if they needed to be restarted to show the dupligroup mesh, but it didn't help.  However, it's interesting to note that when trying Idea 1 (Fix Missing Files) and then trying Idea 2 (Libraries/Lib) the Fix Missing Files option did fix the path in Libraries/Lib so it appeared correct, it just didn't fix the dupligroups.  I'm using Using 2.76b, but I know I had this same problem with an older version of Blender. That was a while ago and I just gave up and re-linked the dupligroup. That's okay for a couple dupligroups, but in a big scene with dozens of dupligroups that have all been moved/rotated to specific positions this becomes a big deal.  I get the feeling I must be missing something really obvious because I'm sure this is a common problem. Any ideas would be appreciated. Thank you.

Is there a way, after a library is linked to move that library to another location? I have a library that is in a different folder than my scene file and for the sake of more easily sending it to a renderfarm I want to move it all into one folder. Is there a way to edit link paths?


I used to use Easeus Todo for Windows, or Norton Ghost. What options do I have for linux?

I'm a new Linux user. I've reinstalled my Wubi from scratch at least ten times the last few weeks because while getting the system up and running (drivers, , etc.) I've broken something (X, grub, unknowns) and I can't get it back to work. Especially for a newbie like me, it's easier (and much faster) to just reinstall the whole shebang than try to troubleshoot several layers of failed "fixing" attempts. Coming from Windows, I expect that there is some "disk image" utility that I can run to make a snapshot of my Linux install (and of the boot partition!!) before I meddle with stuff. Then, after I've foobar'ed my machine, I would somehow restore my machine back to that working snapshot. What's the Linux equivalent of Windows disk imagers like  or ?  Note: I found a similar question:


Given a polynomial function f(x), prove that f(a) - f(b) is divisible by a - b. I tried it with a few examples and it is coming out to be true. Is it true and if so how do we prove it ? Thanks

I have seen this lemma elsewhere.   Suppose $A$ is a domain, and $f \in A[X]$. Prove that  $$a - b \mid f(a) - f(b)$$    I need to prove this.   $$f(a) - f(b) \equiv 0 \pmod{a-b}$$ basically.  Let, $a - b = c$  $$f(a) - f(b)/(a-b) = f'(\xi)$$ for Some $\xi \in (a, b)$.  But I dont see it showing divisibility


I had a wonderful fantasy book, which was part of a series, in the mid '90s. On the cover was a man that looked like Kratos from God of War.  In the story, he at one point got a gem shoved into his chest by an old wizard that was giving him powers and glowing.  WTF is this book?  I can't find it ANYWHERE on the internet.  HELP!

I remember reading this book back in late 90's. It is about a slave that gathers some friends and goes into a desert to find/fight a dragon. There is also a revolt/uprising in the slaves' home town. I can't remember if this is a single book or a trilogy.  I think the rulers were called Sorcerer-lords or Sorcerer-Kings. And I remember one character was called Boris or Borys.


Let $X$ be a real Banach space and $T: X \rightarrow X^*$ a linear operator such that $[T(x)](x) \geq 0$ for all $ x \in X$. Prove that $T$ is bounded. So, I need to prove that there exists an $M \geq 0$ such that $\|T(x)\| \leq M \|x\|$, for all $x \in X$. I can't really see where to start with this. Any help would be appreciated. Thanks.

For a real Banach space $X$ let $A:X\rightarrow X^*$ be a positive operator in the sense that $(Ax)(x)\geq 0$ for all $x\in X$. Show that $A$ is bounded.   I don't know how to do that, maybe it's an application of the closed graph theorem?


I am almost a little embarrassed to be asking this question since my education and experience is in mechanical engineering.  However, I've drawn a few diagrams, but am still a little puzzled by this question...  In my diagrams, the vectors I've drawn don't seem to actually produce a resultant force that would actually push the vehicle one way or the other when a turn is desired....    From everyday experience, the short answer is that the actual forces that cause a vehicle to turn are due to frictional forces.  Anyone that has driven a car on reduced traction roads due to slush and ice can attest that those conditions result in a car usually not wanting to turn in the direction the steering wheels are turned.  Furthermore it isn't hard to imagine a car already in motion on a totally frictionless surface - turning the front wheels one way or the other would not make the vehicle turn in that direction at all...  For this case, please only consider a car with rear wheel drive and front wheel steering.  It seems rather obvious that in vehicle configurations where the steering wheels are also driving wheels (that is, front wheel drive, AWD, or 4WD), then the vehicle turns in the direction the steering wheels are turned because the actual forces the road surface exerts on the wheels are turned relative to the centerline and CG of the vehicle.  In a car with front steering and rear driving wheels, every part of the car forward of the rear driving wheels is being pushed forward by the rear driving wheels.  The car wants to go in a straight line.    Imagine that the car is in motion going forward and that the front wheels are turned only very slightly to left or right (a few degrees left or right of directly straight ahead), what force vectors and resultant actually produce the 'kick' that causes the entire front end of the vehicle to turn in the desired direction?  It is obvious that a rolling tire wants to continue rolling and that turning the wheel relative to its initial straight-ahead path would produce a scuffing situation - a high friction situation compared to rolling.    In a related situation, we can examine when a car is not in motion, but stopped. When a vehicle is at a complete stop and the front wheels are turned in the direction of an intended turn and obviously not rolling in the forward direction, what are the force vectors that result in the front of the vehicle turning in the direction of intended motion?  In my diagrams, I've isolated and examined the forces on the steering tires' contact patch with the road, but still cannot resolve a frictional force vector that would explain why the front end of the car turns...  I've even considered the gyroscopic effect of rotating wheels and thought that it might be due to a force that is exerted on a rotating wheel that has its rotating axis deflected when the wheels are steered - again I wasn't able to find anything and the gyroscopic restoring force would not explain how a stationary turned wheel causes a vehicle to turn anyway...  Please help me understand this seemingly simple concept....

When a ball moves to the right, friction acts to oppose the motion, in other words, to the left. However, when a car travels around a bend, the friction acts in the perpendicular direction to the car's velocity and provides the centripetal force. I just cannot understand why friction would act in that direction.


View from Disk Utility:   Output of diskutil (for this disk only):  /dev/disk6 (external, physical):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:     FDisk_partition_scheme                        *80.0 GB    disk6    1:               Windows_NTFS                         34.9 GB    disk6s1    2:                      Linux                         10.7 GB    disk6s5    3:                 Linux_Swap                         2.1 GB     disk6s6    4:                      Linux                         32.2 GB    disk6s7   The first NTFS partition, "--", mounts just fine as read-only. But I can't get to either of the Linux partitions. I've tried mount, diskutil mount, and diskutil mount readOnly, but but they all result in   Volume on disk6s5 failed to mount If the volume is damaged, try the "readOnly" option If the volume is an APFS Volume, try the "diskutil apfs unlockVolume" verb   Also tried diskutil apfs unlockVolume, but it's not an APFS volume. Any ideas? Using macOS Sierra 10.12.6.

Is there a safe, stable application for reading from and writing to  file systems on Mac OS X?  If not, what's the best way to access the contents of an ext4 file system on Mac OS X?


Let $M$ be an $n \times n$ matrix over $\mathbb F$, where $\mathbb F\in \{\mathbb C, \mathbb R\}$. Define the linear map $T: \mathbb F^n\rightarrow \mathbb F^n$ by $Tv= Av$.  Suppose the sum of the entries in each column of $M$ is equal to $k$.  I want to determine that $k$ is an eigenvalue and find a corresponding eigenvector.  I am able to show that it's an eigenvalue indirectly, namely by showing that the map $T-kI$ is not invertible.  But I think that I should show that $k$ is an eigenvalue by obtaining an eigenvector. This way I find the eigenvector I want, too.  However, I cannot come up with one. How could I find such an eigenvector? Note that I am following Axler's book, which avoids using determinants when dealing with eigenvalues. So I would appreciate an explanation that does the same.  Edit: I was linked to a possible duplicate. The question is similar to  mine, but the only direct answers involved this fact: $[1, \ldots, 1]A= [k, \ldots, k]=k[1, \ldots, 1]$. The problem here is that the operator $T$ I defined above has the form $Av$. So I would want $Av =kv$ for some $v$. This means that $v$ must be a column vector, not a row vector as described in the possible duplicate.  I am specifically looking for a nonzero vector $v$ such that $Tv=kv$, were $v$ is considered as a column vector.

This is a question from an algebra homework and I am just looking for some tips.  The question is:                   We have:   $M$: an $n\times n$ matrix with real entries $c$: a real constant the sum of the entries of each column of $M$ is equal to $c$   We have to prove that $c$ is an eigenvalue of $M$.  I started out by writing out the form of the matrix and see if anything was popping up without much success. I found a similar question except that they were working with a $2\times 2$ matrix and that the sum of entries in each column $= c$ as well as the sum of entries in each row. Also, in this question they are looking for eigenvectors. In this case the question is pretty easy as we can notice that each column or row is composed of the same entries (in different order or not).  link (p4):   Hence I looked at the sum in the columns to find some kind of pattern or hint that could help me solve this question without any success. It is obvious that the entries in each column might not be the same.  Anyhow I am stuck there.  Again I am not asking for the answer, just a hint.  Thank you for your time and good luck.


Let $D$ be a domain and let $f,g$ be analytic in $D$. I need to prove that if $f(z)g(z)=0$ for all $z\in D$, then $f(z)=0$ for all $z\in D$ or $g(z)=0$ for all $z\in D$.This is my answer.   Assume there exists $z_0 \in D$ such that $f(z_0)\neq 0$ and $g(z_0)\neq 0$. Since $f,g$ are continuous in $D$ there exists $r_1,r_2>0$ such that $f(z)\neq 0$ for all $z\in D_{r_1}(z_0)$ and $g(z)\neq 0$ for all $z\in D_{r_2}(z_0)$. Ler $r=min${$r_1,r_2$}. Then, $$f(z)g(z)\neq0,z\in D_r(z_0)$$ This is a contradiction. Thus $f(z)=0$ for all $z\in D$ or $g(z)=0$ for all $z\in D$. Is this correct? Any improvements?Better answers? Thanks

Let $f,g$ be entire functions such that $g \not\equiv 0.$ If $fg\equiv0$ in $\mathbb{C},$  could anyone advise me how to show $f \equiv0$ in $\mathbb{C} \ ?$  Thank you.


For example i'm making a library which provides function void foo( std::string color )  And i need to somehow tell the user of my library that function foo supports only certain values for argument color (for example only "red", "green" or "blue").  Usually i make something like this  namespace ColorValues {   enum values   {     RED,     GREEN,     BLUE   }    std::string toString( ColorValues::values value )   {     switch( value )      {        case RED: return "red";        case GREEN: return "green";        case BLUE: return "blue";        default: return "error";     }   } }  void foo( ColorValues::values value ) {    std::string theStringINeed = ColorValues::toString( value ); }   But thats just ... too cumbersome, but i dont know any other way and cpp doesn't support string enums.   What to do?

I have a bunch of enum types in some library header files that I'm using, and I want to have a way of converting enum values to user strings - and vice-versa.   RTTI won't do it for me, because the 'user strings' need to be a bit more readable than the enumerations.  A brute force solution would be a bunch of functions like this, but I feel that's a bit too C-like.  enum MyEnum {VAL1, VAL2,VAL3};  String getStringFromEnum(MyEnum e) {   switch e   {   case VAL1: return "Value 1";   case VAL2: return "Value 2";   case VAL1: return "Value 3";   default: throw Exception("Bad MyEnum");   } }   I have a gut feeling that there's an elegant solution using templates, but I can't quite get my head round it yet.  UPDATE: Thanks for suggestions - I should have made clear that the enums are defined in a third-party library header, so I don't want to have to change the definition of them.  My gut feeling now is to avoid templates and do something like this:  char * MyGetValue(int v, char *tmp); // implementation is trivial  #define ENUM_MAP(type, strings) char * getStringValue(const type &T) \  { \  return MyGetValue((int)T, strings); \  }  ; enum eee {AA,BB,CC}; - exists in library header file  ; enum fff {DD,GG,HH};   ENUM_MAP(eee,"AA|BB|CC") ENUM_MAP(fff,"DD|GG|HH")  // To use...      eee e;     fff f;     std::cout<< getStringValue(e);     std::cout<< getStringValue(f);


I am smoothing the relationship between a binary variable y and a continuous variable x. For this I've looked into both GAM and LOESS, but I cannot find a good comparison of the pros and cons of the two methods. Could someone explain when to use one over the other?  I will not be using the smoothing for any predictive modeling, but only as a way of visualizing the relationship. I would of course prefer to find the most interesting aspects of the relationship between the two variables. I am not that interested in this question related to any particular dataset, but more in the general case of when to use one model over the other. That is why I haven't posted any plots or data.

I wish to better understand the pros/cons for using either loess or a smoothing splines for smoothing some curve.  Another variation of my question is if there is a way to construct a smoothing spline in a way that will yield the same results as using loess.  Any reference or insight are welcomed.


Please I want to Know that if the radius of the black hole = 0 then how it have its surface and how it absorbs things?  $$\begin{align}  g &= \frac{Gm}{0^2} \\    &= \infty \end{align}$$  then without surface and volume how it absorbs things?

In the simple explanation that a black hole appears when a big star collapses under missing internal pressure and huge gravity, I can't see  any need to invoke relativity. Is this correct?


I currently just have ubuntu 14.04 on my laptop. The partition for it is very large, 110.85gb out of my 120gb. I tried to resize it but I can't change it as the minimum = its maximum size. How can I change the partition size? I currently have windows 8.1 on a usb to boot but have no room with it. I was thinking is there a way I could delete ubuntu so then my ssd would be completely free, install 8.1, and then install ubuntu again? Thanks!

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


In the film's close moment we can see that Rey possesses the books, as they are stowed away on the Millennium Falcon. But did she put them there?  Did Yoda know something about it? And why didn't anyone tell Luke about them?

The Falcon appears to contain       another copy of the Jedi sacred texts   How did they come to be located on the ship?      Did Obi-Wan leave it there when he was aboard? Did Han and/or Chewie pick it up at some point? Did they know what they had?


I am currently developing a math-physics program and I need to calculate if two vectors overlap one another, the one is vertical and the other is horizontral. Is there any fast algorithm to do this because what I came up so far, has a lot of repeats. Eg lets say we have vector V1((0,1),(2,1)) and a V2((1,0),(1,2)) where the first parenthesis is the coordinates starting and the second coordinates that the vector reaches. I want as a result to take that they overlap at (1,1)  So far the only idea I came up is to ''expand'' each vector to a list of points and then compare the lists e.g for V1 its list would be (0,1) (1,1) (2,1)

How do I determine whether or not two lines intersect, and if they do, at what x,y point?


I need a deterministic encryption scheme. Objectives:   Same plaintext is always encrypted to the same ciphertext. Related plaintexts are encrypted to unrelated ciphertexts. (For example, attacker that knows two ciphertexts cannot learn whether corresponsing plaintexts start with the same prefix.) Minimum space overhead. Authenticated encryption, of course.   There are also some conditions that can make it easier:   I will encrypt small chunks of data (few dozens of bytes). It is OK to store them in RAM and then start the encryption. The data will be padded to the same length all the time. So, we can conclude that the length of the data is some constant. Not high performance requirements.   My first idea was to derive IV from plaintext using HMAC and then use some authenticated encryption that requires just unique (potentially predicable) IV, like AES-GCM. This requires both IV and authentication tag to be stored alongside the encryption.  But I have an idea how to reduce the space overhead even more: Use (H)MAC of plaintext as both IV and authentication of the message. I know this is generally dangerous scheme close to encrypt-and-mac, so I specify further requirements for primitives to mitigate its risks:   The encryption will not leak anything when decrypting attacker-manipulated data. Stream ciphers like AES-CTR look suitable here, because there are no risks related to padding oracle. It just “decrypts” any attacker-provided garbage to another garbage (rejected by MAC check later) without any side channel if the AES-CTR implementation is correct. The encryption requires just unique IV, but it does not have any other requirements. Thill, AES-CTR looks suitable here. The MAC does not leak any data. HMAC (potentially truncated to 128b) looks suitable there, because failing to do so would at least weaken preimage resistance of the underlying hash function. Encryption uses a key completely unrelated to authentication key, of course. (This requirement might not be strictly needed when using, say, AES-CTR with HMAC-SHA256. However the requirement makes reasoning about security easier.)   The whole schema looks somewhat exotic to me, but I believe that I have resolved risks arising from the unusual design.  Is there any existing work that aims to do the same? Is there any research that would tell me anything about security of this scheme?

I was thinking of how to create an IV for a block cipher that doesn't require stored state, and I came up with the idea of using an HMAC of the (padded) plaintext and a (possibly distinct) key as the IV.  This seems to be secure:   The IV will only be reused if there is an HMAC collision or if the plaintext and key are the same.  The former would imply that the HMAC is broken and the latter is harmless, since it is just producing the output twice. The HMAC is verified after decryption, but before padding is checked, so padding-oracle attacks should not be an issue.   In particular, if the HMAC and the block cipher use different keys, there seems to be a very simple proof of security, assuming that either (1) the HMAC cannot be distinguished from a random function or (2) the block cipher is secure against maliciously-chosen (but unique) IVs:   The attacker cannot forge the HMAC, since this would require knowledge of the signing key. Since the signing and encryption keys are different in this case, and the HMAC is assumed random, malicious IVs cannot be triggered by an attacker.   Alternatively, if the cipher is secure against malicious (but unique) IVs, then the security of the cipher+security of the HMAC seem to prove the security of the system.  This (obviously) provides no protection against replay attacks, but that requires state anyway.  However, I am not a cryptographer so I do not trust my conclusions on this matter.  If this technique is secure, it would appear to be quite useful in practice, as it is simple and provides both encryption and authentication.


You are given a set of points {(X1,Y1), (X2,Y2),...}  which represent a hand-drawn circle, so it's not perfect. You are asked to find the center and radius of this circle.  My intuition tells me this involves minimization, and I need to find the coefficients in a non-linear generalized least squares model. Am I not thinking of a simpler or more "proper" approach?

Consider n point $(x_1,y_1), (x_2,y_2),\ldots, (x_n,y_n)$. For $n = 3$ it is easy to find the center of the circle passing through the three points. I wanted find the approximate center of the circle passing through more than three points.   The application is as follows. I have circles on a sheet of metal. I can poll different points on the circle to get the their co-ordinates. By polling three points on every circle I can predict the co-ordinates of the center. But I wanted to improve the accuracy of the prediction. A Google search reveals only the center of the passing through three points.  Edit 1: In response to Hoda's comment, I am adding that the measurements related to the points on the circle have errors. The objective is to minimize the error in the position of the center by polling more points on the circle.


I have a problem with one file, which is located in my /var/www/html order on my raspberry pi which runs apache2 and php.  Before I restarted my pi, the file was totaly normal reachable. Now I got the following message, when I enter the directory and execute the command ls.  ls: cannot access nav.php: Structure needs cleaning   What does this mean? I can also not cat or anything else doing with that file. Of course I can recreate the file under a new filename, but I want to know, what was going wrong.  Thanks for every response.

I have an external hard drive which is encrypted via LUKS. It contains an ext4 fs.  I just got an error from rsync for a file which is located on this drive:  rsync: readlink_stat("/home/some/dir/items.json") failed: Structure needs cleaning (117)   If I try to delete the file I get the same error:  rm /home/some/dir/items.json rm: cannot remove ‘//home/some/dir/items.json’: Structure needs cleaning   Does anyone know what I can do to remove the file and fix related issues with the drive/fs (if there are any)?


I often like to create links to specific email threads and put them in my calendar so that I have the relevant information at my fingertips.  Ever since I enabled the preview pane, this has been impossible.  Does anyone know how I can get it?  Maybe some button I have to press or perhaps even a userscript that I can use with TamperMonkey?

In vanilla Gmail, clicking on a conversation alters the fragment ID in the URL, allowing you to link back to that conversation.  (It opens in its own Gmail interface.)  I am using the preview pane, which is great, except that the URL no longer updates when viewing specific emails, so there appears to be no way to get the link to the currently-viewed conversation.  (The 'open in new window' button doesn't help, since it pulls its contents in on the client side; it isn't a standalone link.)  The only solution I've found is to turn off the preview pane, find the message again in the list, open it, grab the link, go back to the message list, and turn preview pane back on.  That's fairly onerous for something I do often though (to clip Gmail conversations to Evernote, where my GTD setup lives).


When I search only one word (which isn't URL) in address bar, Firefox treats it as URL and Website Unavailable notification is displayed with OpenDNS search page. How to replace OpenDNS with Google here?

I went into about:config and have the following:  browser.search.defaultenginename Google  browser.search.official true  browser.search.order.1 Google  keyword.URL https://www.google.com/search?p=   And still, when I type in the search bar, it pulls up Time Warner Cable Road Runner search instead of Google. It looks like only if I have more than 1 word does it decide to use google -- maybe using only 1 word means I type a malformed URL? How can I fix this to use Google as a proper search engine?


Scenario-> I have pro-red creature like .  I cast  for 2, targeting the forgetender and my opponent.  I then cast   Does the 2 damage to the forgetender get prevented by Divine Deflection or by the protection from red?  Does my opponent take 2 damage from Divine Deflection?  Also, if the damage would just be redirected, would it work the same?  For example, replace Divine Deflection in the last scenario with .  Is the damage prevented by protection from red or is it redirected?

How are replacement effects handled in multiplayer? Here's a concrete example.   Player A, B, and C are seated around the table. It is Player A's turn. Player A has a  (double all damage), and  (prevent damage to opponents, and create 3/1 tokens instead) in play. Player A casts  (2 damage to each creature and player). Player B responds with  (prevent all damage from spell, gain life equal to damage prevented). No one has any more responses, no other permanents are in play.   What possible different life totals and 3/1 tokens are generated when the stack resolves? Who gets to make the choice(s)?  Do the possibilities change if Player B or Player C are the active player? What are  the possible results?


I think I didn't encrypt my drive when I installed Ubuntu and I would like to use the opportunity to change that when I install Ubuntu 20.04. I'd like to make sure that all data is permanently wiped before I do a fresh installation, but that's turning out to be a bit of a problem. All I found online on the topic was the advice to go on the manufacturer's website to see how to proceed.   I have a Samsung 970 EVO SSD, and the tool that Samsung offers (Samung Magician) appears to be available exclusively for Windows. Any ideas how to get this done?

I'm planning on selling a USB external hard drive that currently contains an old Ubuntu installation with stored passwords and banking information.  How can I securely erase the drive before selling it?


Since I upgrade to 17.10 when I do PrtScr or Ctl+Sht+PrtScr it just get the screen shot in the Pictures directory. Before I had a popup window with different options (naming, pasting into clipbboard, etc).  Is there a way to have this popup back ?

I take screenshots a lot. I usually take screenshot of an area, I then recheck if I have the desired area and then copy it to clipboard.  I want to change this behaviour so that immediately upon  pressing Shift+PrntScr the screen capture application allows me to select an area, and immediately afterwards it provides me with the option to save to a particular location or clipboard.  I want Shift+PrntScr to bring up a pop-up screen like this:


guys I was wondering how to remove the extra comma and space from the array? When I run the program it gives me {1, 2, 3, 4, 5, }. What I want is  {1, 2, 3, 4, 5}. Main must stay the same. PrintArray method is the one I need help with.   Referring to duplicate question statement. This is different because it asks a user for a number and prints the array accordingly. This is not a duplicate question.      public static void printArray(int[] myArray)     {          System.out.print("[");         for(int i = 0; i < myArray.length; i++)         {             myArray[i] = i + 1;             System.out.print(myArray[i] + ", ");         }         System.out.println("]");     } }

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


I am using Apache 2.4, on Debian 9.  I can access all my subdomains from my mobile phone.  However on my local network, from separate clients (windows 8,  Debian (not the server), and Mac OS 10.10), from different browsers (Firefox, Chrome, Brave), I get mixed results. One subdomain doesn't load at all (nextcloud), but I guess that is specific to nextcloud.  Just perlpexes me, that I can reach all of them from my phone, and weird behavior on local network.  Anyone able to offer a tip on how I can resolve this??  UPDATED: Thanks for the immediate replies.  I have to admit, a "hairpin NAT" is outside of my scope of knowledge. I am not using a NAT. I do have a local DNS server running (Pihole), but that doesn't seem to be a factor, since it affects machines with it (and those without Pihole configured to be used as it's dns server). So, I do not think that is a factor.  Also, don't think it's a browser, OS issue, because I just failed on two configurations (Windows/Mac), jumped on my VPN (outside location), and everything worked (was served) as expected.  I am starting to narrow down that one of my virtualHosts is figured incorrectly. I have one setup to work as a ReverseProxy, per a tutorial (so I can run gitlab from apache, instead of nginx--nginx is disabled). From what I read about ReverseProxy's, I don't know exactly why we would need one? But, ok. Here is virtualHost file.

This is a  about Hairpin NAT (Loopback NAT).   The generic form of this question is:  We have a network with clients, a server, and a NAT Router. There is port forwarding on the router to the server so some of it's services are available externally. We have DNS pointing to the external IP. Local network clients fail to connect, but external work.   Why does this fail? How can I create a unified naming scheme (DNS names which work both locally and externally)?   This question has answeres merged from multiple other questions. They originally referenced FreeBSD, D-Link, Microtik, and other equipment. They're all trying to solve the same problem however.


I am looking for a word that means my nervousness for my future. In other words i like to know what will happen to my life in the future, and i am looking for a word that could describe this.thanks and i would be very happy and thankful if somebody could answer me.

Is there any word to describe the fear of unknown future? Like when you cannot anticipate your future, you don't know what will happen or what can happen, not near or immediate future, but some future far away.  Like what will happen five years from now? You can't control it so you're fearful.


I have tried many different XPATH but still I am not able fetch city from displayed list and perform click on it.I have posted this question earlier also suggested answers couldn't help.With my code was just able to see list but couldn't click from list displayed.Can anyone please see what exactly the problem because it's my project.All Answers will be highly appreciated and will be helpful.  HTML STRUCTURE   <input ng-if="isGoogleMapsAvailable()" required="" type="text" id="city" name="city" ng-model="registrationData.city" ng-minlength="2" validation-match="selectedCity" ng-change="cityFieldEdited()" ng-class="{'ng-touched': forms.userForm.city.$valid, 'auto-detected': autoDetectAddress.city}" tabindex="1" class="ng-pristine ng-valid-minlength ng-not-empty ng-valid-validation-match ng-valid ng-valid-required ng-touched auto-detected" placeholder="Enter a location" autocomplete="off" style="">

                               Chicago Heights                  IL, USA

                  South             Chicago Heights                  IL, USA

                  Arlington              Heights                  IL, USA

       Thank you,

I am beginner in automation field, I am trying to automated one of the module, I have tried many different XPATH to fetch proper XPATH for City field o UTest site. Im trying to automate registration module as one of my assignment. I have tried my different xpath example below:  //xpath="//body/div[@class='pac-container pac-logo']/div/span[2]/span" //div[@class='pac-item']/span[3] //div[@class='pac-item']/span //div[@class='pac-container pac-logo']/div/span[2]/../span[3]   the following code written:  //xpath to send data in field @FindBy(xpath="//input[@placeholder='Enter a location']") WebElement city;  //xpath for list to appear @FindBy(xpath="div[@class='pac-item']/span") List<WebElement> City;  public void EnterSignupTwo(String CiTy) throws Exception {     city.clear();     city.sendKeys(CiTy);     Thread.sleep(3000);     System.out.println("the size of List " +City.size());//printing list size      for(int i=0; i<City.size(); i++ ) {         String cities = City.get(i).getText(); //storing list element in String         System.out.println("Converted value of city :"+cities); //print of total list      if(cities.contains(CiTy)) //if parameterized match with Available then click     {         System.out.println("enter specific value of city :"+City.get(i).getText());         City.get(i).click();         break;     } }   kindly refer the


Having an issue when trying to compare strings in If statement.   private String browser = XMLreader.getData("browser");  if (browser == "chrome"){     System.out.println(browser); } // Will not print anything  if (browser != "chrome"){     System.out.println(browser); } // Will print chrome    Any idea what am I missing?   Thanks

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?


Is it possible to have the ISO, Aperture, and other setting save with the JPEG or RAW image when taking photos?   I have the Canon T5i, and I'm fairly new to photography. I can keep a log book with these settings, but I didn't know if there was a way to store this information with the saved image.

I am new to photography and enjoying shooting with my Nikon D3200 camera. Once I take a photo, is there any tool by Nikon or a third party which can give me info like F-stop, ISO, Shutter speed, etc? If there is no tool, does Nikon camera support this after the photo is shot?


I have completed three sequences of courses in QM, and I'm very much eager to to do the functional analysis of QM on my own in my spare time.  Can someone suggest some books? I like books with mathematical rigor, and I'm taking this step to understand the mathematical foundations of Hilbert Spaces used in QM.  Also, please do let me know the pre-requisites to study the book(s) you're mentioning.

I'm interested in quantum mechanics book that uses high level mathematics (not only the usual functional analysis and the theory of generalised functions but the theory of pseudodifferential operators etc, certainly the modern mathematics). If there isn't something similar please give me a reference to the book that is strictly supported by mathematics (given a set of mathematically descripted axioms author develops the theory using mathematics as a main tool).


After reading some related question on how to insert an image into a TeX file I tried to do the following:      \documentclass[11pt,a4paper]{report}     \usepackage[utf8]{inputenc}     \usepackage[T1]{fontenc}     \usepackage{lmodern}     \usepackage{graphicx}     \begin{document}     \section*{a section}     \subsection*{a subsection}     some text\     \begin{figure}     \centering     \includegraphics[width=0.7\linewidth]{vagabon}     \caption[]{an image}     \label{fig:vagabon}     \end{figure}\     some other text     \end{document}   but the output was:   with the image before the sections, and not in between the 2 lines of text. why is that? and what's the proper way to insert an image in the middle of a paragraph?

Is there any package or a method to force LaTeX to keep floating environments like table and figure closer to where they are declared?


I am trying to create a Caesar Shift cipher encryption and decryption program. I need it to be able to accept user input until the user wishes to quit(q), but I end up just getting an extreme repetition of everything.  Here is my Shift Class  import java.util.Scanner; public class CaesarShift { //initialize private string for the alphabet private final String ALPHABET = "abcdefghijklmnopqrstuvwxyz"; //public encryption code public String encryptionMethod(String normText, int caesarShift) {     normText = normText.toLowerCase();     String cipherText = "";     for (int a = 0; a < normText.length(); a++)     {         int charP = ALPHABET.indexOf(normText.charAt(a));         int shiftValue = (caesarShift + charP) % 26;         char replaceValue = this.ALPHABET.charAt(shiftValue);         cipherText += replaceValue;     }     return cipherText; } public String decryptionMethod(String cipherText,int caesarShift) {     cipherText = cipherText.toLowerCase();     String normText = "";     for (int a = 0; a < cipherText.length(); a++)     {         int charP = this.ALPHABET.indexOf(cipherText.charAt(a));         int keyValue = (charP - caesarShift) % 26;         if(keyValue < 0)         {             keyValue = this.ALPHABET.length() + keyValue;        }        char replaceValue = this.ALPHABET.charAt(keyValue);        normText += replaceValue;     }     return normText; }   }  Here is my tester method where I tried to instantiate the while loop  import java.util.Scanner; public class CaesarShiftTester { public static void main(String args[]) {     //import of the scanner method to ask the user for the input they would like     Scanner in = new Scanner(System.in);     System.out.println("What is the text you would like to do something with?(q to quit)");     String normText = in.nextLine();     System.out.println("What is the Caesar Shift Value?");     int caesarShift = in.nextInt();     //new declaration of the CaesarShift class to report back to easily     CaesarShift shift = new CaesarShift();     //declare the while method loop     while(normText != "q")     {     //decalre the need properties for the encryption     String cipherText = shift.encryptionMethod(normText, caesarShift);     System.out.println("Your normal text is: " + normText);     System.out.println("Your text after encryption is: " + cipherText);     String cnormText = shift.decryptionMethod(cipherText, caesarShift);     System.out.println("Your encrypted text is: " + cipherText);     System.out.println("Your decrypte text is: " + cnormText); } }   }


I have a string of html contained in between [marquee][/marquee] tags in the string like so:  var s = '[marquee]
some html here 1
[/marquee][marquee]
some html here again 2
[/marquee]';   what I would like to do is match each one of these marquees to create an array with each marquee as an array element.   What I've tried so far is:  var marqueeArray = s.trim().match(/\[marquee\][\s\S]*\[\/marquee\]/g);   but all i get back is and array with the length of 1. both marquees end up being included as one string like this:  ["[marquee]
some html here 1
[/marquee][marquee]
some html here again 2
[/marquee]"]   what i would like is this:  ["[marquee]
some html here 1
[/marquee]", "[marquee]
some html here again 2
[/marquee]"]   eventually i will need to remove the brackets ([marquee] and [/marquee]) from each element and replace with  and join one big string for use in the application. any point in the right direction on that would be great as well.

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}?


We have a standard Wordpress installation being used as a CMS. We're using standard pages with basic permalinks (e.g., /page/ or /parent/page/).  We'd like to have that exact same content mapped to a virtual subdirectory as well (e.g., /vip/page/ or /vip/parent/page/).  Now, obviously, I could duplicate the pages in Wordpress, but that's too much of a pain to manage. The content in both versions would be identical, but we'd do a few minor things in the Wordpress template to display things slightly differently based on the detected URL.  I'm fairly certain there should be a way to do this using .htaccess, but I can't find the right combination of Google keywords to find my answer. Can someone point me in the right direction?  EDIT: It's also worth noting that I'm aware of the potential penalties for SEO, but I plan on supplying canonical meta tags for Google's purposes. The separate URL system is predominantly for marketing and tracking purposes only.

I just came across this page with almost similar requirements as mine    i have to achieve same functionality but i also want to pass some parameters to the page where all these URL will be map. say example  http://mysite.com/test/link1 http://mysite.com/test/link2  http://mysite.com/test/link3    i want to map them to same URL  http://mysite.com/test/finalDestination   along with it i also want to send some other parameters like   user email user name   so that i can use them at that page for my custom logic.i know how to do it in JSP/Java where i can send them as a request parameters in POST request and can reterieve them in the final JSP  how i can achieve this is wordpress using php.my prefrences are not to use any query string.  Or is it possible like if i create URL with like   http://mysite.com/test/user1 http://mysite.com/test/user2  http://mysite.com/test/user3   where user1 etc can be fetched from the database and we can ensure that they will be unique through the application and mapping these URLs to same end point. how can i fetch the username in my final page?  Thanks in advance


I'm planning a trip from Chicago to San Francisco and wanted to drive and was looking for one way car rentals and there charging upto a $95 daily return fee making a 7 day journey with $1200. I looked at hotwire priceline and all individual car rental websites. I was wondering if such a rental would actually cost that money. Any tips to waive the one way rental fee.

I'm planning a road trip for this summer, roughly between San Diego and Seattle, and I'm looking at car rental options for this one-way trip (I wouldn't be returning to the pick-up location).  I've been searching this and other forums and still don't get a clear picture about the one-way fee. Even though I assume having to pay it is quite probable, there seem to be some cases in which it is waived. I'll give first what information I've gathered and ask a couple of questions at the end.  Doing a search on www.drive-usa.de (I'm European) for San Diego - Seattle, I get a lot of options with Alamo with a "free" one-way fee. However, searching directly on Alamo's website doesn't offer this. A look at the rental terms on drive-usa.de shows the following on one-way fees:     Not permitted in the category LM.      One Way Rentals from/to Alaska are not permitted.      One-Way fee is waived within Florida, California, and within an island   in Hawaii. Fee also waived for rentals between California and Nevada,   between California and Arizona, and between the airports of Seattle   and Los Angeles/San Francisco.      One-Way rentals in the convertible category with pick up in San   Francisco in July and August are subject to a $455 one-way fee.       For all other categories and rentals starting at a San Fransisco City   locations a special one-way fee of USD 390 applies for rental ending   in Las Vegas or San Diego, USD 195 applies for rentals ending in Los   Angeles.       For all others the following applies:      Distance between locations.......One-Way Fee   0 - 200 Miles.................................USD 129   201 - 500 Miles.............................USD 195   501 - 1000 Miles...........................USD 390   over 1000 Miles............................USD 650         All fees listed include taxes and fees.   (I haven't found mention of these terms on Alamo's website.) None of the fee-waiving possibilities applies between San Diego and Seattle, though. In any case, if it means avoiding the fee, I wouldn't mind renting from LAX instead. A search on the same website for rental between LA and Seattle also shows "free" one-way fee on a lot of results with Alamo.  However, in both cases, there's also a pop-up next to the "free" one-way fee quote:     The indicated one-way fees represent the current fees. Rental car   companies reserve the right to change these fees prior to pick-up. In   order to determine the total one-way fee due, rental car companies use   the total distance between the pick-up and drop-off locations. The   amounts listed include taxes and fees.   My questions are then: Does the one-way fee waiver offered by drive-usa.de hold any weight when I actually pick up the car, or is it just an eye catcher and it'll be a gamble? If I were to rent a car between LA and Seattle airports, would the rental terms be any guarantee that the one-way fee is waived?  And a bit tangential: What are the advantages, if any, of renting through a European intermediary like drive-usa.de as a European citizen?


How can I change codepage in console (Ctrl+Alt+Fn, not in terminal) to UTF8? I'm using ukrainian locale by default, so most programs have cyrillic symbols in their output, but they're displayed incorrect, while in gui terminal everything is OK.  # locale LANG=uk_UA.UTF-8 LANGUAGE= LC_CTYPE="uk_UA.UTF-8" LC_NUMERIC="uk_UA.UTF-8" LC_TIME="uk_UA.UTF-8" LC_COLLATE="uk_UA.UTF-8" LC_MONETARY="uk_UA.UTF-8" LC_MESSAGES="uk_UA.UTF-8" LC_PAPER="uk_UA.UTF-8" LC_NAME="uk_UA.UTF-8" LC_ADDRESS="uk_UA.UTF-8" LC_TELEPHONE="uk_UA.UTF-8" LC_MEASUREMENT="uk_UA.UTF-8" LC_IDENTIFICATION="uk_UA.UTF-8" LC_ALL=  # cat /etc/locale.gen | grep -v [#] en_US.UTF-8 UTF-8 ru_RU.UTF-8 UTF-8 uk_UA.UTF-8 UTF-8  # locale -a C C.UTF-8 en_US.utf8 POSIX ru_RU.utf8 uk_UA.utf8

How can I change the default codepage/charset on a linux system from latin1 to utf8? I need to do this on two systems, one is running Ubuntu and the other Debian.


I have a fresh installed computer with Windows 7, 64-bit, Service Pack 1.  After a few minutes after startup, svchost.exe is consuming 100% of one cpu core.  I know there are many threads which are dealing with this problem, but none of them helped me.  I installed this updates: KB3050265 and KB3065987  I used this "Microsoft Fix it"-Tools: MicrosoftFixit50123 and MicrosoftFixit50362  I installed the current Windows Update Agent:   I tried to remove the SoftwareDistribution directory:  net stop wuauserv net stop bits rd /s /q %windir%\softwaredistribution net start bits net start wuauserv wuauclt.exe /detectnow   And I tried to connect the computer with my home network over a usb/ethernet-adapter, and I tried to disable IPv6.  For diagnostic, I post here the WindowsUpdate.log file (after removing the SoftwareDistribution Directory, waiting until the service is hanging on 100%):

I've observed a strange behaviour with Windows Update (Win7 SP1). The process svchost is consuming an entire core of my Virtual Machine (VirtualBox) doing nothing (i.e., there is no network traffic and the folder C:\Windows\SoftwareDistribution remains at the same size with the same number of files). Moreover, the process sometimes consumes a large quantity of memory (> 1 GB). I've also noted that sometimes the folder SoftwareDistribution increases in size during a period of time, and after that nothing happens and svchost continues to consume an entire core.  I know that the problem is with Windows Update, since I've tracked (using Resource Monitor) what service is related with the behaviour related above.  The image below shows what I'm facing:    The next image shows a detailed information about svchost:    If I try to perform the update, nothing happens. The Windows Update doesn't progress. See the image below:    I left this machine trying to do the update for 4 hours. During this time the consumption of CPU remained high (as related above) and no update was installed.  My question is the following:   What is the reason why Windows Update doesn't work and still consumes an entire core of my processor doing nothing?  Related Question(s):


The books give an impression that Xenophilius Lovegood is a weirdo with crazy beliefs and ideas (he has an ornamental horn in his house he absolutely believes belongs to a Crumple-Horned Snorkack, which in reality turned out to be an Erumpent horn(or may be he was referring to an erumpent but just with a different name? )) but he believed in the Deathly Hallows and they turned out to be real.  Did any other creatures (including plants, fruits, vegetables, bacteria, fungi, virus or any other magical and non magical things that can be considered "living") that Xenophilius or Luna believe to exist, actually exist in Harry Potter?   For example:     Moon Frogs   Blibbering Humdingers   Crumple-Horned Snorkacks   Heliopaths   Umgubular Slashkilters   Nargles   Aquavirius Maggots   Wrackspurts   Gulping Plimpies   Dabberblimps

The Crumple-Horned Snorkack is one of various weird and wacky things which Luna Lovegood believes in and most people (especially the ever-rational Hermione) don't. Now we know that Luna is a bit ... odd, and believes in a lot of nonsense; but on the other hand, Hermione's pooh-poohing isn't always to be believed either - Divination, for instance, is a real thing in the Potterverse.  Is it ever established for sure, in canon, in-universe, whether or not Crumple-Horned Snorkacks exist?


I have to prove the following problem:  $$\int_{0}^{\cos^2{x}}\arccos\sqrt{t}\ dt + \int_{0}^{\sin^2{x}}\arcsin\sqrt{t}\ dt =\frac{\pi}{4}$$    I know that $\arccos(x)+\arcsin(x)=\frac{\pi}{2}$ but now, I don't know what more to do...

For the following integral problem, we must show the sum of the 2 integrals is equal to $\pi/4$.  $$\int_{0}^{\sin^2x}\sin^{-1}(\sqrt{t})\ dt \; +\int_{0}^{\cos^2x}\cos^{-1}(\sqrt{t})\ dt= \frac{\pi}{4} $$  We must use the Fundamental Theorem of Calculus to resolve this problem, because calculating this integral takes far too long to do!


On the "Ask Question" page, when the keyboard focus is in the entry box for "Tags", on the right hand side we see a box with some information on "How to Tag".   Can we add an item in there to indicate to users that, after selecting a tag, they can hover the mouse over the selected tags (which now appears below the entry box) to read the Tag-Wiki excerpts, to see if they have selected an appropriate tag? I think this will help with the problem of new users applying grossly inappropriate tags because they don't actually understand what a particular tag is for. (This happens a lot on Math, but also a bit on TeX and other sites that I read.)

We have a tag wiki, it's actually really good. Here's the one we have in .  The  wiki is beautiful for newbs, it really is. It covers off:   The basics What JS is How to ask a JS question How to learn more JS Awesome previous questions Useful links, tools, specs...   What more could they ask for, really? It's nearly the combination of things we endless tell newbs in the chat room or in the questions they ask -- like, endlessly, asking what jsFiddle is, how do you use it, what's JSON, why doesn't JSONwork... again, and again, and again.  Wait a minute--we have an awesome resource on it. Maybe we need to just edit it. Or tell more of them it's there.  Okay, so I told a bunch of newbs about it. Turns out the new newbs don't know about it because... they're new, and nobody told them about it, and they didn't see it. So why bother improving it, if the only people who really find it are the people who aren't new to the site?  Right now, to get there I have to do this:   Look at the page, nothing there, maybe I'll click on JavaScript. List of questions, eh? I know, I'll look at more questions Well, that didn't work. What's this tiny nonchalant "about" link next to the tag? Oh wow, a page full of information.   We're effectively demoting importance of the wiki to the people it will be the most useful to.  So, what can we do on SO such that newbs will find the wiki? Because I'm really tired of explaining what jsFiddle is.


I have a laptop that came with Windows 7 originally. It was then (1) upgraded to Windows 10 during the period in which Windows 10 was free and (2) and clean-installed with Ubuntu. As such my system at the moment only has Ubuntu installed.  During (1), there was no step to enter the Windows 10 CD key and between (1) and (2), I created a Macrium Reflect backup of my Windows partition. That backup is now misplaced.  I'm contemplating reinstalling Windows 10 on this laptop using an unmodified ISO. Will I be prompted for a CD key this time? Is there a chance that the Win 10 copy in (1) stored a copy of its credentials somewhere so that the system will remember those when I reinstall Windows?

Where can it be find?  At activation panel i can only find option to change the activation key. The current key is not presented on this screen.


I wanted to install an ISO of Linux on a regular CD, sadly it was installed on my external backup HDD which i had on my computer. Now i have an ISO image ~2gb on it. As i said it is my backup HDD, so the data on it is really important. How can i remove the ISO and get my data back?  I already installed testdisk and making an analysis with it if i can somehow restore it. Sadly I am not an expert in recoveries, i luckily never had to do one.  Searching the internet I mainly found how to recover ISOs on usb flash drives. Since I am pretty new to Ubuntu, I would massively appreciate a step by step guide, if possible.  Filesystem      Size  Used Avail Use% Mounted on udev            4,1G     0  4,1G   0% /dev tmpfs           823M  2,2M  821M   1% /run /dev/sda2       248G   29G  207G  13% / tmpfs           4,2G   68M  4,1G   2% /dev/shm tmpfs           5,3M  4,1k  5,3M   1% /run/lock tmpfs           4,2G     0  4,2G   0% /sys/fs/cgroup /dev/loop0       91M   91M     0 100% /snap/core/4571 /dev/loop2      210M  210M     0 100% /snap/gimp/40 /dev/loop1       34M   34M     0 100% /snap/gtk-common-themes/3 /dev/loop3       91M   91M     0 100% /snap/core/4650 /dev/loop4       37M   37M     0 100% /snap/gtk-common-themes/319 /dev/loop5      129M  129M     0 100% /snap/winds/63 /dev/loop6      166M  166M     0 100% /snap/gitkraken/62 /dev/loop7      166M  166M     0 100% /snap/gitkraken/58 /dev/loop8      190M  190M     0 100% /snap/vlc/190 /dev/loop9      496M  496M     0 100% /snap/intellij-idea-community/48 /dev/loop10     4,0M  4,0M     0 100% /snap/gnome-system-monitor/41 /dev/loop11      97M   97M     0 100% /snap/zenkit/1 /dev/loop12     223M  223M     0 100% /snap/gimp/39 /dev/loop15     107M  107M     0 100% /snap/bitwarden/4 /dev/loop16     147M  147M     0 100% /snap/gnome-3-26-1604/64 /dev/loop14     131M  131M     0 100% /snap/ghost-desktop/46 /dev/loop13      65M   65M     0 100% /snap/pencilsheep/5 /dev/loop17     4,0M  4,0M     0 100% /snap/gnome-system-monitor/45 /dev/loop18     218M  218M     0 100% /snap/gimp/38 /dev/loop19     208M  208M     0 100% /snap/vlc/365 /dev/loop21     496M  496M     0 100% /snap/intellij-idea-community/51 /dev/loop20      94M   94M     0 100% /snap/ktube-media-downloader/2 /dev/loop22      11M   11M     0 100% /snap/dosbox-x/11 /dev/loop23      91M   91M     0 100% /snap/simplescreenrecorder/1 /dev/loop24     543M  543M     0 100% /snap/supertuxkart/8 /dev/loop25     154M  154M     0 100% /snap/skype/30 /dev/loop26     543M  543M     0 100% /snap/supertuxkart/6 /dev/loop27     4,0M  4,0M     0 100% /snap/gnome-system-monitor/39 /dev/loop28      11M   11M     0 100% /snap/currate/5 /dev/loop31     144M  144M     0 100% /snap/skype/33 /dev/loop29     166M  166M     0 100% /snap/gitkraken/54 /dev/loop30     130M  130M     0 100% /snap/winds/64 /dev/loop32     166M  166M     0 100% /snap/inkscape/4019 /dev/loop33     266M  266M     0 100% /snap/electronic-wechat/7 /dev/loop34      96M   96M     0 100% /snap/vectr/2 /dev/sda1       536M  4,9M  531M   1% /boot/efi tmpfs           823M   17k  823M   1% /run/user/121 tmpfs           823M   99k  823M   1% /run/user/1000 /dev/loop35     496M  496M     0 100% /snap/intellij-idea-community/58 /dev/sdb1       2,1G  2,1G     0 100% /media/rhu/Ubuntu-MATE 18.04 LTS amd64

I written an ISO image to my hard disk using sudo dd if=image.iso of=/dev/sda. I meant /dev/sdc, and now running sudo fdisk -l returns only one partition on /dev/sda while there is supposed to be 6. Is it possible to recover my data?  I didn't shut down (reboot) my computer yet.


I have this expression
de José Saramago; Ilustração:  João Caetano&nbsp;
   i made this one
de (.+)   but is getting everything and i just want this part  José Saramago   Do you have any idea how i can do that?

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}?


I have a Canon 600D and in manual mode, if I make the shutter speed higher, then the screen turns blackish/black; but with the same settings when I open the camera's flash it works well. In the day, the flash looks bad--that's why I can't shoot at daytime in public.

I was taking photos a few days ago, and I had it set to Manual. After about four photos, the rest started coming out black. I could see through my eyepiece clearly, and it took the photo normally, but when I reviewed it they were all black.


When taking combat or direct damage, this is not the same as loss of life, right? Yes, your life total goes down. But some cards have activated abilities when "loss of life" happens. For example, if I get dealt combat damage, this would not trigger a "loss of life" ability, correct?

From reading the rules it would appear there are two kinds of damage and then straight loss of life:     118.3 If an effect causes a player to gain or lose life, that player's life total is adjusted accordingly.   From reading that I would guess that effects like Extort are not sources of damage. You simply lose the life.      119.2a Damage may be dealt as a result of combat. Each attacking and blocking creature deals combat damage equal to its power during the combat damage step.   So damage from creatures during combat is combat damage.     119.2b Damage may be dealt as an effect of a spell or ability. The spell or ability will specify which object deals that damage.   And that is direct damage from an object.  So the arguments are these:  Does loss of life as outlined by rule 118.3 (at top) count as being dealt damage? Do triggered abilities that redirect or reduce damage effect loss of life?  My second related question: You put  on a  and tap her to deal one damage to your opponent. Am I right in saying that because the damage was direct damage (not dealt during combat) then the triggered ability of preventing the combat phase of the damaged player is not triggered?


Hopefully easy question for those of you into electronics, but as software person bit out of my depth.  What power supply should I be getting for the following LED strip for nice even light single color strip with dimmer attached? (that's not going to blow up/burn out)  Length: 10 meter (2 joined 5 meter strips)  Color: Red  Led per meter: 60  Wattage: 14.4 per meter  Voltage: 12v  Dimmer: LED dimmer mini RF 12-24V 12A  Been checking and calculating (12v /5A? ) but so confused by watts  volts, amps starting to doubt every answer I come up with

I'm making this right now -   Each 5m roll of LED takes 60W power (). He's using two of these rolls, so a total of 10m LED Strip.  My question is, that he's using a 19v 3.14A adapter which gives out a wattage of 60W. Isn't this lesser than what is required for the overall 10m (60w + 60w = 120w?). What's the effect of using this lower wattage on the LED output?   Instead, I thought of connecting the two rolls in parallel but the 19V adapter and connecting in parallel will probably burn the LEDs due to the fact that the LED strips are rated at 12v. Can I connect the two sets of 5m LEDs in parallel to a 12V 5A (which will result in 60W, the maximum wattage the LEDs can handle) DC Power supply? I'm assuming that then both the 5m strips are running at full brightness then. Or am I wrong and since a total of 120W is required, should I go for a 12v 10A DC SMPS Power supply? I studies Physics a long time ago in school and I'm pretty clueless here. What I'm looking for basically is the best way to extract the maximum light out of the LEDs. Thanks a lot guys!


When I was browsing SO, I came upon a unexpected syntax highlighting quirk. In C# code, the "set" keyword, used in properties, was highlighted, but not "get". Could this be changed?  Here's a sample from a SO answer that I screen-captured.

I noticed that sometimes my code gets highlighted in different colors when rendered.   What is syntax highlighting? How does it work? Why isn't my code being highlighted correctly? How do I report a bug or request a new language? How do I use syntax highlighting? What languages are currently available on Stack Exchange?


I sometimes notice that scissors is being used as a plural word. I guess there is some confusion to it that people can't understand or maybe it's me who doesn't know something about it becoming plural?  As long as I remember "scissors" has always been singular even though it ends with an "s".   Scissors is a tool to cut paper, cloth and many other materials. This scissors has proven to be of very high quality.   But I can't imagine it being plural:   Are these scissors old? Scissors are mostly made of stainless steel.

I'm wondering why I need to say scissors instead of just 'scissor'. Are there any rules about it?  I would think that I only have one scissor, meaning it would be singular and not plural. (That's at least how it is in my native language.)  This would only be one scissor in Danish.    Can anyone tell me why it needs to be plural?


I'm in Germany atm and every time I go to google.com they redirect me to google.de. Even if I call google.com/ncr they just redirect me to google.de again! I even tried google.com/?hl=en, which sets the site itself to English, but still gives me German search results. At this point I'm so annoyed I'm actually considering to just use bing. How can I use google.com?  (I use Chrome as browser, if that helps. Also I noticed right after installing the browser google.com/ncr worked just fine, but as soon as I bookmarked it it stopped working for whatever reason. Now it doesn't even work anymore when I type it in manually.)

I'm too bored of seeing sites like Google and such show up in my native language, I would rather like them to be in English. Yet, I have to explicitly change the URL to .com and en and that kind of parameters in order for them to show up in English. Can I somehow force this?  So, how is Google configured?  However, it is set to English on the site itself so it has to be my browser:    Then, how does my browser land up on non-english pages, like Google?  It usually shows up in non-English when I'm performing a search, which uses:  {google:baseURL}search?{google:RLZ}{google:acceptedSuggestion}{google:originalQueryForSuggestion}{google:searchFieldtrialParameter}{google:instantFieldTrialGroupParameter}sourceid=chrome&ie={inputEncoding}&q=%s   When performing a search, it fills these variables in with non-english values.  How can I tell my browser to fill these in with the English values?  My Google Chrome options give preference to English:


I am trying to answer problem 3.3 part b in :     (b) Show that the total energy $Q=\int \mathcal{T}^{00} d^3 x$ is invariant under the addition of a total derivative to the Lagrangian, $\mathcal{L}\rightarrow \mathcal{L}+\partial_{\mu} X^{\mu}$.   When I try to show this, I find that it is in general not invariant, meaning I am making an error somewhere. Here is my attempt:  The (canonical) energy-momentum tensor $\mathcal{T}^{\mu \nu}$ is defined by:  $$\mathcal{T}^{\mu \nu}\equiv \sum_{i} \frac{\partial \mathcal{L}}{\partial (\partial_{\mu} \phi_i)}\partial^{\nu}\phi_i - \eta^{\mu\nu}\mathcal{L}$$  Since a total derivative $\partial_{\mu}X^{\mu}$ doesn't change the action, and $\mathcal{T}^{\mu \nu}$ is defined through the action, the new energy-momentum tensor will simply be the old one with $\mathcal{L}$ replaced with $\mathcal{L}+\partial_{\mu}X^{\mu}$.  $$\begin{align} \mathcal{T'}^{\mu \nu}&=\mathcal{T}^{\mu \nu}+ \sum_{i} \frac{\partial \left(\partial_{\rho}X^{\rho}\right)}{\partial (\partial_{\mu} \phi_i)}\partial^{\nu}\phi_i - \eta^{\mu\nu}\left(\partial_{\rho}X^{\rho}\right)\\ &=\mathcal{T}^{\mu \nu}+  \sum_{i} \partial_{\rho}\left(\frac{\partial X^{\rho}}{\partial (\partial_{\mu} \phi_i)}\right)\partial^{\nu}\phi_i - \eta^{\mu\nu}\partial_{\rho}X^{\rho}\\ \end{align}$$  The new energy $Q'$ is given by:  $$\begin{align} Q'&=\int d^3 x \mathcal{T}'^{00}\\ &=Q+\int d^3 x \, \left[ \sum_{i} \partial_{\rho}\left(\frac{\partial X^{\rho}}{\partial \dot{\phi}_i}\right)\dot{\phi}_i -\partial_{\rho} X^{\rho}\right] \end{align}$$  So I need to show that the second term vanishes, but I don't know how. That's a 4-derivative sitting inside the integral, so if it was $d^4 x$ I'd just use the divergence theorem and say "oh well assuming $X^{\rho}$ vanishes at infinity we get our desired result". But it's an integral over $d^3 x$.   What do I do?

I've been trying to find how the energy-momentum tensor changes if we add a total derivative to the lagrangian: $$L\to L+\mathrm d_\mu X^\mu.\tag{1}$$   From the answer key:  $$T^{\mu\nu}\to T^{\mu\nu}+\partial_\lambda F^{\lambda\mu\nu}\tag{2}$$ Where $$F^{\lambda\mu\nu}=\frac{\partial X^\lambda}{\partial(\partial_\mu\phi)}\partial^\nu\phi -\frac{\partial X^\mu}{\partial(\partial_\lambda\phi)}\partial^\nu\phi.\tag{3}$$ Is the above answer right? I'm not able to get this result! any help?


How I got interested:- A few days ago I was watching a few YouTube videos about reversing entropy and how it was impossible. But while thinking about it, it suddenly seemed like gravity reverses entropy. My understanding of entropy:- Entropy is the measurement of disorder in a system. The more disorder, the more entropy. And the second law of thermodynamics states that entropy of a closed system must increase. Why does it seems to me that gravity reverses entropy:- Let's take the local group as a closed system. It is gravitationaly bounded. Exclude dark energy. As time will pass, slowly every galaxy will start to merge with each other because of gravity. So the local will become more and more ordered as time passes rather than dissipating and increasing disorder. So it seems that gravity decreases disorder, which means it reverses entropy. Question:- Obviously it is not likely that I have discovered something new by doing no math. So it is likely that I have missed something. So my question is that what did I miss?

Please forgive: I am a layman when it comes to physics and cosmology, and have tried finding an answer to this that I can understand, with no luck.  As I understand it, the solar system evolved from a massive molecular cloud. To me, this seems to break the second law of thermodynamics, as I think it suggests order from disorder.  I know there must be something wrong with my logic, but am really stuck.  Can anyone explain this one in layman's terms?  (Posting to both "Astronomy" and "Physics", as it seems to overlap these subjects)


I just made a fresh install of Ubuntu 20.04 on my dual boot. It was working well until all desktop icons in the application menu disappeared. The apps are still usable via command line or favourites, but gnome menu doesn't show anything. Searching for a specific app doesn't work either. Also, when I try to switch from All to frequent, the menu crashes and desktop refreshes itself. I looked around and found someone experienced a similar thing on Arch Linux with gnome, and a few things like reinstalling gnome-core or changing the format settings to a different country, but none solved it.  Edit: Here is a list of all apt files I have, since I was installing in batches I don't know exactly when the menu first broke:  chrome-gnome-shell clamav-daemon debfoster firefox-locale-en fonts-powerline gir1.2-unity-5.0 git gnome-tweaks keepassxc language-pack-gnome-en linux-generic-hwe-20.04  mtools neofetch neovim shim-signed tlp ubuntu-desktop ubuntu-standard ucaresystem-core vlc wbritish

I did an upgrade today to the latest version of ubuntu. Everything looked good and fine only for me to discover that I cannot find my applications after clicking the 'Show Applications' icon. The same applies when I search for an application in the search bar, I do not see it. It shows me an endless search.  These are the screenshot images of the problem:      In the meantime, I access my applications from the menu at the top bar and also use the terminal to run applications with CLI.


I just posted and answer at S.O. and the answer link when I visit it with chrome I get a phishing warning.   Someone should check:

I just got a Chrome phishing warning on main for   Is it just me, Chrome screwing things up or do you people have work to do?  The message in English:     Known phishing site detected.   Google Chrome has denied the access to stackoverflow.com. This site is reported as phishing site.      Phishing sites are designed to mislead you, so that you disclose your login credentials, password or other personal data. These sites occur as sites which you probably trust.


In .NET, we have the types interface and class. There are a few relationships between these two types. In this example, we have all the relationships in .NET:  class Vehicle { }  interface IMovable {    void Move(); }  class Engine { }  class Car : Vehicle, IMovable {    private readonly Engine _engine;    public Car(Engine engine) { _engine = engine; }     public void Move() {} }    Car extends Vehicle - a Car is-a Vehicle Car implements IMovable - a Car can-do IMovable Car needs an Engine to create itself - a Car has-a Engine   But I don't understand Ruby's modules because they have functionality but they aren't interfaces (in that they define method bodies, so they are more akin to subclassing), but they aren't superclasses (because multiple inheritance is not done in Ruby).  Can someone help me understand the usage of modules in Ruby and possibly give an analogy to .NET?  EDIT: Seeing the 3 votes to close due to duplicate, I must clarify. I am asking what is the relationship between classes and modules (given that classes implementing interfaces is can-do in .NET). The 'duplicate' answer does NOT address that question.

I came from Java, and now I am working more with Ruby.   One language feature I am not familiar with is the module. I am wondering what exactly is a module and when do you use one, and why use a module over a class?


I am trying to figure out why my code won't allow me to correctly print any values in the array that are above the average value. I looked at a stackoverflow example of another user with a similar issue but it still didn't make sense. I don't even understand the current output for the values above the average.  How do I print the values in the array that are above the calculated average of all the array values?  I'd appreciate the help.  My code:  public class Inequality  {     public static void main(String[] args)      {         // list of incomes in thousands          int[] income = {2,10, 532, 4, 53, 28, 291, 38, 6, 17, 73, 21};          int sum = 0;          int average;          int aboveAverage = 0;           for (int i = 0;i< income.length;i++)          {              sum = sum + income[i];          }          average = sum/income.length;          System.out.println("Average of income array: " + average);           for (int i = 0; i < income.length; i++)          {              if (income[i]>average)              {                  aboveAverage++;              }          }          System.out.println("There are " + aboveAverage + " numbers above the average.");          System.out.println("Range of numbers above the average: " + income);     } }   My output:  Average of income array: 89 There are 2 numbers above the average. Range of numbers above the average: [I@15db9742

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


In the classic American children's show Spongebob Squarepants, one line in the theme song goes like this:     If nautical nonsense be something you wish   and it is then followed by the chorus.  My question is on the use of the word be in this context. Although it could simply be a form of silly, "pirate-speak" to be entertaining, I am wondering if this could be a form of the subjunctive. The sentence is asking if you might want to watch a show about hi-jinks in in the ocean (hence the phrase "nautical nonsense") and so thus is a hypothetical and in my understanding, hypothetical statements are supposed to be used with the subjunctive.  So, is this proper English grammar, or simply a sentence intended to sound funny? If it is proper grammar, then why has this usage largely disappeared?

, a question exists regarding the usage of the word "that" in the following sentences:   Assume that A = B. Assume A = B.   A well-known author suggests that users elect Option 1 in mathematical writing.  A discussion arose whether or not Option 1 is perfectly acceptable usage of the subjunctive, with a caveat: that the glyph "=" be read "equal" and not "equals."  The author of the book in question also further suggested that the word "that" be used only if it helps parse a sentence, "Assume that A is a group" vs. "Assume A is a group." This point was less contended, but in the subjunctive discussion, contrary concerns also arose whether the usage "Assume A be a group" is correct archaically, is correct presently, or has never been correct at all.  First question: given that "Assume..." is functionally equivalent to necessity in mathematical writing, is the sentence "Assume that A equal B" a proper use of the subjunctive?  Second question: Is, or has ever been, the usage "Assume that A be a group" been proper conjugation of "is" in a properly-used subjunctive?  Third question: Is there anything structurally unsavory about the use of the conjunction "that" in the form "Assume that A equals B" (note the s)?


When I open/compose an email in Outlook, the window is kept in the Outlook stack, as following:    What I'd like to do is have the emails be stacked as a new icon, so clicking the Outlook icon will immediately maximize Outlook, rather than displaying the stack. How can I do this?

There are three options for customizing taskbar buttons in Windows 7:   Always combine, hide labels Combine when taskbar is full Never combine   Is there any way to hide labels and not combine taskbar buttons? Or even better, to exclude only certain applications from combining?  My main problem is that I switch a lot between two instances of a single application, and having to hover over combined icon and then choosing the correct one. Alt-Tabbing is not a good alternative when I'm switching between more than three applications; clicking on taskbar only once is what I'm looking for.


I was trying to install a software. This pop up appeared  And now I can not do anything, I tried to press okay but it doesn't work. What is the solution of this? Which button exactly I need to press? I'm using Ubuntu 20.04.1.

After a recent update, ttf-mscorefonts-installer prompted me to accept its license agreement.     ┌─────────────────┤ Configuring ttf-mscorefonts-installer ├─────────────────┐  │                                                                           │   │ TrueType core fonts for the Web EULA                                          │                                                                               │ END-USER LICENSE AGREEMENT FOR MICROSOFT SOFTWARE                             │                                                                               │ IMPORTANT-READ CAREFULLY: This Microsoft End-User License Agreement           │ ("EULA") is a legal agreement between you (either an individual or a          │ single entity) and Microsoft Corporation for the Microsoft software           │ accompanying this EULA, which includes computer software and may include      │ associated media, printed materials, and "on-line" or electronic              │ documentation ("SOFTWARE PRODUCT" or "SOFTWARE"). By exercising your          │ rights to make and use copies of the SOFTWARE PRODUCT, you agree to be        │ bound by the terms of this EULA. If you do not agree to the terms of          │ this EULA, you may not use the SOFTWARE PRODUCT.                              │                                                                               │                                  <Ok>                                         │                                                                           │   └───────────────────────────────────────────────────────────────────────────┘    Screenshot:   For some reason my terminal will not allow me to accept, or for some reason I am pressing the wrong hotkey...  I've tried every letter on the keyboard and Enter among others...  I'm sure there is a very simple and obvious solution to this.  I've also just tried to remove the package completely however the terminal states that due to the package not being correctly installed, I should reinstall the package before removing it.  Very frustrating!  Essentially, because I cannot successfully install this package, I can't really ever upgrade my system because I always have to end up terminating the terminal with the license agreement (thus the upgrade fails).


On a freshly installed Ubuntu 17.10, I can use ssh on remote servers using terminal. But I can't with Remmina.  I get a black screen with a little white square (flashing or not). I also tried to use UTF-8 in preferences character.  Here is what I get in command lines :  me@myubuntu:~$ /usr/bin/remmina  Remmina plugin RDP (type=Protocol) registered. Remmina plugin RDPF (type=File) registered. Remmina plugin RDPS (type=Preference) registered. Remmina plugin VNC (type=Protocol) registered. Remmina plugin VNCI (type=Protocol) registered. Remmina plugin SFTP (type=Protocol) registered. Remmina plugin SSH (type=Protocol) registered. Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.  (remmina:22188): Gtk-WARNING **: Allocating size to GtkScrollbar 0x55700821c610 without calling gtk_widget_get_preferred_width/height(). How does the code know the size to allocate?   Maybe you advise to use other software than Remmina? My need is to have a servers list as I did with MRemoteNG on Windows.     How possibly five people say it is a duplicate of VNC problem?! I   never spoke about VNC but only SSH. First thing you can see in this   other problem, the person tells everything is fine for him with SSH,   the exact opposite of me!   I answer to myself... uninstall the Remmina version coming from   official Ubuntu and run sudo apt-add-repository   ppa:remmina-ppa-team/remmina-next sudo apt-get update sudo apt-get   install remmina remmina-plugin-rdp remmina-plugin-gnome   libfreerdp-plugins-standard

I'm trying to connect two PCs for desktop sharing, I was able to set up ssh shell and file sharing but I failed to connect to VNC server.  There are additional packages that I need to install on my machines?  And how should I fill this dialog:


Suppose $P$ and $Q$ are $n\times n$ matrices of real numbers such that   $P^2=P$ $Q^2=Q$ $I−P−Q$ is invertible, where $I$ is a $n\times n$ identity matrix.   Show that $P$ and $Q$ have the same rank.

Let $P,Q$ real $n\times n$ matrices  such that $P^2=P$ , $Q^2=Q$ and $I-P-Q$ is an invertible matrix.  Prove that $P$ and $Q$ have the same rank.  Some help with this please , happy year and thanks.


Let $Y$ and $Z$ be linear subspaces of a Banach space $X$ , such that $ Y$ is finite-dimensional and $Z$ is closed in $X$ , then is $Y +Z$ also closed in $X$ ?

Let $E$ be a Banach space and let $S$ and $T$ be closed subspaces, with dim$\space T<\infty$. Prove that $S+T$ is closed.  To prove that $S+T$ is closed I have to show that for any limit point $x$ of $S+T$, $x \in S+T$. So let $x$ be a limit point that subspace. Then, there is a sequence $\{x_n\}_{n \in \mathbb N} \subset S+T$ : $x_n \rightarrow x$. $x_n \in S+T \space \forall \space n \in \mathbb N$. This means that $x_n=s_n+t_n$ with $s_n \in S$ and $t_n \in T$ $\forall \space n \in \mathbb N$. Well, I couldn't go further than this. $\{s_n\}_{n \in \mathbb N}$ and $\{t_n\}_{n \in \mathbb N}$ are sequences in $S$ and $T$ respectively. I would like to prove that both of them converge to some points $s$ and $t$, for if this is the case, the hypothesis would assure $s \in S$ and $t \in T$. Then, I would have to prove that $x=lim x_n=lim s_n+t_n=lim s_n+limt_n=s+t$ and from all the previous steps I would conclude $x \in S+T$. $$$$Maybe I could start by proving that $\{t_n\}_{n \in \mathbb N}$ is convergent. But I don't see why this is true, I've tried to prove that $\{t_n\}_{n \in \mathbb N}$ is a Cauchy sequence (in a Banach space this would imply that the sequence converges) but I couldn't.


I'd like to make a program that prints colors in the python terminal but I don't know how. I've heard that you can use certain escape sequences to print text in color, but I'm not sure of this. How can I print a string in a specific color using the python terminal?  Side note: I run a version of Linux.

How can I output colored text to the terminal in Python?


How can I show that     $\sum_{k=1}^{\infty}ka^k(1-a) = \frac{a}{1-a}$   I tried to integrate the series, but that did not help me.

I've tried to calculate this sum:  $$\sum_{n=1}^{\infty} n a^n$$  The point of this is to try to work out the "mean" term in an exponentially decaying average.  I've done the following:  $$\text{let }x = \sum_{n=1}^{\infty} n a^n$$ $$x = a + a \sum_{n=1}^{\infty} (n+1) a^n$$ $$x = a + a (\sum_{n=1}^{\infty} n a^n + \sum_{n=1}^{\infty} a^n)$$ $$x = a + a (x + \sum_{n=1}^{\infty} a^n)$$ $$x = a + ax + a\sum_{n=1}^{\infty} a^n$$ $$(1-a)x = a + a\sum_{n=1}^{\infty} a^n$$  Lets try to work out the $\sum_{n=1}^{\infty} a^n$ part:  $$let y = \sum_{n=1}^{\infty} a^n$$ $$y = a + a \sum_{n=1}^{\infty} a^n$$ $$y = a + ay$$ $$y - ay = a$$ $$y(1-a) = a$$ $$y = a/(1-a)$$  Substitute y back in:  $$(1-a)x = a + a*(a/(1-a))$$ $$(1-a)^2 x = a(1-a) + a^2$$ $$(1-a)^2 x = a - a^2 + a^2$$ $$(1-a)^2 x = a$$ $$x = a/(1-a)^2$$  Is this right, and if so is there a shorter way?  Edit:  To actually calculate the "mean" term of a exponential moving average we need to keep in mind that terms are weighted at the level of $(1-a)$. i.e. for $a=1$ there is no decay, for $a=0$ only the most recent term counts.  So the above result we need to multiply by $(1-a)$ to get the result:  Exponential moving average "mean term" = $a/(1-a)$  This gives the results, for $a=0$, the mean term is the "0th term" (none other are used) whereas for $a=0.5$ the mean term is the "1st term" (i.e. after the current term).


My main goal for trying Ubuntu is to try to run some games. I've been having problems in Win10 with all games crashing to desktop after random periods of time. I've put all of my hardware through various stress tests with no errors. I've reinstalled windows, done clean boots etc., But it's still happening. So, my theory is, if I can get a game to run satisfactorily in Linux, with no crashes, then there must be something wrong with Windows. In which case, if I can get enough of my favourite games to run, I might never have to use Windows again. So, my question is...will I run into any issues with drivers or compatibility for the following hardware?: AMD Ryzen 5 3600 CPU; X570 chipset motherboard; G.Skill Trident Z RGB (4 x 8GB); Nvidia RTX 3070; Windows 10 installed on 1st M.2 NVME; Ubuntu to be installed on 2nd M.2 NVME; Games and other programmes installed on various SATA SSDs and HDDs.

I have a device on which I would like to install Ubuntu. How do I find out if Ubuntu will work on it?


Works fine in IE, but in latest Chrome the part of the graph that says "select an area by dragging across the lower chart" doesn't actually respond to mouse input.

The "select an area by dragging across the lower chart" thing is not working on Chrome.  Tested with Chrome 13.0.782.220 m, works with Firefox 6.0.1 and IE 8  Quirk: For some reason, if I open an incognito window, it works. Tried clearing the cache and cookies, still not working.


I created my LaTeX document using the xcolor package loaded like this  \usepackage[usenames, dvipsnames, svgnames, table]{xcolor}   Now I'm trying to put the document in the journal format and I get a package clash for xcolor so I ended up commenting the line above. The problem now is that all the colored names I use are no longer available. Is there a way to solve this issue before digging in color names and redefining the colors?

Is there a way to apply some options to a package which is loaded in the cls file I am using? For instance, suppose that the cls file loads graphicx, and I want to apply the option demo to it from my tex file.


I want to do something with command blocks like:  /tellraw @a {"text":"[Name of person who activated the command block] Hello!"}   Without the person saying it themselves in the chat

So I am currently making a minecraft custom map (for 1.9). I want to make the player "say" something using /tellraw commands. I did figure out how to make the player name come up using /say commands, but still have no idea how to do it using the /tellraw command.  How do I do that?


In the new mobile view, I noticed that the OP's name is no longer highlighted in comments.    Browser is Chrome 50.0.2661.89 running on Android 6.0.0.  Not sure if this is a bug or an intentional design decision, but we can see the OP's name highlighted again?

On main and in the old mobile site (iirc) the username of the OP is highlighted in the comments.  This is no longer the case after the new design/theme was rolled out yesterday.  Can we get this back?


I am trying to build a shared object(libCalc.so) that depends on a static library(libMath.a)  Static libary is built using  g++ -c math.cpp -Wall -fPIC ar rcs libMath.a *.o  Shared object is built using  g++ libCalc.cpp -std=c++0x -Wall -g -fPIC -c -o ./libCalc.o  g++ -shared -L/path/to/lMath/ -lMath -o libCalc.so libCalc.o  Both of them builds successfully, but after building the shared object when I run "nm" on the libCalc.so, I see some undefined references that are from the static library.  Shouldn't the symbols of libMath.a be defined in libCalc.so? Can someone please explain. How can I create libCalc.so with all the symbols from libMath.a  Thanks

Why does the order in which libraries are linked sometimes cause errors in GCC?


Let $R$ be a ring with unity such that the only left ideals of $R$ are $\{0\}$ and $R$. Show that $R$ is a skew field.   Please help me to solve this problem.

This is question #66 from        Let $R$ be a ring with a multiplicative identity. If $U$ is an additive subgroup of $R$ such that $ur \in U$ for all    $u \in U$ and for all $r \in R$ , then $U$ is said to be a right ideal of $R$. If $R$ has exactly two right ideals, which of    the following must be true?      I. $R$ is commutative.   II. $R$ is a division ring (that is, all elements except the additive identity have multiplicative inverses).   III. $R$ is infinite.     Here is my reasoning: Because $R$ is a ring, $R$ is also a additive group with some identity element $0$. We have a theorem that says $0r = 0 $ in any ring, so $\{0\}$ is a right ideal of $R$. Also, $R$ is a right ideal of $R$. Now I have found two different right ideals and there mustn't be any more.     Edit: As mentioned in the comments, the example below is not a ring, so it is not applicable to the problem. I could not fix it by taking additive closure because that introduced more than two ideals.  A possible candidate for $R$ could be the set of $2\times2$ matrices $\{0,I,-I,a,-a\}$ where $a = [[^1_0] ,[^0_0]]$. The only right ideals are $R$ and $\{0\}$. This ring satisfies only property I, but the answer key says that II is the correct answer.