If I schedule something with 'at` like,  $ at noon warning: commands will be executed using /bin/sh at> echo "Will I be created?" > /tmp/at_test at> <EOT> job 12 at Fri Jun 30 12:00:00 2017   And if I reboot the machine before execution time, will my command be executed?  Unlike regular cron which schedules tasks from file, does at store this 'info' somewhere?

I'm using at to schedule a task for a later time.  Will it survive a reboot, or should I re-assign all the tasks after reboot ?


I got c# project from my prof.(no i can't ask him) I understand all except marked part in this class. Can someone give me short explanation or link to answer, what that part of code actually do?  class AccessConnection {     private OleDbConnection conn;      public AccessConnection()     {         conn = new OleDbConnection();         conn.ConnectionString= @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Bata\Desktop\Izvestaj\praksa\praksa\Studenti.accdb";     }     public void otvoriKonekciju()     {         conn.Open();     }     public void zatvoriKonekciju()     {         conn.Close();     }     /* This is part of code i don't understand     public OleDbConnection Conn     {         get         {             return this.conn;         }     }     */ }

In C#, what makes a field different from a property, and when should a field be used instead of a property?


How to get specific value from this JSON string. I want to get nested nested JSON object "FromUserId": "bd079f57" and pass it to Javascript function.  "notification":{        "title" :"Test",        "message" : "Message",              "android": {                  "data": {                          "priority": "2",                         "profile": "profile",                         "message": "xxx has sent you a Message.",                         "style": "inbox",                         "noteId": "1",                         "visibility": "1",                         "title": "Test",                         "badge": "12",                                           "FromUserId": "bd079f57"                                                     }                     }                  }     "onNotification": function (notification) {                                  var obj = JSON.parse(notification.message.android.data.FromUserId);                         // How to pass this test.FromUserId to ReadData function.                                            ReadData(obj)                     } $scope.ReadData(obj){  //further process of json }

Given a string of JSON data, how can I safely turn that string into a JavaScript object?  Obviously I can do this unsafely with something like:  var obj = eval("(" + json + ')');   but that leaves me vulnerable to the JSON string containing other code, which it seems very dangerous to simply eval.


In my current project I'm trying to execute a .sh file with a python program, giving input and reading output The problem is that I have no idea on how to give the input (I managed to read the output in this way, searching on the internet. I'll listen to any suggestion). Here I write an example code (for the original one is longer and more complicated, but this is the essence and the problem is the same)  import subprocess greet = subprocess.Popen(["bash", "helloWorld.sh"],                          stdout=subprocess.PIPE,                          encoding="utf-8") print(greet.stdout.read())   and this is the simple helloWorld.sh  read name echo "Hello $name"   My OS is Debian (xfce) and I'm wirting in Python 3.7 Ask  for any other detail

If I do the following:  import subprocess from cStringIO import StringIO subprocess.Popen(['grep','f'],stdout=subprocess.PIPE,stdin=StringIO('one\ntwo\nthree\nfour\nfive\nsix\n')).communicate()[0]   I get:  Traceback (most recent call last):   File "<stdin>", line 1, in ?   File "/build/toolchain/mac32/python-2.4.3/lib/python2.4/subprocess.py", line 533, in __init__     (p2cread, p2cwrite,   File "/build/toolchain/mac32/python-2.4.3/lib/python2.4/subprocess.py", line 830, in _get_handles     p2cread = stdin.fileno() AttributeError: 'cStringIO.StringI' object has no attribute 'fileno'   Apparently a cStringIO.StringIO object doesn't quack close enough to a file duck to suit subprocess.Popen.  How do I work around this?


I read that, in simplified terms, if the C++ compiler can prove that a variable is of a certain type, it can inline virtual functions. Why can't it do it in this case (tested with MSVC 2017, clang 4.0, gcc 7.2 and icc 17):  #include <iostream>  class Callable { public:     virtual int sq(int n) const; };  class Square : public Callable { public:     inline int sq(int n) const override final  {         return n*n;     } };  class Call { public:         const Callable caller; };  class Methods { public:     constexpr static const Call c {Square()}; };  int main() {     using std::cout;     cout << Methods().c.caller.sq(5); }   I noticed that clang's optimization output in godbolt (link below) says that Callable::sq will not be inlined because its definition is unavailable. However, Methods::c is static and const. Call::caller is also const. Also, Square::sq is final. As far as I know, there is no way they'll change at runtime. Or am I missing something?  On the other hand, the compiler is able to inline the function in this version:  #include <iostream>  class Callable { public:     virtual int sq(int n) const; };  class Square : public Callable { public:     inline int sq(int n) const override final  {         return n*n;     } };  class Call { public:         Callable const* caller; };  class Methods { public:     Call c {new Square()}; };  int main() {     using std::cout;         cout << Methods().c.caller->sq(5); }   Why is that so?  for godbolt for easy checking.

Someone mentioned it in the IRC as the slicing problem.


I am trying to do the following query:  DELETE FROM main_history WHERE id NOT IN (   SELECT max(id) FROM main_history GROUP BY instance_id, xpath, new_value )   However, I get the following error:  You can't specify target table 'main_history' for update in FROM clause   Is there a way to do this directly in mysql in a single query? I'm currently creating a tmp table like so:  INSERT INTO main_history_new (     SELECT id, instance_id, territory_id, xpath, field, old_value, new_value, max(date)     FROM main_history     GROUP BY instance_id, xpath, new_value )

I have a table story_category in my database with corrupt entries. The next query returns the corrupt entries:  SELECT *  FROM  story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category INNER JOIN         story_category ON category_id=category.id);   I tried to delete them executing:  DELETE FROM story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category        INNER JOIN story_category ON category_id=category.id);   But I get the next error:      #1093 - You can't specify target table 'story_category' for update in FROM clause    How can I overcome this?


Let $R$ be a ring with $r \in R$ and $r^n = 0$ for $n \in \mathbb{N}$. Show that $1-r$ is a unit in $R$.   I tried to use the geometric sum but I dont know how to proceed.

If $ua = au$, where $u$ is a unit and $a$ is a nilpotent, show that $u+a$ is a unit.   I've been working on this problem for an hour that I tried to construct an element $x \in R$ such that $x(u+a) = 1 = (u+a)x$. After tried several elements and manipulated $ua = au$, I still couldn't find any clue. Can anybody give me a hint?


A circle is divided into 360 little parts called degrees.  Why or how did they choose that figure? Is there a very strong reason for that or it just a accidentally choose.

I was just wondering why we have 90° degrees for a perpendicular angle. Why not 100° or any other number?  What is the significance of 90° for the perpendicular or 360° for a circle?  I didn't ever think about this during my school time.  Can someone please explain it mathematically? Is it due to some historical reason?


So I'm feeling a bit guilty. I've been working on a publication proof (my first) of an interesting theorem. The issue is I've been using StackExchange (Mathematics) to answer some similar questions when I get stuck on much smaller parts of the proof.   So the question here is, is it generally ethical to put just my name on a paper, even if I may not have come up with the lemma's using only my ideas, or is there a good way to I should reference StackExchange in a publication?  On one hand, most of the stuff I received answers for was for a learning purpose, similar to  that of me asking a professor or teacher, not so much as a co-author. And although relevant to the publication, the answers I received could be very common in other proofs as well and were not directly related the lemmas themselves.  On the other hand, it was not necessarily my ideas that first assisted the lemma, but those of others through SE.  Take for example a question I asked earlier today. I wanted to see an alternate proof to an equation, so that I could use it as a new method of proving a lemma related, it as the original proof (Euler's Thereom) could not be generalized with such a method . The proof I was looking for was simply done using the Binomial Theorem. Therefore the idea of using the Binomial Theorem in my proof will assist me in my own similar generalization. But even though I was just given the tool, the work will be done myself.

Sometimes we may ask questions on stack exchange or online forums wherein the response is helpful or even essential to a piece of work that gets published in an academic journal. If this occurs, how should credit be given to those involved in the exchange? Should they all be included as authors? Should a link to the forum be included as a reference in the paper?  Once something is in a stack exchange or forum, it's "published". Perhaps in the future, the current peer review model will transform into people writing blogs and posting in forums and databases. But for now, how might this issue be dealt with while forums, blogs, etc coexist with journals?


I need to remount my linux filesystem from ro to rw. But nothing gonna work. I will be very grateful if someone help me.  # mount /dev/mtdblock3 on / type squashfs (ro) proc on /proc type proc (rw) ramfs on /tmp type ramfs (rw) devpts on /dev/pts type devpts (rw) none on /tmp/netslink type ramfs (rw)  # cat /proc/mounts rootfs / rootfs rw 0 0 /dev/root / squashfs ro 0 0 proc /proc proc rw 0 0 ramfs /tmp ramfs rw 0 0 devpts /dev/pts devpts rw 0 0 none /tmp/netslink ramfs rw 0 0   I tried this:  # mount -o rw,remount -t squashfs /dev/root / mount: Mounting /dev/root on / failed: Permission denied   And I tried this:   # mount -o rw,remount -t squashfs /dev/mtdblock3 / Command "mount -o rw,remount -t squashfs /dev/mtdblock3 /" is forbidden!   And just this:  # mount -o rw,remount / Can't find / in /etc/fstab   /etc/fstab:  # cat /etc/fstab proc /proc proc defaults 0 0 ramfs /tmp ramfs defaults 0 0 devpts /dev/pts devpts defaults 0 0   The system doesn't have the root user, but have the root group and I do it by the user which consists in the root group, is it not enough?  What is the right solution? Thanks!

I am working on an embedded device. The fstab shows the following info:  <file system> <mount pt>      <type>  <options>         <dump> <pass> /dev/root       /               ext2    rw,noauto                           0               1 proc            /proc           proc    defaults                            0               0 devpts          /dev/pts        devpts  defaults,gid=5,mode=620             0               0 tmpfs           /tmp            tmpfs   defaults                            0               0 ramfs           /var            ramfs   defaults                            0               0 sys             /sys            sysfs   defaults                            0               0   Running the mount command I get this:  rootfs on / type rootfs (rw) /dev/root on / type squashfs (ro,relatime) proc on /proc type proc (rw,relatime) sys on /sys type sysfs (rw,relatime) devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620) ramfs on /var type ramfs (rw,relatime)   Which means that the root filesystem is read-only.  How can I remount the read-only part as read-write?


I've looked at the other questions about having problems connecting to the internet, but it hasn't worked for me so far.   I bought a netbook and I wanted to try Ubuntu out, which I installed from a usb. So I installed it, replacing the windows7 that came with it, and now it doesn't connect to the internet (it did connect when it was windows). I've run some of the more basic steps, and have tried to install some dkms from the pool files, but it won't let me install anything.   I don't know the commands that well, so I can't say that I'm doing things correctly, so if anyone could please walk me through this - I'd be much obliged.  It also doesn't recognize an ethernet cord.  Using Ubuntu 3.11.0-15-generic               lts-saucy              BCM4312              [14e4:4315]

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


using ArcMap, I want to create data driven pages of road signs along a highway with terrestrial photos that are NOT geo-tagged (Two photos per road sign). The image names/Network folder paths/coordinates are stored in the feature attribute table of signs.   My wish is that the data driven sheets will show these photos, which are automatically inserted near the POINT feature (road signs) they belong to (in data view or layout). The images are on a network folder. So, basically, I wondering how I can implement a script/tool to look inside the table, look at the feature, then the network link, pull the image and insert it next to the feature in layout view or data view. Since there are two photos, they need to be "staggered" (not overlap with one another) so they don't fall on top of each other.   Is there a way to do this in ArcMap (or other method)?  There are 907 signs with approximately 1700 photos.   I'm using ArcGIS Advanced 10.2 with Spatial/3D Analyst extensions.

I have a series of point features which represent road signs and each point has one photo of each sign associated with it.    I want to create a mapbook with the locations of the signs shown as points and the photo displayed next to the point. Each page in the mapbook will have multiple sign locations and photos on it.     Is there an easy way to automate importing photos into an MXD in data view next to a point feature?    There are about 1000 hence need for automation.  Or somehow "labeling" a feature with a photo?


How can I find the questions which has only single tag, e.g. java and not any other tag?

Is there any way to search for questions that have a specific tag and only that lonely tag?  In other words, I'd like to be able to do something like the following to find questions that have a single tag and no other:  [mytag] tagcount:1   This would be very useful for tag cleanup situations to be able to do house-cleaning before nuking a tag.


I was curious by the world record for locomotion of animal. Fastest, Longest, Highest, and many kind of similar records  Because sometimes it use raw number such as speed of Cheetah as fastest animal. And sometimes it use body scale proportion like flea jumping longest  Which, I also have heard that, muscle will have more power in smaller size. That made small creature like flea have far more advantage  So tobe really fair record. I think it should calculate for compensate that, if all animal really scale into the same size, how muscle strength will be scaled into that size  If flea was really scaled up into the same size as hare (If I recalled hare has record holding for highest jump?), flea muscle strength should really drop dramastically. But now who will win the longest jump competition?  So I want that formula to scale the record of animal. For I can find the best mechanic of body plan. Is there a formula like that?

I am interested in why many small animals such as ants can lift many times their own weight, yet we don't see any large animals capable of such a feat.  It has been suggested to me that this is due to physics, but I am not even sure what to search for. Could someone explain why indeed it is easy for smaller objects/lifeforms to support several times their own weight, but this is harder as objects/animals become larger?


For $x,y \in \mathbb R$, let $d(x,y) = |x-y|/(1+|x-y|)$. Determine whether $d$ defines a metric on $\mathbb R$. If it does, determine whether $\mathbb R$ is compact under $d$.  Since $|x-y|=|y-x|$, $d$ is symmetric. If $x \ne y$, then $|x-y|>0$, so $d(x,y)>0$. Since $|x-x|=0$, then $d(x,x)=0$. So, $d(x,y) \ge 0$ with equality if and only if $x=y$. I am having trouble showing the triangle inequality $$\frac{|x-y|}{1+|x-y|} \le \frac{|x-z|}{1+|x-z|}+\frac{|z-y|}{1+|z-y|}.$$ Trying a few values, I'm guessing triangle inequality holds.

Show that $(\mathbb{N}, d)$ is a metric space   with $$d(x,y) = \frac{|x-y|}{1+|x-y|}$$   My attempt:   let $x,y \in \mathbb{N}$,  1) $d(x,y) = 0 \implies |x-y| = 0 \iff x = y$  2) $d(x,y) = d(y,x)$  3) show for $z \in \mathbb{N}$, $d(x,z) \leq d(x,y) + d(y,z)$  Using the triangle ineuqality I managed to get:  $$d(x,z) \leq \frac{|x-y|}{1+|x-y| - |y-z|} + \frac{|y - z|}{1 + |x-y| - |y-z|}$$  but i assume here I must use the fact that $x,y,z \in \mathbb{N}$ but I'm not sure how.  Any hints please:  edit: improvements on solution - Using fact that $|x-y|$ is a metric we have that $$d(x,y) \leq \frac{|x-y|}{1+|x-y| + |y-z|} + \frac{|y - z|}{1 + |x-y| + |y-z|}$$ (Since $|x-z| \leq |x-y| + |y-z|$) Is this correct? From there I can use the fact that $$\frac{1}{1+|x-y|+|y-z|} \leq \frac{1}{1+|x-y|} $$ and $$\frac{1}{1+|x-y|+|y-z|} \leq \frac{1}{1+|y-z|}$$ to conclude?


I have gone through various materials online but all the formulas were for small values of n(number of rows) say like 100,120 etc.But my problem is to calculate the critical value  for values of n(number of rows).Using the tests like t-tests etc are givings unexpected results like the relation which is not actually significant becomes significant.  so how to calculate it?

I have gone through various formulas but all were used for a small data set like 100, 200 rows, but I want to know how to calculate critical values of r for a large data set containing >5000 rows.   I have calculated using T.INV(1-alpha/2,df)/((sqrt(T.INV(1-alpha/2)^2+df)), but this formula is for small data sets, when I used it for a large data set, mentioned above, I got results which were not expected.


What are the best resources to learn, from scratch, mathematics as it appears in physics?  I would like to relearn everything besides basic enumeration / counting, and have absolutely zero understanding of physics. My apologies if the question is super ill formed: I would just like to learn some mathematics and am narrowing that down.

Every once in a while, we get a question asking for a book or other educational reference on a particular topic at a particular level. This is a meta-question that collects all those links together. If you're looking for book recommendations, this is probably the place to start.  All the questions linked below, as well as others which deal with more specialized books, can be found under the tag  (formerly ).  If you have a question to add, please edit it in. However, make sure of a few things first:   The question should be tagged  It should be of the form "What are good books to learn/study [subject] at [level]?" It shouldn't duplicate a topic and level that's already on the list   Related Meta:


I have the following JAVA code where I calculate a customer due amount  Double invsubtot = 0.0;             Double paidtot = 0.0;             Double duetot = 0.0;             try {                 ResultSet invoicesubtotal = InfoIMS.DbConnection.searchResult("select invoice_subtotal from invoice where customer_id = '69' and payment_type = 'Credit' and invoice_status = '1' group by invoice_number");                 while (invoicesubtotal.next()) {                      invsubtot = invsubtot + invoicesubtotal.getDouble(1);                  }                 // customerduejLabel5.setText(String.valueOf(invsubtot));                  ResultSet paidtotal = InfoIMS.DbConnection.searchResult("select sum(payment) from payments where cusid = '69' and ingrtype='1' and payment_status = '0'");                 while (paidtotal.next()) {                      paidtot = paidtotal.getDouble(1);                  }                 // customerduejLabel5.setText(String.valueOf(paidtot));                 duetot = invsubtot - paidtot;                 customerduejLabel5.setText("Customer Due : " + String.valueOf(duetot));   But the Output result is Customer Due : 6999.999999999999  But the real values of the first & second MySql queries are as follows  1. invoice_subtotal = 13891.30 2. sum(payment) = 6891.30   So it should be giving me the output as Customer Due : 7000 But Why is it giving me 6999.999...? Any way to solve this?  And I am not satisfied with the indirect answers given in   Where it shows why it happens but not how to avoid it clearly

double r = 11.631; double theta = 21.4;   In the debugger, these are shown as 11.631000000000000 and 21.399999618530273.  How can I avoid this?


long time Linux participate and virgin mobile customer, I couldn't be happier with my virgin mobile service. It's tops, and Ubuntu has been my favorite os since 2012 when it left all other Linux wanting to be as polished in my opinion. I want to bring those two things together and get in on developing Ubuntu for mobile. Best idea I have so far is unlocked sprint Samsung Galaxy s3 but I don't want to spend the money if it's going to have major issues as I'm not the very best programmer, if any of you have a idea for a less expensive, better performance or both device I could try then please let me and others know!

With the announcement of the Ubuntu Phone OS I'd like to know what phone (and tablet) models are supported at this time.  Note from foss & Oli: We are making this the master question for all future "Will this work on <insert random tablet/phone/device here>?!" questions


Let's say I have:  \bigcup_{a \in X}   This will print a big U with $a \in X$ below it. Now, let's say I also want to write $b \in Y$ and $c \in Z$below that big U. Is this possible?

I have the following equation, where there is a lot of stuff under the sum symbol:  \begin{equation} d(\vec{x},\vec{y})=   \sum_{Z_{xy}\in\vec{Z}_{xy},\forall x\in\vec{x},\forall y\in\vec{y}}      f(Z_{xy}) \end{equation}   In the resulting document, I find it kind of hard to read. Is there a way to write the equation to make the result more readable, e.g. putting the stuff under the sum symbol on different lines?


I'm really confused with this question... Let $X$ be a separable Banach space. Prove that $X$ is quotient space $\ell_1$. I have some denotations.  $\{ \xi_i \}$ - convergent dense sequence in $K_1(0)$ =  $\{ x \in X \mid \|x\| \leq 1 \}$ - closed balls with center $0$. $ \alpha :  \{ x_i \} \mapsto \sum_i (x_i \xi_i),\{ x_i \} \in \ell_1 $  How can these denotations help me to prove statement? Thanks in advance.

How to prove the following mind-blowing fact?     Let $X$ be a separable Banach space and let $\ell_1$ be the space of all absolutely summable scalar sequences. Then there exists such closed subspace $A\subset \ell_1$ that factor space $\ell_1/A$ and $X$ are isomorphic as normed spaces.   Edit: So what, this is like a classification up to isomorphism of all separable Banach spaces? Each separable Banach space corresponds to some closed subspace of $\ell_1$?


"You can [not go] to school."   Can this sentence mean that you can stay here and not go, or does it automatically become a negative sentence if I say it like this?

I always try to remember to use "cannot" when applicable as in "I cannot take an umbrella" (because I do not have one).  I also thought that the problem with "I can not take an umbrella" was that it was ambiguous: it could also mean that I could decide not to take an umbrella. Trying to write unambiguously most of the time, I would therefore never use it.  Now I see it claimed that it is in fact not ambiguous, and only carries the second meaning. Usually I would accept such advice at face value and start using "can not" when the second meaning is unambiguously meant, but this comes from a style guide I have other reasons not to respect very much.  Does "can not" have a single unambiguous meaning?  (I have read  but my question is more about current usage. The length of the answer to that question does confirm my prejudice a bit, though)


I am curious whether there is a way to install a module through an existing module's update hook?

There is a lot resource for doing it in Drupal 6, but I didn't find a solution for Drupal 7.  How can I install and enable selected modules?


Here is signature of the function:  public static T[] Shuffle<T>(T[] array)   Inside the function I want to check the type:  var t = T.GetType();   But I get this error:  'T' is a type parameter, which is not valid in the given context   Any idea why I get error and how to get type of T?

Let's say I have a generic member in a class or method, like so: public class Foo<T> {     public List<T> Bar { get; set; }          public void Baz()     {         // get type of T     }    }  When I instantiate the class, the T becomes MyTypeObject1, so the class has a generic list property: List<MyTypeObject1>. The same applies to a generic method in a non-generic class: public class Foo {     public void Bar<T>()     {         var baz = new List<T>();                  // get type of T     } }  I would like to know what type of objects the list of my class contains. So what type of T does the list property called Bar or the local variable baz contain? I cannot do Bar[0].GetType(), because the list might contain zero elements. How can I do it?


I used a Disk cloning device to clone my C Drive because it was running out of space. I used a 2 tb hard drive to upgrade to however the Cloning unit but only copied the 1 tb onto the drive leaving a empty 1 tb partition left. I formatted the partition and loaded some data on it but then realized I would like the C Drive to be a one partition, 2 tb drive. How do I remove the partition without losing the data on it?

I have a computer harddisc with 3 NTFS partitions:  C /dev/sda1/ D /dev/sda2/ extended /dev/sda5/ E /dev/sda3/    C and E are both 10 GB and D is 55 GB.  I want to merge C and E (or rather expand C to 20 GB).  (E comes from shrinking D using gPARTED...).  I have tried to change the size of C in gPARTED in serveral ways...  Please help me!


I struggle with putting image on one face of the cube. What I'm stuck is to set "Mapping" options of the texture. The problem is I cannot manage to have it there at all.  I'm using blender 2.79 I found notice to disable "Use nodes" in Node Editor. However, it didn't help. I attach screenshot:  Can you help me with that issue? Please note I'm beginning Blender user and I don't know where the most options are located. I'd appreciate screenshot and animations.

I'm trying to texture a simple plane, but whenever I go to mapping I don't find the UV option that should be there. Here are my steps:   Make new object (ShiftA) then add mesh > plane Add texture and then open the texture I want to use  Go to mapping and then click the coordinate option and there is no UV option.


I have a Nexus 6, and have noticed that even on the lock screen, there are still things you can do besides enter the passcode.  You can turn the wifi/bluetooth and airplane mode on/off, use the torch, use the camera, turn the phone off.  I don't want to be able to do any of this. The only functionality I want on the lock screen is to be able to enter the passcode to unlock.  In the instance my phone is stolen, I want my phone to remain on, and online, for as long as possible.  Is this possible?  Thanks

I'm sure this would have been asked before. But I couldn't find out yet.  I recently updated to Lollipop in my Sony Xperia Z phone. The notification bar and pull down settings are great.   But on lock screen, I don't want to turn on/off any WiFi, Bluetooth or any  settings. Simply pull down settings should not be allowed on lock screen. How can I do that? Is there any option?  I have pattern lock already.


This question wants me to use a previous result, that if $e$ is a central idempotent in $R$ then $R \cong Re \oplus R(1-e)$. I was thinking about maybe some sort of induction would help here but I can't see exactly how I am going to get to the result I want.  I would like to know how to do the problem this way, because this is the way the book recommends. However, I also have heard that this problem can be done another way, by realizing that $R$ is a vector space over $Z_2$ and there has a finite basis, and i am under the impression that the result is not far away knowing this, but I can't quite connect the dots.  If somebody could guide me along these two different routes of solving this problem I would really appreciate it! Thanks!

Let $A$ be a ring which may not have a unity. Suppose every element $a$ of $A$ is an idempotent. i.e. $a^2 = a$. It is easily proved that $A$ is commutative. Suppose every ideal of $A$ is finitely generated. Can we determine the structure of $A$?


I am confused to use the word "whom" in a sentence.Is the above sentence correct? Give me a bit of your mind at what contexts we generally use whom with proper examples.

I can never figure out whether I should use who and whom. Most people use who for both colloquially, but some people say this is not correct.  What’s the rule for using who and whom correctly?


I am having a problem with my references, the error message is       Bibliography not compatible with author-year citations.    I have stripped down all tex and references files however I still have the same problem.  I have tried the following:   Delete all the temp file. I am using WinEdt8  I have year in my reference  Using \citet instead of \cite Try \usepackage[square,sort,comma,numbers]{natbib}   It will be much help you can help point out where did I went wrong :(  Here are the content of the files   .tex file:  \documentclass[english]{article} \usepackage[T1]{fontenc} \usepackage[latin9]{inputenc} \usepackage{babel} \usepackage[authoryear]{natbib} \begin{document} Text here  \citet{Ioannou2001}  \bibliographystyle{IEEEtran} \bibliography{reference}  \end{document}   .bib file (with only one record)      @ARTICLE{Ioannou2001,       author = {Ioannou, G and Kritikos, M and Prastacos, G},       title = {A greedy look-ahead heuristic for the vehicle routing problem with   time windows},       journal = {J Oper Res Soc},       year = {2001},       volume = {52},       pages = {523--537},       number = {5},       month = apr,       __markedentry = {[duongh:6]},       issn = {0160-5682},       owner = {d},       publisher = {Palgrave Publishers Ltd},       timestamp = {2013.03.29},       url = {http://dx.doi.org/10.1057/palgrave.jors.2601113}     }

I have a basic tex file and a bibliography which is exported from Mendeley  However, when I want to cite in the author-year style, I get the error:   Package natbib Error: Bibliography not compatible with author-year citations. (natbib) Press <return> to continue in numerical citation style.  Any clue what's wrong?  Minimum working example:  \documentclass[letterpaper, 10pt]{article}  \usepackage[authoryear]{natbib} \usepackage{lipsum}  \begin{document}  \lipsum[1-4] \nocite{*}  \bibliographystyle{apalike} \bibliography{articles}  \end{document}    A snippet of my .bib library:  @article{shortcode, author = {Lastname, Firstname}, file = {:/path/to/file.pdf:pdf}, journal = {Journal name}, number = {xx}, pages = {x--xx}, title = {Title}, volume = {xx}, year = {xxxx}     }


Can an object be transformed into a werebear (a shapechanger) using True Polymorph? Werebears have a particular kind of "shapechanger" ability that allow it to transform into a bear or just half-bear.  We know that "Shapechangers aren't affected by this spell." But would this stop the spell from making a shapechanger?

Can a lycanthrope or other shapeshifter be willingly affected by the spell True Polymorph? I know that it can be affected by regular Polymorph, but the text for the enhanced version seems to differ.


I have the following hamiltonian:  $$H = \frac{p_1^2}{2}+\frac{(p_2-k\;q_2)^2}{2}   ,\qquad  k\in\mathbb{R}.$$  I know that the hamiltonian isnt explicitly dependent on time so $H$ is a motion constant. But, is the hamiltonian equal to energy?

In classical mechanics, the Hamiltonian is well defined by the Lagrangian. Whereas, energy is a very ambiguous term. We just say $E=T+U$, and usually it equals to Hamiltonian. Does there exist a way that, by just looking at the Lagrangian mathematically, we immediately know the relationship between the Hamiltonian and the energy of the system?  And if we have a system, the Hamiltonian of which does not equal to energy, what is the physical meaning of that difference?


Please consider the following. Supposing the context is such that the frame was never stolen, is it acceptable to use "could have been stolen" instead of "could be stolen"? What would be the difference?  The original frame, which was made of gold, was replaced with a marble one before it could have been stolen

Non-native speakers often get confused about what the various tenses  and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter.  I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be  incorporated into the diagram.    Nota bene: What this is not is a discussion of whether there are  more than two tenses in English. , to which this question is not intended to supply arguments one way or the other.  Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better.  Breaking News There is now an excellent ELU blog article titled  . It is highly recommended reading.


Let's start with the bottom-line question. Say I have an UPDATE statement as following:  UPDATE my_table SET    my_column = <some new value>,        my_other_column = my_other_column   Is there a performance penalty for the unnecessary my_other_column = my_other_column assignment?    Now, to the real scenario. In my case, I have a function update(a, b) as following:  create function update(integer, integer) returns void as $$     UPDATE my_table     SET    a = case when $1 is not null then $1 else a end,            b = case when $2 is not null then $2 else b end $$ language sql volatile;   I am wondering what happens when I call select update(150, null). This resolves to:  UPDATE my_table SET    a = 150,        b = b   Is there a performance hit for that redundant b = b assignment? Are we now re-writing the b column, instead of only the a column if we were to remove that assignment from the UPDATE statement? Or are rows always written as a whole anyway, regardless of the actual updated columns? Or maybe, is the planner or executor smart enough to filter such redundant assignments out?

This is a question about the inner-workings of Postgres (v10) and performance.  Given a table, github_repos, with a multi-column unique index on org_id and github_id columns, is there any performance difference (or other issues to be aware of) between the two bulk upsert operations below? The difference is that in the first query, the org_id and github_id columns are included in the UPDATE, whereas in the second query they are not. Since the UPDATE runs ON CONFLICT, the updated values of org_id and github_id will be the same as the old values, but those columns are included in the UPDATE because the underlying library I am using is designed that way. I'm wondering if its safe to use as-is or whether I should be explicitly excluding those columns in the UPDATE.  Query #1:  INSERT INTO "github_repos" ("org_id","github_id","name") VALUES (1,1,'foo') ON CONFLICT (org_id, github_id) DO UPDATE SET "org_id"=EXCLUDED."org_id","github_id"=EXCLUDED."github_id","name"=EXCLUDED."name" RETURNING "id"   Query #2:  INSERT INTO "github_repos" ("org_id","github_id","name") VALUES (1,1,'foo') ON CONFLICT (org_id, github_id) DO UPDATE SET "name"=EXCLUDED."name" RETURNING "id"   github_repos table:        Column       |       Type        | Collation | Nullable  -------------------+-------------------+-----------+----------+  id                | bigint            |           | not null |  org_id            | bigint            |           | not null |  github_id         | bigint            |           | not null |  name              | character varying |           | not null |  Indexes:     "github_repos_pkey" PRIMARY KEY, btree (id)     "unique_repos" UNIQUE, btree (org_id, github_id)


I have a doubt about using 3rd party PCIe SSD or SSD generally with HP DL380p Gen8. Do someone have tested it by any chance with 3rd party PCIe SSD and/or SSD's and/or normal HDD's ?  or by any chance if tested with OCZ 240GB PCI Express RevoDrive 3 X2 SSD ?

I was wondering if anyone had any specific experience using Intel DC3700 SSDs (or similar) in the HP (DL380p) Gen8 servers?   I'm upgrading a set of database servers that use direct-attached storage. Typically, we use HP-branded everything in our server configs, and beyond a few SSD'd desktops (all of which have worked flawlessly), I have not otherwise used SSDs - certainly not in a server.   The servers we're upgrading run SQL Server (2005) on Windows. We're moving to SQL 2012. Current boxes host a single 200GB database on DL370 G6 provisioned with 72GB 15K SFF drives in RAID 1+0 as follows: OS (2 spindles), tempdb (4 spindles), t-logs (8 spindles), data (20 spindles). Performance is not an issue (CPU load is typically 20% / peak 30%, disk queues are typ = 1). The data volume disks are running in MSA50s off a P800 - so there's probably 5K IOPS there tops. The hardware is approaching 4 years old, and so it's time for a refresh.  Data usage, as reported by the individual hard disks, shows write volume of < 100TB since deployment on the data volume; < 10TB write on the transaction log volume; and ~ 1TB on tempdb.   That's the use case. Now consider a new, identical disk subsystem. It's going to run ~ $15K per server (34x 15K HDD @ $250 + 2x D2700 shelf + Smart array P421 for the external storage).   Consider a similar SSD deployment, say 6x 200GB SSD for the data volume, and 2 each (100GB) for OS, tempdb, and logging. Perhaps overkill, but using Intel DC S3700 for all with a second array card brings me in around $5K per server. Plus, it fits in one 2U box (use the expansion cage on the DL380p) and saves several hundred dollars in electricity every year. With the increased SSD performance, this might even cover some sloppy queries ;-).   An equivalent "no-worries" HP SSD solution is going to run ~ $10.5K. Twice the price with less warranty, lower endurance, but guaranteed performance and manageability.    Certainly, there are loads of in-between solutions that could work. I'm also quite aware of the vendor supported solution vs. 3rd party trade-offs. What I don't have is experience integrating these specific products to help quantify those trade-offs. I'm hoping someone out there does, and is willing to share his experience.   Questions that come to my mind are:  Does the S3700 play well in the Proliant environment with the Array P42x/P822 cards? If using the S3700, would there be an advantage to using a 3rd party card, say the LSI 9270-8i? How (well, easily) are firmware upgrades or management alerts accomplished with the third party solution as I've outlined?  If there are particular issues with the assembly, how have you worked around them - assuming you have?  With the changes that SSDs has introduced into the storage arena, storage solutions are way less straightforward than even a few years ago. I'm sure they will be very different in another few years, and we had expected to wait another cycle before seriously considering using SSDs in any server application.   Before I head too far down this road, is there anyone who would share their relevant experience with any of this? Please tell us why we're smart, crazy, or something in between.


Function returned from another function gets closures Closures is a permanent memory Variables and functions that never referenced from the parent function inside the inner function don't go into the inner function's closures.  For example, here's the code: function parentFunc(){   let x = 10;   let anotherX = 10;    function childFunc(){     console.log(x);   }        return childFunc; }      let generatedFunc = parentFunc();      generatedFunc();  Only x will go into the inner function (which ends up being generatedFunc) and not anotherX because it was never referenced from the childFunc. Could anyone please tell me if I'm missing out on something here?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


I am creating a list on SharePoint and want to include a simple field in which users can answer a question by choosing a radio button. When I save my changes I see that Sharepoint has included an extra line (or choice) I simply wanted YES, NO and UNSURE as my options. I do not want an empty field. Any help would be great.

The choice field adds a blank option in all my sharepoint lists. How do I remove this? the column settings does not have a blank option.


I'm using Cox-Regression to analyse the risk of loan portfolios.   I found out that with increasing sample size, my regressors are getting more and more significant (p-values are shrinking) due to shrinking standard errors.  How valuable are these p-value statistics in the end? I'm concerned that these p-values are only "good" due to my large data set. Is there maybe like a limit of how big the data set should be?

I am running into a problem where an independent variable, which should have no predictive power on the dependent variable based on domain knowledge, comes out with very small p-value because the sample size is very large(~100,000). If I only use < 5000 data points, then the p-value becomes large enough to support the prior that the variable is insignificant. However, I don't think tweaking the sample size to get to the desired conclusion is a good practice. Is there any procedure to adjust for small p-value simply due to huge sample size?


Why do I save in .ai though the editable .pdf do the same thing?

I use illustrator a lot and I'm always exporting PDFs. Since the PDF is a "save as" rather than an export, I end up editing the PDF and saving out. This causes version conflicts. Could I just work in PDF? What would be lost if I never used the ai format?


I know this question gets asked a lot but my situation is a little different. I am using Qt and the user has the ability to change timezones. Therefore, the following commands need to be used (America/Los_Anegles can change):  $ sudo ln -sf /usr/share/zoneinfo/America/Los_Angeles /etc/localtime   I would like to run these commands without a password. I read that you could write the following in  /etc/sudoers :  user = (root) NOPASSWD: command   where command is something like:   sudo ln -sf /usr/share/zoneinfo/America/Los_Angeles /etc/localtime   However, the command has to be specific and as I stated before, America/Los_Angeles could potentially change. Is it possible to make this work?

I have two programs in Java that I'm calling from bash script:  java program1 arg ... arg sudo java program2 arg ... arg   I want to run program2 as sudo without being asked for password. I'm aware of sudoers file, but I'm not sure how to configure it to run java programs as sudo without being asked for password. Any thoughts?


I was surfing the web looking for the incoming conferences in computer science, and I finished in this website     Here, it seems that the conferences are ranked as A*, A,B C.  While this is the only place where I have found this rank explicitly, I have heard many other researchers refer to a conference as a "A* conference" or so.  So I am wondering: is this ranking official? Who is maintaining it? And on what is it based?

I know it's rather difficult to establish a ranking of publications, especially because the ones in charge of establishing values for venues might be biased by their field, and several other aspects. However, I know some well-accepted (at least locally) ranking, that consider all fields under research, e.g.  - in portuguese - that includes both confs and journals, and  - this latter has served as baseline for some class A conferences in Computer Science (my research field), in some countries other than Australia.   Hence, I wonder about the existence of another "global ranking", that has been applied overseas, thus including at least the most prominent events and journals in every field. For journals, it's a little bit easier to measure its importance, by looking at their Impact Factor values, but for conferences it's a little bit tough. To the best of my knowledge, I don't know a largely-applied means of measuring the impact of a conf.  I'd like to hear from you. Thanks in advance.


I'm trying to clone my 680GB HDD to a new 500GB SSD, trying EaseUS and Carbon Copy Cloner. The goal is to replace my HDD with the SSD, so I need to boot from it. There's only about 100GB of used disk space on my HDD so I figured it's doable to clone, unless it's literally trying to copy every sector, empty or not, in which case my SSD is too small. Any thoughts on how to do this? Would using the Disk Utility be another option? I've read up on Time Machine, or Restore option in Disk Utility, but it's hard to find a clear answer and so far what I've tried hasn't worked. I managed to copy the contents over to the SSD but it won't boot up from it. And when I tried reassigning the startup disk to my SSD, it still didn't boot from it. Not sure what else to try. Thanks in advance.

I want to upgrade the hard drive in my 2012 Macbook Pro to an SSD. I have the parts, but had a question about how to clone the contents of my current drive so I can install it onto the SSD.  I've seen tutorials where people suggest connecting the new SSD to the Macbook prior to installation and using a Carbon Copy Cloner to clone the drive, and then installing the SSD drive.  My question is, can I do a Time Machine backup of my current hard drive on an external hard drive, install the SSD, and then use the Time Machine backup from the external to transfer it onto the newly installed SSD? Is this the same as using the clone program above?


My son has 2 devices. Tablet and phone. I gave a limit to 1 hour. And I realized that the limit is assigned to both devices. So in the end he has 2 hours. How can I assign the limit as a sum for all devices?

I can't find a way to set a daily limit to my daughter regardless of her devices. I want her to spend 2h max on screen no matter which device she uses on that day.  Yet she's getting 2h on her tablet and 2h on her smartphone.  Am I missing something? Does Family Link only allow to set device-specific limits?


We use Data Guard to replicate production Oracle database. We have a need to grant read access to replica DB and at the same time need to restrict that same login gaining read access to production.   Since the data guard replicates everything (including user/roles) is there any way we can apply this restriction to the production databases? Should I look into to database server inbound port restrictions? Any thoughts on this are greatly appreciated.

One of the physical standby databases in my environment is open in read-only mode and used for reporting purposes . I want to give users access only to this particular standby, not to primary db.   The best approach I found so far is to create AFTER LOGON ON DATABASE trigger which checks v$instance (or maybe v$database), and throws error for depends on  values of host_name/instance_role columns  .   I wonder if there is a better way to do it.


I want to define some alias iex="iex -S mix" only for one directory - this alias should work only when I cd'ed to this directory. Another requirement - this functionality should be placed inside this directory, hook file or something other, because I want to share this directory as a git repo.  How can I do that?

Suppose you have an alias go, but want it to do different things in different directories?  In one directory it should run cmd1, but in another directory it should run cmd2  By the way, I have an aliases for switching to the above directories already, so is it possible to append the go alias assignment to the foo alias?  alias "foo=cd /path/to/foo"   Working in bash(?) on OSX.


I'm trying to insert a number into my vector "heapvect." I keep changing from references and pointers and it still won't allow me to pass in num into the vector. I have made this without template and making a dynamic array (constructor/destructor), I'm unsure if having a vector and template made me think differently of the whole heap sort.  I tried having pointers for heapvect and getheapvect.  //main.cpp #include"heap.h" #include<iostream> #include<vector> using namespace std; int main() {     int size;     int num;     cout << "USER:" << endl;     cout << "Enter size for heap: " << endl;     cin >> size;     heap<class T> yeet;      cout << "Enter in " << size << " of items:" << endl;     for (int i = 0; i < size; i++) {         cin >> num;         yeet.getheapvect().push_back(num);     }     system("pause");     return 0; }    //heap.cpp #include "heap.h" template<class T> heap<T>::heap() { } template<class T> heap<T>::heap(int size) {     getheapvect().resize(size*2); } template<class T> heap<T>::~heap() { } template<class T> void heap<T>::insertin(const T item) {     getheapvect().push_back(item);     int index = distance(getheapvect().begin(), item);     while (index != 0 && getheapvect()[parent(index)] > getheapvect()[index]) {         swap(getheapvect[index], getheapvect()[parent(index)]);         index = parent(index);     } } template<class T> void heap<T>::minheap(int size, int index) {     int large = index;     int left = (2 * index) + 1;     int right = (2 * index) + 2;      if (left < size && getheapvect()[left]>getheapvect()[large])         large = left;     if (right < size && getheapvect()[right]>getheapvect()[large])         large = right;     if (large != index) {         swap(getheapvect()[index], getheapvect()[large]);         makeheap(size, large);     } } template<class T> void heap<T>::heapsort(int size) {     for (int i = (size / 2) - 1; i >= 0; i--)         makeheap(size, i);     for (int i = size - 1; i >= 0; i--) {         swap(getheapvect()[0], getheapvect()[i]);         makeheap(i, 0);     } } template<class T> void heap<T>::print(int size) {     for (int i = 0; i < size; i++)         cout << getheapvect()[i] << ' ';     cout << endl; } template<class T> void heap<T>::PRINT() {     print(getheapvect().size()); } template<class T> void heap<T>::swap(T  a, T  b) {     T temp = a;     a = b;     b = temp; }    //heap.h #ifndef HEAP_H #define HEAP_H #include<iostream> #include<vector> using namespace std;  template<class T> class heap { private:     vector<T> heapvect;     void print(int size); public:     heap();     heap(int size);     ~heap();     void insertin(const T item);     void minheap(int size, int index);     void heapsort(int size);     void PRINT();     void swap(T a, T b);     int parent(int i) { return ((i - 1) / 2); };     int leftchild(int i) { return ((2 * i) + 1); };     int rightchild(int i) { return ((2 * i) + 2); };     vector<T>& getheapvect(){ return heapvect; }; }; #endif    Output is supposed to bring out a sorted vector in ascending order.

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


The Data Science SE site requires syntax highlighting feature as the posts contain code from multiple languages/syntaxes including but not limited to Bash, Regex, Python, Julia, Java, R.  We collected a list of some posts which would benefit from this feature .  PS: I am one of the moderators of that site.

It seems syntax highlighting is not enabled on every SE site, but later on turns out to be rather advantageous. As an example,  may not have sounded like needing it, yet there is , and I think it's justified since many answers have code in them, e.g. JS for InDesign scripts, some GREP-regex and (rather obviously) HTML and CSS. While I'd appreciate having syntax highlighting activate on that specific site (so please upvote ), this question is more general about two points:   Why is syntax highlighting disabled on some sites at all? Are the additional resource costs really so high? Couldn't caching improve that then? How to actually proceed when it should become activated on a specific site? It seems feature requests on the specific meta site are not exactly handled quickly (the request mentioned above is from 2013!), and also appear overkill for a simple "please switch that site's config bool for syntax highlighting".


I wonder that  what is the difference between ;  using (var con = new OracleConnection(oradb))             {                 con.Open();                 // Do sth.                 con.Dispose();                 con.Close();             }   from this;  oradb = ConString; OracleConnection con = new OracleConnection(oradb)) con.Open(); // Do Sth. con.Dispose(); con.Close();   Both of them works for me, However didn't understand the basic behind of this.  Which one should i use ?

What is the purpose of the Using block in C#? How is it different from a local variable?


I want to be able to search through entire table without specifying each column. I want to be able to look for a record where each column may look LIKE '%QASHQAI%'. This table has about 100 different columns. Naming all of them like   SELECT * FROM vehicle WHERE ... LIKE '%QASHQAI%' OR ... LIKE '%QASHQAI%' OR ... LIKE '%QASHQAI%';  Is there a quicker way of searching through the table?

Is it possible to search every field of every table for a particular value in Oracle?  There are hundreds of tables with thousands of rows in some tables so I know this could take a very long time to query. But the only thing I know is that a value for the field I would like to query against is 1/22/2008P09RR8. <  I've tried using this statement below to find an appropriate column based on what I think it should be named but it returned no results.  SELECT * from dba_objects  WHERE object_name like '%DTN%'   There is absolutely no documentation on this database and I have no idea where this field is being pulled from.  Any thoughts?


Hi! I'm working on simulating an ocean; after working on it for quite a while, I've come to the realization that my ocean is missing the characteristic ocean foam and spray.  I saw some vids where there is a fluid that interacts with objects and foam and spray appears; how was this accomplished? (I tried to use dynamic paint but it didn't work, at least not the way I did it.)  Any help appreciated!   Thanks,  EvilAsuratos

Is there a way to make the ocean modifier fake foam spray? I already displace the water with dynamic paint, but I still am stumped as to how to create the foam. I'm assuming it's a particle system of some sort, but I'm not where to place the emitter or what general settings to change (I just need some general tips).


Assume that a creature was True Polymorphed for the entire duration of the spell and is thus permanently transformed.  When said creature drops to 0, does the creature revert to it's previous form or does it die?  Can you stack True Polymorphs to create an possibly infinite HP pool?

The  description says:     Creature into Creature.   The transformation lasts for the duration, or until the target drops to 0 hit points or dies. If you concentrate on this spell for the full duration, the transformation lasts until it is dispelled.   Does the second sentence imply the creature won't revert to its normal form, even being killed? (providing the caster were concentrating on the spell for the full duration)  If so, isn't "until the target drops to 0 hit points" enough? Why the "...or dies" addition? A creature can't die having more that 0 hit points, can it?


Let $R$ be a U.F.D. and $0\neq d\in R$.   I want to show that there are finitely many different principal ideals that contain the ideal $(d)$.   $$$$   We have that $R$ is a U.F.D. iff $\forall r\in R\setminus \{0\}$, $r\notin U(R)$ the following hold:    $r=a_1 \cdots a_k$ with $a_i$ irreducible  If $r=a_1 \cdots a_k=b_1 \cdots b_t$ with $a_i, b_i$ irreducible then $k=t$ and $a_i=b_iu_i$ with $u_i\in U(R), \forall u=1, \dots , k$.    $$$$   A principal ideal is generated by a single element, say $i$,  and so that it contains the ideal $(d)$, $i$ must divide $d$, right?   To show that $d$ has finitely many divisors do we use the definition of a U.F.D. ?   $$$$   EDIT:   We have that $d=a_1^{k_1}\cdots a_r^{k_r}$ with $a_i$ irreducible.   Since $R$ is a U.F.D. the irreducible elements are prime.   Does it follow from that that the divisors of $d$ are of the form $a_1^{j_1}\cdots a_r^{j_r}$ with $0\leq j_i\leq k_i$ ?   From that we get that the set of the divisors is finite, right?

If R was a unique factorization domain, can we deduce that for a nonzero element d in R, d has a finite number of divisors?   I need this in solving this question  "If R is a unique factorization domain then there are only finite number of distinct principal ideals that contain the ideal (d)."  My idea to solve it: if a divides d then (d) is contained in (a), so if we have finite divisors then we have finite principal ideals. Am I wrong?


I found in Flask  next code:  from flask import Flask app = Flask(__name__)  import yourapplication.views   Is it's correct to place import not on file header?

states:  Imports are always put at the top of the file, just after any module comments and docstrings, and before module globals and constants.  However if the class/method/function that I am importing is only used in rare cases, surely it is more efficient to do the import when it is needed? Isn't this: class SomeClass(object):      def not_often_called(self)         from datetime import datetime         self.datetime = datetime.now()  more efficient than this? from datetime import datetime  class SomeClass(object):      def not_often_called(self)         self.datetime = datetime.now()


How did the definition of bad change over time? When did it change to mean good?

One example that comes to mind is terrific which originally denoted something quite terrorising while now it has positive connotations... How and why did these changes occur?


Currently I am doing: SELECT ROW_NUMBER() OVER(ORDER BY Reputation DESC) AS Rank, Id AS [User Link], Reputation FROM Users WHERE LOWER(Location) LIKE '%krak%' AND LOWER(AboutMe) LIKE '%ios%' AND Reputation > 10 ORDER BY Reputation DESC;   All ios developers are recognized by most used tag: xcode, ios or swift. How can I fetch that info?;) EDIT:  @Rene It is not duplicated question, because the question ypu refer to is about SPECIFIC TAG. In my question I need to find users who have the most popular tags either xcode, either ios or swift.

I want to see who has the highest score in a specific tag (for example c#) in my country. Is there any query or script for that? I've found , but it doesn't work. Can any one take a look at it and see what's its problem? I also have found  which does similar, however gets users which only have a tag badge.


I have an electronic system waiting to be triggered (no microcontroller for now). My laptop only has USB ports.  I want to trigger it using voice recognition (this part is ok).  For now the only think I can think of is :  Once the right keyword is detected, send a 19 KHz sine on the audio output, because it's inaudible, for 0.1 seconds and uses a microcontroller analog port to detect it.  I only have microcontroller with no USB support available and I've never used a USB connection.  I'm not looking for something perfect, a dirty solution would be all right, this is just to do a prank tomorrow.  Thanks.

I want to send a simple 5V signal to the usb port. The USB cabel's insulation will be removed and connected to a relay which is connected to an electric door system. I think I should write this code in C. Can somebody give me a hint?


It appears that the version info functions in the Win32 API that I know and love have changed their behavior.   now return what the program's manifest is set for, not the actual version.  The new function IsWindows10OrGreater seems pointless since it is only available on windows 10 or greater, so if the program includes it and successfully links it will always return TRUE.  But, in an installer or similar program, how does it determine whether the current environment really is Windows 10 or greater?  It needs this to know what to download or which options to set up for other programs.

I know I can call the GetVersionEx Win32 API function to retrieve Windows version. In most cases returned value reflects the version of my Windows, but sometimes that is not so.  If a user runs my application under the compatibility layer, then GetVersionEx won't be reporting the real version but the version enforced by the compatibility layer. For example, if I'm running Vista and execute my program in "Windows NT 4" compatibility mode, GetVersionEx won't return version 6.0 but 4.0.  Is there a way to bypass this behaviour and get true Windows version?


the question I'm talking about. I'm the OP, the bounty owner, the only one who answered and there aren't any real comments too. Wouldn't be safe to allow awarding part of bounty reputation back to myself (the bounty owner) in such cases?   I did all the hard work after all and reported back my findings to the community.  I think there's no risk I set another bounty on that question after recovering part of my reputation, thus artificially drawing more attention to the question, because there already is an accepted answer and because I still loose some rep each bounty I set. However maybe that, just now, opening a new bounty on that question would be technically possible for me anyways, but, even then, I think it's easy to make the system avoid that possibility: when the OP is allowed to award himself part of the bounty  rep (only in selected cases like mine above), and he does so, his question is automatically closed.   This feature would encourage OPs who set a bounty to find the answer themselves (which I suppose they already are, admittedly, since they set a bounty), and to report it back to the community when the question hasn't received any other answers. We shouldn't understimate that last bit of knowledge sharing: there are so many unanswered questions here I harldy believe the OP really didn't find a solution for any of them. I'm more inclined to think the OP did solve its problem somehow, but he didn't bother to share the knowledge.   Maybe the system could make this feature available to the OP only after the bounty expired, and only if the question hasn't received any other answers except the OP's one, so that we are sure none else would have replied anyway.  The conditions this feature would be available could be:   The OP is the bounty owner The question has only one answer The OP is the answer author too The answer has no downvotes The bounty has already expired   In this case I think letting the OP recover 50% of the bounty points would make sense.  It's like booking a flight after all: if you cancel the reservation you get something back, because for the company is better to return you a part of your money and KNOW they can sell that seat to someone else, rather than keeping all of your money and leaving the seat empty, just because you didn't bother to let them know, since you had nothing to loose.

Consider this question on .  I put out a 200 bounty on the question, but did not get an answer from anyone other than myself that worked.    In fact, my answer is also the highest up-voted on it at this point.  I know that allowing OP's to retract a bounty can be a slippery slope; in fact I think that once the bounty is put up it should stay up.  But why not allow the OP to answer their own questions with a bounty and reward it to them if they receive the same up-votes as others?  Yes, I am fully aware that bounties are a risk.  People will use them for numerous reasons such as trying to draw extra attention to their issues.  However, in my specific question, the only valid answer is the one that I gave.  Had it been anyone else's question, I would have received the bounty, but since it was my own I did not.


I was working on an explicit example for a student of mine, and I ran into a bump.   Assume that the population is $\{1,2,4\}$. I draw samples of size 2 (without replacement) from the population. From the samples, I compute the sample variance of each. This gives me the following:  {1,2}-->$s_1^2=\frac{(1-1.5)^2+(2-1.5)^2}{2-1}=0.5$.  {1,4}-->$s_2^2=\frac{(1-2.5)^2+(4-2.5)^2}{2-1}=4.5$.  {2,4}-->$s_3^2=\frac{(2-3)^2+(4-3)^2}{2-1}=2$.  These should be unbiased estimators of the population variance.  It seems as though the computation for the expectation of the sample variances should be $\mathbb{E}[s^2]=\frac{0.5+4.5+2}{3}=\frac{7}{3}$.  It also seems as though population variance should be $\frac{(1-7/3)^2+(2-7/3)^2+(4-7/3)^2}{3}=\frac{14}{9}$.   Why aren't these two values the same? I thought they would be because sample variance is an unbiased estimator of population variance.  Where am I going wrong?   I did notice that if I divide the sum in the population variance computation by 2 (instead of 3), I do get the value from the sample variance computation; however, I don't have a good explanation for why this should be so (besides the fact that the arithmetic works).

I understand that when sampling from a finite population and our sample size is more than 5% of the population, we need to make a correction on the sample's mean and standard error using this formula:  $\hspace{10mm} FPC=\sqrt{\frac{N-n}{N-1}}$  Where $N$ is the population size and $n$ is the sample size.  I have 3 questions about this formula:   Why is the threshold set at 5%? How was the formula derived? Are there other online resources that comprehensively explain this formula besides  paper?


I am using ubuntu 14.10. I am trying to install all updates, but it's show me the following result:      The package system is broken      Check if you are using third party repositories. If so disable them, since they are a common source of problems.   Furthermore run the following command in a Terminal: apt-get install -f   Details:      The following packages have unmet dependencies:  gcc-4.9-multilib: Depends: gcc-4.9-base (= 4.9.1-16ubuntu6) but 4.9.1-16ubuntu6 is installed                   Depends: gcc-4.9 (= 4.9.1-16ubuntu6) but 4.9.1-16ubuntu6 is installed                   Depends: libc6-dev-i386 (>= 2.11) but it is not installed                   Depends: lib32gcc-4.9-dev (= 4.9.1-16ubuntu6) but 4.9.1-16ubuntu6 is installed                   Depends: libx32gcc-4.9-dev (= 4.9.1-16ubuntu6) but 4.9.1-16ubuntu6 is installed libc6-dev-x32: Depends: libc6-x32 (= 2.19-10ubuntu2.3) but 2.19-10ubuntu2.3 is installed                Depends: libc6-dev-i386 (= 2.19-10ubuntu2.3) but it is not installed                Depends: libc6-dev (= 2.19-10ubuntu2.3) but 2.19-10ubuntu2.3 is installed   Then I removed the third party repositories and run the command in terminal sudo apt-get -f install. But after all I got the following error:       dpkg: error processing archive /var/cache/apt/archives/libc6-dev-i386_2.19-10ubuntu2.3_amd64.deb (--unpack):  trying to overwrite '/usr/include/fpu_control.h', which is also in package libc6-dev-amd64 2.19-10ubuntu2.3 Errors were encountered while processing:  /var/cache/apt/archives/libc6-dev-i386_2.19-10ubuntu2.3_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)    So, now I need the person who can fix the problem. Great pleasure if you can help me to get out this problem. Please...

For example:  $ sudo apt-get install curl Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: bsh : Depends: libjline-java but it is not going to be installed groovy : Depends: libjline-java but it is not going to be installed rhino : Depends: libjline-java but it is not going to be installed E: Unmet dependencies.   Try 'apt-get -f install' with no packages (or specify a solution).   I get the same or similar errors when I attempt to install clojure1.3, leiningen, and several other packages.   When I try the suggestion made in the error message, this is what happens:  $ sudo apt-get -f install  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following packages were automatically installed and are no longer required:   diffstat linux-headers-3.2.0-26-generic linux-headers-3.2.0-26 dh-apparmor dkms html2text libmail-sendmail-perl libsys-hostname-long-perl Use 'apt-get autoremove' to remove them. The following extra packages will be installed:   libjline-java Suggested packages:   libjline-java-doc The following NEW packages will be installed:   libjline-java 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 23 not fully installed or removed. Need to get 0 B/72.0 kB of archives. After this operation, 129 kB of additional disk space will be used. Do you want to continue [Y/n]? Y (Reading database ... 226243 files and directories currently installed.) Unpacking libjline-java (from .../libjline-java_1.0-1_all.deb) ... dpkg: error processing /var/cache/apt/archives/libjline-java_1.0-1_all.deb (--unpack):  trying to overwrite '/usr/share/java/jline.jar', which is also in package scala 2.9.2-400 Errors were encountered while processing:  /var/cache/apt/archives/libjline-java_1.0-1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1)  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  bsh : Depends: libjline-java but it is not installed  groovy : Depends: libjline-java but it is not installed  rhino : Depends: libjline-java but it is not installed E: Unmet dependencies. Try using -f.


I`m new to OOP and need some experienced opinions about what I am doing wrong. As I understood, according to the error I dont have function definition/implementation for the respective call in the int main(). WHile I think I do. Please, give me a hint. House.h: class House { public:       template<class T> bool checkRoom(int nessTemp, int nessHumid, int nessIllum, T obj); private:      int roomCount; };  House.cpp: #include "House.h" #include "Room.h"  template<class T> bool House::checkRoom(int nessTemp, int nessHumid, int nessIllum, T obj) {     tuple <int, int, bool, int> RD = room.getRoomData();     return false; }  Room.h: #include <tuple>  using namespace std;  class Room { public:       tuple <int, int, bool, int> getRoomData(); private:      tuple <int, int, bool, int> RoomData;      void SetRoomData(int setTemp, int setHum, int setIllum);  };   Room.cpp: #include "Room.h"   tuple <int, int, bool, int> Room::getRoomData() {     return RoomData; }  void Room::SetRoomData(int setTemp, int setHum, int setIllum) {     return; }  main.cpp: #include <iostream> #include "House.h" #include "Room.h"  using namespace std;  int main()  {      House house;     Room kitchen;     house.checkRoom<Room>(25, 15, 20, kitchen);       return 0;  }  Result: /usr/bin/ld: /tmp/cccYxx0f.o: in function `main': main.cpp:(.text+0x62): undefined reference to `bool House::checkRoom<Room>(int, int, int, Room)' collect2: error: ld returned 1 exit status

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


int a = (1, 2, 5); printf("a=%d\n", a);   in C, this would print 5.  Can someone explain why 5 is getting printed and in which situation this syntax used?


I have the following code:
     <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown">         Serial No.     </button>

                                                                        <input type="text" class="form-control" placeholder="Query" ng-model="query" />

             {{'{{serial_no.id}}'}}

   style="text-align:center" is aligning (horizontally) the div element, but when the dropdown is selected, my list items are aligned at the left side of the page.   How can I get them positioned directly under the drop down button? How can I get everything positioned vertically (maybe 25% from the top) on the page?

How can I horizontally center a
 within another
 using CSS?

Foo foo


I have a strange syntax of for loop here :  for(--index ; index>=0 ; --index)     // (--index) instead of (forInit)  {     //code }   I know for syntax is like this :  for ( [ForInit] ; [Expression] ; [ForUpdate] ) Statement   How do we have --index instead ForIniti in the loop. I thought that we can only initialise a variable at that place or can leave it blank like this :  for( ; index>=0 ; index--)     {       //code     }   I haven't been introduced to this syntax before. Please explain why this is syntactically correct.

I have seen some very weird for loops when reading other people's code. I have been trying to search for a full syntax explanation for the for loop in C but it is very hard because the word "for" appears in unrelated sentences making the search almost impossible to Google effectively.  This question came to my mind after reading  which made me curious again.  The for here:   for(p=0;p+=(a&1)*b,a!=1;a>>=1,b<<=1);   In the middle condition there is a comma separating the two pieces of code, what does this comma do? The comma on the right side I understand as it makes both a>>=1 and b<<=1.   But within a loop exit condition, what happens? Does it exit when p==0, when a==1 or when both happen?  It would be great if anyone could help me understand this and maybe point me in the direction of a full for loop syntax description.


This is an exercise of Advanced linear algebra of Roman     Find an abelian group $V$ and a field $F$ such that $(V,F)$ can define two distinct vector spaces.   That is: I must find two distinct definitions of scalar multiplication. What I did was choose $V:=(\Bbb R^2,+)$ as the abelian group, and $F:=\Bbb C$ as the field, and defined scalar multiplication by   $(a+bi)\cdot (x,y)=(ax-by,by+ax)$, this defines a vector space because its just the complexification of $\Bbb R$ as a vector space. $(a+bi)\cdot (x,y)=(by+ax,ax-by)$ this is symmetric from the above definition.   But I dont found other example. Can someone show me a non so trivial example, or provide me a general rule to define such alternative scalar multiplications?    UPDATE: it seems that, from a known scalar multiplication defined by $d$, I can define an alternative scalar multiplication by $d\circ f$, where $f:V\to V$ is a group automorphism.

My question  raised another one. How many differents vector space structures over a field $\mathbb{F}$ we may have on an abelian group?  I know that there are abelian groups that we can not endow it with a structure of vector space over any field, for example $\mathbb{Z}_{6}$. But if an abelian group has a structure of a vector space over a field $\mathbb{F}$, is there an upper bound for ways we can define a different structure? Such as the number of automorphisms of the field $\mathbb{F}$. I am conjecturing according to the answer given before.


I know you already have images and links as file attachments. But what if somebody wants to attach a word document to their question in Writers Stack Exchange?  This would really help because then I wouldn't have to post a link to a forum thread about my short story which is about lions. I could just post the word document directly and it would really save some time.

I want to attach a code file to my question, but I am not able to find a link to do it. Is attaching files possible at all?


I'm not sure what how or why this happens but sometimes when I open programs through terminal the terminal continues to attach itself to the program. I can understand this for things like "sudo nautilus" but for regular programs this is extremely annoying.   I cannot detach terminal from program because if I ctrl+c then it closes the program and if I quit the terminal then the program closes as well.  Few questions:   Why does this happen? How do I manually activate/deactivate this function? How do I detach the terminal from the program?   If I am asking too much then I understand. In that case I don't even know how to google the answer so if you can point me to any resources that talks about this or give me the name of the function that is happening that that would be great.   Thanks.

I am new to Ubuntu. I have used Sublime Text. I have realized that after I open Sublime Text from the Terminal, if I close the terminal the application  keeps running. The same isn't true for other applications like geany.   After I open the application from terminal, when I close the terminal the application also closes. I have tried &exit like geany &exit. But this isn't what I am looking for.   How can I keep geany running even after I close it?


I think there is only one $f(x)= x$ mod $4$.

Recently, I have tried to find out how many group homomorphisms exist from $\Bbb Z$ to  $\Bbb Z_n$ .   My argument goes like this: (in the following, $\tau$ and $\phi$ denote the well-known number theoretic functions)  Let, $\psi$ be such a homomorphism. Since $\Bbb Z$ is cyclic, hence $\psi{(\Bbb Z)}$ must be a cyclic subgroup of $\Bbb Z_n$ with the generator $\psi{(1)}$ . Using properties of Cyclic groups, we obtain that $| \psi{(\Bbb Z)}|$ can be any positive integer m such that $ m | n$ , hence there are in total $\tau (n)$ number of possibilities for  $| \psi{(\Bbb Z)}|$ and hence for $ o(\psi(1))$.   Let S denote the set of all positive integer divisors of n, i.e. $$ S = \{d \in {\Bbb Z}^+ : d | n \}$$ , then |S| =  $\tau(n)$ .  Again, since $\psi{(\Bbb Z)}$ is cyclic it follows that for each $d \in S$, we have $\phi(d)$ number of possible distinct images.  Since for each such image (for each divisor) it defines a homomorphism, the required number of homomorphisms are : $$\sum_{d|n} \phi(d) = n$$ and among these n homomorphisms , there are precisely $\phi(n)$ number of epimorphisms.  Conversely, from $\Bbb Z_n$ to $\Bbb Z$ I get that there exists only one homomorphism namely the 0 homomorphism.  Are my claims and arguments correct? If there is any mistake, please help me by correcting it.   I was also trying to find out how many homomorphisms exist from $\Bbb Z_n$ to $\Bbb Q$ i.e. precisely as group homomorphism and as ring homomorphism. Also, conversely, how many homomorphisms exist from $\Bbb Q$ to $\Bbb Z_n$ again as group homomorphism and ring homomorphism seperately and also how many out of these are epimorphisms (in each case).   Thanks in advance for helping.


how to disable lamp shape behind object with glass material when rendering? Its not appear when rendering camera in this order -> camera-lamp-glass object but it is appear in this order -> camera-glass-lamp

I found there is a circle when the point light through my glass material using the circle render.  How could I solve it?


I have a Javascript code that generates a string (similar to uuid) string  Here it is the js code:    var t = "xxxxxxxx-xxxx-xxxx-xxxx-xxxx-xxxxxxxx"   , i = (new Date).getTime(); return e = t.replace(/[x]/g, function() {     var e = (i + 16 * Math.random()) % 16 | 0;     return i = Math.floor(i / 16),     e.toString(16) })   How can I generate this string with python?

How do I create a GUID in Python that is platform independent? I hear there is a method using ActivePython on Windows but it's Windows only because it uses COM. Is there a method using plain Python?


Example of a function ($\mathbb{R}$ to $\mathbb{R}$)  which is continuous only at two point and differentiable only at one of these points.

Give an example of a function which is continuous at exactly two points and differentiable at exactly one of them. Justify your answer.  This question is from a competitive examination. I have of thinked a solution but I didn't get it


My textbook mentions the standard derivation of finding pressure at a depth of a liquid  by considering a cylindrical portion of liquid an then using the equilibrium of forces and hence pressure comes out  to be $$hdg$$.What I want to ask is that the above method is correct but then it is mentioned that pressure on a point of side wall at a depth of $$h$$ would also be $$hdg$$ without giving any explanation. If I try to use the above stated derivation then there is problem that I can't use the weight since gravity acts downward and also I don't know the force exerted by fluid on side walls. So how can I say that pressure at depth is same as pressure on side walls?

from a while ago and answers/comments to  from earlier today both make heavy mention of the fact that fluid pressure is a scalar.  Although this information was surprising to me, it makes sense intuitively, especially when considering Pascal's Principle and liquid depth pressure.  However, I struggle when thinking about the mathematical reasons why pressure is a scalar, and the answers to the first question linked either appealed to intuition, seemed contentious, or unsatisfying.  My confusion comes from the fact that pressure is often defined at the high school/undergrad level as $$P\equiv \frac{F}{A}$$ where this not just a relationship, but often presented as the equation definition of pressure.  Force is a vector, and I had assumed that area was a scalar.  Therefore, I had always figured this was a scalar multiplication problem, and the product would also be a vector.  Now that I know that pressure is a scalar, I just can't see how you would get a scalar for pressure out of this relationship.  I see two possibilities:  1) For reasons I don't currently understand, area is treated as a vector in continuum physics.  As a result, some type of vector algebra must be applied to divide a vector by another vector in order to yield a scalar.  If this is the case, I would like to see at least a framework for this math in the answer.  2) If possibility 1 is not the case, then the other possibility in my mind is that $P=\frac{F}{A}$ is not truly the definition of pressure, and there exists some more basic definition for pressure that would explain its scalar nature.  Are either of these explanations correct, or is there a third possibility that I have not considered?  I've tried to make this a substantially different question than either of the other two questions that I've linked to, but if that does not appear to be the case, please let me know.


I apologize if the question title is unclear.   To clarify, I have to SSH into server1 and then SSH from there into server2. Server2 is where the folder I need to mount is located. I've tried setting the tunnel up using Putty and PAC Manager, but I'm not sure if I'm doing it correctly.  My public key is already on both servers and I can authenticate just fine to both while using the -A flag to access server1.  I'm on Ubuntu 18.04. I don't know what kind of log/config I'd need to copypasta here, but I will provide them if requested.   I was told I could do this by someone who set it up correctly on a Mac with Secure Pipes and Fuse. I have Fuse on this installation, as well as SSHFS.  Any help is greatly appreciated!  EDIT TO REFUTE POSSIBLE DUPLICATE FLAG: The only way I see the 'duplicate' post being helpful is if I'm supposed to use the proxy command host as the sshfs host.

I want to access a computer, say machine A which is based in my university's network. However, this computer is only accessible via the internal network of the university, so I can not use SSH to this computer from home directly.  Here's what I do now:   Log in to a different university machine, say machine B  (This machine B is accessible via SSH from my home computer.) Use SSH on B to connect to A.   Is there a way to do that faster? Using only one ssh command.


What is 10Mohm for? What would happen without it?

How to determine the feedback resistor in negative feedback op-amp configuration ? How does the feedback resistor affect the signal output of op-amp ? What is the consequence of using high resistance or low resistance in feedback circuit ?


I want to put barbs on my map and everything is ok for the most maps until such error occurred     org.geotools.referencing.factory.DeferredAuthorityFactory disposeBackingStore   INFO: Disposing class org.geotools.referencing.factory.epsg.hsql.ThreadedHsqlEpsgFactory backing store   org.geotools.renderer.style.ImageGraphicFactory getIcon   WARNING: Unable to read image at  : Can't create an ImageInputStream!      org.geotools.renderer.lite.StreamingRenderer fireErrorEvent   SEVERE: GC overhead limit exceeded   java.lang.OutOfMemoryError: GC overhead limit exceeded

I'm new to Geoserver, Ubuntu and Java, but have downloaded a virtual machine from gisvm.com and am getting up to speed. I got as far as configuring it with some fairly large shapefiles from a project I've worked on previously.  My question is related to a problem which I see if I show the shapefile using the OpenLayers layer preview option. I see an error:     OpenLayers map preview code="internalError" Rendering process failed.   java.lang.OutOfMemoryError: Java heap space   Googling has led me to plenty of Java command line options to increase heap space, but I have no idea if this should be applied to an environment variable, in a startup script or as a part of the Geoserver config.   Can you help me to understand what I need to edit to get this working?   I'm also wondering if I should be splitting my shapefile into smaller pieces.


Show that an algebraic closed field must have infinite many elements.  Let's suppose that an algebraic closed field $K$ has finite many elements.  But how could I get a contradiction??

Show that an algebraically closed field must be infinite.    Answer  If F is a finite field with elements $a_1, ... , a_n$ the polynomial $f(X)=1 + \prod_{i=1}^n (X - a_i)$ has no root in F, so F cannot be algebraically closed.  My Question  Could we not use the same argument if F was countably infinite? Couldn't we say that if F was a field with elements $a_1, a_2, ... $ then the polynomial $f(X) = 1 + \prod_{i=1}^{\infty} (X - a_i)$ does not split over F?  Thank you in advance


I'm new to photography, just trying to get the right lens!

This is specific to Canon, but what is the difference between EF and EF-S lenses?


I am basically looking for a way to measure how much a certain app has been running on W10 per day. This need stems from parents' request to somehow manage the time my brothers use for gaming. So far I've used Gameplayer timer app, which is not the greatest and can be turned off easily. Isn't there something more elegant? Can I get these information straight from windows? Thaks for help

I need to get a history of which processes have run on my Windows machine, and when they were run.  However, I cannot use any third-party software, as I cannot guarantee that it will always be running.  Is there any way to get this information only using Windows built-in functionality?


I have almost an hour trying to update my installation, this is how I'm trying to do it:  $ sudo apt-get install update [sudo] password for braiam:  Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package update   It just doesn't work! Isn't install update the text I should put after sudo apt-get to install updates on my Ubuntu system? If not, what command should I write?     This question is trying to address some common mistakes by users not used to the APT system and apt-get.

I'm having issues with my ubuntu server version 12.04 installed on a HP550 laptop, when i try sudo apt-get install <programname>, e.g apache2 it will not work, saying E: Unable to locate package apache2.  I have tried to look/edit the sources. but they will not work either the gedit command is broken too, i am trying gedit /etc/apt/sources.list for those wondering, is this a case of the computer network not configured properly? it downloaded a language pack easily enough in the installation though. how do i fix this? a prompt reply would be appreciated.


I want to try if it can increase my reading productivity.

Honestly I like working in a dark environment (Twilight on my all my editors), and recently I switched from a Windows to Linux (Ubuntu 16.04 with Unity Desktop on a PC). And being a night worker the brightness is a little harmful to my eyes.   I searched for a bit and these were some of the commands I have tried so far after realizing that the GUI is just not giving me what I need - A Dimmer Screen.  $ dconf-editor   A  of the values of the dconf-editor.  $ add-apt-repository ppa:indicator-brightness/ppa $ apt-get update $ apt-get install indicator-brightness   Nothing happened after toggling the new indicator.  $ apt-get install xbacklight $ xbacklight -set 40 $ xbacklight -set 20   Enabled Xbacklight at   $ ls /sys/class/backlight/   acpi_video0  I dont seem to have intel_backlight so I didn't do this last hack on my system.  $ gedit /etc/rc.local echo 900 > /sys/class/backlight/intel_backlight/brightness   I am a little lost. I would like to know if there is any tool that I can use to decrease the brightness on the system as a whole besides this or is there something that I am missing as a Noob user?   I use Screen Dimmer for Firefox, Twilight for my Code Editors and the terminal is already black. It is the window applications like the File Viewer, Libre Office etc that needs to be dimmed down. I would consider getting a darker desktop theme also (if that is possible) as a valid answer.   Thank-you for being patient enough to read through this rather unintentionally long question.


My Husbands Visa is Valid from the 30th Sept (Sunday) I'm trying to find out if he can board a flight on the 29th to land on the 30th or if he must board the flight on the 30th when the visa is already valid? I have contacted British Airways (who he's flying with) and all they stated was 'It should be fine but you must contact the UK Goverment'   Does anybody know who I should contact to get it in writing? I can't seem to find an e-mail address for general visa flight inquires. Has anyone done this before and was it okay?  Thank you for any help anyone can give me! It is very much appreciated.

I have a question, I applied for the Schengen visa through Germany, on the form they ask me when I'd arriving (to Germany) and when I'd returning. they take this exact date as the visa period.  I wondering if they would let me get into the plane, even though my flight it a day before the arrival.  Let get the real deal; let say this:  My visa is valid from 02/12/2014 to 02/02/2015. But, my flight is scheduled to be departing on 01/12/2014, but entering Germany 02/12/2014. the flight duration is almost 9hours and there is 7hours difference between Germany and the departing flight country.


I have an account number 1234-5678, I am trying to find it in all files of directories. I used the below command but no result found.  grep "1234-5678" */  Please can someone help me how to find it in all files of directories.

Which is more efficient for finding which files in an entire filesystem contain a string: recursive grep or find with grep in an exec statement?  I assume find would be more efficient because you can at least do some filtering if you know the file extension or a regex that matches the file name, but when you only know -type f which is better? GNU grep 2.6.3; find (GNU findutils) 4.4.2  Example:  grep -r -i 'the brown dog' /  find / -type f -exec grep -i 'the brown dog' {} \;


Do bijective functions exist that map from a function of one dimension to a function of another dimension?  For example, does there exist a function $f : \mathbb{R^2} \rightarrow \mathbb{R^3}$ that is bijective?  If so, would you please provide an example?  If not, how is it possible to prove why this is not possible?

I've heard that it is possible to present a bijection $\phi : \mathbb{R}^n \to \mathbb{R}^m$ due to Cantor that although not continuous show that those sets have the same cardinality independent of the dimension as a vector space. The problem is that I couldn't find about it anywhere. Can someone tell me where I can find about this bijection and how to show it's existance?  Thanks very much in advance!


We have 2 WordPress sites in 2 different sub-domains like test1.abc.com and test2.abc.com . Both sites have wp-require plugin activated and only logged-in users can see the site. We want to make a system where if a user logged into one site, he should be auto-login into the other one.  What I did:  After some searching I know I need to use one database for both sites. So I have done these steps:   I have download the whole database of test2.abc.com site and change all prefix wp_ to wpmo_, replace it in whole database and upload it into first site's database. I added these 2 lines in wp-config.php of the second site, to define that second site should use first site's user table not its own one.   define('CUSTOM_USERMETA_TABLE', 'wp_usermeta');  define('CUSTOM_USER_TABLE', 'wp_users');  Now, the second site is using the first site's users and I am able to login to the second site by the user details of first site. The next problem is cookies, so I added these lines in wp-config of both sites.  define('COOKIE_DOMAIN', '.abc.com'); define('COOKIEPATH', '/');  Now I logged in into  test1.abc.com and when I go to test2.abc.com , it asks me to login. That means cookies are not passing from the first site to the second one.   Both subdomains are on same server and sharing same database user table.   I know it is a cookie issue and I have gone through many articles on that, but they all talk about sharing cookies between a domain and its subdomains. Here I am having 2 subdomains.

I'm having some issues sharing the user sessions across two installs.   (a) site on  (b) site on   I have installed B in the same database as A and I have defined the user and user_meta tables so I am sharing user data and users etc but I can't seem to bridge the sessions.   I have tried using cookies a few different ways but nothing works.   This is what I'm using in (b) wp-config at the moment with no effect,   define('COOKIE_DOMAIN', 'www.stolenmx.com'); define('COOKIEPATH', '/');        does anyone know how to get this working?   I'm actually using UserPro on site (a) to manage registration and login and I have wp-login.php disabled. Could this be why cookie isn't working cause UserPro saves the cookie elsewhere or just simply doesn't use one?


When I user the tag --no-header or the = at the end of the column name the last PID always changes adding 1 to it. Why does it change? Is there a way to fix it?

Why do PIDS under Linux (generally) increment by 4? The only exception I can think of is startup processes run by systemd, which increment by 1 when they are related or 2 otherwise.  How was the number 4 chosen as the default, and is it changeable?


For example, present tense is "God blesses you" but there is another form which is "God bless you" in which "bless" is a different verb tense.  What is that higher verb tense that we use in more formal or higher forms English.

I think grammatically the phrase "God bless America" is wrong; it should be "God blesses America", don't you think so?


Got a simple auction program running, only problem is that if a user is removed before auction is closed his/hers bids are supposed to be removed. I dont have it 100% down yet but I think I am on the right path.  The bids have to be arrays and right now it is kinda removed or just moved maybe. This was a the error earlier.  Top Bid:[Wow 400 kr, Boy 311 kr, Man 33 kr, Dude 2 kr]  command>remove user  Name>wow  Wow has been removed from registry  command>list auctions  Auction # 1: Item. Top Bid:[Boy 311 kr, Man 33 kr, Exception in thread "main" java.lang.NullPointerException  public void removeBid(String name) {      for(int a = 0;a < bidIndex; a++) {         if(bids[a].getUser().getName().equals(name)) {             bids[a]=null;             bidIndex--;             break;         }      }     sortBids();    public void sortBids() {     if(bidIndex > 1) {         for(int a = 0; a < bidIndex -1; a++) {              for(int b = a + 1; b < bidIndex; b++) {                  if(bids[a] == null || bids[a].getBid() < bids[b].getBid()) {                     Bid temp = bids[a];                     bids[a] = bids[b];                     bids[b] = temp;                 }             }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?