The definition of the expected value on the domain $[a,b]$ is given by $$E[X] := \int_a^b x f(x) \, \mathrm dx $$ I understand what the mean is, but I don't fully understand how this specific equation gives you the mean. How can I understand this without just taking it at face value?

This is maybe a trivial question I came up while solving a few examples and understanding Markov/Chebyshev inequalities and subsequently in evaluating Chernoff bounds. Suppose $X$ is a random variable with some distribution $p$ and we need to evaluate $\mathbb{E}[f(X)]$. Here, $f(X)$ may or may not have the same distribution as $X$. In my case, if $f(X) = e^{sX}$, where $s>0$. I would work out this problem by letting $Z = e^{sX}$ and   $\mathbb{E}[f(X)] = \mathbb{E}[Z] = \int_{\infty}^{\infty}z \hspace{0.2em}p(z)dz$.   Now I find the distribution of $Z$ as: $P\{ Z \leq z \} \implies P\{ e^{sX} \leq z \} \implies P\{ X \leq \frac{\log(z)}{s}\} = \int_{-\infty}^{\frac{\log(z)}{s}}x.p(x)dx $  thereby substituting this into the expectation one gets $\mathbb{E}[Z] = \int_{\infty}^{\infty}z\hspace{0.2em} \left(\int_{-\infty}^{\frac{\log(z)}{s}}x\hspace{0.2em}p(x)dx\right)^{\prime} dz$  According to the Law of Unconscious Statistician , this approximates distribution of $Z$ as $p$. I understand the backward proof through calculus, I don't follow the measure theory approach. For example I don't follow how this works if say $X \sim Gamma$. Is there a source I can read through for someone with no measure theory background?


I wanted to use Ubuntu 12.04 for its long term support. But I cannot stand Unity. I cannot find a way to replace it with compizconfig, so I tried replacing it with Lubuntu. When I restarted my computer started to load lubuntu, then just went right on with ubuntu as if nothing had happened. Likewise, it shows lubuntu when it shuts down. What is the deal? I'm confused here, is ubuntu 12.04 supposed to be an operating system or a desktop interface? Can I even run ubuntu with a Lubuntu interface? Is there a way to do this in compizconfig that I should be doing instead?  Thanks everyone. Now how do I mark this question as solved?

I want to install lubuntu on my current (pre-existing) Ubuntu Install because of it's light-weight footprint.   Can I preserve currently installed apps after installation?


I am trying to replace asterisk to some words in a string. e.g: if the string is 'A big giant person scared me', and i need the words 'giant' and 'scared' to be replaced with asterisk. the string should be 'A big ***** person ****** me'  here is my code  int lengthString(char* str) {     int i = 0;     while (str[i] != '\0')             i++;     return i; }  void replace(char* start, int length, char ch) {      for (int i = 0; i < length; i++)             start[i] = ch; }  void redact(char* toRedact, char** dictonary, int dicSize) {     for (int i = 0; i < dicSize; i++) {             char* redact = dictonary[i];             char* lastPos = toRedact;             char* nextPos = strstr(lastPos, redact);             while (lastPos != NULL) {                     if (nextPos == NULL){                       break;                     }                     replace(nextPos, lengthString(redact), '*');                     lastPos = nextPos + 1;             }     } }  int main() {     char* test[4];    char* dictionary[4];    dictionary[0] = "big";    dictionary[1] = "giant";    dictionary[2] = "scared";    dictionary[3] = "person";     test[0] = "A giant scared me";    test[1] = "A big scared me";    test[2] = "A person scared me";     for(int i = 0; i < 3; i++) {      redact(test[i], dictionary, 4);      printf("%s\n", test[i]);    }     return 0;  }      output: seg fualt

The following code receives seg fault on line 2:  char *str = "string"; str[0] = 'z';  // could be also written as *str = 'z' printf("%s\n", str);   While this works perfectly well:  char str[] = "string"; str[0] = 'z'; printf("%s\n", str);   Tested with MSVC and GCC.


What is the effect of acceleration due to gravity on the escape velocity from am object of mass m? I don't even know where to start with this. If the object has radius r and mass m and the acceleration due to gravity on the object is a, how do I find the escape velocity of another object from the first one?

We know the escape velocity from the Earth is 11.2km/s. Isn't it the velocity required to escape from earth if we go normal to the surface of earth? i.e while we derive the formula for the escape velocity from earth we never consider the slanted motion of the object. So when we launch a rocket we need to use very less value of velocity compare to escape velocity to escape from earth because rocket follows a slanted path so curvature of earth has an effect?  If what I said above is right, then how we can say escape velocity is 11.2 km/s?


First off, I apologize if this is the wrong *fault section for this question.  I'm in a small shop with 13 computers. 12 are running Windows 7 Pro (until they fix roaming profile start menus) and one is running Server 2012r2 (2016 once it comes out). We need 12 copies of Microsoft Office Professional. The average cost per copy is $400 on newegg since we need Access.  I'm trying to understand how volume licencing works. I'm a pirate turned IT Admin so this whole legitimate thing is new to me. If I wanted to get 12 licences for 12 computers that will be used by an unknown number of people, how would I do that. Also can I put SQL Server 2016 and eventually Server 2016 on it and if so how.  My final question is, would I be better off just buying the copies from Newegg instead and forget about using Volume Licencing all together?  What would cost the least?  I feel like VL is more for businesses having more systems than licences where less than every system is in use. So any help would be great.  Edit:  You know, marking this as a duplicate once was enough. Hitting me four times is just rude. I can't make comments anymore. This just discourages new people from asking questions. Also, the listed article was just as helpful as the listed answer. The real answer to those who are viewing this question is simple.  Don't ask for Volume License related question on Stack. Call your Microsoft License Dealer in your local area. You'll avoid a reputation beat down and get a real answer.

This is a  about Licensing.    Questions on licensing are off-topic on Server Fault.  If your question has been closed as a duplicate of this question, then this is because we want to help you understand why licence questions are off topic rather than just telling you "it just is". In all likelihood, this question will not address your question directly, it was not meant to.    I have a question regarding software licensing. Can the Server Fault community please help with the following:   How many licenses do I need? Is this licensing configuration valid? What CALs do I need to be properly licensed? Can I run this product in a virtual environment? Can I downgrade this product to an earlier version? Am I entitled to feature X with license Y?


When running this code the application crashes instantly.      Error: java.lang.RuntimeException: Unable to instantiate activity   ComponentInfo{(...).MainActivity}: java.lang.NullPointerException:   Attempt to invoke virtual method 'android.view.Window$Callback   android.view.Window.getCallback()' on a null object reference   Through research I was able to find out the cause of the crash is likely to be that I name two Views before the onCreate() method has run. I could name these Views within the onCreate() method and the following listeners but then the Views cannot be public, so they would be independent from each other which would prevent my App from working as intended. Does someone have any idea on how to prevent this problem without making these Views independent from each other?  MainActivity.java:  public class MainActivity extends AppCompatActivity {     public ConstraintLayout constraintLayout = (ConstraintLayout) findViewById(R.id.constraint_layout0);     LayoutInflater inflater = getLayoutInflater();     public View rectimage3 = inflater.inflate(R.layout.my_rectview, constraintLayout, false);      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          final ImageView rectimage = (ImageView) findViewById(R.id.rectimage);          //set Listeners         rectimage.setOnTouchListener(new MySecOnTouchListener());         rectimage3.setOnTouchListener(new MyOnTouchListener());         constraintLayout.setOnDragListener(new MyDragListener());     }      //OnTouchListener of the first Rect     private final class MySecOnTouchListener implements View.OnTouchListener {         public boolean onTouch(View sview, MotionEvent motionEvent){             int action = motionEvent.getAction();             if(action == MotionEvent.ACTION_DOWN);                 rectimage3.setVisibility(View.VISIBLE);                 constraintLayout.addView(rectimage3);                  ClipData data = ClipData.newPlainText("", "");                 View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(rectimage3);                 rectimage3.startDrag(data, shadowBuilder, rectimage3, 0);                 rectimage3.setVisibility(View.INVISIBLE);                 return true;             } else{                 return false;             }         }     }      //OnTouchListener of the movable Rects     private final class MyOnTouchListener implements View.OnTouchListener {         public boolean onTouch(View view, MotionEvent motionEvent){             int action = motionEvent.getAction();             if (action == MotionEvent.ACTION_DOWN) {                 ClipData data = ClipData.newPlainText("", "");                 View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);                 view.startDrag(data, shadowBuilder, view, 0);                 view.setVisibility(View.INVISIBLE);                 return true;             } else {                 return false;             }         }     }      //OnDragListener of the Layout     class MyDragListener implements View.OnDragListener{         @Override         public boolean onDrag(View v, DragEvent event) {             View view = (View) event.getLocalState();              switch (event.getAction()) {                 case DragEvent.ACTION_DRAG_STARTED:                     view.setVisibility(View.VISIBLE);                     break;                 case DragEvent.ACTION_DRAG_LOCATION:                     view.setX(event.getX()-(view.getWidth()/2));                     view.setY(event.getY()-(view.getHeight()/2));                     break;                 case DragEvent.ACTION_DROP:                     break;             }             return true;         }     } }

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?


I have difficulty in understanding the reason why certain molecules can pass through phospholipid bilayers.  Firstly, I understand that the outer layer of the lipid bilayer is hydrophilic - my understanding is that they "like water" and can interact better with water.    Bilayers can absorb hydrophobic substance like N₂ and O₂.    Does this mean - because the hydrophilic surface are capable of hydrogen bonding - that's why they are able to absorb hydrophobic substances like F , O and N ?    They can absorb non-polar molecules.  They can absorb small uncharged molecules like H₂O and CO₂.   I'm not sure of the reasons behind 2 and 3 ...  And of course , vice versa ... (what can't pass through the lipid bilayer easily).  Any help would be appreciated!

It is commonly told that, hydrophobic/ lipophilic/ nonpolar molecules can quite easily pass phospholipid bilayer, and hydrophilic (polar or ionic) molecules can't pass (when no protein aid that); because hydrophobic nature of the lipid.  But in the same logic, hydrophobic molecules shouldn't pass through the bilayer. Because there are 2 hydrophilic layers in the membrane. i.e.      A and A' .  Then how the hydrophobic molecules can pass through A and A'?   I guess, it is due to thin diameter of A and A' . Is that?


I have a problem with the combination LuaTeX + package microtype + option bindingoffset from the geometry package when typesetting the following example:  \documentclass[11pt,a4paper]{article}  \usepackage[showframe, inner=25mm, outer=25mm, bindingoffset=12mm]{geometry} %\usepackage[showframe, inner=37mm, outer=37mm, bindingoffset=0mm]{geometry}  \usepackage[final]{microtype}  \begin{document}  Functions. According to 1, the free rotator's points are selected in two anyhow  selected \emph{resulting} point 4 and any \emph{not-resultant} sept 2 which  belongs to the rest of the system.  \end{document}   The first line does not break correctly, so a part of the text is written outside the main text frame. This problem only occurs if bindingoffset is set AND microtype is used. It also only occurs with LuaTeX, pdfTeX compiles it correctly. Here are the results of the tests I made:  TeX       bindingoffset  microtype   result ---------------------------------------------- pdfTeX     0mm           yes         ok pdfTeX    12mm           yes         ok LuaTeX     0mm           yes         ok LuaTeX    12mm           yes         WRONG! pdfTeX     0mm           no          ok pdfTeX    12mm           no          ok LuaTeX     0mm           no          ok LuaTeX    12mm           no          ok   I used the following software:   pdfTeX 3.14159265-2.6-1.40.15 (TeX Live 2014) LuaTeX beta-0.79.1 (TeX Live 2014) (rev 4971) package geometry: version: 5.6 (revision: 19716) package microtype: version: 2.5a (revision: 30755)   Is this a bug in geometry, microtype or LuaTeX?

Please see the following screen shots.    As you can see there are two "overfull" hbox there. However, LaTeX does not produced any overfull box warning at all. I tried to produce a minimal working example but without exactly the same layout, and fonts, and line breaks, it cannot be reproduced. So sorry that I cannot include a MWE in this question. (edit: please find an MWE further down).  However I tried to diagnose the problem. Since LaTeX does not see these as overfull box, it could be protrusion problem I guess. I setup the Minion fonts with fontspec (LuaLaTeX) as following,  \setmainfont[ UprightFeatures    = {RawFeature = {protrusion = mnr}}, BoldFeatures       = {RawFeature = {protrusion = mnr}}, ItalicFeatures     = {RawFeature = {protrusion = mni}}, BoldItalicFeatures = {RawFeature = {protrusion = mni}}, RawFeature = {expansion  = default}, Ligatures = {Required, Common, Contextual, TeX}, Numbers = {OldStyle, Proportional}, SizeFeatures = {   {Size =      -8.41,  OpticalSize = 8},   {Size =  8.41-13.01, OpticalSize = 11},   {Size = 13.01-19.91, OpticalSize = 19},   {Size = 19.91-,      OpticalSize = 72}}, ]{Minion Pro}   Ignoring the other things (for example the SizeFeatures is used to work around the problem that fontspec/luaotfload cannot select the right optical sizes). The problems appeared to the line  ItalicFeatures = {RawFeature = {protrusion = mmi}},   Where protrusion is turned on before the fonts setup by \pdfprotrudechars2 and mni is the protrusion setting for Minion Pro Italic. I translated the setting in MinionPro package to be used with LuaLaTeX (as the official release of microtype do not support LuaTeX with opentype fonts loaded by fontspec yet). A portion of the Lua file that setup the protrusion can be found below,  fonts                    = fonts                    or { } fonts.protrusions        = fonts.protrusions        or { } fonts.protrusions.setups = fonts.protrusions.setups or { }  --omitted codes--  fonts.protrusions.setups["mni"] = { -- Minion Pro Italic        factor = 1, left = 1, right = 1,    -- omitted code--   [0x0067] = {-0.070, -0.070}, -- g   [0x0069] = { 0.000, -0.110}, -- i   [0x006A] = {-0.090, -0.150}, -- j   [0x0070] = {-0.040,  0.000}, -- p   [0x0072] = { 0.000,  0.080}, -- r   -- omitted -- }   I I change the protrusion factor of letter g and p, which are the breaking points in the picture above, then the problem solved.  Can anyone explain the problem? Is there something wrong with my fonts setup (the use RawFeatures) or the protrusion setup file (the codes omitted in the above code snipes are just setting for other letters, which I assume should be independent from each other)?  It seems that whenever a linebreak happens at a italic character and protrusion is activated for that character, then the problems always happen. This does not happen for roman fonts.  Edits: Further experiments showing that assigning positive values instead of negative values to the protrusion factors does not cause any problem for the italic fonts. I guess the problem is not with Italic font, but with the negative value of protrusion factors. The reason no such problem for roman fonts is that there are no negative values assigned for any roman characters. But some italic characters has negative protrusion values so that they don't reach out the boundary too much.  Latest Edit: Here's a minimal document that triggers the issue.  \documentclass[a4paper]{article} \usepackage{microtype} \usepackage{amsthm} \newtheorem{proposition}{Proposition} \usepackage{lipsum} \begin{document} \begin{proposition}   \lipsum \end{proposition} \end{document}   With lualatex (showcases the bug):  With pdflatex (perfectly fine):


I develop a new open source named   and I want to add it to ubuntu packages list. how to proceed  ?

As a developer of free software, I want to get my application into Ubuntu.  Should I provide a source tarball and ask for packaging? Or should I create a package myself? Should I target Ubuntu directly, or should I try to get into Debian and then into Ubuntu automatically?


I have a string variable which is receiving a Guid. I need to convert this string back to Guid as the database field is of type Guid.  I tried using:    Guid myGuid = Guid.Empty;; myGuid = Guid.Parse(myId);   But keep getting Format Exception; Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).  Below is my code:   public string addVehicleDetails(string vname, string vtype, string regNumber, string ftype, string fefficiency, string insby, DateTime datecreated, string myId)         {              string result = string.Empty;             tblVehicleDetail myVehicleDetails = new tblVehicleDetail();           //  Guid myGuid = Guid.Empty;             System.Guid myGuid = new Guid(myId);            // myGuid = Guid.Parse(myId);             try {                 // Add details into vehicle details                 myVehicleDetails.VehicleName = vname;                 myVehicleDetails.VehicleType = vtype;                 myVehicleDetails.RegistrationNumber = regNumber;                 myVehicleDetails.FuelType = ftype;                 myVehicleDetails.FuelEfficiency = fefficiency;                 myVehicleDetails.InsuranceBy = insby;                  myVehicleDetails.DateCreated = datecreated;                 myVehicleDetails.Guid = myGuid;                  dc.tblVehicleDetails.InsertOnSubmit(myVehicleDetails);                  dc.SubmitChanges();                  return result = vname;              }             catch(Exception exp)             {                 exp.ToString();                 return result = "Error in Adding Vehicle Details.";             }         }   Any solution for this?

I want to try to convert a string to a Guid, but I don't want to rely on catching exceptions (   for performance reasons - exceptions are expensive for usability reasons - the debugger pops up  for design reasons - the expected is not exceptional   In other words the code:  public static Boolean TryStrToGuid(String s, out Guid value) {     try     {         value = new Guid(s);         return true;     }     catch (FormatException)     {         value = Guid.Empty;         return false;     } }   is not suitable.  I would try using RegEx, but since the guid can be parenthesis wrapped, brace wrapped, none wrapped, makes it hard.   Additionally, I thought certain Guid values are invalid(?)    Update 1   had a good idea to catch only FormatException, rather than all. Changed the question's code sample to include suggestion.    Update 2  Why worry about thrown exceptions? Am I really expecting invalid GUIDs all that often?   The answer is yes. That is why I am using TryStrToGuid - I am expecting bad data.  Example 1 . I might be parsing folder names, checking to see if the text after the final . is a GUID.  c:\Program Files c:\Program Files.old c:\Users c:\Users.old c:\UserManager.{CE7F5AA5-6832-43FE-BAE1-80D14CD8F666} c:\Windows c:\Windows.old   Example 2 I might be running a heavily used web-server wants to check the validity of some posted back data. I don't want invalid data tying up resources 2-3 orders of magnitude higher than it needs to be.  Example 3 I might be parsing a search expression entered by a user.     If they enter GUID's I want to process them specially (such as specifically searching for that object, or highlight and format that specific search term in the response text.)    Update 3 - Performance benchmarks  Test converting 10,000 good Guids, and 10,000 bad Guids.  Catch FormatException:    10,000 good:     63,668 ticks    10,000 bad:   6,435,609 ticks  Regex Pre-Screen with try-catch:    10,000 good:    637,633 ticks    10,000 bad:     717,894 ticks  COM Interop CLSIDFromString    10,000 good:    126,120 ticks    10,000 bad:      23,134 ticks   p.s. I shouldn't have to justify a question.


I have a listing of a directory which contains this entry:  d????????? ? ?   ?              ?            ? dir_name  I can't get into it, even as root. How to access?

Has anyone seen this before?   I've got a raid 5 mounted on my server and for whatever reason it started showing this:    jason@box2:/mnt/raid1/cra$ ls -alh ls: cannot access e6eacc985fea729b2d5bc74078632738: Input/output error ls: cannot access 257ad35ee0b12a714530c30dccf9210f: Input/output error total 0 drwxr-xr-x 5 root root 123 2009-08-19 16:33 . drwxr-xr-x 3 root root  16 2009-08-14 17:15 .. ?????????? ? ?    ?      ?                ? 257ad35ee0b12a714530c30dccf9210f drwxr-xr-x 3 root root  57 2009-08-19 16:58 9c89a78e93ae6738e01136db9153361b ?????????? ? ?    ?      ?                ? e6eacc985fea729b2d5bc74078632738   The md5 strings are actual directory names and not part of the error.  The question marks are odd, and any directory with a question mark throws an io error when you attempt to use/delete/etc it.  I was unable to umount the drive due to "busy".  Rebooting the server "fixed" it but it was throwing some raid errors on shutdown.  I have configured two raid 5 arrays and both started doing this on random files.  Both are using the following config:   mkfs.xfs -l size=128m -d agcount=32 mount -t xfs -o noatime,logbufs=8   Nothing too fancy, but part of an optimized config for this box.  We're not partitioning the drives and that was suggested as a possible issue.  Could this be the culprit?


On Ubuntu 18.10, on my laptop (Lenovo W530), there are 2 ways to easily change the volume:   + / - buttons on the keyboard:  Scroll wheel Up/Down on the speaker icon with the mouse:    Using the + / - buttons has 17 steps from min to max.  Using the scroll wheel has 50 steps from min to max and I find it too low.  My question is: how do we change either step size?  This may look like a duplicate of  but it's not: this question is about Ubuntu 18.10 running Gnome Shell, not Unity.

When I press the volume up/down keys on my keyboard, the volume changes too much. How can I make the step size smaller so that I have finer control?


On the  of Stack Exchange, it has:  Stack Exchange logo Stack Overflow logo Stack Overflow Careers logo Server Fault logo Super User logo  I have 3 requests:  They may be the highest visited sites, but they're not the only sites any more. Could we have the other sites there too? Even if they are at the bottom, in a small icon list, or in a style similar :   As hinted above, SVG format would be really nice to have. If you don't have SVG (why!?) then I will be happy to make some into it - but SVG is so much more useful than PNG.  If you decide to keep it as it is, please remove the word logo:

On , there are download options for only certain logos/icons. Shouldn't this include all the graduated sites logos/icons? I think it should.


I have only found the usage of "nooks and crannies", but no references to the "crannies and nooks" anywhere. Can I reverse them and use it ? Thanks

When we list pairs of words, certain orders seem much more common and natural than others.  A few examples:   Fish and chips instead of chips and fish Ladies and gentlemen instead of gentlemen and ladies (likewise, men and women instead of women and men) I'm sure we've all (?) had those disagreements about whether it's Rob and Salma or Salma and Rob (or whatever)   In most of these cases though, I struggle to rationalise why one order sounds more 'right' than another.  Is it purely a historical accident that one order is more common than another? Or are there subtle linguistic rules that are responsible?


I have recently installed Ubuntu on my PC, but I can't understand how to manage the applications -- as an example, I'm trying to get Chrome to autostart.  I can start Chrome manually, but I'm not able to find the correct exe (to make it autostart).  How can I make this work?

How can I make an application automatically start when I have logged in?


I want to copy one table's content from a remote machine to local. I have tried with psql Command \copy. It's working fine as "copy" is not working due to copying from remote.  But is there any way I can do the same without the command console, and execute a simple query through c# and do it programatically? I am using  Postgres 9.4

I have read-only access to a database on a remote server. So, I can execute:  COPY products TO '/tmp/products.csv' DELIMITER ',';   But on that server I don't have permissions to create/save a file, so I need to do this on my local machine.  When I connect to the remote database, how can I execute a command to save the file on my local machine instead of the remote server?  Or, how can I execute a Linux command to connect to the remote database, execute a query, and save the output as a file to my local machine?


Is it possible to rewrite  \$a'b'c'd'\$ using only NAND gates and NOT gates?  I tried rewriting it using DeMorgan's laws but got AND and OR gates which I cannot use. All help/input is appreciated.  I have 1 XOR gate available too in my project but I don't think that would be possible either.

I am trying to create a logic circuit using only NAND Gates for this expression: (NOT Q AND P) OR R   This question has really gotten me stuck! Can somebody please help?


Let's say I have a list: newList = [0,1,1,0,1,0,1,0,1,0,1,0,1,0,1] I want to split and print them as generator with dimension of 5*3. Final result shall look like this: 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1  The result should not be a list, just plain text like such. Also, what should I do if I need to do it with different dimension (lets say 3*5 instead). I am trying to work out a code to perform this action on a list of arbitrary length and transform them to plain text of user-given dimension.

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


I downloaded Steam from their site,got the steam launcher.deb file opened it with software installer and then this appears on my screen when i try to start steam.I`m using 16.04 LTS Gnome ubuntu


I've made several collages and wanting to print an 8 x 10 I'm constantly told "there will be a resolution" problem.  I guess I'm ignorant of what happens when I reduce the "huge" jpg to a smaller size.  I just assumed that the smaller the picture the more pixels - apparently NOT!  How do I correct this?  Thank you.

What size images do I need for common print sizes, such as wallet size, 8x10, and 16x20?  Is there a general formula?  How could that size change if, for example, a 16x20 was printed on canvas rather than photopaper?


I am using smarty template system on my website.  When it tries to cache some data, a fatal error occurs:  Fatal error: Smarty error: unable to write to $compile_dir '/var/www/html/cache/frontend'. Be sure $compile_dir is writable by the web server user. in /var/www/html/include/smarty/libs/Smarty.class.php on line 1092   I just get my vps today (Centos 7) and made basic LAMP setup.  I have uploaded all the content inside /var/www/html using sftp (root user). Then I have (still using filezilla) set /var/www/html/cache and all it's files/subdirectories to 777.  Whatever I try I can't get apache it to write on the cache folder or subfolder.  And the strange thing is that when doing   [root@localhost ~]# chmod -R 0777 /var/www/html/cache   the cache folder is still set to 2777.  I have also tried to make "apache" as the owner of /var/www/html/cache and all it's files/subdirectories but I still can't write on it.  I am completly lost and very newbie when it comes to server setup.  Any help would be appreciated, thank you.

This is a  about File Permissions on a Linux web server.   I have a Linux web server running Apache2 that hosts several websites. Each website has its own folder in /var/www/.  /var/www/contoso.com/ /var/www/contoso.net/ /var/www/fabrikam.com/   The base directory /var/www/ is owned by root:root. Apache is running as www-data:www-data. The Fabrikam website is maintained by two developers, Alice and Bob. Both Contoso websites are maintained by one developer, Eve. All websites allow users to upload images. If a website is compromised, the impact should be as limited as possible.  I want to know the best way to set up permissions so that Apache can serve the content, the website is secure from attacks, and the developers can still make changes. One of the websites is structured like this:  /var/www/fabrikam.com     /cache     /modules     /styles     /uploads     /index.php   How should the permissions be set on these directories and files? I read somewhere that you should never use 777 permissions on a website, but I don't understand what problems that could cause. During busy periods, the website automatically caches some pages and stores the results in the cache folder. All of the content submitted by website visitors is saved to the uploads folder.


All the hdri (downloaded from hdri haven) appear to me rotated and "duplicated?", I have reset blender to factory values (version 2.90.1) and it remains the same, could someone tell me why this is happening?

I recently upgraded from blender 2.81 to 2.82a, and I've immediately noticed a problem. Blender is not rendering HDRI images like it used to. You used to be able to plug an HDRI image into the background node, and into the world output. However when I do this now, in Eevee or Cycles, it renders what can be described as "as solid color" version of the HDRI instead of the actual HDRI image.   Here are some images to show as examples, each has a difernt HDRI, one is in Eevee, one is in Cycles. Is this a new "feature" of 2.82 or is this a bug? Thanks.


I'm writing a simple webpage with PHP and for security reasons I pass certain form values through the PHP htmlentities() function. However, even though I specify a UTF-8 format it doesn't seem to be able to handle the characters "åäö". This is my code:  echo htmlentities("Hello", ENT_QUOTES, "UTF-8"); echo htmlentities("Hello åäö", ENT_QUOTES, "UTF-8");   The first line outputs "Hello" and the second one outputs "". Why is this? Have I missed anything?  EDIT:  There seems to be a problem with my encoding settings. This is the full code. Propably a silly error but I'm new to HTML/PHP.  <?php header('Content-Type: text/html; charset=utf-8'); ?>  <html>     <head>         <title>Testing</title>     </head>     <body>         <?php echo htmlentities("Hello", ENT_QUOTES, "UTF-8") . htmlentities("Hello åäö", ENT_QUOTES, "UTF-8");?>     </body> </html>

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I got the following sentences from      Wrong: You cannot buy all what you like!   Right: You cannot buy all that you like!   Why is the first one wrong? I do see the structure "you can do what you..." many times, e.g. "how to talk about what you want".

Possible Duplicate:          How can I be sure when to use 'all that' or 'all what' in making sentences. Is there any differences in their meaning. I've tried googling but the results just didn't match. For instance:      All that the president said was published in the dailies.    or     All what the president said was published in the dailies.


please, I need help the Eevee viewport rendered doesn't show any objects, in the cycles it works perfectly but Eevee is not showing any object, I have tried 5 versions of blender they all have the same problem I added all types of lights, I have changed the world color but nothing works.

I don't know why but now, when i go in material preview or rendered (in solid mode it works fine), my object is entirely gray, or invisible idk, because it has the same color of the background. I've been working for days on this project without having this issue, it suddenly showed up. I tried opening other old projects and suddenly they all do the same so i guess it is some blender program setting that applies for all the projects, but idk how it happened cuz i didn't change anything :/, anyone got any tips?


So, I was in the low quality queue, and I came across a particularly easy audit.    One part of it that got my attention was this warning which essentially tells you straight out to recommend deletion:     Our system has identified this post as possible spam; please review carefully   Are you meant to see those messages on audits?  Do they make audits too easy?

While reviewing suggested edits and first posts by new users today, the review system did something new - an alert appeared that suggested that what I was reviewing was probably spam, and prompted me to take a careful look at it.  Should I be doing anything differently than I otherwise do while reviewing when I see this? Additionally, are my actions contributing to helping the spam prevention systems learn?


brand new baby linux user here, never used Ubuntu or any other linux OS before, so be gentle and use short words!  I installed Ubuntu 12.04 on my new Acer Aspire One D270-F61C/KF netbook (it's a Japanese computer which had Japanese windows preinstalled, and I decided to take the plunge and try Ubuntu because English Windows costs the earth and stars). Wifi isn't working; I enter my wireless password, it tries to connect for a while, then asks for my password again. And KEEPS ASKING, every few minutes. Wired connection works fine.  Wireless card is a Broadcom BCM4313; I have the "additional drivers" checked and installed (I tried unchecking and then reinstalling them in case that would help, no joy, and now my home wifi connection isn't showing up in the list of available connections, argh). I've done a lot of googling and I gather there's a lot of issues with Broadcom cards, but some of the answers are for earlier ubuntu builds and many of them are a bit confusing for a new user. I gather I need to try installing some new drivers other than the proprietary ones provided, but I'm having trouble figuring out how that's done.  Anyone got some simple, step by step instructions for me? Please bear in mind, TOTAL N00B.  (EDIT): OKAY, got it fixed finally; after suggestions on the Ubuntu forums and messing around with drivers, what finally worked was installing Wicd. Not... using Wicd, for some reason, just installing it fixed it.  ...I CHOOSE NOT TO QUESTION IT.

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.


Accidentally installed wrong package sudo apt install netplan instead of sudo apt install netplan.io from official Ubuntu repository. I run Ubuntu 18.04, I wanted to edit DNS servers, but instead I've installed some kind of calendar package. It seems that the package is maintained by “Ubuntu Developers” group, not MOTUs. Is there any risk of malware? How trustworthy is the “Ubuntu Developers”?

I'm unsure what the current procedure for package security for Ubuntu is.  When something ends up in the Ubuntu package repositories, are the package audited by a central, trusted team and if so what level of auditing takes place?  I'm interested on whether packages are checked for:   Regular matching against known vulnerabilities/CVEs (as in, package maintainers are notified in realtime of CVE releases, and packages with unpatched (by vendors) CVEs removed). Obvious malicious code (eg reverse shells, random shell code, trojans) Poor code quality (eg unintended command injection vulnerabilities) Full security audit of all code for vulnerabilities


What is the difference between a scalar, vector, matrix and tensor in simple terms? Are vector fields and tensors related?

Why do we call a 1/2 spin particle satisfying the Dirac equation a , and not a  or a ?


Bash  GNU Readline. Readline provides a collection of keyboard shortcuts. However, there are some shortcuts that work on bash and that are not documented in Readline . Some examples are:   C-h - Same as Backspace C-m - Same as Enter (CR I guess)   So why do these shortcuts work? I guess that these may have something to do with  but I am not sure which component provides interpretation of these control sequences as the behavior I have indicated.  Is it the Readline library? Or is it bash itself? Is it my terminal emulator? Is it the kernel? Etc...  What component makes these control sequences behave this way?  Edit: My .inputrc file:  # To the extent possible under law, the author(s) have dedicated all  # copyright and related and neighboring rights to this software to the  # public domain worldwide. This software is distributed without any warranty.  # You should have received a copy of the CC0 Public Domain Dedication along  # with this software.  # If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.   # base-files version 4.2-4  # ~/.inputrc: readline initialization file.  # The latest version as installed by the Cygwin Setup program can # always be found at /etc/defaults/etc/skel/.inputrc  # Modifying /etc/skel/.inputrc directly will prevent # setup from updating it.  # The copy in your home directory (~/.inputrc) is yours, please # feel free to customise it to create a shell # environment to your liking.  If you feel a change # would be benifitial to all, please feel free to send # a patch to the cygwin mailing list.  # the following line is actually # equivalent to "\C-?": delete-char "\e[3~": delete-char  # VT "\e[1~": beginning-of-line "\e[4~": end-of-line  # kvt "\e[H": beginning-of-line "\e[F": end-of-line  # rxvt and konsole (i.e. the KDE-app...) "\e[7~": beginning-of-line "\e[8~": end-of-line  # VT220 "\eOH": beginning-of-line "\eOF": end-of-line  # Allow 8-bit input/output #set meta-flag on #set convert-meta off #set input-meta on #set output-meta on #$if Bash   # Don't ring bell on completion   #set bell-style none    # or, don't beep at me - show me   #set bell-style visible    # Filename completion/expansion   #set completion-ignore-case on   #set show-all-if-ambiguous on    # Expand homedir name   #set expand-tilde on    # Append "/" to all dirnames   #set mark-directories on   #set mark-symlinked-directories on    # Match all files   #set match-hidden-files on    # 'Magic Space'   # Insert a space character then performs   # a history expansion in the line   #Space: magic-space #$endif

I am confused about how Ctrl-key combinations work in terminal. In bash man page, there are various combinations such as:   C-e - go to end of the line C-f - go one character forward   etc.  But then there are some undocumented shortcuts such as:   C-j (OR C-m) for return key. C-h for backspace C-i for tab etc.   Are these shortcuts just forgotten to be documented? Or, because   C-j is LF C-m is CR C-i is Tab   in ASCII, is this somehow a "default" behavior? In other words, is the behavior for C-j, C-m and C-i not implemented by bash but by something else?  Another question is, when I press C-v and left arrow key, ^[[D appears on screen. I.e, ESC-[-d. But when I press ESC-[-d, the cursor does not move left. What is the reason for this?  EDIT:  Initially, I have thought that when I press C-j, the keyboard directly sends 00001010 to kernel. But then I decided that this is not the case, because using programs such as xev or evtest, I have observed that key presses to Control and j appear as different events. So when I press C-j, the keyboard does not send 00001010, but probably multiple bytes. Then where the conversion of these multiple bytes to 00001010 is done?


EDIT: I don't know why this was marked as a duplicate. I know nullpointerexception questions must be common, but in this case the object was initialised and defined properly. The question you linked to doesn't solve my problem at all.  I'm getting an error and I can't understand why. The class was working a few days ago and I'm sure I haven't changed anything. It's a null pointer exception for a button, but I've done it the same way for all my buttons and the rest work. What am I missing here?  This is the error:     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference   Here is the code:  public class Login extends AppCompatActivity implements View.OnClickListener {  Button bLogin; EditText etUsername, etPassword;  UserLocalStore userLocalStore;  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_login);      etUsername = (EditText) findViewById(R.id.etUsername);     etPassword = (EditText) findViewById(R.id.etPassword);      bLogin = (Button) findViewById(R.id.bLogin);     bLogin.setOnClickListener(this);     //This is the line the exception points to }  @Override public void onClick(View v) {     switch(v.getId()){         case R.id.bLogin:             String username = etUsername.getText().toString();             String password = etPassword.getText().toString();              User user = new User(username, password);              authenticate(user);             break;     } }  private void authenticate(User user){     ServerRequests serverRequests = new ServerRequests(this);     serverRequests.fetchUserDataInBackground(user, new GetUserCallback() {         @Override         public void done(User returnedUser) {             if(returnedUser == null){                 showErrorMessage();             }else{                 logUserIn(returnedUser);             }         }     }); }  private void showErrorMessage(){     AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(Login.this);     dialogBuilder.setMessage("Incorrect user details");     dialogBuilder.setPositiveButton("Ok", null);     dialogBuilder.show(); }  private void logUserIn(User returnedUser){     userLocalStore.storeUserData(returnedUser);     userLocalStore.setUserLoggedIn(true); } }   And the XML, just in case:  <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_height="match_parent" android:layout_width="match_parent" android:padding="10dp">  <EditText     android:id="@+id/etUsername"     android:hint="Username"     android:layout_height="wrap_content"     android:layout_width="match_parent"     android:layout_marginTop="50dp"     android:layout_marginBottom="10dp" />  <EditText     android:id="@+id/etPassword"     android:hint="Password"     android:inputType="textPassword"     android:layout_height="wrap_content"     android:layout_width="match_parent"     android:layout_marginBottom="10dp" />  <Button     android:id="@+id/bLogin"     android:text="Login"     android:layout_width="match_parent"     android:layout_height="wrap_content" />  </LinearLayout>   Any help is appreciated, thanks.

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?


I was watching this  which made the case that mass is just a form of bound energy. Essentially massless particles are confined in a small space giving particles the illusion of mass.  Since the heat and pressure inside a black hole is essentially infinite, does that mean that matter can't hold its form at the singularity and therefore reverts back into energy via $E=mc^2$?   Wouldn't the converse (elementary particles keep their mass) lead to infinities (which are impossible) as the black hole tries to infinitely compress particles at the singularity? Should the singularity be instead described as a peak in the energy field of the Universe, instead of a physical object?

I am a layman in physics and just read about black holes on the internet. I read that matter encounters geodesic incompleteness in the singularity in an uncharged black hole.  I heard an analogy of geodesic incompleteness as a straight line on a paper reach a hole on the paper, so it cannot continue. But in this analogy, isn't the straight line possible to continue into 3D (continue down the paper)? So, if matter reaches the singularity, is it possible too (to reach another dimension)?   I also heard that the matter is annihilated when reaching the singularity, does it mean it disappear from this world, and violates conservation of energy?


I installed SCID, a GUI (chess) application, via downloading the sourcecode from "" I then unpacked that and navigated my terminal to the respective directory. I entered "./configure" and then " sudo make install" I can open that programm entering scid in the terminal. Now I want something, i can click and drag into the bar on the left, that does exactly that.  Kind regards  Markus

Possible Duplicate:             I want to add some shell scripts in my launcher as shortcuts..  They are located deep inside and i have to navigate to it every time to execute them...  I tried  link where the 2nd answers seems to solvee it but as said in comments neither can i find any option to add a launcher..  I guess it existed in 11.04 with a "+" button on launcher but i use 12.04.  So how do i get this working?? And i need those commands everytime for sure..!


What are some good introductory book references on time-varying electromagnetic fields? I need a refresher on the physics background on this topic. I intend to do research in electric motor-related research.

What books are recommended for an advanced undergraduate course in electrodynamics?


Is there any number which is a perfect square of some number as well as factorial of some number?  That is, let x be such a number, then x can be expressed as               x = k^2 (for some k)   and,         x = n! (for some n)  The very trivial answer is 1. But is there any number other than 1?

Can $n!$ be a perfect square when $n$ is an integer greater than $1$?  Clearly, when $n$ is prime, $n!$ is not a perfect square because the exponent of $n$ in $n!$ is $1$.  The same goes when $n-1$ is prime, by considering the exponent of $n-1$. What is the answer for a general value of $n$?  (And is it possible, to prove without Bertrand's postulate. Because Bertrands postulate is quite a strong result.)


The profile page shows a number for the total reputation change since you last looked at that tab.  This number seems to include the -1s for downvotes you cast but not the +1s if those posts are later deleted, even though both events show up as highlighted:    The total rep change from the highlighted events is 65; the number in the tab header is 64.  I've seen this consistently across several sites for a while, including MSE with the new Activity page; it's not new or localized behavior.  It's easy enough to figure out what's really going on, but the discrepancy stands out.  Can we make the number in the tab header match reality?  (The deletion didn't immediately follow the downvote, though it was on the same day.  So I don't think I should blame caching.  Besides, I think I've seen these for cases where the events occurred on different days.)

A downvoted and subsequently removed post showed  as being -1, which is clearly wrong.  The  was the only post affecting my reputation since the last view (as can be seen by the yellow shade), so it should have been 0.


Find the sum of $\sum_{n=1}^{\infty} n5^{2n-2}x^{2n+1}$   I am wondering how one would be able to solve this series?

I can not find the function from which I have to start to calculate this power series.  $$\sum_{n=1}^\infty nx^n$$ Any tips?. Thanks.


I am new to Ubuntu and I have a looot of issues :))! I saw that many things can be solved by typing commands in that window, terminal, which is kinda new to me( I am Windows 7 user, not a developer).   Moving to the point, whenever I try to type commands in the Terminal, it is prompting me to type the password. Firstly: which password, since I deactivated typing the password at logon. Maybe it's the same :-?... Secondly, I can't get to type it all, because it tells me: "Sorry, try again." And the 3 password attempts thing.   So, I googled it a little and I found that it's a TextExpander problem. What is that, and how can it be solved? I going crazy, since I can't enter a single command without that annoying password prompt.  Thanks a lot guys, and wait for me, I'm gonna ask a lot of questions, since I found this site is made especially for this! ;))

Inspired by this ....  I am the sole person using my system with 12.04. Every time I issue a sudo command; the system asks for the user password (which is good in its own way).  However I was thinking; without activating the root account; how can I execute the sudo commands which will not ask for user password to authenticate.  NOTE: I want to execute sudo command without authenticating via password; only when they are executed via terminal. I don't want to remove this extra layer of security from other functions such a while using 'Ubuntu software center' or executing a bash script by drag-drop something.sh file to the terminal.


I'm new to ubuntu and I wanted to install MongoDB in my system. For some reason it was not installing properly and I got the solution as I have to change the permission of directories so that I can create /data/db directory.  I ran sudo chmod -R 775 /  and now the whole system is not performing like before. It is not connecting to the router, brightness is not working and many more. Can anyone tell me what had happened and solution to make it proper again?

I accidently ran  sudo chmod 755 -R /   instead of  sudo chmod 755 -R ./   I stopped it after few seconds, but now there is some problems such as  sudo: must be setuid root   How can I revert permissions back?


here is the whole code how do I in this create random number so that numberneedingtobeguessed is generated randomly.  public class Guessing {      public static void main(String[] args) {         // TODO Auto-generated method stub          @SuppressWarnings("resource")         Scanner input = new Scanner(System.in);         int number;         int numberneedingtobeguessed = 26;         int done = 1;          System.out.println("I am thinking of a number in between 1 and 50 what is it?");         while (done < 2) {             number = input.nextInt();              if (number < numberneedingtobeguessed) {                 System.out.println("Too low");             }             else if (number > numberneedingtobeguessed) {                 System.out.println("Too high");             }             else if (number == numberneedingtobeguessed) {                 System.out.println("You guessed correctly");                 done = done + 1;             }         }     } }

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


Savings accounts are insured by CDIC up to $100k. Is it a total of $100k across all savings accounts I have with different banks or 100k per account?

In the unlikely event that a financial institution fails in Canada, what is covered by the Canadian Deposit Insurance Corporation?  What is the limit of coverage?


How can I see all the "" of a datablock?  Is it possible with the Blender's UI?  With Python?  For example, I'd like to know which 3 objects are the users of my material:

How to know which object is using a material.   I know that a material is used 4 time -> picture under:  I'm searching a solution with python and I'm blocked here :   bpy.data.materials['Y.000a'].users   But this function only return the number of users and not the name.  Of course the solutions, that I'm searching for, doesn't have to obligatory use python.


I'm applying for a PhD in engineering and I was asked by the advisor I have chosen to write down a short program (~10 pages) about the "research" I will conduct if I get into the PhD program.  The advisor provided ten choices where the future PhD program will lay. The topics are very large and well studied in the literature. Our "task" is to choose one of them, find out something "new" inside of this big sea and write it down. I did a lot of research on Scholar and downloaded more or less 20 free papers I found interesting. I collected data and results, thought a bit about the problem and found a ( maybe ) new application that fits my interests and past studies and I think it could bring some novelty in the field I'm applying.   Now my question is, which is the best way to format the proposal?   Should I start with the context of the research, point where previous studies went and what kind of results yielded and now focus on my brand new idea? Should I skip 1) and start in medias res with the heart of the matter?

In many countries an application for a PhD position includes a written research proposal, so my questions is what are some advises/strategies to come up with a good topic/idea for a PhD research proposal and how can one assess the quality/fruitfulness of an idea? As an undergraduate student one just doesn't have the experience to foresee which ideas might have promising research results and which probably won't have. (And I doubt that potential supervisors have the time to comment on every idea of every potential applicant in cases where it is possible to establish some kind of contact before the actual application.)


I am trying to understand the proof that uses a maximal-lexicographic ordering.  For an infinite ordinal $\kappa,$ the canonical well-ordering of $\kappa \times \kappa,$ denoted by $<_{cw}$ is defined as follows: $(\alpha_1, \beta_1)<_{cw} < (\alpha_2, \beta_2)$ iff either one of the following holds.  $(1): \max\{\alpha_1,\beta_1\} < \max\{\alpha_2,\beta_2\}$  $(2): \max\{\alpha_1,\beta_1\} =\max\{\alpha_2,\beta_2\}$ and $\alpha_1<\alpha_2$   $(3): \max\{\alpha_1,\beta_1\} =\max\{\alpha_2,\beta_2\}$ and $\alpha_1 = \alpha_2$ and $\beta_1 < \beta_2.$  How would I prove that this ordering is well ordered?  EDIT: I'm not looking for a proof of $\kappa\cdot\kappa= \kappa,$ for infinite cardinals, I'm looking for a proof that the ordering as it's defined is well ordered on $\kappa\times\kappa$.

I don't understand the proof to the a/m claim. How we know that $\eta < \kappa$ and $(\alpha,\beta)<_{cw} (0, \eta) $ and hence $h: \mu \to \eta \times \eta$ is injective? Appreciate if anyone could advise.  Here is an excerpt of the proof:  For an infinite ordinal $\kappa,$ the canonical well-ordering of $\kappa \times \kappa,$ denoted by $<_{cw}$ is defined as follows: $(\alpha_1, \beta_1)<_{cw} < (\alpha_2, \beta_2)$ iff either one of the following holds.  $(1): \max\{\alpha_1,\beta_1\} < \max\{\alpha_2,\beta_2\}$  $(2): \max\{\alpha_1,\beta_1\} =\max\{\alpha_2,\beta_2\}$ and $\alpha_1<\alpha_2$   $(3): \max\{\alpha_1,\beta_1\} =\max\{\alpha_2,\beta_2\}$ and $\alpha_1 = \alpha_2$ and $\beta_1 < \beta_2.$  Claim: For all infinite cardinals $\kappa, (\kappa \times \kappa, <_{cw}) \cong (\kappa, \in).$  Proof: (It has been show that it is true for $\kappa = \omega$) Assume there is a counterexample  $\kappa.$ Let $A= \{\lambda \in \kappa + 1| \lambda\geq \omega \ is \ a \ cardinal \ and \ (\lambda \times \lambda, <_{cw}) \not\cong (\lambda, \in)\}.$ Then, $\kappa \in A.$ Let $\mu$ be least element of $A.$ Thus, $\mu > \omega$ and for all $\lambda,$ if $\omega \leq \lambda < \mu$ and $\lambda$ is a cardinal, then $(\lambda \times \lambda, <_{cw}) \cong (\lambda, \in).$  By Comparability theorem, $(\mu, \in)$ is isomorphic to initial segment of $(\mu \times \mu, <_{cw})$ since $|\mu \times \mu| \geq \mu$ and $\mu$ is cardinal. Let $(\alpha, \beta) \in \mu \times \mu$ such that $(\mu, \in)$ is isomorphic to initial segment of $(\mu \times \mu, <_{cw})$ given by $(\alpha, \beta).$ Let $h$ be the isomorphism. Let $\eta= \max\{\alpha, \beta\}+ \omega.$ Then $\eta < \kappa$ and $(\alpha,\beta)<_{cw} (0, \eta).$ HENCE, $h: \mu \to \eta \times \eta$ is injective.


I'm aware of this question , but my question is specifically targetted to anyone who has used Ubuntu, and fully understands how seamless FTP can be.  I'm looking to natively connect to an FTP server and be able to read and write. And open up folders in Atom or Sublime Text and just start editing files on the server.  Here are the options that I am aware of and have already tried, but none of them are as elegant as Ubuntu where you can just open a remote folder and start editing. If anyone knows of something, please let me know?  At the moment transit is the best option.  -   None of the others can edit whole folders in Sublime by importing the folder structure into the sidebar.  -   -   -

Is there any way around the read-only access that Finder strictly allows so I can get write access to a FTP server through Finder?


We know that a distribution with zero Skewness are symmetric. A quick Google search or looking up in textbooks says that      Symmetric distributions are distributions where the left side mirrors the right side.    In other words, they are symmetric about something. But what are they symmetric about? Their mean? Median? Mode? There probably would be no confusion if this was specified. But if someone talks about (or perhaps, if you're asked in an exam about) a symmetric distribution, what should we assume as the default?   Context: This MCQ in a test I gave --      A distribution has zero skewness if it is:      (a) Symmetrical about its mode      (b) Symmetrical about its mean      (c) Symmetrical about its median

What's the definition of a symmetric distribution? Someone told me that a random variable $X$ came from a symmetric distribution if and only if $X$ and $-X$ has the same distribution. But I think this definition is partly true. Because I can present a counterexample $X\sim N(\mu,\sigma^{2})$ and $\mu\neq0$.  Obviously, it has a symmetric distribution, but $X$ and $-X$ have different distribution! Am I right? Do you guys ever think about this question? What's the exact definition of symmetric distribution?


I have a PHP form where users can enter data. When they do, they use special characters like single quotes.  This prevents their data from being put into the SQL table. I am NOT using MySQL. I am using SQL Server.  How can I fix this?  My code is:  include'dbcon.php'; //connectiontothedatabase $dbhandle=mssql_connect($myServer,$myUser,$myPass) or die("Couldn't connect to SQL Server"); //selectadatabasetoworkwith $selected=mssql_select_db($myDB,$dbhandle) or die("Couldn't open database"); session_start(); $surnum=$_SESSION['surnum']; $email=$_SESSION['email']; $site=$_SESSION['site'];  $query="INSERT INTO ZSURVEYA(SURNUM_0,EMAIL_0,A_0,A_1,A_2,A_3,A_4,A_5,A_6,A_7,A_8,A_9,A_10,A_11,A_12,A_13) VALUES ('$surnum','$email',convert(varchar(max),'$_POST[Q_0]'),convert(varchar(max),'$_POST[Q_1]'),convert(varchar(max),'$_POST[Q_2]'),convert(varchar(max),'$_POST[Q_3]'),convert(varchar(max),'$_POST[Q_4]'),convert(varchar(max),'$_POST[Q_5]'),convert(varchar(max),'$_POST[Q_6]'),convert(varchar(max),'$_POST[Q_7]'),convert(varchar(max),'$_POST[Q_8]'),convert(varchar(max),'$_POST[Q_9]'),convert(varchar(max),'$_POST[Q_10]'),convert(varchar(max),'$_POST[Q_11]'),convert(varchar(max),'$_POST[Q_12]'),convert(varchar(max),'$_POST[Q_13]'))";  mssql_query($query);

I'm looking for the alternative of mysql_real_escape_string() for SQL Server. Is addslashes() my best option or there is another alternative function that can be used?  An alternative for mysql_error() would also be useful.


This is probably basic, but I have not been with SVN for long and am wondering how to do it.   Suppose I have a line of text, say, Hello world!  I would like to search a particular file's history in my SVN repository to see when that line disappeared from there.   What is an efficient way to do that? A command line operation should work. However, something via ViewVC is also an option.  Much appreciated.

Is there a way to perform a full text search of a subversion repository, including all the history?  For example, I've written a feature that I used somewhere, but then it wasn't needed, so I svn rm'd the files, but now I need to find it again to use it for something else. The svn log probably says something like "removed unused stuff", and there's loads of checkins like that.  Edit 2016-04-15: Please note that what is asked here by the term "full text search", is to search the actual diffs of the commit history, and not filenames and/or commit messages. I'm pointing this out because the author's phrasing above does not reflect that very well - since in his example he might as well be only looking for a filename and/or commit message. Hence a lot of the svn log answers and comments.


I've got two databases setup on two different SQL Servers. One is 2012 and one is 2016, but aside from that, they have the same CPUs, same core count, and same RAM. They're both VMs in the same location and all tests were run from the same client.  I created the tables and loaded them using the exact same method (SQLBulkCopy in .NET) and then applied the same CLUSTERED indexes to various fields on the tables (based on usage). I ran a query that is reasonably complex and returns about 200K records from a table that contains 4mil records and is JOINed to a few other tables that contain 10K (or so) records.  On the 2012 Server, my run-times (in ms) are:  21772 22864 23209   This seems pretty much about what I'd expect. But on the 2016 Server, the run-times are:  132440 122569 120030   Removing the CLUSTERED index on the largest table and replacing it with a NONCLUSTERED index results in:  72096 71042 69958   I'm looking for ideas on where to start looking for why the run-times would be so vastly different on two servers that are so similar. The run-times on 2012 are well within reason, but on 2016 they're untenable.

I have a piece of SQL that seems to run really fast in Environment A, but the exact same query runs really slow in Environment B!  Environments are supposed to be the same, so what should I do and/or where should I look in order to see why the query doesn't perform the same?


When I compare ("String"=="String"), what exactly I am comparing, the two objects or two  references?  Please explain the output of following code snippets:      1) System.out.println("String".toString()=="String"); // output is true  2) System.out.println("String".trim()=="String"); // output is true  3) System.out.println("String ".trim()=="String"); // output is false   According to statement 1 and 2, the output of 3rd statement should also be true. Please explain what is going on here.

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


This is really a mystery for me.  What is the "daily reputation cap" that is required to get Epic, Legendary, and Mortarboard badges?

I've found some questions and those two badges "Epic" and "Legendary" regarding the "daily reputation cap". What is it and how can I hit it?


I  installed Picasa 3.9 with Wine, but I did not like it, and now I want to delete it.   I tried uninstalling Picasa with the option from Picasa help menu but it didn't work.   How do I fully uninstall Picasa from Wine?

I am using Ubuntu 11.10. By using wine software i installed some software like nimbuzz and ibibo messenger. Both the programs are not working and showing the bug as We're sorry, but an unknown error has caused ibibo Messenger to close.  So I wanna uninstall those.   How to uninstall those type of programs which I installed through Wine?


HTML:

   CSS:  .container { margin: 0 auto; overflow: hidden; width: 960px; }   I want the footer to remain at the bottom of the page (not persistently), so that it remains at the bottom regardless of the height of the page.  How to accomplish that with the current structure?

I have the following page (deadlink: http://www.workingstorage.com/Sample.htm ) that has a footer which I can't make sit at the bottom of the page. I want the footer to  stick to the window bottom when the page is short and the screen is not filled, and stay at the document end and move down as normal when there is more than a screenful of content (instead of overlapping the content).  The CSS is inherited and befuddles me. I can't seem to change it properly to put a minimum height on the content or make the footer go to the bottom.


I just add a figure but the caption starts on the middle, how can I fix it? I tried with \captionsetup{justification=raggedright,singlelinecheck=false} but it did not move the caption. I want it to start more on the left side Here there is a minimal reproducible example \documentclass[a4paper,fleqn]{cas-dc} \usepackage{float} \usepackage[numbers]{natbib} \usepackage{caption} \captionsetup{justification=raggedright,singlelinecheck=false} \usepackage{blindtext}  \begin{document}      \begin{figure*}[pos=h!]     \centering         \includegraphics[scale=0.7]{example-image}     \caption{Change in number of trips respect to first week of each year, treatment vs. control.}     \label{FIG:1} \end{figure*} \blindtext[2]   \end{document}   Thanks Edit: Fixed the example

I have the following problem:    I want the caption above the table to start flushed left and not with the space.  Here is the MWE copy paste from my project:  \documentclass[a4paper,fleqn]{cas-dc}  \usepackage[numbers]{natbib} \usepackage{graphicx}  \begin{document}  \maketitle  \begin{table*}[pos=t]  \caption{Observed results of the user study.} \label{tab:Result_time} \resizebox{\textwidth}{!}{% \begin{tabular}{lllllllllllll} \toprule                                                          &                   & \textbf{P1} & \textbf{P2} & \textbf{P3} & \textbf{P4} & \textbf{P5} & \textbf{P6} & \textbf{P7} & \textbf{P8} & \textbf{P9} & \textbf{P10} & \textbf{P11} \\ \midrule \multicolumn{1}{c}{\multirow{3}{*}{\textbf{Scenario 1}}} & Accuracy          & 100\%       & 50\%        & 100\%       & 0\%         & 100\%       & 100\%       & 100\%       & 0\%         & 100\%       & 50\%         & 100\%        \\ \multicolumn{1}{c}{}                                     & Time Taken        & 18:13       & 15:40       & 16:26       & 20:32       & 17:10       & 18:08       & 16:22       & 18:50       & 12:18       & 16:27        & 15:41        \\ \multicolumn{1}{c}{}                                     & Number of queries & 18          & 10          & 11          & 15           & 7           & 12          & 16          & 22          & 12          & 10           & 15           \\ \midrule \textbf{Scenario 2}                                      & Time Taken        & 7:35        & 8:39        & 10:20       & 10:41       & 9:47        & 14:28       & 12:24       & 18:28       & 8:29        & 9:11         & 8:24         \\ \midrule \textbf{Scenario 3}                                      & Time Taken        & 6:21        & 4:50        & 5:42        & 7:18        & 4:30        & 4:52        & 4:27        & 5:15        & 5:04        & 6:12         & 5:48     \\ \bottomrule \end{tabular} } \end{table*}  \end{document}   I've attempted to add \captionsetup{justification=justified} but to no avail.


The answer choices are:    $\operatorname{rank}(A) = 0$ $\operatorname{rank}(A) \leq \frac{n}{2}$ (and possibly $>0$)  $\operatorname{rank}(A) \leq n-1$ (and possibly $> \frac{n}{2}$)     I know that 1. is false, but I don't know about 2 and 3.

For my matrix algebra class I need to prove the following:  If $A^2=0$, Proof rank(A) $\le \frac{n}{2}$. So if A is nilpotent prove Rank(A) $\le \frac{n}{2}$  I know already how to solve this, but my initial way of solving is false. I am looking for the mistake, but cannot find one. I know there already exists a question where this is asked. I'm just curious about my particular mistake.  Proof:  $A=\begin{bmatrix}a_1&&a_2&& ...&&a_n\end{bmatrix}$ and $A=\begin{bmatrix}a^T_1\\a^T_2\\...\\a^T_n\end{bmatrix}$   $AA=\begin{bmatrix}a_1 && a_2 && ... && a_n\end{bmatrix}\begin{bmatrix}a^T_1\\a^T_2\\...\\a^T_n\end{bmatrix}$  $=\begin{bmatrix}a_1a^T_1&&...&&a1a^T_n\\...\\a_na^T_1 && ...&& a_na^T_n\end{bmatrix}$  $=\begin{bmatrix} a_1 \cdot a_1&&...&&a_1 \cdot a_n\\...\\a_n \cdot a_1 && ...&& a_n \cdot a_n\end{bmatrix}$  $=0_{nxn}$  So we know the diagonal is zero thus  $a_i \cdot a_i = 0$ this equals $\vert\vert{a_i}\vert\vert^2$ The square root of this equals the length, therefore the length is equal to 0. The only vector with this property is the zero vector. Herefore all vectors $a$ must be equal to the zero vector.   The last however is not the truth, is there anyone who can spot my mistake?


Alice starts editing a post Bob edits the post Bob finish the editing Alice sees the notification that the post was edited and click to reload the post. Alice wants to close the browser tab.   She gets the notification that her edit is not saved.  I guess this is another little bug on the client side... Am I right?

In a certain case, the user will be asked to confirm if he/she wishes to leave the page, due to editing a post, even when he/she has stopped editing.  To reproduce:   Start editing a post (I've only experienced this with a question) Another user finishes editing the post before you and the message "This post has been edited" appears Clicking on the message bar will take you out of editing mode and will show you the updated post from the other user's edits Trying to navigate away from the page will then ask for your confirmation


Apparently my question is different from .  I hadn't noticed because the answer given in the comments to this question was satisfactory for my immediate purposes.  My question pertains to time-independent variation, whereas the other question pertains to time-dependent variations.   By time-independent variation I mean an active variation of the generalized position coordinates which does not change with time for a given configuration point.  That is, one that may be written without an explicit time argument.  Position as a function of time $\left\{q\right\}=\left\{q^{i}\left[t\right]\right\}$ is assumed to be some sufficiently smooth trajectory in configuration space representing the actual physical system being modeled.  At the point in the discussion where the question occurred to me, the only variations considered are active rigid transformations.  These are assumed "infinitesimal" in the case of rotations.  No further definitions for $\delta{q^i}$ and $\delta{\dot{q}^i}$ were given.  See: The Theoretical Minimum: What You Need to Know to Start Doing Physics, by Susskind and Harbovsky.  Apparently, in the case of time-independent variations, $\delta{\dot{q}^i}$ has to be given independently of $\delta{q^i},$ or be defined using the chain-rule, treating the argument $\left\{q\right\}$ in $\delta q^{i}=f^{i}\left[\left\{q\right\}\right]\varepsilon$ as a function of time.    In the case where $\delta{q^i}$ and $\dot{\delta{q^i}}$ are given independently the commutativity has to be part of the definition.  Following Susskind, a variation of the form   $$\delta q^{i}=f^{i}\left[\left\{q\right\}\right]\varepsilon,$$  such that the consequent variation of the Lagrangian is $\delta{L}=0,$ is said to be a symmetry. Using Einstein summation, the variation of the Lagrangian may be written  $$\delta{L}=\delta L=\frac{\partial L}{\partial q^{i}}\delta{q^{i}}+\frac{\partial L}{\partial\dot{q}^{i}}\delta\dot{q}^{i}.$$  Assuming the trajectory of the configuration point has a stationary action integral, and therefore satisfies the Euler-Lagrange differential equation, we may write  $$\delta L=\dot{p_{i}}\delta q^{i}+p_{i}\delta\dot{q}^{i}.$$  If we can justify its application in this context, the basic calculus rule for the derivative of the product gives   $$\delta L=\frac{d}{dt}\left[p_{i}\delta q^{i}\right].$$ Apparently, this applicability depends upon the validity of   $$\frac{d}{dt}\delta q^{i}=\delta \frac{dq^{i}}{dt}.$$  Within the context of discussing the rectilinear motion of a single particle and  variations which are purely translational or purely rotational, the equation  $$\delta \dot{q}^{i}=f^{i}\left[\left\{\dot{q}\right\}\right]\varepsilon$$  was asserted to follow from the corresponding variation of the position coordinates.  The claim is fairly obvious for those circumstances.  But it is less obvious for more general variations such as those applied to a path when seeking a stationary action integral.  I believe the product rule is applicable to all "well-behaved" variations, but I'm having difficulty formulating a satisfactory argument (informal or formal proof) of that fact.  I am assuming that the operators $f^i$ are point functions of the coordinate system and are time-independent.  I believe they will always be affine transformations.  So, my question is: in the context of time-independent variations of the configuration of a system, when and why is it true that  $$\frac{d}{dt}\delta q^{i}=\delta \frac{dq^{i}}{dt}?$$

I am reading about Lagrangian mechanics.  At some point the difference between the temporal derivative of a variation and variation of the temporal derivative is discussed.   The fact that the two are the same is presented in the book I am reading as a rule, commutativity, and possible non-commutative rules are mentioned too.  I do not get it: given a path $q(t)$ and its variation $\delta q(t)$, the equivalence between the variation of the derivative $\delta \dot{q}$ and derivative of the variation $\dot{\delta q}$ seems to me a fact descending straight from calculus, not an arbitrary choice.  References:   B.D. Vujanovic and T.M. Atanackovic,, (2004); p.12. C. Lanczos, The Variational principles of Mechanics.


I have Lidar data which contains multiple .las files for an entire quad. I have figured out which .las is the area I am looking for. I was told the data is in 1.4 meter resolution and would work to create a contour map with 1 foot intervals. So that's what I have to work with.   I am not sure what the 1.4 meter resolution means or how it helps to create 1 foot intervals. Would the first step be to use the las2dem tool? And what would I set the step size/pixel size to?   I have created a DEM by inputting my .las file, no filter, pixel size:1. I then used raster>extraction>contours and input my DEM with interval set to 1. Is this correct for 1' intervals, or is there something I need to do to compensate for the 1.4 meter resolution of the .las?   I am mostly confused on how to make sure the intervals are set to 1 foot and not 1 meter, and what the 1.4 meter resolution means.  Also, I am working in QGIS and using the LAStools set.

I am using ArcGIS 10.1 to generate a DEM (bare earth) from LAS dataset. To accomplish this, I use Las Dataset to Raster tool as described in .  I have read here and there in the web that the the cell size of the output raster should be set at a value corresponding to the average LAS points spacing; somewhere else, they suggest to use a value that is three times the average point spacing.  Now, since I wish to produce a bare earth DEM (i.e., with only ground returns), I am wondering if the cell size has to be set at the average point spacing of the whole LAS dataset (i.e., comprising non-ground, ground, etc), or exclusively of the ground points?  On the basis of the ArcGIS's point file information tool (), I managed to get statistics for each LiDAR class. The average spacing (whole dataset) is 1.5 m, while for ground points only is 0.67.  Any insight into the issue?


I've read this and don't believe it :) I've no compiler here to test.

As Joel points out in , in  (aka: K & R), there is mention of this property of arrays in C: a[5] == 5[a]  Joel says that it's because of pointer arithmetic but I still don't understand. Why does a[5] == 5[a]?


If $F$ is a finite field then is it necessary that $|F|=p^n$ for some prime $p$ and positive integer $n$? I know that given prime $p$ and positive integer $n$, there is a field such that $|F|=p^n$? But is the converse always true?

Let $F$ be a finite field. How do I prove that the order of $F$ is always of order $p^n$ where $p$ is prime?


My previous related  has been drastically downvoted. But now I see that at least on Stack Overflow some forbidden tags are shown in a single line (old BR), others one per separate line.         Looks like the global forbidden tags like “a, on, the” are processed different from site-specific tags like “data” and “programming”.  I think there should be a consistent solution. I suggest that each tag on separate line could be a better choice. E.g.:        The 'data' tag is not allowed.   The 'programming' tag is not allowed.   The 'a' tag is not allowed.   The 'the' tag is not allowed.   The 'on' tag is not allowed.      Suggested duplicate post is not a duplicate of the current one. The old post displays all forbidden tags in a single line. Current - contains new site-specific forbidden tags, which are displayed one per line. Both issues are very similar, but they are about different situations.

When I try to use multiple , the message box text is the concatenated text of all the tags, as if it is one tag.        In this case the correct form could be the next:     The 'a', 'the', 'or', 'on' tags are not allowed.


Exporting select query data from mysql to csv & opening with excel, the leading zeros are gone.  Although the column is varchar, when the data gets exported, it writes like   4567 instead of 04567, is there a way to preserve the leading zero while exporting to csv?

I want to generate a CSV file for user to use Excel to open it.  If I want to escape the comma in values, I can write it as "640,480".  If I want to keep the leading zeros, I can use ="001234".  But if I want to keep both comma and leading zeros in the value, writing as ="001,002" will be splitted as two columns.  It seems no solution to express the correct data.  Is there any way to express 001, 002 in CSV for Excel?


My textbook says that net rate of heat transfer due to radiation is $\epsilon \sigma A(T^4-T_o^4)$ but i couldn't understand it.  Rate of emission is $\epsilon \sigma A T^4$ and rate of absorption is $a \sigma A T_o^4$ so net rate of heat transfer must be $\epsilon \sigma A T^4 - a \sigma A T_o^4$,it is possible only if $a=e$ which means body is in thermal equilibrium.  But that is not always the case. Please help.

Any object can emit and absorb radiation and the power of emission can be represented by the  law:   $$P=A\epsilon\sigma T^4$$  In many texts the net power radiated is the difference between the power emitted and the power absorbed:  $$P_{net}=A\epsilon\sigma (T^4-T_s^4)$$  where $$T_{s}$$ is the temperature of the surroundings.  Why can the surrounding and the object share the same $\epsilon$ ?  If we try to find out the radiation emitted from the surrounding it should be $P_s=A\epsilon_s\sigma T_s^4$, and if $\epsilon_s<\epsilon$, we will get a strange result that energy radiated from the surrounding is less than the radiation absorbed by the body from the surrounding. What am I missing?


When I join a new site, one of my biggest pet peeves is that I cannot see the vote split on a question and/or answer.  This feature is a great education - a +5 / -4 answer tells me a lot more about the consensus of "on-topic" is then a simple +1.  And yet, the feature waits until you have 1000 rep, which is a fairly significant hurdle.  So, why did this feature get put so high on the cookie shelf anyway?

Just curious, why is there a required privilege (especially one as high as 1000) to view vote counts for a post? It's not like someone can mess up a post by just viewing the vote counts. Is it just to give people incentive to reach 1000?


I am aware that this is the Taylor expansion of $e^x$ but how would people have known that the taylor expansion whose derivative is itself is the exponential function $e^x$.

I've been asked by some schoolmates why we have $$ \sum_{n=0}^\infty \frac{1}{n!}=e.$$ I couldn't say much besides that the $\Gamma$ function, analytic continuation of the factorial, is defined with an integral involving $e$. Then I also know that actually $$ \sum_{n=0}^\infty \frac{x^n}{n!}=e^x.$$ Is there a reason for these facts?  P.S. I added the tag "intuition", please remove it if you think it is not pertinent.


I read a submission in a newsletter about grammar. Part of the article discussed the use of who and that. The reader is told to use who as a pronoun for references to people and that as a pronoun for references to inanimate objects. The author provided examples: “Phoebe is the person who lives next door to my daughter.” and “It’s the grocery store that is closest to my house.” In closing of this section the author provides the statement, “When did people become objects?”  Aren't who and that relative pronouns? Also, I don't believe the use of  who or that are needed in the author’s examples. Composing in plain talk, I would compose the author's examples as: “Phoebe lives next door to my daughter.” and “It’s the grocery store closest to my house.”  Comments please...?

I often get confused when trying to use who vs that.  Some examples that often confuse me:  That     The person that went to the store.      The people that went shopping.      The persons that went shopping.      The group that went shopping.   Who     The person who went to the store.      The people who go shopping.   Please explain when to use either for plural subjects and singular subjects.  Animate and inanimate objects as well.


As a trusted user, I can vote to delete answers that have a score of -1 or lower.  Typically, the answers I find myself wanting to vote to delete come from .   These answers are new and thus usually have a score of 0.    I was thinking it would be helpful to the moderators if other 20k users (who are presumably working from the same list of answers) voted to delete such answers ourselves.  (with appropriate comments added to the answer)  But in order to vote to delete I would have to first downvote the answer.  However, I'm not sure if this is something I should be doing.    Should I:   Simply flag the answer Downvote the answer and vote to delete Downvote the answer, vote to delete, and then undo my downvote   Historically of course I would just choose the first option.  I would like to know if any one (or a combination of) these options is ideal.  In sum:  as a 20k user, what should I be doing with these sorts of answers?

I am a non-20k-er on many sites. What am I supposed to do when I encounter a not-an-answer?   Flag it as not an answer? Downvote it? All of the above?   I have 20k reputation on one of the sites. What am I supposed to do when I encounter a not-an-answer there?   Flag it as not an answer? Downvote it? Vote to delete it, if it has negative score? All of the above?   And if the answers to these two questions are "all of the above", why do we need to separate it into multiple actions? Why not have flagging as not-an-answer automatically issue a downvote and, if possible, a delete vote?


So I Have a adventure map and I want to know how to get a head that can only be placed on a certain block. I know how to make blocks that can only be placed on certain blocks, but I want a head that can be placed on a certain block and I want the head to be a TNT head, like so:  /give Angel_Scarz minecraft:skull 1 3 {SkullOwner:"MHF_Tnt"}   How can I make it so that this head can only be placed on a certain block?

I want people to only be able to place TNT on only Quartz Blocks and I've see this done before where you can only place blocks on certain other blocks but I'm not sure of the command used to do that.  Does anyone know?


Any one can tell me why the with the code below I get the alert "Hello world" working on link #1 and link #2 only?   The link #3 is generated after doing a ajax call and the click event seems to be simply not available. I can't figure it out why.  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">           <meta http-equiv="content-type" content="text/html; charset=UTF-8">     <title>Test Page</title>
Link #1

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I tried to answer SEO-related questions which are not having even a single answer in Pro Webmasters. But I was not able to filter a single question with no answer in the SEO tag. Why does it show questions with answers even if I filter “unanswered” in the SEO tag? If no question is available in this case, it should say ”No question is available for this filter criteria”.  I’m sure that there are lot of unanswered questions in SEO tag. How can I filter those questions?   Screenshot:

Why does the "Unanswered Questions" tab show questions that have answers?


I wanted to flag a question as off-topic  (Flagging > Closing > Off-topic > Migration), and point it to  but that option wasn't possible. There were only 5 options possible.  Maybe include the same search box like you get when you click on the StackExchange header bar that says "Find a StackExchange site".

TL;DR: Give the belongs on another site in the SE network option to normal users too, generating a moderator flag.    Often questions are posted on the wrong site on the Stack Exchange network (for volume reasons, most often at Stack Overflow). Then they need to be closed as off-topic, and optionally migrated to a better site.  The "close as off-topic" (or "flag as off-topic", if you don't yet have closing rights) dialog has up to five migration targets (the most likely migrations) build in, and if at least four of the five closers agree on one of them, the question will get migrated there.  Moderators see in this dialog actually one more option:   belongs on another site in the Stack Exchange network   together with a text field which allows selecting a site by its name.    This option can be used to migrate a question to any site. We are normally using this only if it is either a really clear case that the question is on-topic at the target site, or we have asked a moderator of the target site. (Or a moderator of the target site has flagged the question at our site.)  Normal users don't have this option: They can only flag/vote to close as "off-topic", and use the "flag for moderator attention" general reason, and input a reason in the free-form text field:    Most of my flags in the last months on Stack Overflow are actually of this type (mostly for Crypto.SE and TeX.SE).  My feature proposal (actually, three of them)   Add this belongs to another site option to the GUI for normal users, too. Make this generate a normal "off-topic" close vote (if the user has close-voting rights, of course), together with a canned flag for moderators attention (which will be visible in the 10k mod tools).  (So such a vote will not generate a migration by itself, even if five users have the same idea.)  This should also be a possible flag option on questions which already are closed as off-topic. On the moderator side, make it a tiny bit easier to decide about the migrations, and make them happen:   Show in the flag list if a moderator of the target site flagged for migration (these are "good" and need not be checked, other than for off-topic-ness on the source site). (E.g. show a diamond beside the name?) If a question was flagged this way for migration, add the target site as an option to the moderator's close-dialog (so no searching is necessary). (Allow migrating questions which are already closed as off-topic, without reopening.)    Related:  - Waffles' answer says such a search box was intentionally omitted so people don't have to do the hard work. So now moderators have to do this hard work instead (for cases other than the five ones listed). I'm not sure this is really better.


The question  produced answers which agreed that it could not.  However, I notice today that, in Court, children, who had been named for the sake of anonymity as 'child two', 'child three' and 'child four', had been collectively referred to as 'childs two, three and four'.     Earlier in the inquest, the court heard Shukri had gone down to the river after school with Child One and three others — known as Childs Two, Three and Four.     This appears to me to be perfectly correct.  Are the Court, the newspaper report and myself all wrong in thinking that this is a 'standard English' way of properly referring to the children in question ?

Is the word childs ever used instead of children for the plural of child? And was it ever a part of standard English vocabulary but later neglected?


I am confused with these three terms which are used in CSS. What is different between Opacity, Visibility and Display in CSS?

If so, does it effectively deprecate the visibility property?  (I realize that Internet Explorer does not yet support this CSS2 property.)


This is purely a theory question, so, given an "infinite" time to make a trivial program, and an advanced knowledge of C and Assembly, is it really better to do something in Assembly? is "performance" lost when compiling C into Assembly (to machine code)? By performance I mean, do modern C compilers do a bad job at certain tasks that programming directly in Assembly speeds up?

One of the stated reasons for knowing assembler is that, on occasion, it can be employed to write code that will be more performant than writing that code in a higher-level language, C in particular.  However, I've also heard it stated many times that although that's not entirely false, the cases where assembler can actually be used to generate more performant code are both extremely rare and require expert knowledge of and experience with assembly.    This question doesn't even get into the fact that assembler instructions will be machine-specific and non-portable, or any of the other aspects of assembler.  There are plenty of good reasons for knowing assembly besides this one, of course, but this is meant to be a specific question soliciting examples and data, not an extended discourse on assembler versus higher-level languages.  Can anyone provide some specific examples of cases where assembly will be faster than well-written C code using a modern compiler, and can you support that claim with profiling evidence?  I am pretty confident these cases exist, but I really want to know exactly how esoteric these cases are, since it seems to be a point of some contention.


I remember reading a story once where we had all interbred such that there were no longer any blacks, whites, Asians, etc.  We were all 'brown'.  Somehow they 'found' 5 children that were purebred 'races', and I don't remember much else.

I read a story in the 1980's (before 1984) about a future where race (black, white, etc.) had disappeared and for some reason "they" were attempting to bring back the races. The main character was a white boy. At the beginning of the story he meets a girl of another race that is also part of the project to bring back distinct races.   I thought the title was "killing time" but that really does not fit with the story I remember and none of the books I have found with that title fit.  The other detail I remember is that the people counted in octal (base 8) which I thought was cool.


This is super, super annoying.  If I open the News app on my phone, start reading an article and then, say, reply to a message; every time I restore the article the News app just goes back to the home screen.   I'd expect this if my phone was running out of memory but it's not.  Is there anything I can do to prevent this?  Seems like a bug.

Sometimes I'll be interrupted in the middle of reading a story on Apple News and later when I open the app, it didn't save the story I was previously reading. I want to be able to resume reading the article, how can I find it again?


It is said that a clock on a spaceship runs slower than one kept on earth. The clock on earth can be taken to be at rest with respect to the events on earth.So, the clock on the spaceship is in motion with respect to the events on earth.Let the time interval between two events on earth be $t_1$ as measured by the clock on earth. Thus, the interval as measured by the clock on the spaceship will be $t_2=t_1/(1-v^2/c^2)^{1/2}$ [ v= speed of spaceship w.r.t. earth and c= speed of light], which makes $t_2>t_1$. So, shouldn't the clock on the spaceship run faster?

If there are two twins. such that one of them goes on a space voyage maintaining a constant velocity, and that one never returns to earth, and the twins decide to never meet but send information about their age to each other by some light pulse or any other method.  If then one knows that he is younger, won't he know he is the one travelling thus violating the postulate of relativity that all inertial frames are equal w.r.t. all phenomena and that one can never know if he is moving with a constant velocity.


Can somebody help me to draw something like this:   What I tried:  \documentclass[border={10}]{standalone}  \usepackage{tikz}  \begin{document}  \begin{tikzpicture}[x=10pt,y=10pt,>=stealth, scale=.75] \draw[fill=white] (-6,4) .. controls (-3,6) and (1,6) .. (3,4) .. controls (3.5,3.5) and (5,-8) .. (2.5,-10) .. controls (1,-11) and (-1,-11.5) .. (-4,-11) .. controls (-8,-10) and (-9,-8) .. (-6,4);  \end{tikzpicture} \begin{tikzpicture}[x=10pt,y=10pt,>=stealth, scale=.75] \draw[fill=white] (-6,4) .. controls (-3,6) and (1,6) .. (3,4) .. controls (3.5,3.5) and (5,-8) .. (2.5,-10) .. controls (1,-11) and (-1,-11.5) .. (-4,-11) .. controls (-8,-10) and (-9,-8) .. (-6,4); \end{tikzpicture}   \end{document}     These are the two outside contours... I have no idea how to put the arrows or the inside contours.

What packages do you use and recommend for creating graphics in your LaTeX documents?     As this is a community wiki post, please add your package to the accepted answer (or add a comment, and someone with >100 rep will add it to the CW answer), and include a brief description of what differentiates it from others and how it can be used (GUI drawing tool which generates code, type in raw text, or generates image for inclusion in document).   We'll eventually sort these answers under headings.


The command apt-get allows wildcards for (auto) removing packages. However, apt doesn't seem to work the same way. For example...  sudo apt autoremove libreoffice*   ...gives the following error...  E: Unable to locate package libreoffice*   Can apt be used with wildcards, like apt-get?

When I run this command :  apt install libkf5*   I get the following error :  Unable to locate package libkf5*    I'm sure that the packages whose names start with libkf5 exist (tab-completion says so) . So the problem is not about the absence of those packages.(Note the asterisk at the end of that error message , the wildcard's not working at all) I use apt v.1.9. Thanks in advance.


Let $f(z)$ be an entire function whose modulus is constant on some circle. Show that $f(z)=f(z_0) + c(z-z_0)^n$ for some $n \geqslant 0$ and some constant $c$, where $z_0$ is the center of the circle.   I only know a sketch of the proof, using Schwarz reflection Principle. I would seriously appreciate giving details to it.

Find all entire functions $f(z)$ such that $|f(z)|=1$ for $|z|=1$  Hint: First show that $f(z)$ is a polynomial.  Clearly one can not use Cauchy Estimates to prove that $f(z)$ is a polynomial, the other way is to prove that $f(z)$ has a pole at infinity which I am not sure how to prove that, are there any other ways to prove that a given entire function is a polynomial ?  Thank you !