I am using multind.  I am typing a large set of notes.  I want to have two indices, one called "Index" the other "Notation".  The .idx files exist for both of them after compiling.  My problem is that I don't know how to run a makeindex for each of the indices.  This is my first time using TeXshop.  When I run makeindex it searches for a .idx file that has the filename the same as the notes I am typing.  How do I get makeindex run on notation.idx and index.idx?  Better yet, is there a way of setting up a command that runs LaTeX, then makeindex for each index, then LaTeX again?    EDIT: I have changed to imakeidx.  My preamble has in it:  \usepackage{imakeidx} \makeindex{index} \makeindex{notation}   and at the end of the files I have  \printindex{notation}{Notation} \printindex{index}{Index}   I no longer call the package multind or makeindex.


I'm working on derived subgroups because I'm studying for an exam and I want to show that in the case of the dihedral group $D_{2n}=\langle\sigma ,\tau|\sigma^n=\tau^2,\sigma^{\tau}=\sigma^{-1}\rangle$ that the derived series is   $1 \unlhd\langle\sigma\rangle\unlhd D_{2n}$  if n is odd and $1 \unlhd\langle\sigma^2\rangle\unlhd D_{2n}$ if n is even.  I know that the commutator will give $[\sigma,\tau]=\sigma^{-1}\tau^{-1}\sigma\tau=\sigma^{-2}$ which implies that the commutator can always be generated by just sigma , but I am confused as to show the difference between the even and odd cases . any suggestions anyone ?


Undefined reference to template function defined in a separate .cpp file

I've got an error message from the linker undefined reference to wrapper<char>::Free() when I call this function inside ~wrapper(). It appeared after I decided to rewrite the entire class into a template class.  Here the code,  wrapper.h  #include <iostream> #ifndef WRAPPER_H     #define WRAPPER_H #define ALLOC_FAILED 3048  template <class T> struct wrapper {     T * data = nullptr;     int dsize = 0;      void Free();     void Alloc(int s);     void Copy(const wrapper<T> & other);      wrapper(): data(nullptr), dsize(0){               }     wrapper(int s)                    { Alloc(s);     }     wrapper(const wrapper<T> & other) { Copy(other);  }     ~wrapper()                        { Free();       }      const wrapper<T> & operator = (const wrapper<T> & other){ Copy(other); return *this;} }; #endif // WRAPPER_H   wrapper.cpp  #include "wrapper.h" template <class T> void wrapper<T>::Free() {     if(data)     {         delete [] data;         dsize = 0;         data = nullptr;     } } template <class T> void wrapper<T>::Alloc(int s) {     if(data) Free();     data = new (std::nothrow) T[s];     if(!data) throw ALLOC_FAILED;     dsize = s; } template <class T> void wrapper<T>::Copy(const wrapper<T> & other) {     Alloc(other.dsize);     for(int i = 0; i < this->dsize; i++) data[i] = other.data[i]; }   log :  ||=== Build: Debug in wrapper (compiler: GNU GCC Compiler) ===| obj\Debug\main.o||In function `ZN7wrapperIcED1Ev':| wrapper.h|19|undefined reference to `wrapper<char>::Free()'| ||error: ld returned 1 exit status| ||=== Build failed: 2 error(s), 0 warning(s) (0 minute(s), 1 second(s)) ===|   but the code worked just fine when the structure wasn't a template  wrapper.h  #include <iostream> #ifndef WRAPPER_H     #define WRAPPER_H #define ALLOC_FAILED 3048  struct wrapper {     char * data = nullptr;     int dsize = 0;      void Free();     void Alloc(int s);     void Copy(const wrapper & other);      wrapper(): data(nullptr), dsize(0){               }     wrapper(int s)                    { Alloc(s);     }     wrapper(const wrapper & other)    { Copy(other);  }     ~wrapper()                        { Free();       }     const wrapper & operator = (const wrapper & other){ Copy(other); return *this;} }; #endif // WRAPPER_H   wrapper.cpp  #include "wrapper.h"  void wrapper::Free() {     if(data)     {         delete [] data;         dsize = 0;         data = nullptr;     } } void wrapper::Alloc(int s) {     if(data) Free();     data = new (std::nothrow) char[s];     if(!data) throw ALLOC_FAILED;     dsize = s; } void wrapper::Copy(const wrapper & other) {     Alloc(other.dsize);     for(int i = 0; i < this->dsize; i++) data[i] = other.data[i]; }   Thank you for your answers.


Is it safe to delete lost.dir files to save space in an android cellular phone, or is it better to move it to the sd card?


escaping double quotes and percent signs (%) in cron

The following command works from prompt but not from crontab.   grep abc  /var/log/messages | grep "`date '+%B %d'`" | mail -s"abc log of `hostname`" shantanu.oak+`hostname`@gmail.com   I need to add it to daily cron.


What abilities target  that triggers 'Whenever Ashenmoor Liege becomes the target of a spell or ability an opponent controls, that player loses 4 life.'  Would deathtouch qualify?


Is it bad to turn off the water while on vacation?

I'm a little OCD when it comes to traveling. I have learned from experience that when I am away, I constantly have visions that a pipe in the wall had burst and that the water is slowly filling the house. Having been through this enough times, I am tempted to put my worries to rest by simply turning off the main water line (in the garage) before we leave. My new fear with doing this, of course, is that I will cause something else bad to happen.  So I am curious, is it bad to turn off the water and drain the pipes prior to leaving for a week? In addition, what other precautions should I take aside from turning down the water heater? A few details - our house is two story, copper pipes, and we would be traveling in the spring time so temperatures in the house would stay at around 70 F.


I have Sony Vaio laptop. My left arrow key is not working. The same key is used for Home with Fn key. I want to map it to the right Ctrl key, which is the key next to it.


How do I remove a USB drive's write protection?

I have a SanDisk Cruser Blade USB stick that suddenly seems to be write protected. I tried running DiskPart but after I write the command "attributes disk clear readonly" it displays this:  Microsoft DiskPart version 5.1.3565  ADD         - Add a mirror to a simple volume. ACTIVE      - Marks the current basic partition as an active boot partition. ASSIGN      - Assign a drive letter or mount point to the selected volume. BREAK       - Break a mirror set. CLEAN       - Clear the configuration information, or all information, off the disk. CONVERT     - Converts between different disk formats. CREATE      - Create a volume or partition. DELETE      - Delete an object. DETAIL      - Provide details about an object. EXIT        - Exit DiskPart EXTEND      - Extend a volume. HELP        - Prints a list of commands. IMPORT      - Imports a disk group. LIST        - Prints out a list of objects. INACTIVE    - Marks the current basic partition as an inactive partition. ONLINE      - Online a disk that is currently marked as offline. REM         - Does nothing. Used to comment scripts. REMOVE      - Remove a drive letter or mount point assignment. REPAIR      - Repair a RAID-5 volume. RESCAN      - Rescan the computer looking for disks and volumes. RETAIN      - Place a retainer partition under a simple volume. SELECT      - Move the focus to an object.   It's like when you type help at the DiskPart prompt, so how do I get past this? This problem started  when I plugged the stick into a laptop which had viruses, if that's any help.


Why is time-reversal represented by an antilinear and antiunitary operator?

Operators related to physical transformations in quantum mechanics are usually unitary and linear except time-reversal which is both antiunitary and antilinear. What is the explanation for this difference?


How many $n$-words from the alphabet $A=${$a,b,c,d$} are there such that $a$ and $b$ are never neighbors.  $\\$ Source : Problem Solving Strategies by Arthur Engel$\\$ The solution given in the book is related to, forming Recurrence relations. The problem is, I am a bit unfamiliar and to Recurrences so is it possible to solve this problem without using Recurrences ?$\\$ Any help would be appreciated. Thanks !!


I have a sentence where I'm unsure about my grammar when discussing planets:   "Branch Technology is revolutionizing the use of 3-D printing to create architectural elements and structures that will enable new home designs not only for Earth but maybe even for the Moon and Mars."   Is this grammar and capitalization correct usage? I always get stuck on "the earth" or just "Earth."


Passing big objecst as parameters in java

I have done some research and I found out that in Java, primitive data types are passed by value and Object and Arrays are kind of passed by refernce.  I am not quite sure if I understand exactly, when the variable is passed as refernce and when is it passed as value.  For example if I pass an object to a click listener It is probably passed by reference, right? But what happens if, I then save the value of that parameter in instance variable inside click listener? Is the data beeing copied?  I have example code below (with some more questions in comments):  //some big class with lots of arrays public class InfoClass{     private ArrayList<SomeObject> array1; //huge array     private ArrayList<SomeObject> array2; //huge array      //methods... }  //listview menuitem click listener which is applied to all items public class ListviewItemClickListener implements View.OnClickListener{      private InfoClass _info; //is this a copy of an object or a reference?     private MyArrayAdapter _adapter;      public ListviewItemClickListener(InfoClass info, MyArrayAdapter adapter){         _info = info;         _adapter = adapter;     }      @Override     public void onClick(View view) {         //do something with info class..         _adapter.notifyDataSetChanged(); //update adapter     } }  //also: //what about this, is this inefficient? private class SomeClass{     public String printValueAndObjectType(Object value, Class type){         return  value.toString()+" "+type.getName();     }     //example call: printValueAndObjectType("value", String.class);     //is the String.class beeing copied? }


On some beta sites, the "top questions list" on the home page is completely gone, both when logged in and logged out. This appears to have started happening in the last several minutes.  :    :


If you just look at a picture of one there are no eyes readily apparent but they clearly know where they are going. Could their screeching be some form of echo-location?


My question is, how would I make the visible HDRI/Enviroment Map be image 1 and then have reflections as Image 2? If someone can post a node setup, or a .py file that would be great <3 I was thinking maybe using the Is Camera Ray node but I'm not confident it would work, and have no idea where to start.


Why do I get an Excel warning about file format and extension mismatch when I try to download an excel file?

I have a Customer.jsp file on the server to send the content in an Excel file. I have kept the simple text "TestContent" to help me debug this.  <%     response.setContentType("application/vnd.ms-excel");     response.setHeader("Content-Disposition", "attachment;filename=Test.xls"); %>  TestContent   When I download the file on the client side open, Excel(version 2013 or 2016) opens the file, but I get the following message:     The file format and extension of Test.xls don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway?   I have also tried to set the header   application/vnd.openxmlformats-officedocument.spreadsheetml.sheet`    and file format as .xlsx, but it also doesn't help because the warning still appears.    To address the duplicate notice, in the  the author says to not use plain HTML tables with an application/vnd.ms-excel content type. However, because I'm not using any html content, so how would that solution affect my situation (removing the warning)? I have padded all the request headers and content.  Also the target question asks     Is it possible under tomcat to just write a file as if it was a normal Java application [...] ?


Should "Restarting worked for me" be a comment?

:     What should I do, if the "Open Call Hierarchy" is broken (empty for every method in a project)? It is very useful for code navigation, do not know, how to work without it!    (now converted to a comment):     I have had the same issue. Closing and re-opening the project fixed this issue for me. You might want to give that a try.   The comment on the answer (before it was deleted):     This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post


How can I invite a friend to my single player world on Minecraft?

How can I invite a friend who lives in a different country to my single player world on Minecraft? I have tried going on YouTube to see if I could get help there, but no luck; it was too confusing.  How can I do this?


Change file system state in recovery mode

Sorry for the format, but im trying to do this on my smartphone since my ubuntu is down lol. I am trying to run the command sudo apt-get purge nvidia-current in the root shell prompt but I am getting a few errors since I'm not in write mode. How do I fix this? My computer keeps booting to a blank screen right before asking for my login after I recently tried updating my nivida drivers.


Let $σ$ be the relation on $R×R$ in which $(a,b) σ (x,y)$ if and only if $a ≤ x$ and $b ≤ y$. Prove that $σ$ is a partial order relation.

I can prove it is reflexive and transitive but I cannot prove that it is antisymmetric. Help.


error.log file in public_html which is publically viewable?

There is a file in my public_html folder called error.log which is viewable by anyone if they just enter the URL in their browser, like: example.com/error.log  I'm running Apache. My question is, how can I hide or perhaps move this error.log so that it isn't visible to regular users?  ErrorDocument 401 default ErrorDocument 403 default ErrorDocument 404 default ErrorDocument 500 default  <IfModule mod_rewrite.c> RewriteEngine On  #   If you are having problems with the rewrite rules, remove the "#" from the #   line that begins "RewriteBase" below. You will also have to change the path #   of the rewrite to reflect the path to your XenForo installation. #RewriteBase /xenforo  #   This line may be needed to enable WebDAV editing with PHP as a CGI. #RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]  RewriteCond %{REQUEST_FILENAME} -f [OR] RewriteCond %{REQUEST_FILENAME} -l [OR] RewriteCond %{REQUEST_FILENAME} -d RewriteRule ^error\.log$ - [F] RewriteRule ^.*$ - [NC,L] RewriteRule ^(data/|js/|styles/|install/|favicon\.ico|crossdomain\.xml|robots\.txt) - [NC,L] RewriteRule ^.*$ index.php [NC,L]


I think I pressed something by accident, and now my regular movements are jittery.

Normally when I press the "g" key everything is smooth. But suddenly as I was working on my model. Everything is moving very jittery and I cant control anything that is happening. The vertices would jump around the point but wont land at the specific area I want. Is there a way I could fix this?


Why does NEF file get washed out/highlights while my JPG look normal?

TLDR. is just the title.  I know nothing about photography, sorry. My dad has a d90 he never uses, so I use it to take photos when I need them for something.  Anyways, I put it on raw mode. when I open the photos on my computer, the jpg looks like the viewfinder view. The NEF looks like the jpg for a second, then gets "rendered..?" with boosted highlights so it looks washed out. This is actually what the playback looks like on the low resolution camera display.  Im probably doing the settings wrong, but I cant explain why the jpg looks normal.


What story is set on planet where time runs faster as one approaches the pole?

short story (or novelette?) read in the 1960s or '70s, likely in an anthology from the 1950's plus or minus: planet where time ran faster as one approached the (north?) pole, and the language used by the characters became more abridged as part of that speed-up - a "war" was going on, perhaps because someone fired a missile over the pole and it came back at themselves?


In an integral domain $R$ associates of an irreducible element are irreducible.

My attempt :  Let $p$ be an irreducible element in $R$.Let $q$ be an associate of $p$.Then there exists a unit $u \in R$ such that $q = pu$.Now if $q$ were reducible then $q$ can be written as $q = ab$ where none of $a$ and $b$ are units in $R$.Then we have $pu = ab$ and so $p = (u^{-1} a) b$.Since $p$ is irreducible one of them should be a unit.Since $b$ is not a unit.So $u^{-1} a$ is a unit.Now I have stuck and can't proceed further.  Please give me a hint to complete it.  Thank you in advance.


Calculate the Gauss integral without squaring it first

We know that the integral $$ I = \int_{-\infty}^{\infty}  e^{-x^2}\ \mathrm{d} x $$ can be calculated by first squaring it and then treat it as a $2$-dimensional integral in the plane and integrate it in polar coordinates. Are there any other ways to calculate it?  I know that we may use the relation $$\Gamma(x)\, \Gamma(1-x) = \frac{\pi}{\sin{\pi x}}$$ but this, in effect, is still taking the square. Well, after I write down the above text, I figure that maybe there is no way to calculate it without squaring, since, after all, the result contains a square root, and it seems no elementary function can "naturally" produce a square root of $\pi$ starting from natural numbers (though I don't know how to describe this more concretely; you are also welcome to comment on this point).  Nevertheless I still post this question in case there are some other ideas. EDIT: the Fourier transformation method at  appears kind of cheat to me, since the very proof of the Fourier transformation formula actually makes use of the value of the Gauss integral (at least in this wiki page ). Thank you.


How to create 3D Box designs with User-Generated Dimensions?

I'm trying to learn . I need this for box designs of different sizes, and so I found this tutorial that makes it easy to create with the use of Photoshop Actions.   While fast-reading the tutorial, I found around Step 10 onwards, the shape of the box is explained on how to shape it... For me, I need these shapes of different sizes (varied length, depth, and height).   How can I set the shape to be varied on user's input? For example, when the action is running, how can I alter the tutorial's method to ask user input for the length, depth and height?   Also, is there ANY software (free/paid) that can let me create these boxes hassle-free? Any Action/script/template in Photoshop that can let me change the dimensions as per requirement?  Thanks.


How to prove this relation between Ramsey Numbers: $R(s,t)≤R(s,t−1)+R(s−1,t)-1$ for $s,t>2$ when $R(s,t-1)$ and $R(s-1,t)$ are even.

I am beginner in combinatorics and have been following this book PRINCIPLE AND TECHNIQUES IN COMBINATORICS by CHEN CHUAN-CHONG. In this book the authors improves the relation $R(s,t)≤R(s,t−1)+R(s−1,t)$ for $s,t>2$ to above relation by making a constraint that $R(s,t-1)$ and $R(s-1,t)$ are both even.  I am unable to follow through the author's reasoning for this proof.  Please help.


Show any collection of non-intersecting lemniscates in the plane is countable

I found this question in a book on introduction to measure theory. The exercise lists several sets and asks me to prove they are countable. I have been able to navigate through the other sets but I don't know how to do this one. How should I go about it?


So, when I start watching a video or something of the like, VLC puts a nice little icon in the tray. The problem is, that when I open and close VLC it keeps adding another nice little icon in the tray.   Here's a SS for example's sake.


Prove that there is a bijection between the set of all subsets of $X$, $P(X)$, and the set of functions from $X$ to $\{0,1\}$.

Given any set $X$, let $P(X)$ be the set of all subsets of $X$, and let $\{0,1\}^X$ be the set of all functions $X \rightarrow \{0,1\}$. Construct a bijection (and its inverse) between P(X) and $\{0,1\}^X$.    Let us define $f: P(X) \rightarrow \{0,1\}^X$ by $f(\alpha) = g_{\alpha}$ where $\alpha \in P(X)$ and $g_{\alpha} : X \rightarrow \{0,1\}$ is defined by  $$g_{\alpha}(x) =\begin{cases}        1 & x \in \alpha \\       0 & x \in X-\alpha     \end{cases}$$  We need to check if this function is well-defined. Let $\alpha, \beta \in P(X)$. If $\alpha=\beta$, then $\alpha$ and $\beta$ correspond to the same set, and so correspond to the same function since both $g_{\alpha}$ and $g_{\beta}$ send that set to 1 and the ($X-$that set) to 0.   If we have a function $g_{\alpha} \in \{0,1\}$, then $\alpha$ is a set in $X$ that is sent to 1. But since $P(X)$ is the set of all sets of $X$, we must have $\alpha \in P(X)$. So the function is surjective.  Finally, if $g_{\alpha}=g_{\beta}$ then both $g_{\alpha}$ and $g_{\beta}$ send the set $\alpha$ or $\beta$ to 1. So $\alpha$ and $\beta$ must be same set. In other words, the function is injective; and hence bijective.   The inverse function is $f^{-1}: \{0,1\}^X \rightarrow P(X)$ where $f^{-1}(g_{\alpha}) = \alpha$.     Another way to prove this is to first construct the inverse function, show that it is well defined, and then show that $ff^{-1}$ and $f^{-1}f$ are the identity functions, right?  So if we let $g_{\alpha}=g_{\beta}$, then $\alpha=\beta$, because otherwise $g_{\alpha} (\beta)=0$ and $g_{\beta} (\beta)=1$; a contradiction.   Now we have $f \circ f^{-1} (g_{\alpha}) = f(\alpha) = g_{\alpha}$ and $f^{-1} \circ f(\alpha) = f^{-1}(g_{\alpha}) = \alpha$ , and so $f$ and $f^{-1}$ must be bijective.


MacOS Reclaim free space on Disk for APFS container after deleting APFS Container

I have an 8 TB disk in my Mac. I had 2 APFS containers on it (disk7 and disk8). After deleting APFS container disk8, I get this:  The space that the deleted APFS container disk 8 used up is lost and not reclaimed by APFS container disk 7. I tried  diskutil apfs resizecontainer disk5s1 0, but no result. I can only use 4.3 TB of my 8 TB disk. How can I make container disk 7 use all 8 TB? sudo gpt -r show /dev/disk5


Installing .NET Framework 3.5 requires .NET Framework 3.5

I have a Windows 10 machine that doesn't have Internet access. So I downloaded the .NET 3.5 Framework from here:   I copied the installer to the Windows 10 machine, and attempted to install. I get the following dialog, which appears to be telling me I need .NET Framework 3.5 to install .NET Framework 3.5:    What else do I need to install this? The installer I have is 330MB, so I assume it's the full package and not the web installer.


If card(A) > card(B) then there is no surjection from B onto A, w/o AC.

I am trying to prove that if cardinality of A is greater than cardinality of B, then there is no surjection from B onto A. Or any logically equivalent implication.   Formally,     card($A$) > card($B$) $\implies$ $\forall$ $f \in A^{B}$, $\exists$ $a  \in A$ : $\forall b \in B$,  $f(b) \neq a$.   It is my goal to avoid the use of the axiom of choice. Earlier I arrived at the equivalent implication     There exists a surjection from B onto A implies there exists an injection from A into B   But after defining the family of sets and failing to sufficiently arrive at the consequence I did some research and found that this statement does require the AC.  So I suppose my specific question is: can any logically equivalent statement be proven without the AC? Or is it just the direct proof of the second highlighted statement that requires AC?  Lastly, to be clear, the definition I am working with for card($A$) > card($B$) is there exists a set C that is a subset of A such that there is a bijection from $B$ onto $C$ but there is no bijection from $B$ into $A$  I will be on the computer for the next while and will be happy to post further information regarding my approaches and attempts if anyone wishes. Also I read through all the information here  regarding cardinals with and w/o AC and still couldn't deduce an answer.


Short-hand assignment to lists in Python

I have declared a (5x6) list called path in Python as:  path = [[' ']*6]*5   Now, when I change the value of any one element as:  path[4][5] = '*'   or  path[0][5] = '*'   I get the output as:  [' ', ' ', ' ', ' ', ' ', '*'] [' ', ' ', ' ', ' ', ' ', '*'] [' ', ' ', ' ', ' ', ' ', '*'] [' ', ' ', ' ', ' ', ' ', '*'] [' ', ' ', ' ', ' ', ' ', '*']   That is, all the elements of the specified column get changed to '*'. Why does this happen? My guess is that maybe this has something to do with the way this short-hand notation is implemented in Python. Maybe the interpreter takes the first row and copies it down for all columns.


I am taking in CSV files from Nasdaq and am using Apache Commons CSV to parse it. For some reason I am getting a NullPointerException and I can't seem to figure out why.  These are my lines where I create the reader and parser  data = new URL("http://www.nasdaq.com/screening/companies-by-industry.aspx?industry=Health%20Care&render=download"); Reader dataReader= new InputStreamReader(new BOMInputStream(data.openStream()), "UTF-8"); CSVParser dataParse= new CSVParser(dataReader, CSVFormat.EXCEL.withHeader());   I am then adding to an ArrayList to store the values:  for (final CSVRecord record : dataParse) {     myArrayList.add(new MyClass(record.get("Symbol"),              record.get("Industry"))); }   It seems to me like the CSV file is fine, so not sure why this would be happening. Thanks


Remove the synonym mapping [generic-programming] to [generics]

"Generics" refers to a language features in C#, Java, and several other languages.  Generic programming typically refers to a programming paradigm used in C++ (as well as in a handful other languages, where it relies on other equivalent language features), where it relies on templates (not generics) and the ability to create specializations for specific types.  They really have nothing in common, other than that both involve syntax with lots of angle brackets. One is a programming paradigm just like functional programming or object-oriented programming, while the other is a language construct found in specific languages.


Vertical space after table on top of a page with text continuing from last page

How can I remove the spacing after a table that appears on top of page 2, when I have a paragraph that starts from page 1 and continues on to page 2? I can't use \vspace since that just moves the whole paragraph on page 1.


Illustrator: select all objects inside a path

I have a big number, more then 100K, objects and would like to select all lying inside a path (big circle in my case). I don't want a clipping mask because I will end up with partial objects. I need whole ones. Any clues?


Convergence/Divergence of infinite product

General condition: $(P_n)_{n\in\mathbb{N}}$ is a sequence of non-zero real numbers. If $\prod_{n=0}^\infty P_n$ exists in reals and is non-zero, then call this infinite product convergent. Otherwise divergent.  I have proven that:  If all $(P_n)_{n\in\mathbb{N}}$ are positive, then its convergence is equivalent to convergence of $\sum_{n = 0}^\infty \log(P_n)$.  If further $(P_n)_{n\in\mathbb{N}}$ are further greater or equal to 1, then the convergence of the product is equivalent to the convergence of $\sum_{n = 0}^\infty (P_n-1)$  Now I am looking for two examples where a)  $(P_n)_{n\in\mathbb{N}}$ are reals. $\sum_{n = 0}^\infty (P_n-1)$ converges but $\prod_{n=0}^\infty P_n$ diverges b) $(P_n)_{n\in\mathbb{N}}$ are reals. $\prod_{n=0}^\infty P_n$ converges but $\sum_{n = 0}^\infty (P_n-1)$ diverges   I have spent a long time on this but failed to find any. I guess it requires complex analysis technique? (Which I don't know) Please help me out. Thank you.


Equation of a circle with a center that passes through a point

Write the equation of the circle with center at (-1,3) and passes through the point (2,-4).


This week the keys hjkl on my (Early 2011) Macbook Pro sort of all stopped working at the same time (and only those keys are affected).  I say "sort of" because they can all start working perfectly again for an extended period of time and then suddenly for no reason they all stop working.    And then in gets weirder.  If the keys are all dead I can repeatably press just one of the keys and (after varying length of time) it comes good.  At which point the remaining bad keys also start working again.  My initial thought was that it is time to replace the keyboard, but the action of the keys all coming good at the same time confuses me.  So is there an explanation to what is going on?  Or is it time to replace the keyboard?


?: Operator Vs. If Statement Performance

I've been trying to optimize my code to make it a little more concise and readable and was hoping I wasn't causing poorer performance from doing it.  I think my changes might have slowed down my application, but it might just be in my head.  Is there any performance difference between:  Command.Parameters["@EMAIL"].Value = email ?? String.Empty;   and  Command.Parameters["@EMAIL"].Value = (email == null) ? String.Empty: email;   and  if (email == null) {     Command.Parameters["@EMAIL"].Value = String.Empty } else {     Command.Parameters["@EMAIL"].Value = email }   My preference for readability would be the null coalescing operator, I just didn't want it to affect performance.


What is the difference between adduser and useradd?

What is the difference between the commands adduser and useradd on Ubuntu?


Why do the Pokemon always have three pawprints?

I was told in pokemon go, the pawprints near the pokemon represent the distance away from me, but as I move around I run into pokemon and all of the distance markers stay at 3 paw prints, never lowering to 2 or 1. What's going on?


Ball A (2 kg) is moving towards ball B (1 kg) at 4 m/s. On the other side, ball C (7 kg) is moving towards ball B at 3 m/s. If all three balls collide elastically at the same time, what is the final velocity of each ball? This is a one-dimensional system with no spin, and the coefficient of restitution is 1.   I've tried having the balls collide one at a time, but I got different answers when A and B collide first and when B and C collide first.


Can anyone explain Lazy loading in Entity Framework?

I want a simple explanation about Lazy loading in Entity Framework with a simple example.   Why do we use Lazy loading? When do we use Lazy loading?


If I plug my iPhone into a Windows computer the photos I believe DCIM folders display as basically a drive. All you do is drag and drop the files you want. This works great!    How can I do this on macOS, preferably without any additional software? Unfortunately on my Mac it forces you to use the Photos application which I do not like. I'm transferring such a large number of files, I don't want airdrop.  AirDrop is to slow and sometimes doesn't work when using differing iOS and MacOS versions.  Right now I hilariously drag the files onto a thumb drive in Windows and then move the thumb drive to my Mac.


Python: How to Replicate a Replicated List Without Cloning

When I enter t=[[False]*2]*2, I get the list [[False, False], [False, False]]. But when I enter t[0][0] = True, t[1][0] also changes to True, leaving me with [[True, False], [True, False]]. I only want [[True, False], [False, False]]. As a second option, I could assign t=[[False]*2, [False]*2] and then changing t[0][0] = True gets me what I want ([[True, False], [False, False]]), but my real list is a lot bigger than that, so I would rather not use option 2. I figured that this was a similar issue to cloning versus copying with lists, so I tried: ([[False]*2])*2  ([False]*2)*2  [[False]*2][:]*2  t = [False]*2 t = t*2  list([False]*2)*2  list([[False]*2])*2  [list([False]*2)]*2. None of these worked. Is there any way to do this without importing any package?


I have made a Java program that could open any application. Suppose there is a file name "*.jpg", the it would allow the OS to recognize the type of application and then open the default application. Another example: Suppose the file's name is "*.flv", then it would open up the default media player just like when you click an icon in nautilus but the only difference was that it was in command line. Here is the java program for that:  import java.awt.*; import java.io.*; public class OpenFile{     public static void main(String args[]){       try{           String filename = args[0];           System.out.println(args[0]);           Desktop.getDesktop().open(new File(filename));       }       catch(Exception e){           System.out.println("Sorry an exception occured. Could not perform the operation.");       }     }  }   Now this script leads to performance issues. Now I want to write a BASH script to do this task ??


Trigger a php file on every post or page if a condition is met

I was wondering if we can trigger a PHP file on every WordPress post or page if a certain condition is met. Let me detail what I want.   Can we write a simple PHP script that will be automatically loaded on every WP post and page. Once loaded, the script should scan the HTML and if it finds a specific DIV tag with the ID myID it should trigger another PHP file (let's say script.php). Once the target PHP file has been triggered or executed, the target PHP file (script.php) should be able to automatically fetch the URL of the post or page that triggered the file and store it in a variable.   Any ideas??


NO2 CSV downloaded files shows zero values for consider date range using Google Earth Engine

When I am downloading the CSV file, the results show zeros in the CSV file. How can I download exact NO2 values as shown in Chart after running the mentioned below code in Google Earth Engine? // Create a FeatureCollection from the list and print it. var BergamoGeometry = ee.FeatureCollection(BergamoGeometry); print(BergamoGeometry); Map.centerObject(BergamoGeometry); Map.addLayer(BergamoGeometry); //////////////////////////////////////  var dataset = ee.ImageCollection("COPERNICUS/S5P/NRTI/L3_NO2")                  .filterBounds(BergamoGeometry)                   .filter(ee.Filter.date('2019-03-30', '2019-04-29'));                   var NO2 = dataset.select('NO2_column_number_density'); var band_viz = {   min: 0,   max: 0.0002,   palette: ['black', 'blue', 'purple', 'cyan', 'green', 'yellow', 'red'] }; // Create and print the chart. print(ui.Chart.image.series(NO2, BergamoGeometry, ee.Reducer.mean(), 30));


Solution to any classical mechanics problem

Can Lagrangian Mechanics solve any classical mechanics problem, ie in non-inertial frame, involving non-conservative forces etc.


How to keep blanks behind a command without using `{}`

How can I program a command \mycommand such, that a white space is set printed behind it if a white space is used after it and no white space is printed if no white space is used (e.g. when punctuation is used) without using {} after the command usage. I understand that this is kind of against how the LaTeX syntax works, but maybe there is a way around it.  With  \documentclass[a4paper,10pt]{article} \usepackage[utf8]{inputenc} \newcommand{\mycommand}[1][i]{\ensuremath{\frac{#1}{2}}} \begin{document} This \mycommand[1] is \mycommand, \mycommand and \mycommand. \end{document}   I get    but I would like to get    without having to add {} behind the third \mycommand.


I would appreciate your help.  I have been struggling with this for way too long.  I could easily get around this by creating two separate model classes with a duplicate list of properties, but I'd like to learn how to achieve this with the base class.  So, an IntSensor and ExtSensor are both a Sensor.  From another class I parse a json file with all of the data and that works great.  But, trying to call a method that returns a List<Sensor> baseclass and trying to cast it as either subclass is killing me.  What am I doing wrong... or is there a better way?  Thank you!  PS: this may look like a duplicate question, but I tried the other solutions and they are marked in the `Repository class' as "//seen on other StackOverflow Posts -- fails" in the code.   //Model classes  public class Device {     public string IP { get; set; }        public string Name { get; set; }     public IList<IntSensor> InternalSensors { get; set; }     public IList<ExtSensor> ExternalSensors { get; set; } }  public class Sensor {     public string Name { get; set; }     public string ActualTemp { get; set; }     public string HighTemp { get; set; }     public string LowTemp { get; set; } }  public class IntSensor : Sensor {} public class ExtSensor : Sensor {}   //Business Class -- parsing json   public class ParseJsonData {     public static RoomAlertModel GetRoomAlertModel(JObject jsonTree)     {         RoomAlertModel model = new RoomAlertModel();         model.IP = jsonTree["ip"].ToString();         model.Name = jsonTree["name"].ToString();          return model;     }      public static List<Sensor> GetSensors(JToken jToken)     {         var sensors = new List<Sensor>();          try         {             foreach (var item in jToken)             {                 var s = new Sensor();                 s.Label = item["lab"].ToString();                 s.ActualTemp = item["tf"] != null ? item["tf"].ToString() : "";                 s.HighTemp = item["hf"] != null ? item["hf"].ToString() : "";                 s.LowTemp = item["lf"] != null ? item["lf"].ToString() : "";                  sensors.Add(s);             }         }         catch (Exception)         {         }                      return sensors;     } }   //Repository  public class RoomAlertRepository     {         internal RoomAlertModel Retreive()         {             var filePath = HostingEnvironment.MapPath(@"~/App_Data/RoomAlertsData.json");              var json = File.ReadAllText(filePath);              JObject jsonTree = JObject.Parse(json);             var internalSensorTree = jsonTree["internal_sen"];             var externalSensorTree = jsonTree["sensor"];              var model = ParseJsonData.GetRoomAlertModel(jsonTree);              var baseList = ParseJsonData.GetSensors(internalSensorTree);              //seen on other StackOverflow Posts -- fails             var iSensorsTry1 = baseList.Cast<IntSensor>();             //seen on other StackOverflow Posts -- fails             var iSensorsTry2 = baseList.ConvertAll(instance => (IntSensor)instance);             //seen on other StackOverflow Posts -- fails             var iSensorsTry3 = baseList.OfType<IntSensor>();              model.InternalSensor = iSensorsTry1.ToList();               return model;         }     }


How to delete (invalid) files with colon in their name under Windows?

I've got a rather large number of files on my Windows drive that have a colon in their name. (These came from unpacking some Unix archives.)   When I try to delete them, Windows (XP) complains that the file does not exist, and refuses to delete it. This happens when trying to delete or rename it from explorer or the command line. Still, chkdsk does not complain about those files nor fix the problem.   Any ideas on how to get rid of them?


Interpreting plot of residuals vs. fitted values from Poisson regression

I am trying to fit data with a GLM (poisson regression) in R.  When I plotted the residuals vs the fitted values, the plot created multiple (almost linear with a slight concave curve) "lines".  What does this mean?   library(faraway) modl <- glm(doctorco ~ sex + age + agesq + income + levyplus + freepoor +              freerepa + illness + actdays + hscore + chcond1 + chcond2,             family=poisson, data=dvisits) plot(modl)


How to safely turn off swap permanently and reclaim the space? (on Debian Jessie)

I installed Debian Jessie with default partitioning on my SSD drive. My current disk partitioning looks like this:    As I have 16GB of RAM, I assume I don't need . But since I have other disk drives I may  for example, on one of the other drives instead.  Can you tell me what steps I should take to remove the  partition correctly and permanently for it not to occupy disk space? I wish to delete the swap partition as I currently have only 128GB SSD.  Here is what I tried and rebooted each time; each of these steps being not permanent, or did not do anything:   Using the  utility:  swapoff --all  Using the  utility:  Right-clicking the  partition and clicking Swapoff. Commenting out the  partition's  in the following file:  /etc/fstab  Commenting out the  partition's  in the following file:  /etc/initramfs-tools/conf.d/resume  Running these commands in the end (both in this and the opposite order):  update-grub  update-initramfs -u


Meta's tag pages inaccessible due to self-redirect loop

Tag pages (route /questions/tagged/tagname) redirect to themselves indefinitely:  $ curl -D - http://meta.stackexchange.com/questions/tagged/featured HTTP/1.1 302 Found Cache-Control: private Content-Type: text/html; charset=utf-8 Location: /questions/tagged/featured X-Frame-Options: SAMEORIGIN Date: Fri, 05 Jul 2013 16:47:42 GMT Content-Length: 143  <title>Object moved</title>
Object moved to here.
    This only happens on Meta, so far, but only applies to any meta-tag that doesn't have a dash in it; those with a dash seem to be exempt, as do invalid tags:    redirects.  does not.  does not.


I have been reading about . I was wondering if this attack is feasible while signing with RSA and, if yes, how?    Also, how this kind of attack is applied with DH?   Talking about timing attacks in general, in which way AES is affected and how to solve it? (I mean, with RSA the "problem" is at multiplication level, while for AES where is the problem that makes the cipher implementation key or data dependent?)


I typed  sudo apt-get upgrade   And I got this  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following packages will be upgraded:   bind9-host dnsutils google-chrome-stable libbind9-161 libdns-export1104   libdns1104 libirs161 libisc-export1100 libisc1100 libisccc161 libisccfg163   liblwres161 python3-distupgrade ubuntu-release-upgrader-core   ubuntu-release-upgrader-gtk 15 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/61.1 MB of archives. After this operation, 1,769 kB of additional disk space will be used. Do you want to continue? [Y/n]  dpkg: unrecoverable fatal error, aborting:  unknown system group 'smmsp' in statoverride file; the system group got removed before the override, which is most probably a packaging bug, to recover you can remove the override manually with dpkg-statoverride E: Sub-process /usr/bin/dpkg returned an error code (2)   Can any one throw any light on this?


I was poking around my performance settings tabs and clicked on one that showed users. It has the single account that was set up (as Admin) and a Default user account.  I am curious to know why it is there. Does it serve some purpose?


Short story about a man betting a group he could tell a story, and one of them would disappear and the others would not notice

In about 1966 or so, a stand-in teacher at our primary school spent the afternoon reading short stories to us. There was a wide genre, but I was particularly fond a one which was science fiction/mystery.  It involved a group of people who were talking about mysteries, and another man from outside the group bet the he could tell a story, and one of them would disappear and the others would not notice. The final line was something like "he kicked over the stool and walked from the room".


What is the height of a man walking away from a street light 12 ft high, if his shadow is moving twice as fast as he is?

The goal is to find h, the man's height. The height of the light post is given, 12ft. Also, we know that the change in position of the shadow is twice as much as the change in position as the man. From this, I got:  height (h) / 12 = Shadow Distance from Man (S) / Man's Dist. from light (M) + S  12s = h(M+S), so h= (12s) / (M+S)  This is where I was confused. I know I can derive with respect to time, with dh/dt = 0. However, there are three variables and we only know 1 of them: 2*dM/dt = dS/dt.


How do I find what type of file system is of an attached USB or SD card?

How can I find the file system type of USB drive without using computer? Drive is attached to Android phone and I can see the files in it. I want to know if it is extFAT etc.


How to find limit of the sequence $\sum\limits_{k=1}^n\frac{1}{\sqrt {n^2 +kn}}$?

How can I find the limit $$\lim_{n\to\infty}\displaystyle\sum_{k=1}^n\frac{1}{\sqrt {n^2 +kn}} \quad?$$  I have tried to solve it using squeeze theorem: $$\sum_{k=1}^n\frac{1}{\sqrt {n^2 +kn}} > \displaystyle\sum_{k=1}^n\frac{1}{\sqrt {n^2 +n^2}} = \displaystyle\sum_{k=1}^n\frac{1}{\sqrt {2n^2}}=\frac{1}{\sqrt {2}} $$ and $$\sum_{k=1}^n\frac{1}{\sqrt {n^2 +kn}} <\displaystyle\sum_{k=1}^n\frac{1}{\sqrt {n^2}} = 1.$$  But I could not find the sequences with the same limits.  Please help - how to solve this?


Am I correct to assume that when ; joins two commands on a line, Bash always waits until the first command has exited before executing the second command? And similarly, in a shell script containing two different commands on different lines, Bash always waits until the command on the first line has exited before executing the command on the second line?  If this is the case, is there a way to execute two commands in one line or in a script, so that the second command doesn't wait until the first command has finished?  Also, are different lines in a shell script equivalent to separate lines joined by ; or &&?


How to properly uninstall Ubuntu from dual boot?

Is there any other way than this  ?   Don't have a windows 7 disk and my laptop won't go to recovery mode since the keys are broke on the laptop.  Is there any way to uninstall it without seeing   No such partition  GRUB Rescue:  Thanks in advance


Save specific combination of layers as PNG

Unfortunately I don't have any experience yet with PS scripts, so I would highly appreciate your help. I'm looking for a way to export a specific combination of layers to a PNG.    My file is laid-out where I have 12 groups.  Group 1-11 is named after a colour. Each group from 1 to 11 contains 6 layers named as T1, T2, T3, T4, T5, T6. Group 12 is different, it has 6 layers: R1, R2, R3, R4, R5, R6.  I would like to export the combination of the layers to PNG as follows (keeping the original canvas size, not trimmed to layer content sizes.)  R1+T1 (R1 from group 12 and all the T1-s from Group 1-11). In total that is 11 variations.  R2+T2 (once again, R2 is from Group 12 and T2-s are from Group 1-11.)  R3+T3 R4+T4 R5+T5 and R6+T6.  I tried to do so with PS built in script, but it did not really work, it exported bad layers and just kept going and going.  Would you be so kind to help me how can I achieve my goal with all the different PNG files described above?    Additional information:  The "R" layers blend mode are set to "Color dodge" I would like to keep this when merging and exporting with the T layers.  The linked topic did not solve my problem - Composite script gave me an error when opening in CS5.5. Also, I'm not sure if it answers the same question.    Updates  Layer comps should be the solution. At least it saves time by clicking "Save as" and set output as PNG and also adding a name to each file.  So thanks for your help, it's far better than doing everything manually!


Does there exist a continuous bijection from $(-1,1) \to (-1,1]$?   Suppose that $f$ is a continuous bijection from $(-1,1) \to (-1,1]$.Then $f^{-1}(1)=a$ where $a\in (-1,1)$.  Since restriction of a continuous map is continuous so $f|_{(-1,a)\cap (a,1)}$ is  a continuous map its image is $(-1,1)$.  But it is not giving anything.Please give some hints.I am unable to proceed.


How do I copy music to my iPhone using iTunes 11?

I've always managed my iPhone/iPad/iPod Manually, I recently updated to iTunes 11 and now I can see no way to get my music onto my device.  I used to be able to just drag songs from my library to my device, now there is seemingly no way to do this.  I can view the music on my device by clicking on it on the top right corner of iTunes, but I can't seem to get to a state where I can drag music from my computer onto my device.  I'm using iTunes 11.0.1.12 for Windows if that makes a difference.


I want to show that $(1+\frac{x}{n})^n \leq e^x$ for all $x \geq -n$, $n\in \mathbb{N}$. I already showed that positive case ($x>0$) and zero case $(x=0)$. Not sure how to approach the negative case, because in the case $x>0$ I used that $x^n$ is an increasing function on $(0, \infty)$. But I can't do the same when $x$ is negative.


Can I specify a custom command before launching interactive bash session?

Please note: Although this question is essentially the same as , I did not mark it as "solving my problem" because the answers provided there are not very satisfactory. The answer I accepted below is cleaner and simpler. Take a look!   I know how to pass bash a custom command to execute, e.g. like this:  bash -c "/bin/echo hello"   When I do this, bash executes the argument of -c and then exits. How can I get it to give me an interactive prompt when I'm done? Adding -i has no effect. I don't want to write the custom commands into a file that .bashrc always reads.   I've been making do with bash -c "commands; exec bash -i", but it's not ideal since it starts bash twice. Is there a way to get the same effect while starting bash only once?


I have a folder where my untagged music is where I want to launch a script to delete all the .png and .jpg except those beginning by the word 'cover'. Here's what I tried:  find . -name '*.jpg' -or -name '*.png' -not - -name 'cover.*'   find . (-name '*.jpg' -or -name '*.png'\) -not - -name '*.png'   And other variation of the two, none worked. (I didn't included the -delete at the end on purpose)


I'm searching for a word to indicate something that was current at some time in the past, but not necessarily now.    For example:       The doctor's report of June 2008 set forth the patient's ?{then-current} complaints.


I need help doing this question, and I believe a 'standard' solution would require proof by induction. Here is the question: Suppose that n ≥ 3 and a simple graph G has n vertices and at least $\frac{n^2−3n+6}{2}$ edges. Prove that G is orientable.


How to add common pagenumber without decreasing page size?

I can include pdf documents as they are in the common pdf document, but I cannot do it with common page numbering in the top right corner.  The following fancyhdr does not have any effect on have page numbering on the top of pdf documents.  It would be great if the page numbering would be on top of pdf documents because they are just articles where plenty of space there.  Code proposed based on the thread  about base document  \documentclass{article} \usepackage{pdfpages}  % https://tex.stackexchange.com/q/56316/13173 \usepackage{fancyhdr} \pagestyle{fancy} \fancyhf{} \fancyhead[R]{\thepage}  \renewcommand{\headrulewidth}{0pt} % Werner, remove top margin border  \begin{document} \includepdf[pagecommand=\thispagestyle{plain}]{sforzo.pdf} \includepdf[pagecommand=\thispagestyle{plain}]{testData.pdf} \includepdf[pagecommand=\thispagestyle{plain}]{sforzo.pdf} \end{document}   Fig. 1 Output with pagestyle{plain} where you see that the approach decreases the size of the page,  Fig. 2 Output with pagestyle{fancy} and renewcommand     The fancy pagestyle looks better, but I would still like to maintain  the page size.  The following Werner's proposal stays in loop and never ends, so I cannot get any output with it  \let\oldincludepdf\includepdf \renewcommand{\includepdf}[2][]{\oldincludepdf[pagecommand=\thispagestyle{fancy},#1]{#2}}   Werner's correct answer  \usepackage{letltxmacro} \LetLtxMacro\oldincludepdf\includepdf \renewcommand{\includepdf}[2][]{\oldincludepdf[pagecommand={\thispagestyle{fancy}},#1]{#2}}   Output without decreasing the page size    TeXLive 2016 OS: Debian 8.5


How do I check the quality of a download Ubuntu iso?

I have downloaded Ubuntu 14.04 from its official website. I've had problem installing it on my PC. Now I want to check whether my download was good or not as it took a long time to download .iso file. If the download isn't the problem, this would mean something else went wrong here and it would save me 6 hours of downloading this again.     I have  no technical knowledge, so is there any simple way that I can understand?  Now i have checked hash for the iso file and it doesnt matches, how can i repair it? any app is there to help me? as i have no knowledge for using codes or understanding them, what now? don't know what to do.  i have no linux os in my pc. so i can't use the terminal to download ubuntu. can i use terminal using livecd demo?  but using livecd demo slows my pc. how can i get a good download in windows?  any other suggestion ?


I am trying to fill two overlapped regions using fill and pattern. My problem is that the opacity option is not working in my example:   \begin{figure}[ht!]   \centering    \begin{tikzpicture}[scale=0.85]     \begin{axis}         [ticks=none,         ymin=0,ymax=1.7,         xmin=0,xmax=1.7]           \addplot[pattern=dots,mark=*] coordinates {                 (0,0)                 (0,1.3)                 (1.1,1.1)                 (1.3,0)                 (0,0)        };     \addplot[fill=green,fill opacity=0.2,mark=*] coordinates {                 (0,0)                 (0,1.3)                 (1.3,0)                 (0,0)    };      \end{axis}     \end{tikzpicture}    \end{figure}   `   which produces the follwing figure:    I need to reduce the opacity of the green region.


Can I benefit from cover against an effect that destroys that cover?

The  spell creates a destructible wall, with each 10-foot section having 30 hit points:     The wall is an object that can be damaged and thus breached. It has AC 12 and 30 hit points per 10-foot section, and it is vulnerable to fire damage. Reducing a 10-foot section of wall to 0 hit points destroys it and leaves behind a sheet of frigid air in the space the wall occupied.   Suppose a fireball spell detonates on the opposite side of the wall from me, such that the wall provides total cover against it. However, the fireball deals 27 fire damage, which is enough to destroy any sections of the wall caught in the blast (since the wall is vulnerable to fire damage). So, the fireball will definitely destroy my cover. So before the fireball, I definitely have cover, while afterward I definitely don't have cover any more. However, it's not clear whether I still have full cover against the effect of the fireball itself.  More generally, in any case where I have cover against an effect but the effect itself destroys that cover, do I gain the benefit of that cover before it is destroyed, or does the cover get destroyed before I can benefit from it?


Is it OK to leave "What have you tried?" comments?

Some questions boil down to "how can/do I do X?" Here's an .  Sometimes, people leave comments under such questions that ask "what have you tried?" Is it OK to leave comments like that? Should all questions contain snippets of non-working code?


Why can a discontinuous function not be differentiable?

I don't really understand why a discontinuous function cannot be differentiable.  In Stewart's Calculus, the definition of a function $f$ being differentiable at $a$ is that $f'(a)$ exists. Earlier it gives the definition of the derivative as $f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}$. It also has a theorem that if $f$ is differentiable at $a$, then $f$ is continuous at $a$. There is also a definition that a functions $f$ is continuous at a number $a$ if $\lim_{x\to a}f(x)=f(a)$.  Take for example the very simple function:  $$ f(x)=\begin{cases} x+1 & x\geq0, \\ x & x<0.  \end{cases} $$  It is discontinuous at $x=0$ (the limit $\lim_{x\to 0}f(x)$ does not exist and so does not equal $f(0)$), but if I find the derivative using the limit above, I get the left and right limits to equal $1$. So therefore, the derivative exists.  According to the book, the function shouldn't be differentiable at $x=0$ as it has a discontinuity (continuity is a necessary condition of differentiability). What am I doing/understanding wrong?


QGIS 2.6.1 doesn't load python plugins on Ubuntu after upgrade

I have experienced this scenario once before and now today, whenever I updated my QGIS installation on Ubuntu, it didn't reload python plugins under ~/.qgis2/python/plugins when started, only c++  plugins are available. I can't really recall what I did previously but when I restarted my machine it seemed to work out of the box. Any ideas?


problem installing Collada-dom 2.4.4 headers and build tools

I got a notification that I need to install updates, and I clicked yes, but since then I am getting this stop sign on the top right corner because of unmet dependencies.  when i run:  sudo apt-get install -f   I get bunch of packages to be removed and then:  The following extra packages will be installed:   collada-dom2.4-sp-dev The following NEW packages will be installed:   collada-dom2.4-sp-dev   When I click yes:  Selecting previously unselected package collada-dom2.4-sp-dev. (Reading database ... 306874 files and directories currently installed.) Preparing to unpack .../collada-dom2.4-sp-dev_2.4.4.1-ubuntu1~trusty1_amd64.deb ... Unpacking collada-dom2.4-sp-dev (2.4.4.1-ubuntu1~trusty1) ... dpkg: error processing archive /var/cache/apt/archives/collada-dom2.4-sp-dev_2.4.4.1-ubuntu1~trusty1_amd64.deb (--unpack):  trying to overwrite '/usr/lib/cmake/collada_dom-2.4/collada_dom-config.cmake', which is also in package collada-dom2.4-dp-dev 2.4.4.0-ubuntu1~trusty1 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing:  /var/cache/apt/archives/collada-dom2.4-sp-dev_2.4.4.1-ubuntu1~trusty1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   when I run sudo apt-get autoremove I get:  You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  collada-dom-dev : Depends: collada-dom2.4-sp-dev but it is not installed E: Unmet dependencies. Try using -f.   Any help would be appreciated, thank you.


Minimize the expression $|x-1|+|2x-1|+|3x-1|+\dotsb +|119x-1|$

Find the value of $x$ so that $|x-1|+|2x-1|+|3x-1|+\dotsb +|119x-1|$ is minimum. Based on my trial-and-error method in Desmos, I am getting $x=\frac{1}{118}$; how do I get the correct answer?


Why does Cooper send the NASA coordinates in Interstellar?

What is the point of Cooper sending himself the coordinates of NASA in Interstellar, only to moments later scream at himself to "STAY, you fool"?


Getting those %#!^& signs in the footnote!

This is basically an expanded version of part of  .  The original questioner there wants to redefine \href so that all the links end up in foonotes (rather than in the main document) so my suggestion was the old \let\oldcmd=\cmd \def\cmd{reimplement \cmd in some fancy way} trick.  Turned out that that didn't solve the problem.  But what broke this solution isn't really about the solution, it's about those @&*@%y$#@ characters in URLs and ... *sigh* ... footnotes.  Not being an expert on hyperref, I appeal to the community to help.  (And half an hour gazing at the documentation and source of hyperref has not brought enlightenment either.)  I've tried the solutions at  and  to no avail (though perhaps I'm doing them wrong ... sorry, incorrectly).  Also, note that  is the wrong way around for this: the questioner wants the clickable link in the footnote.  Here's the URL that the questioner presented me with, embedded in a MWE:  \documentclass{article} \usepackage{hyperref}  \begin{document} Hello\footnote{\href{http://www.google.com/#sclient=psy&hl=en&site=&source=hp&q=numbers&aq=f&aqi=&aql=&oq=&pbx=1&fp=d5033c56880e0199}{b}} world.  \end{document}   This produces the error:  ! Illegal parameter number in definition of \Hy@tempa. <to be read again>                     s l.9 ...qi=&aql=&oq=&pbx=1&fp=d5033c56880e0199}{b}}                                                    world.   which makes me think that it is the # that is causing the problem.


I am having difficulties understanding and solving the following problem.    So far I think I understand the first line. I know what the graph of floor[t] looks like and I understand they're asking to integrate from 0 to some value of n and that integral always equals the equation on the right. I do not really understand what they are asking for in the second line or how that differs from the first equation.  I have checked through my notes and various online sources and we've just covered the fundamental theorem of calculus and discussed integration using partitions on an interval to calculate area but I am also unsure about how to relate these to this problem if they are even needed.  Any pointers, explanations or solutions would be greatly appreciated.  Thank you.


Number of results on Google's 'site:' search

I have come across something puzzling with Google's 'site:' search results. When searching a site that I know to have far more than 10 million indexed pages, Google displays 564,000 results. Is there any reason/logic behind this? Is this an indicator of a large number of indexed but low quality pages?


modifying napili community template lightning components

Is there a way to view & modify the code of standard lightning components that are visible when editing the Napili template in the community builder. I was wondering if I could modify some of the code and use it as lightning out.


A large vase (lays / is laid) in the corner of our front hallway

A large vase lays in the corner of our front hallway.      A large vase is laid in the corner of our front hallway.   Which is the right sentence?  Should I use lays or is laid?


Let $K ⊂ L$ be an extension. Let $α ∈ L$ algebraic over $K$. Show that $α^2$ is algebraic over $K$.  Let $n$ be the degree of the minimal polynomial $p(x)$ of $α$ over $L$ and $m$ be the degree of the minimal polynomial $q(x)$ of $α^2$ over $L$.  Since $α^2 ∈ L(α)$, we have $L(α^2) ⊂ L(α)$, then $m\leq n$.  I have trouble understanding the last statement. How do I know that $α^2 ∈ L(α)$ and why is $L(α^2) ⊂ L(α)$


Mutual set of representatives for left and right cosets: what about infinite groups?

Let $G$ be a group and $H$ a subgroup of $G$. If $G$ is finite, then according to Philip Hall's "marriage theorem" there is a left transversal $T$ of $H$ in $G$ (that is, $T$ contains precisely one element from each left coset of $H$) such that $T$ is also a right transversal of $H$.   Does this theorem generalize to infinite groups? The original theorem treats only the case where $|H| < \infty$ and $[G:H] < \infty$.  What can we say when $|H| = \infty$ and $[G:H] = \infty$? What about $|H| < \infty$ and $[G:H] = \infty$? Also $|H| = \infty$ and $[G:H] < \infty$?


Humans meeting aliens deep in space -- only to discover they are humans, also

Asking for a friend: The story involved humans meeting aliens at the front of the colonization wave working its way around the spiral arms of the galaxy. The aliens turn out to be humans coming from around the other direction, with enough time having been taken that evolution produced changes so that the humans coming clockwise were unrecognizable to the humans coming from counter-clockwise.  What is the story?


I keep getting update of numix-icons-theme package everyday, how to stop it?   I've installed that update many times still it keeps showing up.


Steps to replicate   Go to review first posts. Flag the post. Now, retract the flag (Use case: because my initial flag was a mistake and I needa change the flag to a different one). I cannot Flag it anymore. But, I am able to click I'm Done button but it is not actually true.   I think we need a fix for this so that the reviewed first posts are more accurate.


Minecraft keeps crashing and won't launch

When I open up my Minecraft Launcher it launches with no problem, but when I hit play, my launcher closes and then nothing else opens up. After a while, my Minecraft Launcher will reopen and say a crash occurred, this is what the crash report said:


I've been cooking a 15 lb (7 Kg) pork shoulder for 24 hours, and the temperature has been around 140°F (60°C) for both meat and liquid. I didn't realize the temp was so low until just now when I stuck a thermometer in it.  Its a new (to me) slow roaster that is quite large, and has temperature written on the dial.  I had the dial set to 275°F (135°C), but obviously the actual temperature is much lower that.  I've turned up the temperature and will get it to a cooking temp of 275°F, but will it be safe to keep cooking the meat this way? I think I should get the meat close to 190°F (90°C).


Does the event of big bang violates first law of thermodynamics?

First law states that energy can neither be created nor be destroyed. So how did the big bang gathered so much energy to expode?


Scifi novel where humans defeat an ancient AI enemy by firing a wave of "slowness", preventing hyperdive space travel

The main premise is that as you head out of the galaxy, the more god-like you become. The inside is the 'unthinking depths'  There was an AI like enemy being, that computer archaeologists let escape, that wants to take over the universe.   One of the god-like beings puts the 'key' of the enemy's destruction into a human created from pieces of an old space battle.  The hero and the created human, who seem to be the only humans left in existence, go to a lower level, less evolved, civilized world, where a human explorer landed long ago who succumbed to the local forces or lizard people, to find the other part of the key and finally defeat the enemy AI by sending a wave of 'slowness', powered by their sun, making most of the galaxy not traversable by hyperdrive, effectively locking the enemy AI in 'space' with no means to travel.  Help!


Should you include press interviews and articles about your work in your CV?

Is it appropriate to include interviews (published online or in print magazines) in an academic CV?   What about articles/news published about your works? I mean brief (one paragraph) news that professional magazines publish about significant research articles.  If yes, how do you do this to avoid exaggeration?


Where can I learn more about neural network optimization?

I have limited experience with matlab's nn toolbox but I can manage to train a network and get it to generate decent results. However, I have no idea how many hidden layers, hidden nodes, which transfer function for each layer, and which training method to use.  I tried searching online for tutorials but all of it seems really vague and subjective. Can someone direct me to any good websites?


Disable smart (contextual) quotes for entire document?

Is it possible to disable smart (contextual) quotes for an entire document? If yes, how?  In particular, can the single quote ', double quote ", and backtick ` be left as-is by some option or method to directly disable such substitutions?    \documentclass{article} % minimal document which illustrates the issue. \begin{document}  Can "double quotes", 'single quotes' and `backticks` substitutions to any curly, smart, quote, contextual  be switched off for the whole document?  \end{document}   The package  appears limited to the \verbatim type sections. The package  has commands and environments for user-definable ‘smart quotes’ … yet, some switch to just completely disable smart quotes has been elusive.  The question  is looking for a package plus macros and rather than an off switch.  The systemic impact of add packages vs. toggle a switch(option?) have intrinsic differences.  On one hand, "adding a package" is a downstream approach. Downstream files have added cluster and complexity in the authors' files.  , add this package x for macro y, then add that package z, then override a, then define b so that b can then itself be overridden.  Each added package, definition and override also likely adds some computational complexity to the dynamic runtime execution as well.  On the other hand, "toggle a switch" is a upstream approach. I'm guessing these quote substitutions originate in the various TeX/LaTeX engines. Hypothetically or ideally, a smart quote option switch could be compiled and linked for execution efficiently at the source … with some pseudo logic like:  // over simplified pseudo code if smartQuotesOption == true {   // make quote substitutions happen } else {   // just skip the substitutions.   // so, maybe nothing or little to do. }   then conceptually users would use a command line option:     pdflatex --no-smart-quotes document.tex   or use some direct switch like the following in the LaTeX/TeX files:    \smartquotesdisable \smartquotesenable % default for backward compatibility   Such smart substitution enable/disable toggles do exist in document creation environments like various markdown tools, pandoc and mainstream word processors.  So, "Can smart quote substitutions just be toggled off?" …  If yes, great.   If no, then where would one submit a feature request for a smart substitution toggle? Or, find out if such a feature is already on the roadmap? :-)


Using regularization when doing statistical inference

I know about the benefits of regularization when building predictive models (bias vs. variance, preventing overfitting).  But, I'm wondering if it is a good idea to also do regularization (lasso, ridge, elastic net) when the main purpose of the regression model is inference on the coefficients (seeing which predictors are statistically significant).  I'd love to hear people's thoughts as well as links to any academic journals or non-academic articles addressing this.


What is the basic structure of American higher education?

When I go to university for four years and study, e.g., law or medicine, do I earn an undergraduate degree? And do I have to go to university for another two years or so to get a graduate degree? Also, is it the same university then, or do I have to go somewhere else? And do you have to get a graduate degree? I’m really confused by the American academic system.


Using xy package, I have produced a figure. But I have a problem:  How can one create a colored arrow in xy package? (In fact, I intend to have colored arrows in the following flow chart).  \documentclass[reqno]{amsart} \usepackage{enumitem} \usepackage[all]{xy} \usepackage{newlfont} \usepackage[centertags]{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{plain} \usepackage{mathrsfs}  \setcounter{page}{1} \renewcommand{\baselinestretch}{1.5} \oddsidemargin=.25cm \evensidemargin=.25cm \textwidth=15cm \topmargin=0cm \textheight=21cm \begin{document} \title{Graphical Abstract} \maketitle  \begin{figure}[!h] \small {\[\xymatrix{ \framebox[0.33\textwidth]{\textbf{Partition of Unity}\quad \textbf{\&}\ar[d] \quad \textbf{State}}  & &  \framebox[0.42\textwidth]{\textbf{State}\quad \textbf{\&} \quad \textbf{Hyper Injective Mapping}} \ar[d] \\ \framebox[0.36\textwidth]{\textbf{Entropy of a Partition of Unity}}\ar[d] \ar[r] & \ar[d]  & \framebox[0.45\textwidth]{\textbf{Hyper Injective Hyper $MV$--Algebra DS}} \ar[l] \\ \framebox[0.2\textwidth]{\textbf{Properties}} \ar[d] & \framebox[0.2\textwidth]{h(T, U)} \ar[d] \ar[r] \ar[l] & \framebox[0.2\textwidth]{\textbf{Calculations}} \ar[d] \\ \framebox[0.3\textwidth]{\textbf{Theorem of Isomorphism}} \ar[r] & \framebox[0.2\textwidth]{h(T)} \ar[ul] \ar[ur] \ar[l] \ar[r] & \framebox[0.32\textwidth]{\textbf{Kolmogorov-Sinai Theorem}} \ar[l] \\ \framebox[0.45\textwidth]{\textbf{Hyper Injective Hyper $MV$--Algebra DS}} \ar[dr] & \ar[r] \ar[l] & \framebox[0.48\textwidth]{\textbf{Semi-Independent Hyper $MV$--Algebra DS}} \ar[dl] \\ & \framebox[0.2\textwidth]{\textbf{$MV$--Algebra DS}} \ar[ul] \ar[ur]& } \]} \caption{\label{1}} \end{figure} \end{document}


Practical strength of non-2^n RSA key lengths

It has for many years been popular to use RSA keys that have lengths that are powers of two. E.g. 1024-bit, 2048-bit and 4096-bit key lengths are all popular for use with OpenPGP implementations such as GnuPG, and with OpenSSH, etc, and these key lengths are often either defaults in the software generating the keys, or are recommended by organisations whose participants are required to generate keys (e.g. ).  I have heard it said that, because cryptanalysts in practice will have devoted more resources towards breaking keys with popular lengths, and because popular lengths are powers of two, choosing a key length that is not a power of two would provide a practical security advantage, even if this means choosing a slightly shorter key length than one would otherwise desire (e.g. 4093-bit key instead of 4096-bit).  Is there any sense in that saying? Put another way, what (if any) are the reasons for which a cryptanalytic attack that would succeed against a 4096-bit key would fail or take significantly longer against a shorter key whose length is not a power of two?


How did the letter Z come to be associated with sleeping/snoring?

In cartoons and comics it's not uncommon to see a series of Z's to indicate that a person is in deep slumber, such as in the following political cartoon.    How and when did the letter Z come to be associated with sleeping?


A continuous surjection makes $m \geq n$.

Let $m,n \geq1$, $U$ is a nonempty open subset of $\mathbb{R}^m$, $f:U \rightarrow \mathbb{R}^n$ is a surjection, if $f$ is continuous on $U$, then $m \geq n$?  Is this right?


Create column to identify in which polygon does the point lie (QGIS)

I have a polygon shapefile and a point shapefile. At the point shapefile, I want to create a column, which will inform me about the polygon where each point exists. What do you suggest?  I mainly use QGIS, but I am also familiar with ArcMap.


How can I create a dictionary from 2 lists, one representing keys and the other values?

As the question says, I have two lists that look like this:   list1 = ["key1", "key2"] list2 = ["value1", "value2"]   I would like to create a dictionary like this:   dict1 = {"key1": "value1" , "key2" : "value2"}   Is there are an easy way to do so?


Using my email and webpage screenshots in my thesis

My research is about data-driven marketing methods and applying those methods in education. In my PhD thesis, I use some screenshots of commercial emails in my email box from companies such as Amazon, Les Mills, etc. An example:  I also used some screenshots from part of a webpage from companies such as Mailchimp. An example:  I have a copyright question: Do I need to seek permission for using these images? P.S. I study at the University of South Australia


Take the output of another program in python

So, what I want to do is a module which can automatically look for some things, but for that I need to take outputs from NMAP, specifically the Software Version. I have only written this, I just want to know how could i make this or if it is possible   def check(): while True:     cmd = raw_input("smb(check) > ")   This is an actual scan of NMAP  PORT      STATE    SERVICE  VERSION 21/tcp    open     ftp      ProFTPD 1.3.5b  What i want to do is to set that ProFTPD 1.3.5b as an object


Good reasons to prohibit inheritance in Java?

What are good reasons to prohibit inheritance in Java, for example by using final classes or classes using a single, private parameterless constructor? What are good reasons of making a method final?


How do I enter multiple locations in USA on an ESTA application (same trip)?

I'm travelling to Orlando, then travelling to 2 other states on my trip via airplanes—how do I enter these on my ESTA application?


Trying to identify a very old short story about aliens colonizing human bodies

Don't remember the exact start to the story, but it went something like "walking along a path" or something, and when he hears what sounds like a shotgun blast behind him, he then feels something strike him in the butt. He passes out, and when he awakens, he discovers that the "shotgun blast" was actually a miniature spaceship that exploded and shot miniature aliens into his body. The aliens prove to be very beneficial because they clean up all the toxins and other poisons in his body. They can be transmitted through kissing or sexual activity.  Any help with the name of the story would be greatly appreciated.  Dan


We are trying to build out stack on top of geo-spatial data, this means storing more than 10000records per a second. we are using Storm to accelerate receiving the data, but we would like to use some powerful tools like Cassandra to store data. The problem with Cassandra is that it lucks some GIS features. Do you recommend any other Data storage platform to easily query this massive data later ?


Capture console output from existing process(es) to file

We have a requirement to troubleshoot an existing system running Busybox, we have Telnet access. It would be helpful to log the system's console output (ideally the last n lines of it) to a file for debugging.  There's plenty of examples on redirecting the stdout/stderr of a command to a file at the point of invocation, but I can't find anything conclusive on capturing output from a running process or processes.  It seems like we should perhaps be able to capture/redirect from /proc/<PID>/fd/1 but searching suggests this is not possible, and I haven't managed to find an incantation to make it work.  Being a small embedded system we can't install more packages, so if it can't be done with basic command-line kung-fu we'll have to go back to the drawing board.  Any suggestions?


What has priority - owner/user vs group permission?

I have just run into the case in which the owner-group of a file has more permissions than the owner-user of a file.  user1@pc:/tmp$ ls testfile -l ----rw---- 1 user1 user1  9 Okt 16 13:16 testfile   Since the user user1 has no permissions to to read the file I get this  user1@pc:/tmp$ cat testfile cat: testfile: Permission denied   This suprised me as user1 is member of the group user1 which has permission to read the file.  Interesstingly when doing this:  root@pc:/tmp$ addgroup user2 user1 Adding user `test' to group `ress' ... Adding user test to group ress Done. root@pc:/tmp$ su user2 user2@pc:/tmp$ cat testfile content of testfile user2@pc:/tmp$   I can read testfile's content.  It seesms the permissions granded (or not) on the user-owner level take precedence over anything later like the permissions existing due to group membership.   My question is if there is a reference to this behaviour I experience in my linux system (that is that not having user-permissions takes away group-permissions)  Also is there a use case for this behaviour?


Is there a need for this. and me. on properties

I was asked, what I thought was a simple question, until I thought about it.  "Is there ever a need for using Me. (VB.Net) or this. (C#) - when referring to properties belonging to the same scope?"  i.e. There are some legacy projects we work on and a co-worker was using class properties via Me.[Property] - I noticed this and explained that he can simply access the property directly (remove the Me.).  (VB.Net) Public Property Name() As String Me.Name = "My Name" vs. Name = "My Name"  (C#) public string Name{ get; set; } this.Name = "My Name"; vs. Name = "My Name";   I was wondering though, is there a reason (other than passing the entire class / object, which I believe is a different topic) that you would ever need to call Me. or this.  Or is it simply legacy code left in place that causes no harm (has no positive or negative effect)?


Quick Liquid and Smoke doesn't work in viewport

When I make smoke by Object > Quick effect > Quick Smoke/Liquid it appears nothing on the viewport.  Once I bake it appears just right in viewport, but still error while rendering.  I don't know what is wrong with my scene.


I was stuck when trying to write to a system file to change the cpu frequency:  $ cat   /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed <unsupported>  $ echo 1600000 | sudo tee  /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed 1600000 tee: /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed: Invalid argument   Changing user to root has the same problem:  $ sudo su # echo 1600000 >   /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed bash: echo: write error: Invalid argument   The following should probably be unrelated. Previously, the above commands all worked, but then my Ubuntu was frozen an hour ago when I plug the usb plug of my laptop cooler into one usb port of my laptop, so I had to reboot it by hitting the power button of my laptop, and then I have the above problem.  Previously when it worked, cat   /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed output some value instead of <unsupported>. After trying many times with the above invalid argument error, now I just  ran echo 1600000 | sudo tee  /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed once again, and it works without the invalid argument error. Around the same time, ubuntu reported some cpu frequency utility error, which I don't remember exactly.


I am sure there must have been several philosophers in history who have investigated this question. However finding any specific and good research on that topic is not easy.   In our everyday life, most of us implicitly assume every event having a cause even if we do not or cannot know what the cause is. However, it seems there is no plausible case against events that have no cause at all. Or is there?  Can an event without a cause take place?


How long does it take for Google to re-index pages or update the link titles?

On one of our classified sites, when doing site:[mysite.com] in Google, the link text is simply [product name] - [mysite.com], where as it should read [product name] classifieds for sale in...  I suspect that the site map may have been submitted when we just had [product name], and updated the page titles later.  However, it has been a couple of weeks that I have confirmed the longer page titles, and still they appear shortened in organic results.  How can I get this looking right in Google's organic results?


A static method parseInt(char[]) that converts an array of numeric characters to an int value

Here's my code  public static int[] parseInt(char[] myChar) {           int[] myInt = new int[myChar.length];     for(int x = 0; x < myChar.length; x++)     {                 myInt[x] = (int)myChar[x];     }     return myInt; }   When I System.out.println(object.parseInt(myChar)); with values {'1','2','3'} I would expect it to print myInt with the corresponding unicode values for {'1','2','3'}.  Instead I get [I@15db9742  Any ideas on what I'm doing wrong?


How to map the F11 and F12 keys to Volume Up/Volume Down

I have chosen to use the F1-F12 keys with their original -PC- behavior, because I want F5 to refresh the page in Firefox! (and not control the backlight of the keyboard)  Now I would like to "remap" the Volume Up/Volume Down key as originaly intended: F11 and F12 keys (I'm used to that). I don't want to have to press Fn everytime.  I've searched everywhere I can't find a way to do that (for now I have to press Fn+F11 and Fn+F12).


I just logged-in to my Gmail and I saw following message:     You’re out of storage space and will soon be unable to send or receive   emails until you free up space or purchase additional storage.   After quick reviewing of my Drive storage, a large portion went to Gmail and Google Photos. I started using Gmail back in 2004 and needless to say I have millions of emails and it's not easy to clean it up.  What's the most efficient way to do clean up my Gmail? (It's not like I can sort by size and see which emails are taking most of space.)  * UPDATE *  after using certain label, such as this:     label:freebsd-questions -label:starred   I hit Delete and a minute later I saw this:     Oops… the system encountered a problem (#793) - Retrying in 1s…   and when I opened another tab to Gmail I saw this:   Gmail by Google   Temporary Error (500)     We’re sorry, but your Gmail account is temporarily unavailable. We apologize for the inconvenience and suggest trying again in a few minutes. You can view the Apps Status Dashboard for the current status of the service.  If the issue persists, please visit the Gmail Help Center »  Try Again Sign Out   Hide Detailed Technical Info Numeric Code: 167   Any advise?


How to describe arbitrary accelerations in special relativity

Describing acceleration in special relativity is in principle straightforward, and for simple cases the resulting transformations are simple. Examples include  and constant acceleration in the accelerating frame (the ). Anything more complicated is going to have to be done numerically, which is fine, but it's not immediately obvious to me how you'd go about this.  Let's call our frame $S$, and our metric is just the Minkowski metric. If we can write down an expression for the trajectory $x(t)$ in our coordinates $x$ and $t$ then everything is straightforward. But this isn't likely to be the case. It's more likely that the aceleration will be given in the accelerating object's frame $S'$ i.e. all we know is $a'(t')$.  So given that all we know is the form of $a'(t')$, how do we set about calculating the rocket's trajectory in our coordinates $S$? General principles will be fine as I'm sure I can work out the fine detail. It's just that I'm not sure where to start.  Assuming I'm not skirting too close to the homework event horizon, this might make a good blog type question. I've been thinking about writing an answer your own question post about acceleration in SR for some time.


I have only had basic classroom experience with physics but I have done a lot of research on my own and I am wondering why a newly formed star or any planetary body composed purely of hydrogen will adopt any state of matter besides its gaseous state.  I understand that as you get closer to the core 'gravity increases" but wouldn't the pull from the surrounding atoms negate any effects strong enough to cause a change in state?


I am trying to recover an installation of Linux on my machine, preferably without having to reinstall Linux (and possibly Windows) altogether.  I have installed  first, and then installed Windows 7. I can no longer boot into Linux, presumably because Windows has overwritten the boot sector and/or master boot record.  I have tried to use  to gain access to my Linux install, without much luck.  What can I do to fix this?


Backstory: I've recently bought a new computer and monitor for my grandpa. When trying to set things up for him, I've encountered weird behavior with one of the cables. I have an HDMI-to-DisplayPort cable that doesn't seem to work. I have 2 different monitors to test, one of them has DisplayPort input only, the other DisplayPort and HDMI, and 3 different computers with an HDMI output (running Windows 10, ArchLinux, MacOS). When using the HDMI-to-DisplayPort cable, none of the computers recognize any of the two monitors to even exist (e.g. xrandr says disconnected). If i use an HDMI cable to hook up the HDMI-capable monitor to the computer(s), it works out of the box in all three cases. Am I correct to conclude that the cable ist just broken and I should return it to the store where I bought it, or is there something else I can try or some quirkyness about HDMI-to-DisplayPort adapters that I'm not aware of that can explain this behavior?


mnt/sdb1 is not ready or present press "s"to skip "M"

I installed Ubuntu 14.04 and all was well until a recent update mess things up. Now when I boot up it get stuck at    mnt/sdb1 is not ready or present press s to  skip M to manually repair   plus another choice. If I select M you get to a dead end and have to reboot. I usually skip to boot. The other choice gets me to the boot screen where you can choose Ubuntu and other choice. Right next to U the Ubuntu choice I see *Ubuntu that is very strange . Can you help? I don't want to reinstall.


Typing a link in comments displayed with http prefix

Is there a way to type in a link in the comments but while keeping the "http://" prefix visible?   Eg. when I type in http://10.0.0.10/wp/ it's converted to 10.0.0.10/wp/ in comments. I'd like it to be displayed just as I typed it, or at least I need some way to make it look like the original...


Leaving macbook plugged in and on 100% all the time

So for the past few years, I've been under the impression that with any modern macbook (e.g., 2015 and later), it's better for the battery health to leave it plugged in as often as you can since the battery deteriorates based on cycle count, so if you leave it plugged in, it's not using the battery and thus not increasing the cycle count. Then I saw this article from last summer  that seems to contradict what I've seen suggested the past few years, which is recommending that your unplug your laptop daily and let it drop to 30-40%. So I am confused on what advice to follow. Each dichotomous suggestion seems to have a basis, but which one is valid?


Why is StringBuilder insert ambiguous with insert(int,Object)?

Could someone help me understand why insert(Integer, char) below is ambiguous with insert(int,Object) ? Although the first parameter is an Integer and second parameter is a primitive char, shouldn't it be clear to call insert(int,char) ? StringBuilder sb = new StringBuilder(); char c ='a'; Integer i=0; sb.insert(i,c);   However, on changing Integer to primitive int, the code compiles fine. I don't understand why that is. char c ='a'; int i=0; sb.insert(i,c);   Edit : I don't see how duplicate marked question answers my question. My question was, method was ambiguous due to second parameter (to my understanding), but changing first parameter code gets compiles.


Changes on one particle system affect other particle systems

I'm making a rabbit, so I used a particle system to make the fur. I made multiple systems by making vertex groups but I faced a problem: when I started to edit the particle system, all the systems make the same changes. For example, I clumped my first particle systems by 1.000 all of them  have the same changes. Can anyone help me thank you  Here's a picture


Is there any insight to Harry Potter's wealth after the first movie?

TLDR   Is  the best indication of Harry's wealth according to our/wizard standards? Is his wealth ever mentioned again after the first book?   I missed the first movie in the Harry Potter marathon running today, but if I remember right the book and the film both had a scene where Harry Potter is confirmed to be "wealthy."  I found this  while trying to see how rich he is. Within it makes it sound as though the business connections were routinely sold off until Harry's father inherited a Scrooge McDuck bank pile of money and left it to Harry upon his death.  According to  (same link as above) Harry's wealth may not be "that" much, though it does not calculate all the pieces or the assets in his name either. Is there any better indication other than this link?


What is the minimum distance between an electron and a positron so that they do not annihilate?  I want to assume that the location of an electron can be determined with an accuracy of 0.004 Angstroms, as described here:  p.127  Under this premise, is there an exclusion criterion for annihilation concerning their spatial distance?


Imagine that I've got a big $N \times N$ boolean matrix (all entries are $0$ or $1$). At the beginning, the matrix is full of zeros.  Then, I execute the following algorithm  Matrix M empty of type N x N while (there is a 0 in M) {     Position pos;     do {         pos = random position in M     } while (pos is 1);     // Here pos is 0     mark pos as 1; }   I want the cost of the previous algorithm (suppose that "there is a $0$ in $M$" has no cost, and that "random position in M" has constant, i.e. $\Theta(1)$, cost).   My intuition says that it is $\Theta(\cdot)$ of $$ 1 + \textrm{Geom}\left(\frac{N^2 -1}{N^2}\right) + \textrm{Geom}\left(\frac{N^2 -2}{N^2}\right) + \cdots + \textrm{Geom}\left(\frac{1}{N^2}\right) $$


In a simple circuit, composed only of a lamp, a generator and a switch that connects the generator to the lamp. What happens with electric current when the switch is open? Electrons turn around? They go in the air scattered in infinity (lol)? I would like to know (I am a beginner).


math.ceil() has a weird behavior...math.ceil(122.0000000000000001) showing 122 while math.ceil(122.00000001) showing 123

math.ceil(122.0000000000000001) showing 122 while  math.ceil(122.00000001) showing 123  There is a limit in math.ceil and why is that for.


I created a . It works great: It displays 60.0 fps normally. If I artificially slow down the game loop, it drops.  My 'game' at the moment is a single keyboard-controlled sprite, so it should be possible to render more frequently than 60 frames a second.  I figured turning off vertical synchronization would increase the FPS cap:  public Game1() {     _graphics = new GraphicsDeviceManager(this)                     {                         PreferredBackBufferWidth = WindowWidth,                         PreferredBackBufferHeight = WindowHeight,                         SynchronizeWithVerticalRetrace = false,                     };     _graphics.ApplyChanges();     Content.RootDirectory = "Content"; }   However, even though the above code seems like it should turn off vsync, it doesn't seem to be. Is there something wrong with my constructor, or perhaps my FPS calculations? Or is there something else that may be limiting the frame count?


Idiom for trying to cover up defects in one's work

Is there any idiom for someone trying to hide or to gloss over or to understate the defects in their work as opposed to covering up to make themselves not look bad?  By "covering up" I mean do something superficial or nominal to pacify the person who pointed out the error but do not actually address the problem (admittedly not precise). By "hide" I mean not acknowledge the problem at all or just disregard the problem or pretend as if there is no problem.


Why Fisher Information uses Log Likelihood and not Plain Likelihood

I would like to know that to determine Fisher information from the Likelihood model, why do we take the log of the likelihood first instead of using normal likelihood ?


I'm looking for a method to center a div in the body, a div without defined dimentions?  Any help would great.


after a loop runs and populates a data table I want to calculate the totals of the columns and display them on the last row.  This is my code to populate the table...I need to build the last row:

     Source Of Issues	     First Issues	     second Issues	     Changes
    <c:forEach var="bean" items="${beans}" varStatus="loopCount">
       ${bean.sorCode}	       <fmt:formatNumber value='${bean.firstissue}'                              type="currency" groupingUsed='true' />	       <fmt:formatNumber value='${bean.secondissue}'                              type="currency" groupingUsed='true' />	       <fmt:formatNumber value='${bean.changes}'                              type="currency" groupingUsed='true' />
   </c:forEach>


What command gives me the highlighted operator?

I need to write this equation in latex, but I don't know how to get the vertical line and the B subscript below it. If anyone knows the operator or command, it'd be very helpful.


Find the positive root of the equation $ce^{-c}-2(1-e^{-c})^2=0$

Can you help me find a root for $c$ in the equation below?   $$ce^{-c}-{10\over5}(1-e^{-c})^2=0$$   By expanding this I got, $$ce^{-c}-2 + 4 e^{-c}-2e^{-2c}=0$$ now grouping, $$(c+4)e^{-c}-2-2e^{-2c}=0 \tag{1} $$  Let $$ e^{-c} = x$$ then $$ c = -\log x$$  Substituting these values in (1), $$x^2 + (\log x - 4) x +1 = 0$$  Now if I apply formula to find the root of quadratic equation, $(\log x -4)$ term is coming inside the square root and making it complex to find the root. Am I proceeding right? Is there any other way to find the root of this equation?  If I plot a graph for this the curve is cutting x axis at $0.49$, which is one of the root. How to arrive at this mathematically?   ?


How do I get constraints to work in game engine?

In the game engine, my object needs to point at a target. How can I get it to aim at something that is constantly moving in unpredictable patterns? The constraints actuator does not have a "track to" that I can see however the 'track to' is exactly the effect I want. I'm using v. 2.71.


Using natural deduction to prove that $p \implies q \vdash \lnot p \lor q$

Using only rules of natural deduction, I am trying to prove that $$p \implies q \vdash \lnot p \lor q$$ but am having a lot of difficulty. I was able to prove the other direction.   Could anyone show me or point me to the right direction?


Java - Unexpected O/P Of Float Converted To Doubl

When I run the following code:  public static void main(String[] args) {     float number = 10.0f/6.0f;     System.out.println(number); }   My output is:  1.6666666   This sort of makes sense to me - float has seven digits of accuracy. Not sure why the integer portion doesn't count as one of those digits, or why the last digit isn't a 7, but okay. Similarly, when i switch to double:  public static void main(String[] args) {     double number = 10.0/6.0;     System.out.println(number); }   My output is:  1.6666666666666667   This also sort of makes sense. Double has greater accuracy. 15 digits according to my textbook. I've got a 16 digit mantissa and this time it rounds up to 7 at the end. Not sure why the deviation in the number of digits, and maybe the 7 at the end where we had a 6 at the end of the float is due to the fact that the original calculation is happening in binary and being converted to decimal.  What I don't understand though is what happens when I do this:  public static void main(String[] args) {     double number = 10.0f/6.0f;     System.out.println(number); }   My output is:  1.6666666269302368   My understanding is that the division results in a float that is implicitly converted to a double when it is assigned to the variable, but where do all the extra digits come from? I expected zeros. I thought that it might be that the java compiler treats the situation specially because it sees that the mathematical expression is part of the declaration and initialization of a double type variable, but the following code has the same output:  public static void main(String[] args) {     float number1 = 10.0f/6.0f;     double number2 = number1;     System.out.println(number2); }   Again:  1.6666666269302368