Improving "demonstrate a minimal understanding" close reason

Note: the eventual outcome of this discussion involved dropping this particular off-topic reason, along with other changes. See:    —Shog     I was using the reason "demonstrate a minimal understanding" myself quite frequently, but the more I review, the more I have doubts about it and I think this reason can either be dropped entirely or at least rephrased, so I started to use "problems with code you've written must describe the specific problem" instead:     Questions asking for code must demonstrate a minimal understanding of the problem being solved.   So the poster has posted some description, maybe even a snippet of code and in his mind that already proves that he has that minimal understanding required. After all he described the problem and what he tried to solve. So telling him that he lacks that understanding is rather rude, and from the posters point of view doesn't even apply. What both version of the reason not emphasize is that a description of a problem is not various versions of     it doesn't work   but that we rather mean really specific details (see below). I can often see in the reopen review queue that the "improved" version just includes a more verbatim description, while what usually would be expected is some specific error message, a trace or a log, or whatever applies.  Then it continues with:     Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist   comparing it to:     problems with code you've written must describe the specific problem — and include valid code to reproduce it — in the question itself. See SSCCE.org for guidance.   Which says essentially the same, only in more detail.   So the "minimum understanding" reason is IMO a more rude version of the reason telling the user that an SSCCE is missing.  The intent of giving this reason is to tell the user that he needs to give exact details to be able to help him, so IMO a checklist would be much better. Something like:     Your question was closed because it may not provide enough details. Things you can do to improve your question to get an answer include:         Format the code in a way that makes it readable and easily understandable.   Provide the smallest working sample of code demonstrating the problem (link to SSCCE)   Include your input and output.   If applicable provide logs (i.e. Android debugging log, stack trace, etc.).   If applicable provide the exact error messages (compiler, etc.).      And something like this should be best included already in the banner that appears when a question is closed instead of being hidden in some pages you often enough have to actively looking for.  It might be helpful to adjust this, based on the tags or close reason, as I realize that I'm more focused on the programming area, and the above list may not apply to other areas of SO.  Update  Another thing I forgot to mention (but wanted to) is this:     Questions asking for code   Is IMO essentially an invitation of the type of questions     I have a problem, can you provide the solution? (with an optional please)   while     Questions concerning problems with code you've written   puts at least some emphasis on the fact that the poster has to put some effort himself in trying to solve the problem by providing the code which he used to attempt the solution.


How to reduce space between two columns in html table

I am using data table for displaying data from the database. There is some space between two columns of the data table. How to reduce the space between them. I tried cellspacing but it is deprecated in html5. Is there any possible way to do this.


Proving that $f(x)$ is less than or equal to $1+\pi/4$

Suppose $f$ is a real valued differentiable function defined on $[1,\infty)$ with $f(1)=1$. Suppose also that $f$ satisfies $$f'(x)=\frac{1}{x^2+f^2(x)}.$$ The question is to prove that $f(x) \leq 1+\pi/4$ for every $x \geq 1$    I tried to solve the differential equation but could not bring it in some known form. I examined the derivative of $\tan^{-1}x$ which looks similar to that  in the question. However I could not get any idea with that. Any help shall be highly appreciated. Thanks.


Installed libncurses5-dev, but can't make menuconfig!

I installed Kernel and required libraries. I don't know why I'm getting this error   batman@tx:~/kernel/linux$ sudo make menuconfig scripts/kconfig/mconf  Kconfig init/Kconfig:409: unexpected 'endchoice' within menu block init/Kconfig:1759: unexpected end statement make[1]: *** [menuconfig] Error 1 make: *** [menuconfig] Error 2   If run without sudo I'm getting like below  batman@tx:~/kernel/linux$ make menuconfig  *** Unable to find the ncurses libraries or the  *** required header files.  *** 'make menuconfig' requires the ncurses libraries.  ***   *** Install ncurses (ncurses-devel) and try again.  ***  make[1]: *** [scripts/kconfig/dochecklxdialog] Error 1 make: *** [menuconfig] Error 2   Ok, I copied config from /boot/.., so I want to continue without configuration. Again, I got this  batman@tx:~/kernel/linux$ make -j5 KDEB_PKGVERSION=1.veeru dep-pkg scripts/kconfig/conf  --silentoldconfig Kconfig init/Kconfig:409: unexpected 'endchoice' within menu block init/Kconfig:1759: unexpected end statement make[2]: *** [silentoldconfig] Error 1 make[1]: *** [silentoldconfig] Error 2 make: *** No rule to make target `include/config/auto.conf', needed by `include/config/kernel.release'.  Stop.   In another video, they compiled the kernel like this  batman@tx:~/kernel/linux$ fakeroot make-kpkg -j5 --initrd --append-to-version=veeru kernel_image kernel_headers  exec make kpkg_version=12.036+nmu3 -f /usr/share/kernel-package/ruleset/minimal.mk debian APPEND_TO_VERSION=veeru  INITRD=YES  ====== making target debian/stamp/conf/minimal_debian [new prereqs: ]====== This is kernel package version 12.036+nmu3. test -d debian             || mkdir debian mkdir: cannot create directory ‘debian’: Permission denied make: *** [debian/stamp/conf/minimal_debian] Error 1 Failed to create a ./debian directory: No such file or directory at /usr/bin/make-kpkg line 984.   So, why I'm getting these errors, can someone explain that make.. command(I know -j is for jobs). Most of the times I don't know what I'm doing(What's happening, why I'm doing like, etc). So, is there any articles for newbies like me for GREAT start to know KERNEL stuff :-)   UPDATE:  I just want to know, why those errors are coming even I installed the rightpackages(). What are the way to compile the Kernel. Why different ways?  Ubuntu 14, Downloaded Kernel from kernel.org(4.2 Release)


Is $\sum_{k=0}^n \left(k+1\right)\left(C^n_k\right)^2 = \frac{n+2}{2} C^{2n}_n$ for any positive integer $n$?

Today I had a test about IMO which is pretty hard though, I have worked on a combinatoric question that I found a special formula: $$\sum_{k=0}^n \left(k+1\right)\left(C^n_k\right)^2 = \dfrac{n+2}{2} C^{2n}_n$$ I don't know it is true or not, but it seems true because I have tested for some small $n$ and it is true. I have thought of using binomial theorem and breaking the $C^{n}_k$, but I still can't prove it. Luckily, I can do the question without using this formula, but I still someone can prove this formula. Tips and comments are welcome too.


I'm writing a LaTeX document and want to include several listings for source code examples.  Is there a way to disable the selection of line-numbers when selecting the source code?  My prof just wants to copy/paste the source code from the final pdf-file without manually removing all the line numbers afterwards. Does anyone know how to fix this problem?


Disk errors during boot, failed command: READ FPDMA QUEUED

Ubuntu boot takes long time, and on boot I get these errors:    Similar errors appear on shutdown (which is also slow), however Windows 10 on the same SSD boots normally. I tried to reinstall Ubuntu, but that fixed nothing and same errors occur when I boot from live USB. What's the problem and how can I try to fix it?


What guidelines exist for players creating characters for organized play?

With Hoard of the Dragon Queen releasing as the first part of the Tyranny of the Dragons storyline I was wondering what guidelines and rules exist for players looking to create and run characters for organized play.


For all PRNGs (including CSPRNGs) lets say there is a sequence x, y, z, then when the PRNG cycles back to x, then the sequence following it will be exactly the same as before. Is this true for all PRNGs?  Are there any rules about minimum cycle length for CSPRNGs used for Stream Cipher? Because if a cycle happens, then the One Time Pad is no longer a One Time Pad and becomes insecure, right?   What are the average cycle lengths for commonly used Stream Cipher algorithms?    Is it not possible to prevent cycling by making the algorithm dependent on what it is encrypting - i.e. something like   The stream cipher is used for encrypting communication between Alice and Bob. Alice's key is K1 & Bob's is K2. This is the conversation  Alice: Hello, Bob Bob: Hello, Alice Alice: How are you?    So    K1 is used to generate the stream for encrypting "Hello, Bob" and it's sent.   The next stream generated not only depends on state of the PRNG after generating the stream for "Hello, Bob" but "Hello, Bob" is also used as input for this stream. And this will be used for encryption "How are you?" and so on.


Why a tesselation of the plane by a convex polygon of 7 or more sides is not possible?

I read in several places, including Wikipedia, that a tessellation of the plane by a single, convex, $n-$sided polygon is not possible for $n\geq7$. I was not able to locate a proof, or a paper that discusses this. Maybe it is too trivial, but I am not able to figure it out myself.   So I would like to ask you for help. Where can I find a proof for this?  Also, I am interested in the mathematical background behind plane tiling (especially periodic), If you can suggest papers on the topic it would really help.


I got a pair of diamond earrings(worth $1600) for my wife while in India. My question is can I bring it back with me to the US as my personal possession or do I have to declare it at the customs?  Thanks,


Could not get lock error when trying to install wine

I tried installing wine using the command   sudo apt-get install wine   but I got the following  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?   I don't understand. Any help?


Finding remainder of dividing and moding large exponents

Can anyone explain how to calculate the remainder for types of problems like this:     $2^{2131312213123}$ divided by 100      $13^{6601}$ mod 77


Let's solve the (real) equation $$x^{x^{x^{\dots}}}=2\qquad (x>0).$$ If we call $E(x):=x^{x^{x^{\dots}}}$, it holds that $x^{E(x)}=E(x)$, but our equation says that $E(x)=2$, so it holds that $x^2=2$, whence $x=\sqrt2$. Noew, lets solve $$x^{x^{x^{\dots}}}=4\qquad (x>0).$$ A similar arguments, leads us to to solve $x^4=4$ whose solutions are $x=\pm\sqrt2,\pm i\sqrt2$, so the only positive solution is, again $x=\sqrt2$. But this yields to the contradiction that $2=4$. So, my question is... what's wrong here?  My intutition says that is has something to do with the complex solutions of $x^4=4$, but I'm not really sure. Als0 it may something to do with the convergence of the next sequence: $$S_1(x)=x>0,\qquad S_{n+1}(x):=x^{S_n(x)}$$ but I'm not able to study its convergence.


I run a script like:  sleep 20 & PID=$! kill -9 $PID >/dev/null 2>&1   I dont want the script show the output like:  line 51: 22943 Killed  sleep   I have no idea why this happen, I have redirect the output to /dev/null


I tried to execute sudo add-apt-repository ppa:graphics-drivers/ppa to install the latest GTX 1070 driver as explained   This command ended up with an error:     Get:12  any InRelease [23.2 kB]   Err:12  any InRelease         The   following signatures couldn't be verified because the public key is   not available: NO_PUBKEY 696DBE66A72D76DA Fetched 23.2 kB in 3s (8,640   B/s)       Reading package lists... Done W: An error occurred during the   signature verification. The repository is not updated and the previous   index files will be used. GPG error:    any InRelease: The following   signatures couldn't be verified because the public key is not   available: NO_PUBKEY 696DBE66A72D76DA W: Failed to fetch     The following   signatures couldn't be verified because the public key is not   available: NO_PUBKEY 696DBE66A72D76DA W: Some index files failed to   download. They have been ignored, or old ones used instead.   Then I added the PUBKEY with     sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 696DBE66A72D76DA    as explained .  Now I get this error:     Get:12  any InRelease [23.2 kB]          Reading package lists... Done      E: Repository   ' any InRelease' changed its   'Origin' value from 'packagecloud.io/sensiolabs/sensiolabs' to   'packagecloud.io/blackfire-io/stable' E: Repository   ' any InRelease' changed its   'Label' value from 'sensiolabs' to 'stable' N: This must be accepted   explicitly before updates for this repository can be applied. See   apt-secure(8) manpage for details.   How can I solve this issue?


Variance of linear combination of random variables

Let $X_1, X_2,...,X_{2n}$ be random variables such that $V(X_i)=4, i=1,2,...,2n$ and $Cov(X_i, X_j)=3, 1\leq i\neq j\leq 2n$. Then find  $V(X_1-X_2+X_3-X_4+...+X_{2n-1}-X_{2n})$.  I know that      $V(\sum\limits_{i=1}^{n}a_iX_i)=\sum\limits_{i=1}^{n}{a_i}^2V(X_i)+2\times\sum\limits_{i,j(i\neq j)=1}^{n}a_ia_jCov(X_i,X_j)$   So, for this problem,  $V(X_1-X_2+X_3-X_4+...+X_{2n-1}-X_{2n})$  $=\sum\limits_{i=1}^{2n}V(X_i)+2\times\sum\limits_{i,j(i\neq j)=1}^{2n}a_ia_jCov(X_i,X_j)$  $=8n+2\times\sum\limits_{i,j(i\neq j)=1}^{2n}a_ia_jCov(X_i,X_j)$  But I cannot calculate the $\sum\limits_{i,j(i\neq j)=1}^{2n}a_ia_jCov(X_i,X_j)$ part.  Please anyone help me solve the above problem. Thanks in advance.


MLX90616 Infra Red Temperature Sensor problem

Recently I have been trying to interface with the MLX90616 an infra red temperature sensor by Melexis. After reading the datasheet I have I have written a program to take the object temperature readings via the on board SMBus. Everything on my end seems to be working however the the temperature readings are taking extremely long (greater then 10 minutes) to reach the object temperature. Based on the datasheet the temperature should settle within seconds thanks to the inbuilt thermal gradient compensation. Is there some EPROM setting I have missed to turn on the thermal gradient compensation to acquire fast stable readings?  Further more has anybody had a similar experience with this sensor? I am unable to find any details of others who have used this particular sensor in the past so some details would be greatly appreciated.  I have attached the main body of my code for your reference:   I2C1_Init(50000);                   //I2C clock must be in the range of 10kHz to 100kHz for operation according to the SMBus specifications   //delay_ms(100);                      //Allow time for the SSP module to initialise    I2C1_Start();   //Sometimes if I2C read is peformed without an acknologment it can hang the I2C BUS error check on each operation is therefore necessary   if(I2C1_Wr(0xB4) == 0)           //Address for a write operation to 0x5A   {     if(I2C1_Wr(0x07) == 0)         //Address for RAM command to 0x7     {       I2C1_Repeated_Start();       if(I2C1_Wr(0xB5)== 0)        //Address for read operation to 0x5A       {         lowerByte = I2C1_Rd(1);         upperByte = I2C1_Rd(1);       }     }   }   I2C1_Stop();


I played Monopoly, and I passed Go, and landed on the Community Chest 2 spaces after the Go space. I picked up the "Pay $10, or draw a Chance Card". I drew a Chance card and I got "Go back three spaces."  Now, since I passed Go backwards, do I get $-200 (i.e., pay $200), and/or do I get another $200 the next turn when I pass Go forwards again?


How to correctly pin the users folder to the sidebar after changing their location from the C drive to the D drive

I've changed the location of the library folders from the default C drive to the D drive.  When I pin the music library folder quick search, which is in the D drive, it pins a music library folder with the location on the C drive, which doesn't even exist; it I try to unpin it, it doesn't work; the only way it unpins is if I create the music folder on the C drive and change the location of the music folder that is on D to the C drive again.  This behavior's happening on the music and videos folder, but not on the documents, downloads, pictures or desktop folder.  The following error appears when I click the pinned folder on the quick access:  and the folder looks like ; the location appears to point toward the C drive, but I clicked on pin on the folder of the D drive.  What can I do?


I have a list where new users are added as they input there information. The problem is that if a user do a search they can pull up other users ss. How can I prevent other users from searching in the search for other users information. If that make sense?


Is "Too old to migrate" a good reason NOT to migrate?

I flagged this question:  with a note:     Should this not be moved to codegolf? It is that type of question...   And I got the response:     declined - Too old to migrate.   What does that mean? CodeGolf did not exist when this question was posted, and now it does, so it should be migrated  We have done this before countless times, especially with many questions which used to be on Stack Overflow and now are here on meta.  As shown by the selected answer here: , We should be migrating old questions.


Simplify $0 \binom{n}{0} + 2 \binom{n}{2} + 4 \binom{n}{4} + 6 \binom{n}{6} + \dotsb,$ where $n \ge 2.$ Enter your answer in the form $f(n) 2^{g(n)},$ where $f(n)$ and $g(n)$ are polynomials in $n$ with integer coefficients. I know how to do this question where the numbers are consecutive and I also know that $\binom{n}{0} + \binom{n}{2} + \binom{n}{4} + \cdots = 2^{n-1}. $ How do I use this information to solve this problem?


How to install Realtek RTL8723BE wifi PCIe Wireless Network Adapter

My system is Ubuntu 14.04 32 bit and kernel is 3.13.0-24-generic. How can I download and install wifi driver for above mentioned Network adapter Realtek RTL8723BE?


I am trying to install oracle jdk7 64bit on my computer.   I found this   It uses update-alternative -install to install the JDK which is new to me.   I used to only extract the files and add the jdk location to the PATH environment variable before.   Now it seems that I have to run the following commands more than once if I want to install other executables:  sudo update-alternatives --install "/usr/bin/xx" "xx" "/usr/lib/jvm/jdk1.7.0/bin/xx" 1 sudo chmod a+x /usr/bin/xx   Just like the post said:     N.B. remember - Java JDK has many more executables that you can   similarly install as above. java, javac, javaws are probably the most frequently required.   I think this is rather inflexible. So I want to know what the advantage of using update-alternative to install jdk over other methods is.


Basic question about inseparable field extension

Suppose $L/K$ is not separable. Does this imply that there is an $a\in L$ such that $a^p\in K$ but $a\not\in K$? I know that the characteristic of the fields must necessarily be $p>0$. By definition, there must be some $a\in L$ that is inseparable; that is, it must have a minimal polynomial that has multiple roots in a field extension. Equivalently, its derivative must be $0$. Where to go from here?


Characterization of two-step 2x2 stochastic matrices

Show that:     A 2 x 2 stochastic matrix is two-step transition matrix of a Markov chain if and only if the sum of its principal diagonal terms is greater than or equal to $1$.


Using field calculator unable to keep time and date format

I was looking to keep the date/time as is when using field calculator to keep the format as I'm not able to maintain the time in the new field "da". This is what I get when trying to do so. I tried searching for solutions, but to no avail so far.  Update based on comments:  I'm using field calculator to solve this. I'm calculating into a date field from string field. Data source is a shapefile


I got a strange icon I've never seen before on my Samsung A3. It's in the top left corner, shaped like an 'o' letter, but with the top right quarter of the circle broken. Its not a sync icon (that has arrows and it's broken in two halves). Does anybody know what it means? I could not find it anywhere on the web. In the notification swipe screen there is nothing that points at its meaning.  See answer


"Should be done by" or "should have been done by"?

Which of these should I use?      My test result should be done by last Wednesday.   or     My test result should have been done by last Wednesday.   What is the difference in meaning?


R seq gives very small, non-zero output for specific sequence


Convex cyclic hexagon $ABCDEF$. Prove $AC \cdot BD \cdot CE \cdot DF \cdot AE \cdot BF \geq 27 AB \cdot BC \cdot CD \cdot DE \cdot EF \cdot FA$

Convex hexagon $ABCDEF$ inscribed within a circle. Prove that $$AC \cdot BD \cdot CE \cdot DF \cdot AE \cdot BF \geq 27 AB \cdot BC \cdot CD \cdot DE \cdot EF \cdot FA\,.$$  I was thinking of represending the inequalities in trigonometry then use Language multiplier. For example let $\angle AOB = \theta_1$, $\angle BOC = \theta_2$, represent the inequality in trigonometry, subject to constraint $\theta_1 + \theta_2 + ... + \theta_6 = 2\pi$. But it's still quite a bit of work and I didn't manage to get to the end. It also seems a bit overkill -- might be better solution? Would like to see any approach.


NullPointerException error when using Robolectric to write android tests

Test code:  @RunWith(RobolectricTestRunner.class) @Config(constants = BuildConfig.class) public class MainActivityTest { private MainActivity mainActivity;  @Test public void testMainActivity() {     MainActivity mainActivity = Robolectric.setupActivity(MainActivity.class);     mainActivity.findViewById(R.id.visual_button).performClick();     Intent expectedIntent = new Intent(mainActivity, VisualActivity.class);     ShadowActivity shadowActivity = Shadows.shadowOf(mainActivity);     Intent actualIntent = shadowActivity.getNextStartedActivity();     Assert.assertEquals(expectedIntent, actualIntent); } }   error reports:  java.lang.NullPointerException   my Robolectric version is 3.1.4... l have tried to find some solutions but failed. l'm sure that my test code are under src/test, not src/androidTest, can anybody help me ? Thanks in advance!


How to calculate a heading on the earths surface?

Given an initial position and a subsequent position, each given by latitude and longitude in the WGS-84 system.  How do you determine the heading in degrees clockwise from true north of movement?


Example of a finitely generated module with submodules that are not finitely generated

I'm looking for an example of a finitely generated module with submodules that are not finitely generated.  I've found  dealing with group (i.e. an example of a finitely generated group with subgroups that are not finitely generated). But I can't figure out whether that question do help to this one.  And I actually want to find a more "module-like" example rather than an example derived from a 'strange' group.  Can you please help? Thank you!


Is there a interpretation difference between "..." and '...'?

All coding "tutorials" I've used so far use single quotes (' '), but they need to escape apostrophes using a \.  So I've switched to use double quotes (" ") because they work just as well without the need to escape special punctuation signs.  Is there a difference how JavaScript or jQuery interprets the string depending on the type of quote I use? Is there a speed or possible syntax issues with using one over another?


Given a function $f(t)$, is it possible to construct Lagrangian $\mathcal{L}$ such that $\frac{\mathrm{d}}{\mathrm{d}t}\frac{\partial\mathcal{L}}{\partial \dot{f}}=\frac{\partial\mathcal{L}}{\partial f}$, when solved with appropriate boundary conditions, gives $f(t)$.


I have watched many physics debated and in everyone of them, physicists take big bang for granted. But, is the big bang actually proven, or there are many evidence that indicate that it did happen?


Proving the so-called "Well Ordering Principle"

Is there anything wrong with the following proof?  Theorem. Every non-empty subset $B \subset\mathbb{N}$ has a least member.  Proof. Assume not. Then, of necessity, we'd have to have $B=\varnothing$, for if $B$ contained even one $b\in\mathbb{N}$, then that $b$ would satisfy $b=min(B). $ Contradiction, end proof.  I get the sense there is something wrong here, but I can't seem to define exactly what. Also, is there a context where one can simply take this principle as an axiom, and not have to prove it? After all, it is extremely intuitive. Thanks.


Include .txt file in existing javascript function

I have this javascript function which requires some variables I would like to be called from an external .txt file instead:  <script language="JavaScript">  StartCountDown("1070","08/21/2014 15:32 +0300") StartCountDown("1071","08/21/2014 16:00 +0300") StartCountDown("1072","08/21/2014 16:00 +0300")  ... rest of the function </script>   would be better if  <script language="JavaScript">  **include stuff from variables.txt here**  ... rest of the function </script>   Is there any way to do this? Thanks.


Drawing Torus with semi-dashed line on it

I would like to draw :     To draw the above torus, I have used the following codes :   \documentclass[margin=2mm,tikz]{standalone} \usepackage{pgfplots} \begin{document} %Oberflächenproblem \begin{tikzpicture}[rotate=180] %Torus \draw (0,0) ellipse (1.6 and .9); %Hole \begin{scope}[scale=.8] \path[rounded corners=24pt] (-.9,0)--(0,.6)--(.9,0) (-.9,0)--(0,-.56)--(.9,0); \draw[rounded corners=28pt] (-1.1,.1)--(0,-.6)--(1.1,.1); \draw[rounded corners=24pt] (-.9,0)--(0,.6)--(.9,0); \end{scope} %Cut 1 \draw[densely dashed] (0,-.9) arc (270:90:.2 and .365); \draw (0,-.9) arc (-90:90:.2 and .365); %Cut 2 \draw (0,.9) arc (90:270:.2 and .348); \draw[densely dashed] (0,.9) arc (90:-90:.2 and .348); \end{tikzpicture} \end{document}     It produces:      This is not the same what I want. How can I do the desired torus?


Why int r = (int, int, int); doesn't give error and r has the value of the last integer?

r has always the last integer between the parenthesis.  What is the output of the following program?  #include <iostream> using namespace std; main() {     int i = 1, j = 2, k = 3, r;     r = (i, j, k);     cout << r <<endl; }   Possible answers:  A - 1 B - 2 C - 3 D - Compile Error   What I want to know is why does this happen.


I don't know whether this is a foolish question or not. Is there a way to make two separate dual-core systems to run as a single quad-core system under a single operating system?


I was wondering what you do when developing a new application in terms of estimating database size.  E.g. I am planning to launch a website, and I am having a hard time estimating what size I could expect my database to grow. I don't expect you to tell me what size my database will be, but I'd like to know if there are general principles in estimating this.  E.g. When Jeff developed StackOverflow, he (presumably) guesstimated his database size and growth.  My dilemma is that I am going for a hosted solution for my web application (its about cost at this stage), and preferably don't want to shoot myself in the foot by not purchasing enough SQL Server space (they charge a premium for this).


I have a stack of $n$ distinct cards. I randomly draw $N$ cards from the stack with replacement. Assume that $N \ge n$.  What is the probability that I observe all cards at least once?  I got this far:  The probability that the multiplicities of the states in the sample are $m_1, \dots, m_n$ is:  $$\frac{1}{n^{N}}\frac{N!}{m_1! \dots m_n!}$$  Therefore, the probability we want is found by evaluating the sum:  $$\frac{1}{n^{N}}\sum_{\begin{subarray}{c} m_{1}+\dots+m_{n}=N\\ m_{k}\ge1 \end{subarray}}\frac{N!}{m_{1}!\dots m_{n}!}$$  However, I'm stuck since I'm not sure how to evaluate this. I tried a change of variables $r_k = m_k - 1$, but this messes the factorials in the denominator.  Update: I found this paper, which contains a solution:      Kullback, Solomon. 1937. “On Certain Distributions Derived From the   Multinomial Distribution.” The Annals of Mathematical Statistics 8(3):   127–44. .


Prove or disprove: Every bounded lattice is complete. It can be easily proved that every complete lattice is bounded. But is the converse true?


What is the probability of player A winning this Coin Toss Game?

Player A throws a fair coin n+1 times. Player B throws the same coin n times. Player A wins if she throws more heads than Player B. What is the probability of player A winning the game?  My approach has been that since the answer is independent of n, so I chose n=1. So, A can win 3 out 8 times (assuming that Head-Tail is same as Tail-Head) hence the probability is 3/8. Is my assumption correct? What about the approach? How can the solution be generalized?


Changing a simple database class in order to support prepared statements

My question is about my code. I have created 2 websites. But it's on mysqli PHP OOP. Someone told me that these queries are SQL Injection. So, i wanna change my database structure to prepare statements. Then, i can save my websites from SQL Injection. For that, I need your help. Here is my database structure: config.php  <?php  define("DB_HOST", "localhost"); define("DB_USER", "root"); define("DB_PASS", ""); define("DB_NAME", "lunch"); ?>   Database.php  <?php     $filepath = realpath(dirname(__FILE__));     include_once ($filepath.'/../config/config.php'); ?> <?php  Class Database {      public $host = DB_HOST;     public $user = DB_USER;     public $pass = DB_PASS;     public $dbname = DB_NAME;     public $link;     public $error;      public function __construct() {         $this->connectDB();     }      private function connectDB() {         $this->link = new mysqli($this->host, $this->user, $this->pass, $this->dbname);         if (!$this->link) {             $this->error = "Connection fail" . $this->link->connect_error;             return false;         }     }      public function select($query) {         $result = $this->link->query($query) or                 die($this->link->error . __LINE__);         if ($result->num_rows > 0) {             return $result;         } else {             return false;         }     }      public function insert($query) {         $insert_row = $this->link->query($query) or                 die($this->link->error . __LINE__);         if ($insert_row) {             return $insert_row;         } else {             return false;         }     }      public function update($query) {         $update_row = $this->link->query($query) or                 die($this->link->error . __LINE__);         if ($update_row) {             return $update_row;         } else {             return false;         }     }      public function delete($query) {         $delete_row = $this->link->query($query) or                 die($this->link->error . __LINE__);         if ($delete_row) {             return $delete_row;         } else {             return false;         }     }  }  ?>   And i am writing my queries like this:  <?php     $filepath = realpath(dirname(__FILE__));     include_once ($filepath.'/../lib/Database.php'); ?>  $name = mysqli_real_escape_string($this->db->link, $data['name']); $query = "INSERT INTO users(name) VALUES('$name')"; $result = $this->db->insert($query); if($result != false){     header("Location: index.php"); }  $query = "SELECT * FROM users WHERE user_id = '$user_id'"; $result = $this->db->select($query); $value = $result->fetch_assoc(); $name = $value['name'];  $query = "DELETE FROM users WHERE user_id = '$dlt_user'"; $result = $this->db->delete($query); if($result){     header("location: rd-user.php"); }  $query = "UPDATE users SET name = '$name' WHERE user_id = '$userid'"; $result = $this->db->update($query); if ($result){     header("Location: index.php"); }   Hey Your_Common_Sense brother! See this screenshot:  So, kindly please check my database structure and queries and tell me how can i change my db structure to prepare statements and how can i prevent from SQL Injections. Please help me.


If the Terminator had killed Sarah Connor in 1984, would he have gone on a mass killing spree until he was destroyed?

If the Terminator had completed his mission in 1984 by killing Sarah Connor, is it likely that he would have gone on a mass killing spree until he was destroyed by the police/military?  In other words, did Skynet give him a secondary mission other than just killing Sarah Conner and what was that mission?


Today I encountered this problem after the dictation of some lines with Dragon 13. The problem is eliminated if I copy and paste the same content on another page, or when I delete part of the things dictated with dragon. so if I rewrite the same things with the keyboard, the problem does not occur. I do not insert the MWE because it would not make sense. I insert two screenshots  --------------------FIRST--------------------  \begin{align} 10\cdot 100= 1\cdot^{3} \;\rightarrow\; R_{e} =\nicefrac{10^{3}}{10^{-5}} = 10^{8}\nonumber \end{align} Le dissipazione viscose pertanto, non possono indicare se esiste o meno una condizione di turbolenza nel momento in cui l'aria attraversa la collina. Quest'aspetto invece è fondamentalmente legato alle forze di galleggiamento e quindi al numero di Froude. Nel caso di \textit{stratificazione stabile}, le forze di galleggiamento smorzano le oscillazioni che subiscono le particelle e il flusso rimane laminare ossia non si genera turbolenza.\\     --------------------SECOND--------------------  \begin{align} 10\cdot 100= 1\cdot^{3} \;\rightarrow\; R_{e} =\nicefrac{10^{3}}{10^{-5}} = 10^{8}\nonumber \end{align} Le dissipazione viscose pertanto, non possono indicare se esiste o meno una condizione di turbolenza nel momento in cui l'aria attraversa la collina. Quest'aspetto invece è fondamentalmente legato alle forze di galleggiamento e quindi al numero di Froude. Nel caso di \textit{stratificazione stabile}, le forze di galleggiamento smorzano le oscillazioni che subiscono le particelle e il flusso rimane laminare ossia non si genera turbolenza.\\ La stratificazione è \textit{stabile} quando si hanno densità maggiori in basso e minori in alto ($caldo/freddo$). In questa condizione pur incontrando un fenomeno perturbativo, non si genera distacco dalla vena, poiché vi è un pacchetto di strati fluidi che in corrispondenza della collina vengono compressi. Il mescolamento pertanto, avverrà subito dopo la stratificazione stabile, cioè superata la collina il flusso si allarga con turbolenza decrescente.\\     ---------------UPDATE---SOLUTION----------------  I found the solution. it is not an image, but a too large "note" box, which was influencing the above text. I neglected the detail.  bla bla bla  \begin{itemize}      bla bla bla \end{itemize}   bla bla bla  \begin{align}  bla bla bla \end{align}  bla bla blaa:  **\newpage**   %<----------------------- \begin{note}{Riassumendo}     \begin{itemize}          bla bla bla         ..................     \end{itemize}  \end{note}


can you find the geometric mean of a continuous variable, in a similar why to find the mean of a continuous variable.

Can you find the geometric mean of a continuous variable, in a similar why to find the mean of a continuous variable. To find the regular mean of between to points on a function you do $\frac{\int_{a}^{b} f(x) \,dx}{b-a} $ If there is 1 point that lands in $0$ it would all become all zero so it might not make any sense to take a geometric mean of a continuous variable. Mean $$\frac{\sum_{n=1}^{k} a_k}{n}$$ Geometric Mean $$(\prod_{n=1}^{k} a_k)^{\frac{1}{n}}$$


Scaling a tikzpicture to fit in a beamer frame

How can I vertically scale the figure to accomodate on the frame?  \begin{frame}{P\textsuperscript{H}metry studies} \begin{figure}[scale=0.5\textheight] \begin{tikzpicture} \node [block] at (0,6) (GERD){GERD}; \node [block] at (-3,4) (Esophagitis){Reflux esophagitis}; \node [block] at (0,4) (NERD){NERD}; \node [block] at (3,4) (Barret){Barret's esophagitis}; \node [block] at (0,2) (Ph){Ph testing}; \node [block] at (-3,0) (positive) {Ph +ve NERD}; \node [block] at (3,0) (Negative){Functional heart burn}; \node[] at (3,-2)(Symptoms) {\footnotesize {Symptoms associated with P\textsuperscript{H} changes?}}; \node [block] at (5, -4)(hypersensitive) {hypersensitive esophagus}; \node[block] at (1,-4)(unassociated){Acid unassociated heart burn}; \begin{scope}[cyan!40!black] \draw[->] (GERD) -- (Esophagitis); \draw[->] (GERD) -- (NERD); \draw[->] (GERD) -- (Barret); \draw[->] (NERD)--(Ph); \draw[->](Ph)--(positive); \draw[->](Ph)--(Negative); \draw[->](Negative)--(Symptoms); \draw[->](Symptoms)--(unassociated); \draw[->](Symptoms)--(hypersensitive); \end{scope}  \end{tikzpicture} \end{figure} \end{frame}


For example  If arrayToSearchThrough(i + j) <> patternToFind(j) Then     found = False     Exit For End If   What does <> this mean in Visual Basic .Net


I read  article about the working of Full Joins. The article says that a Full Join, which combines the results of Left Join and Right Join, "retains duplicate rows". Therefore, in order to simulate a FULL JOIN, we use UNION ALL instead of UNION. But, when I perform a FULL JOIN on two tables in Oracle, I do not find duplicates at all. (I believe, Oracle internally uses the 'UNION ALL' operation on left and right joins to perform a FULL JOIN.) The left join and right join contain some common rows, but when I run a full join, those common rows don't appear twice. Results of Left Join : SELECT * FROM ORDERS LEFT JOIN CUSTOMER ON ORDERS.CUSTOMERID = CUSTOMER.CUSTOMER_ID;  Results of Right Join : SELECT * FROM ORDERS RIGHT JOIN CUSTOMER ON ORDERS.CUSTOMERID = CUSTOMER.CUSTOMER_ID;  Results of Full Join : SELECT * FROM CUSTOMER FULL OUTER JOIN ORDERS ON CUSTOMER.CUSTOMER_ID = ORDERS.CUSTOMERID;  As you can see from the results of FULL JOIN, it "Does not contain duplicate rows" , even though left join and right join have some common rows. So, why is it believed that a full join contains duplicate rows ? Am I missing something ?


For a game I need OpenGL 2.1 or higher, but I want it to run on my good old Win XP box with an ATI Radeon 9200SE graphics card. It currently seems to have OpenGL 1.3.1008 WinXP Release and graphics driver version 6.14.10.6542 installed.  Searching for OpenGL 2.1 to download only resulted in several downloads of version 1.1 for Windows 95.   Do I need a separate OpenGL installation/upgrade or has it to be included into my graphic card driver? Where can I get it?


I am a regular user of stack overflow... I am not getting my reputation notifications(on cup) when someone upvotes or downvotes me from today morning but can see my reputation goes increasing... Why this is happening?


How can you quickly get the complete path to a file for use in terminal?


Could someone please explain, why the pronoun and the verb "be" are omitted in the following sentence?   "it allows communication even for people far away from each other"  Shouldn't this sentence be "it allows communication even for people WHO ARE far away from each other"?


In Bridge, what is the punishment for misclaiming tricks?

Down to the last two rounds in rubber bridge.  Declarer claims remaining tricks only to discover that he has miscounted.  He claims the two tricks with Q-10; however, opponent holds the J and depending on how he plays the cards could lose one trick.  How is this handled?  Is scoring affected?  Consider the same scenario only opponent holds the Q.  Do opponents just get the one trick and game is scored as usual?


test class coverage differences in sanboxes

I have created a test class for a trigger and apex class for trigger code coverage is 80% and test class is 81% in Sandbox1.          when I have created same test class for a trigger and apex class, for trigger code coverage is 0% and test class is 0% in another sanbox2.          Both sanbox1 and sanbox2 are identical but I don't know why the code coverage is not happening in sanbox2. Can anyone know the reason?


Show that $\lim_{p→∞} ||x||_p = ||x||_∞$

For any $x ∈ \mathbb{R}^n$ and $p ≥ 1$, define $$||x||_p = \left(\sum_{i=1}^n|x_i|^p\right)^{\frac1p},||x||_∞ = \underset{1≤i≤n}{\max}|x_i| $$   Show that $$ \underset{p→∞}{\lim} ||x||_p = ||x||_∞$$   I understand this in theory, that if $x_i < x_j$ then as they are both raised to the power of ∞ then $x_i$ will become arbitrarily small relative to $x_j$, and so their sum to the power of $\frac1∞$ is $\approx x_j$. But I don't know how to go about proving this formally.


Are neutrinos affected by electromagnetic forces?

I know they don't interact with matter nor any electromagnetic forces, but I know they have mass, very little mass but they have. When something has mass it must be attracted by gravity and other objects (electromagnetic) right?


A word that means to both encrypt and decrypt

I am currently writing a small class in C# which will take an image, decompile it down to a byte array, obfuscate the data into a proprietary format (thus making it unreadable), and store said data into a file. The class will also optionally recompile the data, thus decrypting the proprietary format back into an image so that it can be used.  I was just wondering if someone with a better vocabulary than myself could throw a couple of words at me that would mean the same thing as encrypt and decrypt, but as a single word. I understand that there may not be a word for this, because the words hold very different meanings at their base level. However, if someone has anything good I would love to hear it.


When should I start an LLC for my side work?

I am doing quite a bit of sidework this year and wondering at what point would it be a good idea to "start a business" and bill through that.


Which one is correct if I am asking about a group of people that someone is going to meet?  I know that the it should depend if the following word is on singular or plural, but on this case I am not sure as "who is going to the PLACE A" has no indication of plural or singular. Who is going feels right.... but I might be wrong.


$$\int_0^{2\pi}e^{\cos x}\cos(\sin x)dx$$  I tried Integration by parts but failed. Wolfram alpha gives answer in decimal points which are same as of $2\pi$. Any hints or suggestions will be helpful.


If I am instructing someone to make a number negative, is there a verb I can use?  Negitivise? Negify? Negate, for me, does not work as this is to cancel out, rather than turn a number into the negative equivalent.


When would one choose a 50mm f/1.4 over 85mm f/1.8 (or vice versa) for portraits?

Say you are using a crop body, and you have both 50mm/1.4 USM and 85mm/1.8 USM lens in your bag. Now, you want to take a portrait where there is adequate light and space, and you have decided to take the shot at f/2.2.   Now I want to know which lens will be good to use to take such a shot, and why.


Should I ask a question that is easily Google-able?

Meta appears to have come to a consensus that when a user asks a question that is easily answered with Google that we should not close the question but rather answer it properly.        However, what does this mean about asking questions that can be answered easily with a Google search?  More specifically, should we encourage or discourage such behavior, and how?  Here are some reasons that I can think of for each option.  Reasons to Encourage  ""   And that includes answers easily accessible via Google search   Sometimes we want to  another answer to a  that   Sometimes we want to save others the Google searching we did by asking and answering the question ourselves. In this case, we did do the research, but the question by necessity must not show research effort.  Reasons to Discourage  Question quality may drop, as users will feel less incentive to Google their problem. This will also probably result in a greater quantity of questions as well that have already been answered on StackOverflow, as Google searches often result in StackOverflow answers.


How do I backup and restore my IPA app backups in iTunes 12.7?

Today, Apple released iTunes 12.7. Surprisingly for a point-release this version removes the iOS App Store and iOS app management features:      Apps can now only be downloaded on an iOS device using an iOS device, and the same goes for ringtones.    I have diligently saved IPA backups of apps I have purchased from the iTunes / iOS App Store for the eventuality of when an app publisher removes an app from the App  Store - or if the developer of an app changes a feature in a way that I don't like. This happens regularly:   Electronic Arts has a poor reputation for removing its games from the App Store when they stop being notable, including apps that you needed to pay for to download. And many non-game apps often add new features that users don't like, or remove features that are useful to many users (either for making things simpler for other users, or for a copyright or patent infringement reason).   Unfortunately, with iTunes 12.7 removing the ability to backup and restore IPA files I seem to be now SOL. Fortunately I still have iTunes 12.6 installed on my computer, but here's my question:  "If I have saved an IPA backup of an app that has since been removed from the iOS App Store, or if I have saved an older version of an app that has been upgraded such that I want to continue using the older version, how can I install that on my new iPhone 8?"


I  don't  have any clue . Can  chinese  remainder  theorem  can  be  used?  I am  studying  number  theory  but I am not  an  expert  as  you  can  see. This  question  was  set  in  the exam  and  I could  not  answer.


logout script to restore "clean" user environment with 18.04 Desktop?

I'm configuring a bunch of laptops for a teaching lab, running 18.04 Desktop. They have an admin account and a standard account for students. I would like the student account to behave as much like the Mac OS Guest account as possible, so that at GUI logout, the entire user home is wiped and replaced with a fresh one from /etc/skel . I did this successfully a few versions ago, but that was with lightppd. How do logout scripts work with gnome-shell?


What happens to leftover money in a 529 College Savings Plans?

Assuming a child goes to college and everything is paid from a 529 college savings plan. Once that child graduates and there's leftover money in the savings account, what can be done with that money? Assuming there are no more educational expenses to be paid for.


What will I see if I travelled to a distant planet in 100 times faster than speed of light and look back?

Consider this scenario. I enter a space ship at 10:00 AM, it starts to move at a speed 100 times faster than  light, I travel for 55 mins. And then slow down to very much less than speed of light and land on another planet at 11:00 AM. Now I look at Earth with a telescope. What period of Time am I going to see?


What can I learn at open-house events for PhD programs that would be difficult to learn through other channels prior to accepting an offer?

I have received a few offers for PhD programs in the US that I am interested in, and several of these have open-house events coming up in the next few weeks.  I have been in contact with potential advisors at several of these programs, but have had very limited or no contact with current graduate students there.  My current information on these programs comes from offer letters, interactions with professors (both my undergraduate advisor, and professors at institutions hosting these open-houses), and departmental websites.  My primary goals with these events are:   Meet with potential advisors, and determine who I could work well with, and Talk to current PhD students; see if I can learn anything about departmental politics, the funding situation, and anything else that the department doesn't advertise to prospective students.    Which questions should I be sure to ask, and to whom?  What opportunities do I have at open-houses that I will never have again before I need to accept an offer?  If it matters, the programs I am considering are in physics, geophysics and Earth sciences departments, depending on which department the space sciences faculty happen to be in.


How to escape a "\" in command parameters

I have a command   path/to/forticlientsslvpn_cli --server <host>:<port> --vpnuser testpass\101   When I run the script, linux puts a space between testpass and 101. I want the script to see "testpass\101" as the username  I hope I make sense


When closing a question I am presented with this dialog:    Which is nicely laid out and clear what options are available to me (As to why the question should be closed).  However when I choose Off Topic.  I get this dialog which IMO appears cluttered and a bit too full on, making it harder to chose the correct option.    In a future release would it be possible to maybe have a bit more of padding between the options or colour contrast (Black and grey) or a heading, like in the first dialog.  For example:  General Computing Hardware/Software     .... specific content   Does not demonstrate a minimal understanding of the problem being solved     .... specific content   I think this would make it slightly easier on the eye and make the options stand out.


How can this user review more than 20 edits per day?

Today, in the ,    How is this possible?   is not even a .


The best way to store and protect game data

I'm writing a sandbox-type game and i'm looking for a good way to store game data. I tryed Lua and plain text files, but the have a big minus - player can edit them his self!  So how do I protect data from player? Thank you!


How to show $\lim_{n \rightarrow \infty} \int_0^1 n x^n f(x) \; dx = f(1)$ for continuous $f$?

Let $f$ be a continuous function. I wish to show $$\lim_{n \rightarrow \infty} \int_0^1 n x^n f(x) \; dx = f(1)$$ I can try to split up the integral over intervals $[0, 1-\delta]$, $[1-\delta, 1]$. The integral over $[0, 1-\delta]$ vanishes as $n \rightarrow \infty$, but I am having difficulty estimating the integral over $[1-\delta, 1]$. Thanks!


How to avoid the hyperlink on a particular \ref

I use hyperref and I produce the pdf via pdflatex. Everytime I use \ref I get in the pdf a clickable link and I am happy with it... but I would like to disable the hyperlink in the pdf for one particular \ref, is it possible?


A Representation Theory Problem in Putnam Competition

The following was the B6 problem of 1985 Putnam Competition: Suppose $G$ is a finite group (under matrix multiplication) of real $n\times n$ matrices $\{M_i\}, 1\leq i\leq r$. Suppose that $$\sum_{i=1}^r tr (M_i)=0$$, prove that $$\sum_{i=1}^rM_i=0.$$  Here is an official proof from the committee which I didn't understand:  Lemma: Let $G$ be a finite group of order $r$. Let $\rho: G\rightarrow GL(V)$ be a representation of $G$ on some finite dimensional vector space $V$. Then $$\sum_{g\in G}tr \rho_g$$ is a non-negative integer divisible by $r$, and is zero iff $$\sum_{g\in G}\rho_g=0$$.  Proof: Let $\chi_1,\cdots, \chi_s$ be the irreducible characters of $G$ and $\chi= \sum_{i=1}^s a_i\chi_i$ and $\psi=\sum_{i=1}^sb_i\chi_i$ be arbitrary characters. Then by the orthogonality relations of characters, we have $$\frac{1}{|G|}\sum_{g\in G}\chi(g)\overline{\psi (g)}=\sum_{i=1}^sa_ib_i$$. Applying this to the character of $\rho$ and the trivial character $\mathbb{1}$ shows that $\frac{1}{|G|} \sum_{g\in G}tr \rho_g$ equals the multiplicity of $\mathbb{1}$ in $\rho$, which is a non-negative integer. Now suppose that the matrix $S=\sum_{g\in G}\rho_g$ is non-zero. Choose $v\in V$ with $Sv\not=0$. The relation $\rho_hS=S$ shows that $Sv$ is fixed by $\rho_h$ for all $h\in G$. In other words, $Sv$ spans a trivial subrepresentation of $\rho$, so the non-negative integer of the previous paragraph is positive.  QED  We now return to the problem at hand. "Unfortunately the $M_i$ do not necessarily define a representation of $G$, since the $M_i$ need not be invertible." Instead we need to apply the lemma to the action of $G$ on $\mathbb{C}^n/K$ for some subspace $K$ ...  I do not understand wthe sentence in "". Isn't the set of $M_i$'s form  a group under multiplication? why they need not to be invertible? The above proof is copied from Kedlaya, Poonen and Vakil's Putnam competition 1985-2000. Thanks for helping


Hi I make this class A amplifier but how to replace R5 (10 ohm/10 W) with transistor because its getting really hot and how to achieve up to 10 Watt with +/- supply. I have +/-25v with 4A please help


This shirt is the cheaper of the two   I wonder why the comparison is cheaper and not cheapest. Aren't the sentence is referring to more than two items and so it should use -est? And cheaper will be used when comparing two items.


There are eight points, connection between each other.  In addition to the red dot, any three line segments do not intersect at one point.        How many triangles are there in the picture?     If you remove three segments, maximum number of triangles left?      Thanks a lot!


Macedonia Entry with EU-permanent resident card?

Can i enter Macedonia with a valid EU permanent resident card and a valid Passport? I have heard so much controversy that it is not possible and both possible without a problem?


How to change current user to www in ubuntu?

Anyone knows?   root@fsdfssfewgfdgfng1:~# su www Cannot execute /sbin/nologin: No such file or directory root@fsdfssfewgfdgfng1:~# id www uid=1000(www) gid=1000(www) groups=1000(www)


I have to cut double values to for digits, but i don't know how to do it with values from tables. i need to get from 0.254300 this 0.2543. This is my code, so how to cut extra zeros.  public class Diagonal{ public static void main(String[] args){       double [][] tab = new double [5][5];       for (int i = 0; i < 5; i++){         for (int j = 0; j < 5; j++){             tab[i][j] = (int) (Math.random() * 9000) / 10000.0;          }     }     for(int i = 0; i < 5; i++){         for (int j = 0; j < 5; j++)             if(i==j || i+j==4)                   System.out.printf("%4f", tab[i][j]);             else                 System.out.printf("%4c",' ');              System.out.println();        }                      }  }


What is better performance wise with i7 2600k: 1x4GB or 2x2GB RAM?

Is it better to use 2x 2GB or 1x 4GB RAM with a i7 2600k Sandy Bridge performance-wise for:   Applications? Games? Both?


If any two indices are equal, then the term is zero

Let $X$ be a topological space. Let $U_i$ be an open cover, with the index $i$ running through some set $I$. For $i_0$, $i_1$, ..., $i_n \in I$, write $U_{i_0 i_1 \cdots i_n}$ for $U_{i_0} \cap \cdots \cap U_{i_p}$. $\def\cE{\mathcal{E}}$Let $F$ be a sheaf of abelian groups on $X$ and $F_{i_0,i_1,...i_n}:=F(U_{i_0 i_1 \cdots i_n})$, we will write the group operation additively.  Let $I$ to be a set of indices, and $i_0, i_1, i_2... \in I$. For each array $(i_0,i_1,...i_n)$ associate a set $F_{i_0,i_1,...i_n}$ and take  $$(f_{\large i_0,i_1,...i_n})_{i_0,i_1,...i_n\in I}\in \prod_{\large i_0,i_1,...i_n}F_{\large i_0,i_1,...i_n}.$$  Define $d((f_{\large i_0,i_1,...i_n})_{\large i_0,i_1,...i_n\in I})=(\sum_{i=0}^{n+1}(-1)^kf_{\large i_0,...\hat{i_k},...i_{n+1}}|U_{i_0 i_1 \cdots i_{n+1}})_{\large i_0,i_1,...i_{n+1}\in I} $  I wonder if the following statement is true:     Assume $d((f_{\large i_0,i_1,...i_n})_{\large i_0,i_1,...i_n\in I})=0$. If any two of the indices ${k_0,k_1,...k_n}$ are equal, then $f_{\large k_0,k_1,...k_n}=0$     See  for the description pf the cohomology w.r.t. an open cover and  for the original question(from Rick Miranda's book).  I have made no constructive approach to this problem so far. One idea is to prove it backwards, first prove that it's zero when all of the indices are equal, then it is zero. But there will be an evenness-oddness problem.    Update:  I referred to the wrong problem earlier. It should be problem N.


How to show the transfer progress and speed when copying files with cp?

Otherwise, is there any alternative command line utility that can achieve this?


Problem understanding unusual syntax of the new keyword

I stumbled across this piece of code, and could not understand how the new operator was used in this case:  student* setname(string name) {   student* stu=(student*)malloc(sizeof(student));   new(stu) student;   stu->age=12;   stu->name=name;   return  stu; }   I would expect new to be used like stu = new student;. How is new(stu) student different?


Website being indexed twice by Google, one with the correct sublinks and the other with all sublinks redirecting to homepage

As that title says, my website is being indexed by Google twice.  Both indexes have the right SEO information for the home page, such as title and description. However for the sublinks there are two versions, one version of the indexed site that has the correct sublinks and sublink information, and the other version that has all sublinks pointing to the home page with the format of these wrong sublinks being http://example.com/#random%20text  I have gone into webmasters and chosen my prefered domain, I have tried removing these wrong sublink pages, but due to redirecting to home, it stops home from being indexed, so I reverted this change, I have tried demoting the sublinks, it did not work, I've tried adding <meta name="fragment" content="!"> to my header, it did not work, I have tried disabling all plugins on WordPress to see if that was the reason, it was not.  I've everything I can think of and would really appreciate some help as to how I can stop Google indexing one version of my website with all the wrong sublinks.  If it's of any help, when I search for the business website name on Google as "businessexample" it shows the broken link index version, and when I search as "business example" it shows the correct version.  Update : Still not able to figure this out, any help is welcome.


I am brand new to QGIS.   I have downloaded the BLM's public land survey system from their website (), which has a file format of .lpk.    I cannot seem to open that file format in QGIS.    Anyone know how to get around this problem?


Undefined citations in Overleaf online tutorial using biblatex

I am using  to learn how to cite paper. And the code in main.tex is:  \documentclass[letterpaper,10pt]{article} \usepackage[english]{babel} \usepackage[utf8]{inputenc}  \usepackage{biblatex} %Imports biblatex package \addbibresource{sample.bib} %Import the bibliography file  \begin{document} Let's cite! The Einstein's journal paper \cite{einstein} and the Dirac's book \cite{dirac} are physics related items.    \printbibliography %Prints bibliography   \end{document}   The code in sample.bib is:  @article{einstein,   author =       "Albert Einstein",   title =        "{Zur Elektrodynamik bewegter K{\"o}rper}. ({German})         [{On} the electrodynamics of moving bodies]",   journal =      "Annalen der Physik",   volume =       "322",   number =       "10",   pages =        "891--921",   year =         "1905",   DOI =          "http://dx.doi.org/10.1002/andp.19053221004",   keywords =     "physics" }  @book{dirac,   title={The Principles of Quantum Mechanics},   author={Paul Adrien Maurice Dirac},   isbn={9780198520115},   series={International series of monographs on physics},   year={1981},   publisher={Clarendon Press},   keywords = {physics} }   The result is:    But there are many errors as following. I don't know how to solve this question.


What is the preffered version of building XML tags for returning a list of name/value pais?  <variables>   <item>ok</item>   <another>123</another>   <catch>me</catch> </variables>   or  <variables>   <variable name="item" value="ok"/>   <variable name="another" value="123"/>   <variable name="catch" value="me"/> </variables>   I think the second form is better, but are there any official W3C recommendations or "desing patterns"?


What does temperature refer to in the vacuum of space?

If light was released ~.38MY after the big bang and the expansion of the universe has caused it to shift into the microwave region why is it referred to as being 2.7K? Temperature is the movement of excited molecules in a medium whereas radiation only has frequency and intensity. What does the "temperature" mean?


HTML is showing in election page - give me a ``

This happened while voting on Academia Stack Exchange today. Not the biggest of priorities, of course, but still, figured I should throw it up here.


What is this folded paper text effect called and how do I achieve it in Photoshop?

I am struggling to get this effect in Photoshop, but I am also unaware of what its technical name is. Can somebody please let me know what the name of the the effect that is being used below, that would be of great use to me!


Going to chat.stackexchange.com takes me to Area 51?

If I type chat.stackexchange.com into my browser, it resolves as area51.stackexchange.com.   The same happens if I click the chat link from the dropdown on a site, as well.   This just started within the last couple of minutes. I'm using Chrome, if that matters any.


The task is to scale a polygon in QGIS. The procedure is performed tracing the polygon and then apply a scaling factor ( the factor used is " Distance on the ground" / " Distance on map " ) .  Both ArcGIS and AutoCAD there is the "scale" tool.  Is there any way to do Qgis or plugin?


Difference between Present Perfect and Present Perfect Continuous

I know this question has been asked a lot, but I still don't fully understand the difference between Present Perfect and Present Perfect Continuous (if there is one).     Sometimes the two tenses are interchangeable[...]. But sometimes they are not. Essentially, it depends on whether the action denoted by the verb is regarded by the speaker as completable or not. By this definition, living and learning, for example, are not completable, in which case both tenses are possible:   -I have been living in London since 2001.   -I have lived in London since 2001.   Is one of these tense carrying more sense regarding the fact that I am/am not currently living in London?     It has been 13 years I am living in London   Is it grammatically correct? If yes, would it be closer to Present Perfect or Present Perfect Continuous? Does this mean that I am still living in London?


What is the fastest way to get a shallow copy the data of an object?

Vanilla JS only please  That is, its the output should be an object that only contains data, and ignores the original's methods/prototype.  Complex data structures that inherit from the default Object, like Array, can be copied in a shallow manner, as references.  The way I do it now is:  function shallowCopyObjectData(obj) {   output = {};   for (var i in item) {     output[i] = obj[i];   }   return output; };   The other way I've seen is:  function shallowCopyObjectData(obj) {   return JSON.parse(JSON.stringify(obj)); };   What is the most performant way to do it?  I've made a running jsPerf to compare speeds.  If you come up with a solution, please feel free to fork and add:   Edit @Barmar: I know a , but it asked about the fastest way to clone an object, which implied a deep copy that keep the constructor, prototype, etc.  This question asks about the fastest way to copy just the data in the top level


We now define a Hermitian manifold is a complex manifold in which unmixed components of metric tensor vanish $g_{ij}=g_{\bar{i}\bar{j}}=0$. Is this a propert of a Hermitian manifold? Or is it an extra imposed condition on the metric - this case Kaehler metric?


Is it a good practice to ask before exiting an application (with nothing to save)?

Every now and then, I come across applications that, when clicking on the main window's "X", ask me whether I'm sure that I want to quit the application.    I'm not talking about asking me to save unsaved documents, but about applications that aren't document related at all.  This always bothers me, since I feel totally interrupted in my workflow. I was already thinking two steps ahead of what I want to do next, and this message box abruptly pulls 100% of my attention.  My question:  Are there any valid use cases where a non-document-centric application should ask me whether I'm sure that I want to exit the application?


I have a geoserver installed on my local machine and on it i have published the map which is connected to Postegresql.  Now i can view a map on geoserver using the openlayers viewer (url-"")"  Now i have code api of leaflet to customise a map which is hosted on geoserver.  Here is a HTML code:      <!DOCTYPE html>        <title> Leaflet Demo </title>      <link rel="stylesheet" href="https://npmcdn.com/leaflet@1.0.0-rc.3/dist/leaflet.css" />            <form id="form1" >

      var map = L.map('map').setView([55.67, 12.60], 11);      var mywms = L.tileLayer.wms("http://localhost:8081/geoserver/test/wms", {     layers: 'k101:theme-startkort',     format: 'image/png',     transparent: true,     version: '1.1.0',     attribution: "myattribution"     });     mywms.addTo(map);
     </form>     But when compiling on visual studio ,browser displays : a code itself  Any idea, what to do?


Migrate files from one cloud storage provider to another

Is it possible to directly move files from one cloud storage provider to another, bypassing the bandwidth-intensive step of downloading the files locally and then re-uploading them?  In other words, completing a file transfer in the cloud without making it rain?  For example, [Files stored with Dropbox] --> [Files stored with Mega]  Edit: Are there any solutions apart from the dedicated, albeit pricey, services such as  and ?


I find it hard to believe that photons always travel with 3 x 10^8 m/s just from the start. But there must be some acceleration of light. Maybe huge or taking place in picoseconds. So what maybe the acceleration of light or photons?


Who ate my rep changes on Area 51 (again)?

Over the last week or so, the official top bar has returned to Area 51.  It was there briefly a few months back, but seems to have returned for good.  Definitely a positive, as I have always welcomed our new top bar overlords.  The rep dropdown (of yore) was the only way to see new reputation changes on Area 51, though.  Since the Area 51 reputation tally is not integrated with the rest of the SE ecosystem and there is no designated area on the Area 51 profile for recent rep changes, I'm down to the old abacus for keeping track of changes.  Having this reputation information may seem trivial, and it is, but I do use the growth in number of new followers as a cue to check on my proposals.  I certainly don't think it's worth anyone's efforts to crowbar the old Area 51 system into the new top bar, and I understand all of the issues in , but is there any way to monitor these rep changes in the meantime, or could we just get the old rep dropdown back again for a time, like it had been up until last week?    I'm not a begging person, but any hint of an Area 52 would be nice, too.


As a Canadian Citizen, F1 visa to a B1/B2: will I have to leave the US and re-enter?

I am a Canadian citizen, and I intend to travel to the US for a student clinical elective at a university in Texas for the months of September and October. The university will help me obtain an F-1 status. However, I want to attend a few conferences and educational seminars which are being held in November/December for which I will be using a B1/B2 visa.  Will I have to leave the US and come back in November using a B1/B2 visa, or is there another way to change my visa status, or can I apply for both visas upon entering the US?


What is a good package for taking note of draft ideas?

What is a good package for taking note of draft ideas, and have them emphasized in the output document? For example:  This is a very brilliant idea for a  research topic \somecommandthathighlightsanotetoself{(Try to find out exactly why this is a brilliant idea.)}   In the output document, I would like to see the note in red or any other color to call out my attention as I review my work. As a bonus, perhaps some note in the margins for additional attention-calling.


Prove that two bases for a vector space are equinumerous

If $B_{1},B_{2}$ are two bases for a vector space $V$, prove that there exists a bijection $f:B_{1}\rightarrow B_{2}$. It is known to all that the statement is true for finite-dimensional vector spaces, with quite a lot of elegant proofs. I suppose there at least should be one or two similarly elegant proofs for the infinite-dimensional version, assuming that the Axiom of Choice is correct.


Java 8 lambda returning an empty list of map keys based on a filter applied to map objects

I'm currently playing with Java 8 lambda's and having a small issue.  What I want to do  I have a built a prototype website using spring, it takes in a transaction object and stores it in a map. The transaction class has a long value and String type (e.g. hotel). What I'm trying to do is, run a lambda expression that filters out all of the transaction objects which have a certain type and return a List which is the list of their keys.  Basically I just want to see a list of the keys to objects in the map which have a specific type.  Simple test I have tested it by filling in an object which has a type of car and a value of 3000. I then passed in car on the web form to filter the map based on this. I outputted what the input type is (to check the webform received it correctly), the type stored in Map object and if they're equal which is all correct, however the lambda is still returning an empty list.  I have the code written as below:  Offending Method:      HashMap<Long, Transaction> transactionMap = new HashMap<>();  @RequestMapping(value = "transactionservice/types/{type}", method=RequestMethod.GET) public ResponseEntity<List<Long>> getSameType(@PathVariable String type) {      System.out.println("Input type is: " + type);     System.out.println("What is stored at 1: " + transactionMap.get(Integer.toUnsignedLong(1)).getType());     System.out.println("Values are equal: " + type.equals(transactionMap.get(Integer.toUnsignedLong(1)).getType()));      List<Long> listSameType = transactionMap.entrySet()             .stream()             .filter(s -> s.getValue().getType() == type)             .map(Map.Entry::getKey)             .collect(Collectors.toList());     System.out.println("List size of keys: " + listSameType.size());      return new ResponseEntity<List<Long>>(listSameType, HttpStatus.OK); }   Output:  Input type is: car What is stored at 1: car Values are equal: true List size of keys: 0


how to capture a final variable with preg_match

Im having problems with RegEx in preg_match (php). Im using this code:  $str = 'text code-product?key=1Jh49XPA8qRzi1-lINwt7TB9CO&action=edit'; //print -> 1Jh49XPA8qRzi1-lINwt7TB9CO //$str = 'text code-product?key=1Jh49XPA8qRzi1-lINwt7TB9CO'; //print -> 1Jh49XPA8qRzi1-lINwt7TB9CO //$str = 'text code-product?key=1Jh49XPA8qRzi1-lINwt7TB9CO&action=delete'; //print -> 1Jh49XPA8qRzi1-lINwt7TB9CO  preg_match('/product\?key\=(.*)(\&|$)/', $str, $match); $id = isset($match[1]) ? $match[1] : null;  echo $id;   When I try to get the ID, it not always work. I need get the ID between product?key= and the last & (if it exists). Thx so much.


So what does Cyanogen Inc shutting down mean for CyanogenMod and similar ROMs?

So Cyanogen Inc (cyngn), known for their support for their support for CyanogenMod and their efforts to integrate Cyanogen OS into devices such as the OnePlus One, Alcatel POP Mirage, and . Cyanogen Inc just recently .  What does this mean for CyanogenMod, Cyanogen OS, and the devices which originally shipped with Cyanogen OS? Will they no longer receive OTA updates?


Generate a random string from a list for each iteration

I need to generate a random amount of string for a certain amount of times; so for example:   for k in range(5):    print("Country", location)    print("Animal", animal)   so location and animal will be randomly generated from a list, and each of the 5 times it gets printed, it will have random number of locations and animal, so for every iteration a  random number of locations and animals will be printed from a given list


I often find myself posting a comment simply to point out a code mistake in my own old comment, or to add a caveat to another user's comment. To avoid polluting SO/SE with lots of redundant comments, it would be nice to have a privilege to enable editing of all comments, old and new, our own and others', to enable basic curating of this content.  Flagging existing comments is not at all the same. For example, in case of a typo, the goal should be to give credit to the original commenter for providing useful input, while correcting a minor aspect of that input.  The main goal of this feature would be to avoid several comments which could have been merged into a single, much more useful and concise comment. Comments take up valuable screen space, so they should be as flexible as answers.


Add markdown option for ordered lists with brackets

I searched for this first and couldn't find it already suggested.  I'm finding I'm coming across posts (often from new users) where an ordered list is included but is not formatted properly, because they've used brackets rather than periods.  1) Here is an example 2) of what they do   When really They wanted it to look like this   It can be fixed with a quick edit, but not all users do this (or know how). I was wondering whether the markdown parser could be extended to also recognise this alternative notation?


Error Attempt to invoke virtual method. on a null object reference

this doesn't work after doing project cleanup and code cleanup im getting the following error Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setCustomView(android.view.View, androidx.appcompat.app.ActionBar$LayoutParams)' on a null object reference  final ActionBar abar = getSupportActionBar();     //line under the action bar     View viewActionBar = getLayoutInflater().inflate(R.layout.app_bar_layout, null);     ActionBar.LayoutParams params = new ActionBar.LayoutParams(//Center the textview in the ActionBar !             ActionBar.LayoutParams.WRAP_CONTENT,             ActionBar.LayoutParams.MATCH_PARENT,             Gravity.CENTER);     TextView textviewTitle = (TextView) viewActionBar.findViewById(R.id.actionbar_textview);     textviewTitle.setText("WizChat");     assert abar != null;     abar.setCustomView(viewActionBar, params);     abar.setDisplayShowCustomEnabled(true);     abar.setDisplayShowTitleEnabled(false);     abar.setDisplayHomeAsUpEnabled(true);     abar.setIcon(R.color.background_color);     abar.setHomeButtonEnabled(true);   you can see here the code this is my manifest file as you requested  <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"     package="com.example.logindesign"     android:versionCode="1"     android:versionName="1.0" >     <application         android:allowBackup="true"         android:icon="@drawable/ic_launcher"         android:label="@string/app_name"         android:theme="@style/AppTheme" >         <activity             android:name="com.example.logindesign.MainActivity"             android:label="@string/app_name" >             <intent-filter>                 <action android:name="android.intent.action.MAIN" />                  <category android:name="android.intent.category.LAUNCHER" />             </intent-filter>         </activity>         <activity android:name="com.example.logindesign.Welcome"/>     </application> </manifest>   you can see here the code this is my style file as you requested  <resources>     <style name="AppBaseTheme" parent="@style/Theme.AppCompat.NoActionBar">     </style>      <style name="AppTheme" parent="AppBaseTheme">     </style> </resources>


Free tool for monitoring Broadband usage on Windows 7

Possible Duplicates:             I need a free tool ( non browser ) to monitor my broadband usage on Windows 7 since my ISP has placed a cap on monthly downloads.  I need a PC based solution since I use a USB router to connect to the internet.All other solutions I found were router/network based and also wasn't sure of all the freeware tools I found on Google to do this job.Need suggestions personal experiences.


Which Stack Exchange site is best for AutoCAD questions?

Which Stack Exchange site is best for AutoCAD questions like using Blender for graphical design?


How to deal with lock that keeps jamming?

I have a kryptonite U lock and lately it's been sticking a lot while trying to turn the key. Usually I can eventually get the key turned. It was getting worse though and a few days ago I (unable to find any lube/wd-40 etc) cleaned it out with soap and water which seemed to help a great deal. I also started being very careful to make sure the little key-hole guard engaged. Last night when I was totally unable to get my bicycle unlocked and had to leave it there and walk home. The key would fit into the lock and turn half way and then stop. I'm going to go try and pick it up now, but I don't know the best way to try and make sure this doesn't keep happening. It's winter here and I wonder if that might have something to do with it.  Edit: I ended up at the hardware store and the guy there (who had built his own bike in his garage, conveniently) recommended jig-a-loo. This made the lock move really well but I still couldn't get it open. This is when I noticed that my key was twisted (From trying to force the lock probably). I flattened the key back in a clamp and was able eventually to unlock it, but I can't seem to lock it again, so I ordered new keys. I'll have to wait till they come to see if that solves anything or it's actually a problem with the lock...  Edit again: Some graphite and new keys seemed to do the trick!


Does anyone know what this probability question is asking?

I have no idea what the first problem on this list is asking? The others I can figure our, but does anyone know what the first one is actually asking? If so, how would you set it up?  Nate can only invite 8 people to his birthday, but has 13 friends he’d like to invite.  Eight of his friends are boys and five are girls.  Three of the girls are roommates and must stay together.  If Dante randomly selects 8 people, determine the probability for each scenario.   Dante’s random selection is a valid outcome Dante does not invite any girls Dante invites an equal number of boys and girls


I'm trying to understand how the String pool works and what are the rules for a string to be equal to another String.  For example this snippet :  public static void main(String[] hi){     String s1 = "lol";     String s2 = "lol";     String s3 = new String("lol");     System.out.println( s1 == s2 );// true     System.out.println( s2 == s3); // false     s3.intern(); //line 1     System.out.println( s1 == s3); // false     testString(s1);  }  private static void testString(String s1){     String s4 = "lol";     System.out.println( s1 == s4); // true }    At //line 1: the string is added to the string pool. Since it's not equal to s1 I assume there is a duplicate in the string pool. Correct ? What is the rule for having a duplicate in the pool ? In other words when does someString == someString return false even though both string have the same char sequence ?   PS: I use string1.equals(string2) everywhere no matter what. I just want a deeper understanding of the underlying mechanism.


Change of basis of a real symmetric matrix to its Jordan form is always orthogonal?

I am confused with the following (Sorry if this is a duplicate):  Let $S$ be a real $n \times n$ symmetric matrix, which is diagonalizable, of course, and let its Jordan normal form  be $J=\text{diag}(\lambda_1,...,\lambda_n)$, where each $\lambda_i$ is an eigenvalue. Consider $M$ the change of basis, i.e. $M$ is an invertible matrix such that $S=M^{-1}JM$. We know it is possible to choose $M$ such that it is orthogonal, but can we guarantee that $M$ is always orthogonal?


Hanging picture on a very hard concrete wall

Situation: Appartment in a panel building. Very hard concrete walls -- all, thick or thin. No plastic hooks (like  that usually work for people around do not work for me, the little nails band when hammered in, and so does the larger nail.  So far, I have been hammer-drilling everything, even a hook/nail/screw for the clock, drilling 5mm hole and using wall plugs.  However, this is very inconvenient (dusty, I have to borrow the hammer drill from my family every time and it's not a cheap thing, I get big holes in the wall if I remove any picture or alike).  Is there any other option? I thought that maybe a small hole could be created at an angle and then a small nail inserted. If the hole had 2mm in diameter and the nail had 2.2mm in diameter, it could work. However, I have no idea how to create such a small hole. Or something like that... Any suggestions are welcome.


How does "delta"-like three phase power source avoid short circuit?

A delta-like 3-phase power source is as below:         – Schematic created using   This diagram is equivalent to "Fundamental of Electric Circuits, 5 Edition" Figure 12.6 (b)  Will it be short circuit?


Photoshop: How to resize image without cropping or distorting?

i have an image 1920x900. My client want this size 1920x400 without using crop. i tried to edit image size in image menu in photoshop, but it is not allowing me to do it to maintain its height and width in proportion, becauz 400 is very less than 1920. So kindly help is there any other way.


What's the difference between 'any more' and 'anymore'?

In the phrase Can't afford to spend any more time, I am not sure if I need a space between any and more.  I have checked two sources including  and . They suggest the following:        Any more is A determiner   It is similar to some more and describes an indefinite quantity of something.          Example:   Would you like any more tea?   Anymore =  adverb It means 'no longer' or 'in the past, but not now'     Example:   The cost of electricity is not cheap anymore.   So, in the phrase, Can't afford to spend any more time, which would you use?  There is an indefinite quantity of time, so based on the examples above it would be 'any more'. But then, the phrase also implies that they had time in the past but no longer, so does that mean it would be 'anymore'?  Also, does it make a difference if you are using American or British English, as the Cambridge link kind of suggests that anymore applies more to American English?


Node count published, unpublished and total

I have been on this for a while, considering my low php knowledge. Anyway I would like a view that lists users with total number of articles created, total number of those articles that are published and total number of those articles that are not published per user. I have looked around for an answer to this and the closest I get is node view count which does not do what I need.


\r or \n added in arguments list from Python

i have some scripts that take as input one or multiple paths as on argument.  The script is run like that: myScript.py D:\Folder1,E:\OtherData\Files  In the script, i split the path arguments in the comma and i read the paths.  The problem is that Python adds a \r in the end of each path for no reason. So the script tries to read D:\Folder1\r and E:\OtherData\Files\r.  Why is this and how can i solve it?


This is my first question at stats.  I need to impute some factors and numbers in my data set in R. What are my best options regarding packages and also a source to read more about the theory.


Is there any information in canon to indicate that Dumbledore knew that the Marauders were Animagi?

Is there any information in canon (or from JKR) to indicate that Dumbledore knew that three of the Marauders were Animagi?  I can't recall anything, but Harry seems to be firmly convinced that Dumbledore knows "everything that goes on around here," and that assessment seems to be accurate during Harry's years.


Dos and/or Windows versions of Unix SCRIPT command

Back in university, when we had to submit an assignment in CS, we would have to perform a series of steps including running script, date, whoami, etc., and then running our program.  The script command would pipe all text sent to the display to both the display and a specified file as well.  Ever since, I have been looking for a Dos and/or Windows version, but have come up empty. Some programs can be redirected to a file, but then the display is not echoed, and some programs don’t seem to work with redirection at all.  Any ideas?    Edit:  So far, the answers that I’ve gotten seem to work exactly like the standard redirection commands (<, >, |). These do not work with all programs. For example, the Microsoft C++ compiler CL.EXE. If you run cl /? through a redirection command or pipe it through another program (such as TEE), you will not get the header/banner text.  Another example is a program I wrote a while back in Pascal (I think the last compile was in FreePascal). The help text does not get redirected at all. I have seen this occur with other programs as well like MKISOFS. It has a long help text, but cannot be paused by piping it through MORE or redirected to a file!  I have wondered about this for many years. I used to think that it may be because the text is being written directly to the screen (eg port B800) or something, but I have yet to pin down the cause, let alone find a program that can do this job.


How do I delete a question that has been labeled a duplicate?

I asked a question. It was put on hold. I rephrased the question but later decided to repost the edited question. It was flagged as a duplicate. Now,  I would like to delete one of them.   How can I do that?


Heisenberg's derivation of Schrödinger's Equation

In Heisenberg's book "The Physical Principles of the Quantum Theory", he presents the following derivation of the Schrödinger Equation from his own, Matrix-based, Quantum Mechanics.  A matrix $x$ has components $x(a'a'')$ (the indices indicate that in this coordinate system the matrix $a$ is diagonal, that is, the basis vectors are eigenvectors of $a$). He starts by proposing the existence of matrices of continuous indices, such that  matrix multiplication $$xy(a'a'')=\sum_{a'''}x(a'a''')y(a'''a'')$$ is replaced by $$xy(a'a'')=\int_{-\infty}^{\infty}x(a'a''')y(a'''a'')da'''$$ He then proposes that the continuous correspondent of the Identity Matrix $I$ is the Dirac-Delta function, such that $$I(a'a'')=\delta(a'-a'')$$ His derivation of the Schrödinger Equation is as follows. To transform  the Hamiltonian  Matrix $H$ from a coordinate system in which the coordinate matrix $q$ is diagonal into a system in which the Hamiltonian is diagonal, in which the Hamiltonian will be denoted $W$, the components of which are the system's allowed energy levels. The equations for this transformation are: $$S^{-1}HS=W$$ or $$HS=SW$$ such that $$\int H(q'q'')S(q''W')dq''=S(q'W')W'$$ with $W'$ being $W$'s diagonal components He then proposes (in one dimension) the following forms for the $q$ and $p$ matrices in the position basis" $$q(q'q'')=q'\delta (q'-q'')$$ $$p(q'q'')=\frac{\hbar}{i}\delta'(q'-q'')$$ He then shows they obey the Commutation Relation $pq-qp=\frac{\hbar}{i}$ but his proof of the commutation relation uses integration by parts incorrectly, having the integral of the Dirac Delta's derivative be $$\int f(\xi)\delta(a-\xi)d\xi=f'(a)$$ instead of $$\int f(\xi)\delta(a-\xi)d\xi=-f'(a)$$ Usingintegration by parts incorrectly once again, he argues that $$qS(q'W')=\int q'\delta(q'-q'')S(q''W')dq''=q'S(q'W')$$ and $$pS(q'W')=\frac{\hbar}{i}\int \delta'(q'-q'')S(q''W')=\frac{\hbar}{i}\dfrac{d}{dq'}S(q'W')$$  So we replace in $H(q,p)S=SW$ $$H\left(q',\frac{\hbar}{i}\dfrac{d}{dq'}\right)S=W'S$$ Which is evidently the Time-Independent Schrödinger Equation, which can be solved for the energy Eigenvalues $W'$  But this is derived with a wrong value for $p$ because the derivation uses a wrong process of integration by parts. The immediately obvious choice would be to have $p(q'q'')=-\frac{\hbar}{i}\delta'(q'-q'')$, so that integrated with the transformation matrix it becomes$\frac{\hbar}{i}\dfrac{d}{dq'}$, but I just can't seem to make it fit the Commutation Relation.  Can anyone help solve this?


I use the following jQuery code to hide my email (name.family@gmail.com) on my website:  $(document).ready(function() {   var n = "name";   var f = "family";   var d = ".";   var t = "gmail";   var l = "com";   var r = 'mailto:' + n + d + f + '@' + t + d + l;   $('.hide-email').attr('href',r).html(r); });   Does this actually stop spambots from collecting the email address? They also request my web page, load it and then analyze it for email addresses, right? And after the web page has been loaded, jQuery would produce the real email address. The only way to really protect my email is with a captcha, which is not so user-friendly...   Am I wrong?  UPDATE: The main question for me is - does the "hide email with JS or jQuery" method work at all?


How to treat differentials and infinitesimals?

In my Calculus class, my math teacher said that differentials such as $dx$ are not numbers, and should not be treated as such.  In my physics class, it seems like we treat differentials exactly like numbers, and my physics teacher even said that they are in essence very small numbers.   Can someone give me an explanation which satisfies both classes, or do I just have to accept that the differentials are treated differently in different courses?  P.S. I took Calculus 2 so please try to keep the answers around that level.  P.S.S. Feel free to edit the tags if you think it is appropriate.


If $G:=S_4$ and $H:=\{id,(12)(34),(13)(24),(14)(23)\}$ Show that $G/H$ has order $6$ and all of its elements have order less than or equal to $3$ (so by the classification of the groups of order 6 up to isomorphism, $G/H\cong S_3$)   $H$ is normal, since left- and right cosets are equal, There are $6$ cosets:  $\{id,(12)(34),(13)(24),(14)(23)\},\ \{(12),(34),(1423),(1324)\},\ \{(13),(24),(1234),(1423)\}$  $\{(123),(134),(243),(142)\},\ \{(14),(23),(1243),(1342)\},\ \{(132),(143),(234),(124)\}$  What does it mean: All elements of $G/H$ have order less than or equal to $3$?  Each element is a set of 4 permutations, what is the order here ?  $G/H\cong S_3$: How can I construct an isomorphism, since the cosets are disjoint, can I just pick an element from each group and compare them with $S_3$ ?  Thanks in advance.


Training the learning model on the log transformed data?

So I've gone through this , and in my primitive understanding I assume we do log transformation when we 'care' about relative changes and also to even out the positive skweness from our data. So for example let's imagine having a dataset as follows:    Quantity  Area  TotalSF  Year  Price     7     1710   856     2003  321510     6     1262   1262    1976  183190     7     1786   920     2001  228410     7     1717   756     1915  171230     8     2198   1145    2000  201000   After log transforming 'Area', 'Price' and 'TotalSF' the respective plots shows nice normal distribution. The log transformed data looks something like this:     Quantity  Area     TotalSF     Year  Price     7    7.444249   6.752270    2003  18.34     6    7.140453   7.140453    1976  17.75     7    7.487734   6.824374    2001  17.92     7    7.448334   6.628041    1915  17.43     8    7.695303   7.043160    2000  18.12   My questions are:     Are we going to train our model on this log transformed data ? If yes, then do we need to log transform our test data as well ? How do we get back the normal/actual values, say for the variable 'Price', after log transforming it ?   Edit: This question specifically asks for suggestions whether to train a model based on log transformed data or not, and how to get the actual values back - more of a beginner-friendly question. The  that's used to flag this question as a duplicate on the other hand asks whether it is valid to back transform or not. That's a completely different premise, I believe.


LWC: How to create dynamic component in LWC?

I want to show a couple of input text fields whenever I click on a link on my LWC page and again if I do the same there would be a second component having input fields. There should be any limit for no of these dynamic components.   Is there any way of doing that like we had $A.createComponent in Aura Component?


How to pay for toll roads when renting a car in Japan?

I have prepared my international driver's license and I'm going to be driving a rental car in Japan this Christmas holiday, around the areas of Tokyo, Nagano, and Mount Fuji. I'm trying to get snow chains for driving up to Shibu Onsen and Fuji line 5th station from the car rental agency.  I read about some toll fares on the toll roads or highways I might pass.  How do I pay for toll road usage? Is it an electronic toll card system or will it be charged to my car and indirectly to me?


Does documentation for old ArcGIS Pro versions remain available online?

I have a suspicion that  has one more parameter at ArcGIS Pro 2.1.2 than it did at ArcGIS Pro 2.0.  Is the ArcGIS Pro 2.0 Help still available online to check this?  I would have expected to find it linked at the  page like the old documentation for ArcMap is.


What is the origin of the term "back to back", meaning to follow one after the other?

Presumably items would follow each other back to front?  There is such a thing as 'back to back' agreements; for example when you have an agreement with a bank to fund a purchase but contingent on (or following) the sale of another.  Could this be it I wonder, as in 'one follows the other'?


Show that any two different columns of an orthogonal matrix are orthogonal vectors, as are any two different rows.

The solution in the manual is as follows: If P is orthogonal and ci and cj are two different columns of P, then c′i cj is the element in row i and column j of P′P = I, so c′i cj = 0. If ri and rj are two different rows of P, then ri r′j is the element in row i and column j of PP′ = I′ = I, so again ri r′j = 0. I am having a hard time understanding what this is trying to say: my concern comes about why c'i cj = 0 and similarly for the rows. If


Add strings from the moderator page for sending message to user into transifex

String:     name hidden from user   And:         String:     bcc


What does means * in array allocation before size declaration in C++?

table = new myObject*[TABLE_SIZE];   I know that * are for declaring pointers variable and to obtain the value of the variable from a pointer, but what does this mean?


In this type of horizontal circular motion (when the string is also horizontal), Which force balances the vertical force of gravity (Mg) ?


What I'm trying to implement is to run a python script on it's own core on Raspberry Pi 2 with Debian. One can use taskset to bind a process to particular core. But I need this core to be free of OS's and other processes' load at the same time. How can I do it?


What is the ROI effect of switching mutual funds in a taxable account?

Assuming I'm paying long term capital gains tax, what is the break even point where it is more worthwhile to switch from one fund to another?  For (a hypothetical) example, if I have a fund with an expected return of 3.5%, what would be the minimum expected return of another fund to make it worthwhile to pay the capital gains tax and switch to the other fund?  (I'm assuming the answer to this question is an equation involving investment horizon, capital gains tax rate, and my current taxable gains)


Why do virus outbreaks only occur on certain sites?

I have a terrible virus, apparently, on my laptop.  The good news is it only affects Internet usage (I can run desktop apps with no problem); better yet is that certain sites are not affected at all. But there are some that are ALWAYS a problem (another others are NEVER a problem).  What I mean by a problem is that links become unclickable, but the page becomes a "minefield" of invisible "clickspots" which open up other pages (ads, plutotv, reimageplus.com, terxer.com, popup dialogs from "microsoft.com-site.online", etc. - I even had a window today of "free xxx videos" or some such), usually making it impossible to continue on the site, or go back to the site. It is apparently ransomware, at least some of the time.  The sites that NEVER give me a problem are:  jw.org slashdot att.net (email) Gmail Duolingo StackOverflow   Sites that are ALWAYS problematic are:  nfl.com cnnespanol.cnn.com theweek.com jsonline.com   An earlier question on this gave me the idea that I was basically "sunk", that there wasn't much I could do to remove these viruses. So mainly now I'm just wondering: why some sites, consistently, and others not?  Is it that some sites have (much) better anti-virus code written to protect their users, or what?  Here is one of the popups I got this morning:    And unfortunately, SuperUser isn't immune, either: when I added the "Virus" tag, another page opened and got the focus; and after that, this page:  https://mediagemm.com/joinnow/step1.php?lp_tweak=general&aid=859325683544&a_bid=1ed55266&data1=newtst&data2=sites&data3=http%3A%2F%2Fsuperuser.com%2F&data4=DaDKie&a_aid=tVNce   UPDATE  It seems that at least one of my possible problems is an ostensibly helpful app, but which may actually by the problem itself, named "Sparktrust PC Cleaner"


Serious errors were found while checking the disk drive for /. - Ubuntu 14.04

I installed Ubuntu 14.04 with wubi inside Windows 7 and then after installation is completed and system is about to start it shows  -Serious errors were found while checking the disk drive for /.   If I ignore then it shows: -The disk drive for /tmp is not ready yet or not present  Then if I skip -An error occurred while mounting /.  If I skip that too it shows Ubuntu 14.04 LTS tty1 requires login. and gui never shows.  Why does this happen? I tried reinstalling and same thing happens. Any idea?