I am trying to a create a class TemplateTest&lt;T&gt; which accepts a single parameter - the class T. I have the following code which declares the class TemplateTest and the constructor:  //in TemplateTest.h  #ifndef TEMPLATETEST_H #define TEMPLATETEST_H  template&lt;class T&gt;  class TemplateTest {     T property;     public:        TemplateTest(T value); };  #endif // TEMPLATETEST_H   //in TemplateTest.cpp  #include&lt;iostream&gt; #include "TemplateTest.h"  using namespace std;  template&lt;class T&gt;  TemplateTest&lt;T&gt;::TemplateTest(T value) : property(value) {};   I'm not sure where the error is, but when I call the constructor in main.cpp with a parameter p I get the message: undefined reference to TemplateTest&lt;p&gt;::TemplateTest(p).  //in main.cpp  #include&lt;iostream&gt; #include "TemplateTest.h"  int main() {     int g = 6;      TemplateTest&lt;int&gt; temp(g);      return 0; }  //returns "undefined reference to TemplateTest&lt;int&gt;::TemplateTest(int)   What am I doing wrong?
Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)
Resize image in Python without losing EXIF data I need to resize jpg images with Python without losing the original image's EXIF data (metadata about date taken, camera model etc.). All google searches about python and images point to the PIL library which I'm currently using, but doesn't seem to be able to retain the metadata. The code I have so far (using PIL) is this:  img = Image.open('foo.jpg') width,height = 800,600 if img.size[0] &lt; img.size[1]:     width,height = height,width  resized_img = img.resize((width, height), Image.ANTIALIAS) # best down-sizing filter resized_img.save('foo-resized.jpg')   Any ideas? Or other libraries that I could be using? How to tell the order of a Feynman diagram? How can we know the order of a Feynman diagram just from the pictorial representation?  Is it the number of vertices divided by 2?  For example, I know that electnro-positron annihilaiton is first order:   So what's the order of, for instance, a radiative penguin diagram (below) ? $a$ and $b$ are natural numbers and $p$ is a prime number. Prove that if $a^{p}-b^{p}$ is divisible by $p$, then it is also divisible by $p^{2}$.  My attempt: Based on Fermat's theorem $(a^{p}-a)$ and $(b^{p}-b)$ are divisible by p, therefore their difference is divisible by $p$. I.e. $(a^{p}-a)-(b^{p}-b)=(a^{p}-b^{p})-(a-b)$ is divisible by $p$. Since the left hand side of this equation is divisible by $p$, the right hand side also should be divisible by $p$. Based on the problem's assumption $(a^{p}-b^{p})$ is divisible by $p$ therefore we conclude $(a-b)$ must be divisible by $p$. Now We can factorize $(a^{p}-b^{p})$ $$(a^{p}-b^{p})=(a-b)(a^{p-1}+a^{p-2}b+....+b^{p-1})$$ we have to prove $(a^{p}-b^{p})$ is multiple of $p^2$ which means we have to show the right hand side should be multiple of $p^{2}$. But $(a-b)$ is multiple of p therefore we have to show  $(a^{p-1}+a^{p-2}b+\cdots+b^{p-1})$ is multiple of $p$ and I am stuck here. Any help would be appreciated. Today I gave a .  This results of course in a negative score for today.   Since then I don't get any more notifications for new rep in the new top-bar on meta.    Only after resetting the rep indicator by clicking on it I get new notifications. How can I search within a manpage? Recognize this letter Does anybody know how to make the following symbol in LaTeX? I think it is some calligraphic \mathcal{E}.     It is not anywhere in  and online font recognizers do not recognize it.   The general font in the book I got this symbol from, Introduction to Quantum Optics by Grynberg, is not very extraordinary: this is a formula containing the strange symbol: Set margins in maketitle Can't install Ubuntu 18.10 on XPS 15 - EFI\BOOT\mmx64.efi not found I tried to install Ubuntu 18.10 on my XPS 15 9570 earlier. Everything was working fine until I got to the partition selection part of the installation. That's when the installer crashed and I had to shut down my machine. I think it's because I had my SATA configuration set to RAID ON instead of AHCI, which is now fixed.  Now when I try to run the installer from my bootable USB I get the following error  Failed to open \EFI\BOOT\mmx64.efi - Not Found Failed to load image \EFI\BOOT\mmx64.efi: Not Found Failed to start MokManager: Not Fond Something has gone seriously wrong: import_mok_state() failed   Hoping someone might have some idea as to what is going on Mountain Bike on Paved Roads I'm an occasional biker. I bought a mountain bike (nothing fancy) with the idea that I might use it off-road or on mountain trails (of which there are many here in Calgary). However, since I've bought it I've done nothing but bike in the city on streets and paved bike trails.  Is there anything worth doing to my bike to convert it to something more suited to urban biking? In particular, the tires have me wondering; they have large rubber off-roading lugs that surely aren't doing me any favors on pavement. I'm not looking to spend a tons of money on a retrofit, but will do so if its worthwhile. Are there any tools for merging CSS? I have a couple CSS files with overlapping CSS selectors that I'd like to programmatically merge (as in not just appending one file to the end of the other). Is there any tool to do this online? or a Firefox extension perhaps? Given fields $K\subseteq L$, why does $f,g$ relatively prime in $K[x]$ imply relatively prime in $L[x]$? $K,L$ are fields, $K\subseteq L$. $f,g \in K[x]$. Suppose that $f,g$ are relatively prime as elements of $K[x]$. Prove they remain relatively prime  in $L[x]$.  I've tried everything I can think of. I feel like working with the contrapositive may be helpful but that's just a feeling. Should I use single or double colon notation for pseudo-elements? $\lfloor x\rfloor + \lfloor y\rfloor \leq \lfloor x+y\rfloor$ for every pair of numbers of $x$ and $y$ All group homomorphism from $ \mathbb{Z} _m $ to $ \mathbb{Z}_n $  How could I find every group homomorphism? Is the integral $\int_1^\infty\frac{x^{-a} - x^{-b}}{\log(x)}\,dx$ convergent? Two particles with initial positions and velocities $r_1,v_1$ and $r_2,v_2$ are interacting by the inverse square law (with G=1), so that  $$ {d^2r_1\over dt^2} = - { m_2(r_1-r_2)\over |r_1-r_2|^3} $$ $$ {d^2r_2\over dt^2} = - { m_1(r_2-r_1)\over |r_1-r_2|^3} $$  (the inverse square law along the line of separation). What is the complete solution of these differential equations? What is the position of the two objects as a function of time?  After reading a lot on Wikipedia, I've come to the definition of center of mass and relative coordinates:   $$R(t) ~=~ \frac{m_1 r_1 + m_2 r_2}{m_1+m_2}$$  $$\ddot{r}(t) r(t)^2 ~=~ (m_1+m_2)G$$  Where $R$ is the center of mass, and $r$ is the displacement between the particles... Is this correct? How do I proceed to solve the differential equation? We have a situation: someone saw the boy break the window. Can I make this passive sentence?     The boy was seen to break the window.   I use Murphy's Grammar and this structure is never discussed. Center of mass in n dimension, possible? Is it possible to calculate the center of mass for some 20-dimension ($x_i, i=1,\ldots,20$) particles? If it is possible, how can I do that? Buying shares when the price goes down 2% and selling shares when it goes up 2% I noticed that if I run ls -F on a directory, some of the entries have a * or a @ after them.   spuder@ubuntu:~$ ls -F /sbin acpi_available*   getpcaps*           lvmconf*                 ntfscp*        start-stop-daemon* agetty*           getty*              lvmdiskscan@             ntfslabel*     status@ alsa*             halt@               lvmdump*                 ntfsresize*    stop@ alsactl*          hdparm*             lvmsadc@      spuder@ubuntu:~$ ls -F ~ daq-0.6.1/  examples.desktop       noname-cache.lib  snort-2.9.1/   Templates/ Desktop/    jpgraph-1.27.1/        noname.sch        snortfiles/    Ubuntu One/ Documents/     According to the ls man pages   spuder@ubuntu:~$ man ls ... -F, --classify   append indicator (one of */=&gt;@|) to entries ...   I'm guessing that @ means symbolic link,     What do these other indicators mean ( */=&gt;@| )  ?