I want to install the FFTW3 library in my system which runs on Windows 10. My compiler is the minGW GCC 10.1 and I am using Code::Blocks.
I have downloaded the 64bit version from
http://www.fftw.org/install/windows.html and unzipped it in C:\Program Files (x86)\CodeBlocks\myLibraries\FFTW3.
Then I followed the steps described here
https://www.learncpp.com/cpp-tutorial/a3-using-libraries-with-codeblocks/. In step 4 it says "Tell the linker where to look for the library file(s) for the library."
Since there is no .lib file, it had to be created. I copied the libfftw3-3.def file and pasted it inside the bin folder of the mingw64 compiler, so that the dlltool can be used. Note that inside the same bin folder there exists the as.exe executable. I added this directory, namely C:\Users\User\Downloads\minGW_GCC_10_1\mingw64\bin to system PATH.
Then I opened the cmd window as admin and executed dlltool -v -d nlib32.def -l nlib32.lib. The 2KB libfftw3-3.lib file was created inside the compiler's bin folder.
Then, again, I followed the steps that are described in the link I provided above. For convinience, I am posting the steps directly below.
Once per library:
1) Acquire the library. Download it from the website or via a package manager.
2) Install the library. Unzip it to a directory or install it via a package manager.
3) Tell the compiler where to look for the header file(s) for the library. (Here I set the path to be C:\Program Files (x86)\CodeBlocks\myLibraries\FFTW3)
4) Tell the linker where to look for the library file(s) for the library. (Here I set the path to be C:\Users\User\Downloads\minGW_GCC_10_1\mingw64\bin)
Once per project:
5) Tell the linker which static or import library files to link. (Again the path was set to C:\Users\User\Downloads\minGW_GCC_10_1\mingw64\bin)
6) #include the library’s header file(s) in your program.
7) Make sure the program know where to find any dynamic libraries being used.
When I execute the following code
#include <iostream>
#include <fftw3.h>
int main(){
int N = 100;
fftw_complex *in;
in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);
}
I am getting the following error: "Undefined reference to '__imp_fftw_malloc' ".
I don't know what I am doing wrong so that the compiler cannot find the function that I am calling, but I guess that the problem is in step 7, that is in the "Make sure the program know where to find any dynamic libraries being used." step. Note that this is the first time I had to deal with dynamic-link libraries etc so I am still confused.