使用MinGW将FFTW链接至Matlab并编译含FFTW的C代码为MEX文件

Alright, let's walk through both of your tasks clearly—getting FFTW linked up with MATLAB using MinGW, then turning your FFTW-powered C code into a working MEX file. Here's the step-by-step breakdown:

First, let's make sure MinGW can find the FFTW files properly:

• Grab the right 64-bit FFTW binaries for MinGW (your path points to fftw-3.3.5-dll64, which is correct). You'll need three key files from the zip: fftw3.h, libfftw3-3.dll, and libfftw3.a (the import library).
• Copy fftw3.h to your MinGW include directory. If you're using MATLAB's bundled MinGW, this will be something like C:\Program Files\MATLAB\R2023a\extern\include\mingw64 (swap in your MATLAB version/path). For a standalone MinGW, it's usually C:\Program Files\mingw-w64\x86_64-<version>\mingw64\include.
• Copy libfftw3.a to the MinGW library directory—matching the above, that's either MATLAB_INSTALL_DIR\extern\lib\win64\mingw64 or your standalone MinGW's lib folder.
• Place libfftw3-3.dll somewhere MATLAB can access it. The easiest moves are:
  • Drop it in the same folder where you'll save your MEX file, or
  • Add its directory to MATLAB's path with addpath('C:\Users\my_user_name\Documents\fftw-3.3.5-dll64') in the MATLAB command window.

Let's tweak your code first, then compile:

• Fix the include path: Instead of hardcoding #include "C:\Users\my_user_name\Documents\fftw-3.3.5-dll64\fftw3.h", use #include "fftw3.h"—since we already copied the header to MinGW's include folder, the compiler will find it automatically. If you skip that step, you can keep the absolute path, but relative paths or using the mex command's include flag is cleaner.
• Compile with MATLAB's mex command: Open MATLAB, navigate to the folder with your C file (let's say it's named fftw_mex_func.c), then run one of these commands:
  If you didn't copy the header/library to MinGW's folders:

  mex -v COMPFLAGS='$COMPFLAGS -IC:\Users\my_user_name\Documents\fftw-3.3.5-dll64' LDFLAGS='$LDFLAGS -LC:\Users\my_user_name\Documents\fftw-3.3.5-dll64' -lfftw3 fftw_mex_func.c
  

  If you did copy the files to MinGW's include/lib directories (from Task 1), simplify to:

  mex -lfftw3 fftw_mex_func.c
  

  Let's break down the flags:
  • -I<path>: Tells the compiler where to find fftw3.h
  • -L<path>: Tells the linker where to find libfftw3.a
  • -lfftw3: Links against the FFTW library (the linker looks for libfftw3.a here)
• Test the MEX file: Once compiled, you'll get a .mexw64 file. Call it like any other MATLAB function—e.g., fftw_mex_func(input_data)—and verify it works.

Quick Troubleshooting Tips #

• Double-check architecture: Make sure MinGW is 64-bit (matches your MATLAB—run computer('arch') in MATLAB to confirm). Using 32-bit FFTW with 64-bit MATLAB will cause linker errors.
• Missing DLL errors: If MATLAB can't find libfftw3-3.dll, double-check it's in the MEX file's folder or added to MATLAB's path.
• Linker symbol errors: Ensure you're using the MinGW-specific libfftw3.a—not the MSVC version. The FFTW zip has separate libraries for different compilers.

内容的提问来源于stack exchange，提问作者Putham