Combine Fortran with Python

Sometimes, we need to use some fortran code in our project. A good practice is that we can compile the .f90 codes into dynamic link libraries (.so in Linux or .dll in windows). Then, we can use the ctypes in python to load the libs and get the handlers.

compile the code

# as dynamic link lib
mpifort -fPIC -shared -o libtest.so test.f90
python test.py

some tricks

1. we use subroutine in fortran to provide the interface. However, there is no return value. There is a smart way that we can make the following argreement.

   • the subroutine we need to use in fortran only accept array as arguments.
   • we use numpy.array to pass arguments to the fortran handler.

2. Pay attention to the difference in the memory modle between C and fortran. Defenitely, we use the C interface in python.

Test

1. MPI Use.
2. Optimize fortran subroutine in python by scipy.optimize.

Reference

1. https://dektoud.github.io/blog/post/fortran_dlls/
2. https://www.jianshu.com/p/bd8554a13c0c