Simple examples of using f2py to get high-speed Fortran integrated with Python easily. These examples are also useful to troubleshoot problems with f2py.

Fortran compiler is needed:

• Mac: brew install gcc
• Linux: apt install gfortran or yum install gfortran
• Windows

pip install -e .

This will compile the Fortran code (in .f and .f90 files) and create a file pyprod.* where * depends on your operating system and Python version.

• Linux/Mac: .so
• Windows: .pyd

python f2py_demo.py

You will see the output:

x = 3
y = 2
x * y = 6.0
Your system did this in Python using Fortran-compiled library

Fortran 77 is officially full-line comments only. Inline comments are not allowed with f2py as a result in Fortran 77 files. Demonstrate this with:

f2py -m badcomment -c badcomment.f

f2py normally Just Works on Linux, Mac and Windows Subsystem for Linux. However, Windows itself can be more challenging due to inconsistencies in Microsoft Visual Studio.

See the Windows f2py installation guide and troubleshooting guide.