Fortran

Fortran is not dead; it drives global weather forecasting and computational physics (MPI). Fortran 2023 adds better C-interop and conditional expressions.

When to Use

• HPC: High Performance Computing on supercomputers.
• Legacy: 50 years of tested scientific libraries (LAPACK, BLAS).
• Arrays: Native multi-dimensional array slicing is superior to C.

Core Concepts

Modules

Modern encapsulation. USE my_module.

Coarrays

Native parallel programming syntax created for supercomputers.

Implicit None

Always required to disable legacy variable typing.

Best Practices (2025)

Do:

• Use fpm: The Fortran Package Manager (modern tooling!).
• Use iso_c_binding: To call Fortran from C/Python.
• Use do concurrent: To hint optimizations to the compiler.

Don't:

• Don't use fixed form: No .f (77). Use .f90 (free form).

References

• Fortran Lang