F2PY_Example_Reference

This is a f2py compilation example, for any future reference.

Example compilation of f90 Code:

Without dependencies,

Compiling standalone routines..

f2py2.7 -c fib.f90 -m fib

This generates shared object and can be imported into python routines.

Issues to be aware of:

1. Memory copy from python to FORTRAN starts if the dtype of both FORTRAN and python routine is not the same, choking the volatile memory leading to swapping. This can be easily avoided by using same data type, down to bit level. For example: If using numpy int8, use FORTRAN int (kind=1), if any other dtype is used it will lead to copy of data from Python to FORTRAN.

   This is significant is large arrays are being used.

2. Use F contigious array, not the default C-contigious.

Example Usage (in Python):

In [1]: import fib

In [2]: fib?

Type: module String form: <module 'fib' from 'fib.so'> Docstring:
This module 'fib' is auto-generated with f2py (version:2). Functions: fs = fib_series(num)

In [3]: fib.fib_series?

Type: fortran String form: Docstring:
fs = fib_series(num)

Wrapper for fib_series.

Parameters

num : input int

Returns

fs : rank-1 array('f') with bounds (num)

In [4]: fib.fib_series(11)

Out[4]: array([ 0., 1., 1., 2., 3., 5., 8., 13., 21., 34., 55.], dtype=float32)