IO.md

Input

Direct input

Let us enter a real number as a FreeFem++ variable:

import pyFreeFem as pyff

script = pyff.InputScript( b = 5.8 )
print( script.get_edp() )

The resulting FreeFem++ script looks like

real b;
cin >> b;

By default, this declares the variable b, a uses the cin input of FreeFem++ to populate it.

Postponed input

The variable's value needs not be specified, but then its type is required:

import pyFreeFem as pyff

script = pyff.InputScript( b = 'real' )
script += 'cout << b << endl;'
print( script.run( b = 6.7 ) )
print( script.run( b = 3 ) )

Multiple inputs

Inputs can be of different types, postponed or not:

import pyFreeFem as pyff

script = pyff.InputScript( a = 5, b = 'real' )
script += 'cout << a*b << endl;'
print( script.run( b = 6.7 ) )

Declaration

FreeFem++ can't handle multiple declarations, so the following fails:

import pyFreeFem as pyff

script = pyff.InputScript( a = 5 )
script += pyff.InputScript( a = 14 )
script.run()

The solution is to drop the variable's declaration:

script += pyff.InputScript( a = 14, declare = False )

This, however, affects the entire call of InputScript, that is, none of its arguments will be declared.

Output

Ouputs are somewhat simpler than inputs, but the output variable's type needs to be declared:

script = pyff.InputScript( a = 5.1 )
script += pyff.OutputScript( a = 'real' )
print( script.get_output()['a'] )

The function get_output parses the output of FreeFem++, and returns the result as a dictionnary.

I/O Types

pyFreeFem currently handles the follwing variable types:

FreeFem++	pyFreeFem	Python
int	int	int
real	real	float
mesh	mesh	TriMesh
matrix	matrix	csr_matrix
fespace name (typically Vh)	vector	list, array, ndarray