sympy/sympy — pull request #2556 by jrioux (2013-10-28 20:36:57+00:00)
Title: Fortran code printing of logical and relational operators.

Generalize the code printing of logical operators (And, Or, Not) and relational operators (==, !=, >=, etc.) to make them customizable by overriding a dict. Add the correct syntax for Fortran code printing for these and add tests. Also implement Fortran printing of Xor and Equivalent, and fix the precedence order for Relational.