sympy_example

from sympy import Symbol, Add, Mul, Max, RealNumber
from sympy.utilities.codegen import codegen

vars = {'x0': Symbol('x0'),
        'x1': Symbol('x1')}

coefficients = [.5, 1.4, 9.8]

terms = [RealNumber(1), Max(0, Add(vars['x0'], RealNumber(-3.5))), 
         Mul(Max(RealNumber(0), Add(vars['x0'], RealNumber(-3.5))), Max(RealNumber(0), Add(vars['x1'], RealNumber(-6))))]

terms_with_coefs = [Mul(RealNumber(coef), term) for coef, term in zip(coefficients, terms) ]

expression = reduce(Add, terms_with_coefs)

print expression
print expression.subs(vars['x0'], 5.1).subs(vars['x1'],4.0).evalf()
(c_name, c_code), (h_name, h_code) = codegen(('f', expression), 'C')
print c_code