Note that instead of wrapping my little functions with Function, per previous post, as of Python 2.4 I have the new decorator syntax with which to accomplish the same thing: #--- calc.py class Function: def __init__(self, f): self.f = lambda x: f(x) def __add__(self, other): return Function(lambda x: self.f(x) + other.f(x)) def __sub__(self,other): return Function(lambda x: self.f(x) - other.f(x)) def __mul__(self,other): return Function(lambda x: self.f(x) * other.f(x)) def __div__(self,other): return Function(lambda x: self.f(x) / other.f(x)) def __call__(self,x): """call wrapped function with argument x, return result""" return self.f(x) class Pair: def __init__(self, u, du): self.u = u self.du = du def __add__(self, other): return Pair(self.u + other.u, self.du + other.du) def __sub__(self, other): return Pair(self.u - other.u, self.du - other.du) def __mul__(self, other): return Pair(self.u * other.u, \ self.du * other.u + self.u * other.du) def __div__(self, other): return Pair(self.u/other.u, \ (self.du * other.u - self.u * other.du)/other.u**2) @Function def ident(x): return x @Function def one(x): return 1 p1 = Pair(ident, one) newp = p1 * p1 * p1 print [newp.u(i) for i in range(-5,6)] print [newp.du(i) for i in range(-5,6)] #--- Testing:
import calc [-125, -64, -27, -8, -1, 0, 1, 8, 27, 64, 125] [75, 48, 27, 12, 3, 0, 3, 12, 27, 48, 75]
i.e. I get back the functions u(x) = x**3 and du(x) = 3*x**2, per differential calculus. Kirby