Solve and first order ODE system, the right hand side is given as a string.

ode.py

from numpy import *
from scipy import integrate

def ode(f, t0, tf, n_steps, X0):
    """
    Solve an ODE in the time interval [t0, tf] using a number of steps given
    by nsteps, with initial conditions X0. The differential equation is
    written as a system of linear equations
    
        x'_i = f(x_j)
    
    where f is an array of strings that defines the functions, the components
    of the vector X are denoted by X[k] (k = 1, 2, 3... N, being N the number
    of equations).
    """
    t = linspace(t0, tf,  n_steps)    
    def dX_dt(X, t=0): return map(eval, f)
    X = integrate.odeint(dX_dt, X0, t)
    return t, X
    
    
    
## Example
from matplotlib import pyplot as plt
f = ["X[1]", "sin(X[0])"]
t, X = ode(f, 0, 10, 1000, [1.0, 0])
plt.plot(t, X[:,0], t, X[:,1], '--')