Sympy summation with indexed variable

Question

I try to create a sympy expression with a Sum with an indexed variable as previous explain here However, I can not do lambdify of this expression and give an array to get th

Answer 1

You can use lambdify. Just make sure the limits of the sum match the iterables of a numpy array.

from sympy import Sum, symbols, Indexed, lambdify
import numpy as np

x, i = symbols("x i")
s = Sum(Indexed('x',i),(i,0,3))
f = lambdify(x, s)
b = np.array([1, 2, 3, 4])
f(b)