How to do a sum in python

function, python, sum

Solution

something like:

def V(theta,N):
    return sum(a0*(cos(i*theta) for i in range(1,N+1))
print V(theta,N)

or you can use `lambda`:

V =lambda theta,N : sum(a0*(cos(i*theta) for i in range(1,N+1))   
print V(theta,N)

Problem

I was wondering how one can represent a sum in python without loops like here where we have: ``` def rosen(x): """The Rosenbrock function""" return sum(100.0*(x[1:]-x[:-1]**2.0)**2.0 + (1-x[:-1])**2.0) ``` My function is the following: `V(theta) = Sum(i=1->N)[a0*(cos(i*theta)]` Thank you in advance for your help :):)

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