How to write a for loop for summation?

Is there another way to do summation without for loop, or how would I do it with a for loop?

I want to iterate from N = 1 to N = 25 with 0 < x < 2*pi of the equation n*(sin^2(x)+cos^2(x)) I'm not so sure how to do a for loop for the summation

Answer 1

[Birdman]

Do not use for loop. If you Symbolic Toolbox, you may use symsum:

syms x n
fun(x)=symsum(n*(sin(x)^2+cos(x)^2),n,1,25)

Answer 2

[Walter Roberson]

Use sum().

sin(x)^2 + cos(x)^2 = 1, even for complex numbers, so n*(sin(x)^2 + cos(x)^2) is going to simplify to n.