# Homework Help: Evaluating a fourier series using the firs 100terms

1. Aug 23, 2009

### paul143

Well, the problem gave me a symmetric square wave f(x).

f(x) = 1, when |x|<pi/2 and -1, pi/2 < |x|< pi

I was able to solve for its fourier series expansion given by:

f(x) = (4/pi) * $$\Sigma$$ (-1)n cos(2n+1)x / 2n+1

Now the problem asked us to evaluate this series for x=0(pi/18)pi/2 using the first 100terms of the series.

Now this is where i was really stuck, i can't seem to grasp the meaning of "from x=0(pi/18)pi/2". I'm not familiar with this notation. Can anyone enlighten me please?

And if possible, point me in the right direction in evaluating this series thanks so much!

2. Aug 23, 2009

### maverick280857

Welcome to PF!

You have to take the first 100 terms, sum them up, call it some function S(x), and then find values of S(x) from x = 0 to x = pi/2, in steps of pi/18 (which is what the notation means).

Last edited: Aug 23, 2009
3. Aug 23, 2009

### paul143

ooohhh!!! i seee!! thanks very much!! :D now i understand :D