Problem With Fourier Coefficients :(

frank789

Junior Member
Joined
Sep 16, 2017
Messages
58
Hi All,

I am trying to calculate the coefficients for a trigonometric fourier series expansion of a square wave with a height of 1. It is centered at the origin, extending to pi on either side of it. It has a period of 10pi.

I have tried pulling the correct coefficients out for a couple hours now but my attempt to view my solution in a graphing calculator has been in vein and before I break something I decided to post in the forum.

My series expansion came out to:

f = 1/5 + sum{ (2/(n pi) * sin (n pi / 5) * cos(n/5 t)}

I approached this problem in the following manner.

Calculated by a0 term by calculating the average value of the function.

Calculated my an coefficients using an integral of 4/10pi * the integral from 0 to the period divided by 2, times cos(nwt).

Reasoned that my bn terms must be 0 since it is an even function.

The function in a graphing calculator does not resemble my signal at all.

I do not understand what I am doing wrong and if anyone could offer some pointers, I am self taught on the subject and would appreciate them very much.

Cheers
 

frank789

Junior Member
Joined
Sep 16, 2017
Messages
58
for the record and just to close this, the graphing calculator was in radians...no real problem here other than me :(
 
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