Finding Fourier cosine series coefficients with FFT in Matlab

[Carter]

Homework Statement

Homework Equations

All I know is the a's have something to do with the integrals.

The Attempt at a Solution

I used FFT analysis in Matlab but I do not know what I am looking for. How do the a0s relate to the f(t) in the question and how would I even do run that equation in an excell program. I just need to know where to start.

 

[kuruman]

I don't think you need FFT analysis for this. Read the problem statement and do what it says using a spreadsheet. It's a simple plug and chug and plot question.

 

[scottdave]

To find the a0, a1, etc. Compare the format of the given summation to the expansion of f(t) in equation (5.2)

 

[Carter]

To find the a0, a1, etc. Compare the format of the given summation to the expansion of f(t) in equation (5.2)

so would a0 be .2 and a1=(2/pi)(-1)^1/1

 

[Carter]

I don't think you need FFT analysis for this. Read the problem statement and do what it says using a spreadsheet. It's a simple plug and chug and plot question.

what am I pluging into, how do the a's relate to the f(t).

 

[kuruman]

what am I pluging into, how do the a's relate to the f(t).

You are plugging into the equation $f(t)=0.2+\frac{2}{\pi} \sum_{n=1}^\infty~...~etc$ that is given to you. The posts by @scottdave and @Carter explain what the $a_n$ are, they are whatever multiplies each $\cos(4n \pi t)$ term in the summation.

 

[scottdave]

so would a0 be .2 and a1=(2/pi)(-1)^1/1

If you multiply that by sine( 0.2(1)pi) then that will be a1