Fourier cosine series

  • #1
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Homework Statement


upload_2018-4-3_23-11-46.png


Homework Equations


All I know is the a's have something to do with the integrals.
upload_2018-4-3_23-13-22.png

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.
 

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  • #2
kuruman
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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.
 
  • #3
scottdave
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To find the a0, a1, etc. Compare the format of the given summation to the expansion of f(t) in equation (5.2)
 
  • #4
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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
 
  • #5
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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).
 
  • #6
kuruman
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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.
 
  • #7
scottdave
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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
 
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