Verifying correctness of FFT algorithm

Question

Today I wrote an algorithm to compute the Fast Fourier Transform from a given array of points representing a discrete function. Now I\'m trying to test it to see if it is w

Answer 1

I'd use something authoritative like Wolfram Alpha to verify.

If I evalute cos(i/2) for 0 <= i < 32, I get this array:

[1,0.878,0.540,0.071,-0.416,-0.801,-0.990,-0.936,-0.654,-0.211,0.284,0.709,0.960,0.977,0.754,0.347,-0.146,-0.602,-0.911,-0.997,-0.839,-0.476,0.004,0.483,0.844,0.998,0.907,0.595,0.137,-0.355,-0.760,-0.978]

If I give that as input to Wolfram Alpha's FFT function I get this result.

The plot that I get looks symmetric, which makes sense. The plot looks nothing like any of the ones you supplied.