Fast Fourier Transform

12092018, 02:54 AM
Post: #1




Fast Fourier Transform
I hope you can help me. I am trying to understand how the fast Fourier transform is calculated (FFT).
Sample problem: n_0 = 0.54 n_1 = 0.66 n_2 = 0.52 where N = 3 The formula to the FFT (I think) is: X_k = Σ( x_n * e^(i * 2 * π * k * n / N) ) for n = 0 to N1 Using the formula above I get: X_0 = 1.62 X_1 = 0 X_2 = 0 But the fft function on the HP Prime returns: 1.72 0.05  0.12124355653i 0.05 + 0.12124355653i However Wolfram Alpha returns: 0.993042 0.0288675 + 0.07i 0.0288675  0.07i I am confused. Are there different fast Fourier transforms or am I missing something obvious? I want to understand the basic calculation before I attempt to understand the Tukey and Cooley algorithm. Any help and insight is appreciated. Thanks! 

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Messages In This Thread 
Fast Fourier Transform  Eddie W. Shore  12092018 02:54 AM
RE: Fast Fourier Transform  toshk  12092018, 07:59 AM
RE: Fast Fourier Transform  Thomas Klemm  12092018, 11:14 AM
RE: Fast Fourier Transform  Eddie W. Shore  12092018, 05:24 PM

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