brendanashworth / fft-small Goto Github PK

Great work on this DFT and FFT implementation into a one piece of usable code for an embedded platform. Unfortunately, I don't understand how can I see the calculation result after putting my data into fft(int* x, double complex* X, uint16_t N) function?

Hey Brendan ! Thx for opensourcing this amazing implementation!

I'm learning FFT and trying to find some C implementations then I found yours!

I generated a 50Hz sine wave(y=2sin(2pi50t)(under 1200hz sample rate and I sampled the first period of 0~0.02s signals) and tried radix2 on the first try. I changed the FFT input of int* x to double* x to fit my float inputs.

But the calculated modulus doesn't come as expected. While I'm confused I tried fft_slow then it's 100% accurate.
fft radix2:

fft_slow:

I don't know if I'm coding it wrong...Appreciate any help!

Here's my code(Based on 'test.c'.)
https://gist.github.com/2ndMessiah/03f875c8fba6f790cdefebb187c37c9e