I was reading this article to understand the
fft - JACK SCHAEDLER - A WALKTHROUGH OF THE DFT - STEP BY STEP.
I understand that:
- the fft takes a block (256 or 512) of the signal, creates a sinusoidal and cosineidal wave of frequency "f" and multiplies each sample for each sample of the signal to decompose,
- add the value of all the samples of the cosine and sine wave product, if it gives greater than 0 it means that the frequency wave "f" is present in the signal
- the result of the sum of each product wave gives a complex number
now what I want to know what is the next formula to rebuild the signal, ie an inverse fft