Radix2 decimation in time 1D fast Fourier transform FFT

The function implement the 1D radix2 decimation in time fast Fourier transform FFT algorithm

Description

The function implement the 1D radix2 decimation in time fast Fourier transform (FFT) algorithm.

• MATLAB release: MATLAB 6.5 (R13)

[Nicolaie Popescu-Bodorin]

(1) In the present form the function fftf fails to compute fft [test: norm(fftf(x)-fft(x))]

So, in fftf function, instruction
W=complex(cos(2*pi*(k-1)/N),sin(2*pi*(k-1)/N));
MUST BE REPLACED WITH:
W=complex(cos(2*pi*(k-1)/N),-sin(2*pi*(k-1)/N));

   Popescu-Bodorin

[mari chamy]

 

[Alex]

Or you can have a equation for W like:
W=exp(-i*2*pi*(k-1)/N);

norm(fftf(x)-fft(x)) works fine for me.