;return_slow_ft ; ;PURPOSE: ; This function will take an array of length L and return the Fourier ; Transform F(s) with N frequencies. It is different than the FFT in ; that it will calculate F(s) at a range of values between s=0 and s=L/2 function return_slow_ft,Array,NumFrequencies,DeltaT SamplingFreq=1./DeltaT NyquistFreq=SamplingFreq/2 Frequencies=(Findgen(NumFrequencies/2)/(float(NumFrequencies)/2.))*NyquistFreq T=DeltaT*findgen(N_elements(Array)) FT=complexarr(NumFrequencies/2) i=complex(0,1) for s=0, NumFrequencies/2-1 do begin FT(s)=total(Array*exp(-2*!pi*i*Frequencies(s)*T)) endfor return,FT end