ifft in C/C++ - comp.dsp

Parlous wrote: > > I have used FFTW for my fourier operations in the past, but is there a > inverse fourier transform library of some sort out there that is just as > fast? FFTW can already do that. Why would you want another library? Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo nospam@mega-nerd.com (Yes it's valid) +-----------------------------------------------------------+ "The Internet interprets censorship as damage, and routes around it." - John Gilmore, EFF co-founder

Parlous wrote: > > well, holy snot balls. i was unaware that going from "complex to real" in > the fftw meant an inverse transform. i ignored it when i was concerned with > the fft only, thinking it had to do something with going forward/backward > meaning postive versus negative frequencies! Its been a while since I last looked at FFTW, but I believe that you need to use the FFTW_BACKWARD flag to get the inverse FFT. I also seem to remember that you still need to do the scaling by 1/N yourself. Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo nospam@mega-nerd.com (Yes it's valid) +-----------------------------------------------------------+ "I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours." -- Stephen Roberts

Erik, I like your sig. - Eric On Sat, 16 Aug 2003 22:48:12 GMT, Erik de Castro Lopo <nospam@mega-nerd.com> wrote: >Its been a while since I last looked at FFTW, but I believe that >you need to use the FFTW_BACKWARD flag to get the inverse FFT. >I also seem to remember that you still need to do the scaling by >1/N yourself. > >Erik >-- >+-----------------------------------------------------------+ > Erik de Castro Lopo nospam@mega-nerd.com (Yes it's valid) >+-----------------------------------------------------------+ >"I contend that we are both atheists. I just believe in one fewer god >than you do. When you understand why you dismiss all the other possible >gods, you will understand why I dismiss yours." -- Stephen Roberts Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions. http://www.ericjacobsen.org

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7/15/2012 3:48:31 AM