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FFT Speed

• To: mathgroup at smc.vnet.net
• Subject: [mg121961] FFT Speed
• From: to <todummy at gmail.com>
• Date: Fri, 7 Oct 2011 04:48:40 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

I have a 3D matrix with dimensions {355,647,8}.  For each {x,y} I need
to compute the FFT along the z dimension, i.e. 355*647 FFTs of 8
elements each.  The fastest way I found to do this was

Partition[Map[Fourier[#, FourierParameters -> {1, -1}] &,
Flatten[data, 1]], dimx];

I was wondering if there are faster ways to do this.  The reason I ask
is because another package for numerical computations can do this a
lot faster compared to my solution (nearly two orders of magnitude
faster !)

I tried using ParallelMap but this makes things even slower.

• Follow-Ups:
  • Re: FFT Speed
    • From: Daniel Lichtblau <danl@wolfram.com>