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Re: FFT Speed

  • To: mathgroup at smc.vnet.net
  • Subject: [mg121982] Re: FFT Speed
  • From: roby <roby.nowak at gmail.com>
  • Date: Sat, 8 Oct 2011 05:31:57 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <j6mf50$7hu$1@smc.vnet.net>

On 7 Okt., 11:01, to <todu... at gmail.com> wrote:
> 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.


Well,

you may avoid the Flatten:

Map[Fourier[#, FourierParameters -> {1, -1}] &,data,{2}]

no idea what speed gain (if any) this will give.

Regards Robert



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