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Re: 2D FFT Slow. Any ideas? fft2() [message #37233 is a reply to message #37225]

Mon, 08 December 2003 00:06

Brian
Messages: 27
Registered: March 2001

Junior Member

But your matlab fft2 time is still quite a bit faster (3.2 sec vs 8.1 sec).

I have no idea how to use that FFTW but I am going to look into that.

thanks,

brian

"R.G. Stockwell" <noemail@please.com> schrieb im Newsbeitrag
news:Hx6Ab.410$v23.28915@news.uswest.net...
>
> "R.G. Stockwell" <noemail@please.com> wrote in message
> news:wq6Ab.409$v23.28199@news.uswest.net...
>>
>> Hi Brian,
>> I found some time to take a look at this, and I see the same thing you
do.
>> This is on a 1.13 ghz dell inspiron 8100 laptop running win2000.
>> Matlab 6.5 did the fft of 2048 by 2048 array of doubles in 0.9 seconds.
>> IDL 6.0 did it in 4.6 seconds (ram 109 MBs).
>>
>> Wow, that is surprising. The idl version is quite slow.
>>
>> For a double complex array IDL takes 8.1 seconds (ram 174 MBs),
>> matlab takes 1.6 sec (211 mb ram).
>>
>> Interesting.
>>
>> -bob
>
>
> DOH!
>
> Um.... after I posted this, I realized that one should use fft2() in
> matlab.
>
> The matlab time for the fft of a double 2048 by 2048 is 3.2 seconds.
>
> So, it is in line with the IDL times, and IDL seems to handle memory a
> little
> more efficiently.
>
>
> Cheers,
> bob
>
>

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[Message index]

		Re: 2D FFT Slow. Any ideas? fft2() By: Richard French on Mon, 08 December 2003 11:33
		Re: 2D FFT Slow. Any ideas? fft2() By: mmiller3 on Mon, 08 December 2003 06:44
		Re: 2D FFT Slow. Any ideas? fft2() By: Brian on Mon, 08 December 2003 00:06
		Re: 2D FFT Slow. Any ideas? fft2() By: R.G. Stockwell on Fri, 05 December 2003 13:13
		Re: 2D FFT Slow. Any ideas? fft2() By: h_chapman on Sat, 13 December 2003 21:58

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