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Re: Fast matrix filling in IDL [message #13787 is a reply to message #13780]

Mon, 14 December 1998 00:00

Kevin Ivory
Messages: 71
Registered: January 1997

Member

> Stein Vidar Hagfors Haugan (steinhh@ulrik.uio.no) writes:
>>
>> A slight modification of David's program, and adding
>> my favourite speedup method:
>>
>> time = systime(1)
>> array = rebin(reform(v,m,1,/overwrite),m,n,/sample)
>> print, 'Time for Rebin Operations: ', systime(1) - time
>>
>> On { alpha OSF unix 5.2 Oct 30 1998}, this gives:
>>
>> Time for Loop: 0.27343702
>> Time for Matrix Operations: 0.093750000
>> Time for Rebin Operations: 0.067382932
>>
>> Note that the relative speeds can vary quite a lot on
>> different architectures.

David Fanning wrote:
>
> IDL> Print, !Version
> { x86 Win32 Windows 5.2 Oct 30 1998}
> IDL> test
> Time for Loop: 0.10000002
> Time for Matrix Operations: 0.019999981
> Time for Rebin Operations: 0.039999962
>
> The Rebin operations are twice as slow as the matric operations.
> Hummm. Why!?

Wow, this is fun. Linux is infinitely faster on matrix and rebin, but
*real* slow on loops:

IDL> Print, !Version
{ x86 linux unix 5.2 Oct 30 1998}
IDL> test
Time for Loop: 1.0000000
Time for Matrix Operations: 0.0000000
Time for Rebin Operations: 0.0000000

??? Am I missing something?
Kevin
--
Kevin Ivory Tel: +49 5556 979 434
Max-Planck-Institut fuer Aeronomie Fax: +49 5556 979 240
Max-Planck-Str. 2 mailto:Kevin@Ivory.de
D-37191 Katlenburg-Lindau, GERMANY http://ivory.de/

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[Message index]

		Re: Fast matrix filling in IDL By: Kevin Ivory on Mon, 14 December 1998 00:00
		Re: Fast matrix filling in IDL By: steinhh on Mon, 14 December 1998 00:00
		Re: Fast matrix filling in IDL By: davidf on Mon, 14 December 1998 00:00
		Re: Fast matrix filling in IDL By: Kevin Ivory on Mon, 14 December 1998 00:00
		Re: Fast matrix filling in IDL By: Phillip & Suzanne on Sat, 12 December 1998 00:00
		Re: Fast matrix filling in IDL By: davidf on Sat, 12 December 1998 00:00
		Re: Fast matrix filling in IDL By: steinhh on Sat, 12 December 1998 00:00
		Re: Fast matrix filling in IDL By: davidf on Fri, 11 December 1998 00:00

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