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Re: limits of 'invert' [message #46345 is a reply to message #46340]

Wed, 16 November 2005 10:01

Foldy Lajos
Messages: 268
Registered: October 2001

Senior Member

Hi,

as an example, run time for simple matrix multiplication is proportional
to n^3. For your sizes, this would give a factor of 10^6. A 150x150 array
can reside in the CPU cache, so add another 10 for the big array => 10^7.
If "immediate" = 0.1 s, then 10^7 * 0.1 s is about two weeks.

And if you run out of physical memory, swapping to disk can add another
factor of 100 :-(

regards,
lajos

On Wed, 16 Nov 2005, queiny wrote:

> Dear IDL & Maths experts:
>
> Is there a limit for the 'invert' or 'la_invert', program to calculate
> the inversion of a square matrix, provided by IDL?
>
> When my matrix is 150x150, 'invert' return immediatelly, but when it is
> '15000x15000', 'invert' runs for more than a day. I am wondering
> whether it is in some infinite loop, or it simply needs that long.
>
> What is the reasonable upper limit that 'invert' or 'la_inver' can
> operate?
>
> Thanks,
>
> Q
>
>

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[Message index]

		Re: limits of 'invert' By: Paolo Grigis on Thu, 17 November 2005 00:38
		Re: limits of 'invert' By: queiny on Wed, 16 November 2005 12:16
		Re: limits of 'invert' By: K. Bowman on Wed, 16 November 2005 11:07
		Re: limits of 'invert' By: Foldy Lajos on Wed, 16 November 2005 10:01

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