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Re: avoiding for loop when calculating median [message #10952 is a reply to message #10936]

Fri, 30 January 1998 00:00

Alex Schuster
Messages: 124
Registered: February 1997

Senior Member

Oops! I wrote:

> I assume that mat is an idim x jdim array. mat(cnt,*) gives the elements
> no. cnt, cnth+idim, cnth+2*idim etc., I guess it's easier to use
> mat2=reform(mat), so all the elements are in line.

Don't know why I wrote REFORM here, it's TRANSPOSE.
I just tested this with an 5000x5000 float array, there is a HUGE
difference in the execution time.

> Another idea:
>
> index = lindgen( jdim )
> for cnt = 0, idim-1 do begin
> calcmedian(cnt) = median( mat2(cnt*jdim+index) )
> end

Forget this. I thought this were a good idea, but it actually slows down
the calculation.

Alex
--
Alex Schuster Wonko@weird.cologne.de PGP Key available
alex@pet.mpin-koeln.mpg.de

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[Message index]

		Re: avoiding for loop when calculating median By: Alex Schuster on Mon, 02 February 1998 00:00
		Re: avoiding for loop when calculating median By: George McCabe on Mon, 02 February 1998 00:00
		Re: avoiding for loop when calculating median By: Alex Schuster on Fri, 30 January 1998 00:00
		Re: avoiding for loop when calculating median By: George McCabe on Fri, 30 January 1998 00:00
		Re: avoiding for loop when calculating median By: a2652099 on Fri, 30 January 1998 00:00
		Re: avoiding for loop when calculating median By: Michael Werger on Fri, 30 January 1998 00:00

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