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Re: Help me aviod a FOR loop!?!? [message #30436 is a reply to message #30411]

Wed, 24 April 2002 02:01

Malcolm Walters
Messages: 8
Registered: October 2001

Junior Member

"Sean Davis" <sdavis@nis.lanl.gov> wrote in message
news:Pine.LNX.4.33.0204231006000.1744-100000@vglass.lanl.gov ...
> I don't know if this is possible. I have 4 coeffecients,
> a,c,d,cd, that are each 3191-long arrays, and I would like to construct
> 3191, waveforms (of length 128) from these coefeccients.
>
> Here's what I'm trying to do:
>
> x = FINDGEN(128)
> yfit = FLTARR(128,3191)
>
> yfit = (a/cd)*( exp(-1.*c*x)-exp(-1.*d*x) )
>
> In the end, I would like yfit to be an array of (128,3191) or (3191,128).
>
> I can't figure out how to do this without using a FOR loop. Is there any
> hope for doing this without a FOR loop?

I think this calls for use of rebin and matrix multiplication.
The rebin is required to turn 'a' and 'cd' into arrays the same shape as the
result of the matrix multiplications.

so...
a=randomn(systime(/seconds),3191)
c=randomu(systime(/seconds),3191)
d=randomu(systime(/seconds),3191)
cd=randomn(systime(/seconds),3191)
x=findgen(128)
yfit = (rebin(a,3191,128,/sample)/rebin(cd,3191,128,/sample))*(
exp(-c#x)-exp(-d#x) )

Malcolm
>
> THANKS!!!!!!
>
> Sean
>
>
>

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[Message index]

		Re: Help me aviod a FOR loop!?!? By: James Tappin on Thu, 25 April 2002 07:47
		Re: Help me aviod a FOR loop!?!? By: Malcolm Walters on Wed, 24 April 2002 02:01
		Re: Help me aviod a FOR loop!?!? By: gutmann on Tue, 23 April 2002 20:23
		Re: Help me aviod a FOR loop!?!? By: Paul Van Delst[1] on Tue, 23 April 2002 10:06

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