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Re: matrix multiplication [message #63073 is a reply to message #911]

Tue, 28 October 2008 13:59

Chris[6]
Messages: 84
Registered: July 2008

Member

On Oct 28, 8:42 am, David Fanning <n...@dfanning.com> wrote:
> russ writes:
>> Probably a stupid question but I haven't used idl for a while
>
>> Is there a quicker way of doing this?
>
>> a=fltarr(1000,20)
>> b=fltarr(20)
>
>> for i=0,999 do begin
>> a(i,*)=a(i,*)*b
>> endfor
>
> It might be faster to realize the end result is going
> to be an array of zeros than it would be to actually
> write the code. :-)
>
> But, I think you want this:
>
> a = a * rebin(reform(b, 1, 20) ,1000, 20)
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Coyote's Guide to IDL Programming (www.dfanning.com)
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

I also like this shortcut for reform:
a = a * rebin(1#b, 1000, 20)

chris

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[Message index]

		matrix multiplication By: c1dje on Mon, 22 March 1993 14:51
		Re: Matrix multiplication By: Haje Korth on Fri, 14 November 2003 09:48
		Re: matrix multiplication By: Chris[6] on Tue, 28 October 2008 13:59
		Re: matrix multiplication By: russ[1] on Tue, 28 October 2008 14:32
		Re: matrix multiplication By: David Fanning on Tue, 28 October 2008 11:42
		Re: matrix multiplication By: Vince Hradil on Tue, 28 October 2008 19:17

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