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Re: Accelerating a one-line program doing matrix multiplication [message #72744 is a reply to message #72696]

Thu, 30 September 2010 07:59

pgrigis
Messages: 436
Registered: September 2007

Senior Member

[skip]
>
> FUNCTION vc2rc_accel, v0,v1,v2,v3,vc
> npoints = (SIZE(vc, /DIMENSIONS))[1]
> for i=0L, npoints-1 DO BEGIN
> vc[*,i] = vc[0,i] * v1 + vc[1,i] * v2 + vc[2,i] * v3 + v0
> endfor
> RETURN, vc
> END

No, that's using a for loop - that's why it is slow.
You want something like this (no loops):

vc0=vc[0,*]
vc1=vc[1,*]
vc2=vc[2,*]
vc[0,*]=vc0*v1[0]+vc1*v2[0]+vc3*v3[0]
vc[1,*]=vc0*v1[1]+vc1*v2[1]+...
vc[2,*]=vc0*v1[2]+...

Ciao,
Paolo

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[Message index]

		Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Mon, 27 September 2010 02:18
		Re: Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Thu, 30 September 2010 09:38
		Re: Accelerating a one-line program doing matrix multiplication By: pgrigis on Thu, 30 September 2010 08:03
		Re: Accelerating a one-line program doing matrix multiplication By: pgrigis on Thu, 30 September 2010 07:59
		Re: Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Thu, 30 September 2010 04:05
		Re: Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Thu, 30 September 2010 02:41
		Re: Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Thu, 30 September 2010 01:39
		Re: Accelerating a one-line program doing matrix multiplication By: Karl[1] on Wed, 29 September 2010 09:57
		Re: Accelerating a one-line program doing matrix multiplication By: pgrigis on Wed, 29 September 2010 09:05
		Re: Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Wed, 29 September 2010 08:55
		Re: Accelerating a one-line program doing matrix multiplication By: penteado on Wed, 29 September 2010 08:45
		Re: Accelerating a one-line program doing matrix multiplication By: pgrigis on Wed, 29 September 2010 08:34
		Re: Accelerating a one-line program doing matrix multiplication By: Axel Martínez on Wed, 29 September 2010 08:24

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