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Re: Matrix a*b in loop [message #89052 is a reply to message #89043]

Sat, 19 July 2014 13:31

Mats Löfdahl
Messages: 263
Registered: January 2012

Senior Member

Den torsdagen den 17:e juli 2014 kl. 23:16:29 UTC+2 skrev Gompie:
> Hi,
>
> I have a simple question.
>
>
>
> I have two matricies A (696 , 1523854 ) and B (1,696) Matrix .
>
> I wish to have a matrix c whose each row is a product of rows elements of a and b i.e a*b
>
>
>
> I can do it in a loop by saying a(:,i)*b but it takes a lot of time because I (~1523854 ) would be very large number. Is it possible to do it in one go.

Is this what you want to do?

IDL> a = randomu(seed,696,1523854)
IDL> b = randomu(seed,1,696)
IDL> help,a,b
A FLOAT = Array[696, 1523854]
B FLOAT = Array[1, 696]
IDL> c = a ## b
IDL> help,c
C FLOAT = Array[1, 1523854]

http://www.exelisvis.com/docs/Matrix_Operators.html
http://www.exelisvis.com/docs/matrix_multiply.html

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[Message index]

		Matrix a*b in loop By: Gompie on Thu, 17 July 2014 14:16
		Re: Matrix a*b in loop By: Yngvar Larsen on Fri, 18 July 2014 01:43
		Re: Matrix a*b in loop By: Mats Löfdahl on Sat, 19 July 2014 13:31

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