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Re: Using two different arrays in tha same calculation [message #2282 is a reply to message #2243]

Thu, 09 June 1994 09:09

landers
Messages: 45
Registered: May 1993

Member

In article <2t49er$dp5@due.uninett.no>, ragnar@kvark.fi.uib.no (Ragnar Aas) writes:
|> I have the following problem :
|>
|> I have two different arrays, (8) of float and (300,8) of float.
|> I want to vectorize the equation and therefore I need to use both
|> arrays in the same equation. For example :
|>
|> newarray=cos(small_array)*sin(large_array)
|>
|> where I want the data in small_array to be used over and over 300 times
|> in this calculation.
|>
|> Hope somebody can help me.
|>
|> Ragnar Aas

Try like this:

a = fltarr(8)
b = fltarr(300,8)

ia = lindgen(300,8) / 300L

c = a(ia) * b

Here's why.... ia is a 300,8 array of indices into the 8-element array.
So ia(*,0) = 0, ia(*,1) = 1, etc.

Then a(ia) becomes a 300,8 array that repeats the 8-element array 300 times.

Note that you'd have to play with this if the index orders were reversed (like
you were trying to operate on an 8-element and a (8,300) arrays). You'd need
to change ia to be lindgen(8,300) mod 8

;Dave

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[Message index]

		Re: Using two different arrays in tha same calculation By: landers on Thu, 16 June 1994 06:52
		Re: Using two different arrays in tha same calculation By: dan on Wed, 08 June 1994 07:42
		Re: Using two different arrays in tha same calculation By: landers on Thu, 09 June 1994 09:09
		Re: Using two different arrays in tha same calculation By: steinhh on Fri, 10 June 1994 00:44
		Re: Using two different arrays in tha same calculation By: thompson on Thu, 09 June 1994 06:20

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