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Re: do I need this IF statement? [message #43246 is a reply to message #43241]

Thu, 24 March 2005 04:48

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Margrethe writes:

> I find that in some cases I really need an IF statement to make sure
> that I don't address some arrays with index -1. In the example below I
> have vectorized the inner loop over j, but have kept the loop over i.
> Is there a way to avoid the IF statement? Grateful for help! -Margrethe
>
> FOR i=0,N-1 DO BEGIN
>
> d = sqrt ( x(i) ^2 + y (INDGEN(N)) ^2 )
> indx = WHERE ( d LT 3.*sigma, ct )
>
> IF (ct GT 0) THEN BEGIN
>
> v = v1 + vr (i,indx)
> p = some_function ( x(i), y(indx) )
> profile = profile + TOTAL ( p * image(i,indx) )
>
> ENDIF
>
> ENDFOR

JD has me totally intimidated about making sweeping generalizations,
but I'm going to state emphatically that you NEED the IF statement.
We'll see if that turns out to be true. :-)

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		Re: do I need this IF statement? By: Benjamin Luethi on Thu, 24 March 2005 07:29
		Re: do I need this IF statement? By: Benjamin Luethi on Thu, 24 March 2005 07:05
		Re: do I need this IF statement? By: David Fanning on Thu, 24 March 2005 04:48

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