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Re: Dealing with Large data arrays, reducing memory and ASSOC [message #54450]

Fri, 15 June 2007 12:54

Kenneth Bowman
Messages: 86
Registered: November 2006

Member

In article <1181932819.315280.237270@q66g2000hsg.googlegroups.com>,
bill.dman@gmail.com wrote:

>> If you try this with a trailing dimension you get this
>>
>> IDL> x = findgen(4,4)
>> IDL> x[2,0] = replicate(99.0, 4)
>> % Out of range subscript encountered: X.
>> % Execution halted at: $MAIN$
>>
>> To make your expression work, you would have to write
>>
>> fftdc[i,j,*] = fft(dc[i,j,*],-1)
>>
>> which results in some performance penalty.
>>
>> Ken Bowman
> Two issues:
>
> First, it's not exactly true that the base indexing trick works only
> for leading dimensions on the LHS. Its a question of shape matching.
> So your example works ok with x[2,0] = replicate(99.0, 1, 4).

Ah, this is good to know. This trick is in a Tech Tip (I can't find it
in the manual), and the explanation is ... perhaps overly succinct.

Ken Bowman

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[Message index]

		Re: Dealing with Large data arrays, reducing memory and ASSOC By: Kenneth Bowman on Fri, 15 June 2007 12:54
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: bill.dman on Fri, 15 June 2007 11:40
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: Ambrosia_Everlovely on Fri, 15 June 2007 00:26
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: Kenneth Bowman on Thu, 14 June 2007 11:52
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: Kenneth Bowman on Thu, 14 June 2007 11:50
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: JD Smith on Thu, 14 June 2007 09:32
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: Haje Korth on Thu, 14 June 2007 09:18
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: bill.dman on Thu, 14 June 2007 06:41
		Re: Dealing with Large data arrays, reducing memory and ASSOC By: Kenneth Bowman on Thu, 14 June 2007 06:08

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