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Re: Maximum index for arrays? [message #62565 is a reply to message #62562]

Mon, 15 September 2008 01:53

Chris[6]
Messages: 84
Registered: July 2008

Member

On Sep 14, 8:08 pm, "hotplainr...@gmail.com" <hotplainr...@gmail.com>
wrote:
> Hi guys,
>
> Thanks for helping me for the past few weeks. I've managed to get
> CUBLAS and other CUDA programs working in IDL. What I have now for you
> guys is this.
>
> Here is the code
>
> N = 181
> N2 = N^2
> a = fltarr(N2, 141)
> help,a
>
> A FLOAT = Array[32761, 141]
>
> N = 182
> N2 = N^2
> a = fltarr(N2, 141)
> % Array dimensions must be greater than 0
> % Execution halted at: TEST 5 /home/hpr/test.pro
> % $MAIN$
> IDL>
>
> How big can the index go? Its because I need N = 100 to 1000
>
> Regards
> Zaki

The problem is that the line
N = 182
sets N to a 16-bit signed integer (max size 32767-ish). When you
square it (33124), it overflows and becomes negative (-32412). Use
something like
N=182L (long integer with max size about 2 billion) or
N=2. (floating point)

As long as you have the RAM, arrays can have millions or billions (i
think) of elements, so you'll be fine.

chris

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[Message index]

		Re: Maximum index for arrays? By: pgrigis on Mon, 15 September 2008 06:38
		Re: Maximum index for arrays? By: hotplainrice@gmail.co on Mon, 15 September 2008 03:15
		Re: Maximum index for arrays? By: Chris[6] on Mon, 15 September 2008 01:53

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