| Re: Memory question by a newbie [message #31569] |
Fri, 02 August 2002 15:22  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Pat (patt@cnr.usu.edu) writes:
> I am a newbie to IDL and am hoping for some advice on memory issues.
> My programm reads 10 files and places the information (floating point)
> into 10 different 2D arrays. The arrays are about 5000 columns by
> 6000 rows. Each array is subject to simple mathematical manipulation
> that results in a new 2D array. So, I read 10 files and create 10 2D
> arrays. These 10 arrays are intermediate arrays that are used to
> create a final 2D array. Well, you can probably figure out that I ran
> out of memory.
Well, I'm up to 5000 x 6000 x 4 x 10 = 1.2Gbyte already,
and we haven't even done anything yet or created the
output array. :-(
> I read up on memory problems with IDL and it seems
> like this is the way life is in IDL.
Uh, right. That is 1.2 GIGA bytes! Have you tried that
with, say, Microsoft Excel? I'm not going to get JD all
over my case by saying that IDL uses memory in the most
efficient manner possible, but I think everyone would
agree, we are talking about a sizeable chunk of memory
here.
What newsgroup were you reading when you read up
on this, comp.lang.matlab?
> The way I solved the memory
> problem was to break up the files into sections and work with those
> sections, then read the file again only moving the file pointer to the
> end of previous section.
Well, this sounds like a sensible solution to me.
> I used the update parameter of the read
> function to create the final array, so each section is added to the
> final array file. I am wondering if there is a better work around?
I read an interesting book lately about the National Security
Agency. I guess they are spending quite a bit of money looking
into the possibilities of quantum computers. That might be the
Cadillac of work-arounds. :-)
> I found the IDL_MAKETEMPARRAY function but I don't understand what it
> does and am not sure if that is the answer.
I don't know what it does either, but I'm *certain* it's not the
answer. :-)
Cheers,
David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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