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MathGroup Archive 1996

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Re: memory use

  • To: mathgroup at smc.vnet.net
  • Subject: [mg4819] Re: memory use
  • From: Harald Berndt <hberndt9 at mail.idt.net>
  • Date: Fri, 20 Sep 1996 01:12:40 -0400
  • Organization: IDT Corporation
  • Sender: owner-wri-mathgroup at wolfram.com

Russell Towle wrote:
> 
> ... so I thought that writing it to a file might be a good device.
> 
> I use the syntax, (biglist >> "filename"), but to my surprise, the kernel
> requires tons of memory to execute this, even though the list "biglist" is
> already evaluated, and every element in it already resides in memory.
> 
> By allocating 40 MB of memory to the kernel, I was able to write the list
> to a file.  The file size itself was only 3MB.  Why does MMA need 16 

Yeah, well ... I ran into that problem quite often myself. I think the 
problem is that using

     biglist >> "filename"

one makes Mathematica convert all the numbers in the list from Mma's 
internal representation to strings (in particular, each real is 
written as an 18+ digit string), then write those strings to disk. 
Very memory-demanding! A workaround might be to write your own binary 
read and write routines (or just use those available, if that's 
sufficient ... haven't looked at that in detail lately).

-- 
______________________________________________________________________
Harald Berndt, Ph.D.                              Research Specialist,
                                                           Consultant                        

Phone:	510-652-5974                                FAX:			510-215-4299
______________________________________________________________________
"I yam what I yam"...................................Popeye the sailor
(Kryten:............"I thought that was Descartes!"..................)
(Lister:............"So did I. mon, so did I!".......................)



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