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MathGroup Archive 1995

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Re: Writing big files with Mathematica

  • Subject: [mg2528] Re: Writing big files with Mathematica
  • From: withoff (David Withoff)
  • Date: Thu, 16 Nov 1995 06:46:07 GMT
  • Approved: usenet@wri.com
  • Distribution: local
  • Newsgroups: wri.mathgroup
  • Organization: Wolfram Research, Inc.
  • Sender: daemon at wri.com ( )

In article <489hs1$gm7 at ralph.vnet.net> grot at marie.physik.tu-berlin.de  
(Bjoern Grothkast) writes:
> risset at irisa.fr (Tanguy Risset) wrote:
> 
> >Hello
> 
> >I am using Mathematica (version  2.2 for SPARC) to manipulate
> >big list data structures. I have a problem when I try
> >to print the data structure into a file on the disk
> >with the command:
> 
> >data >> "file"
> 
> >The process is very slow and when the data is too big
> >(here approximately 200 Mbytes), Mathematica is exiting
> >(completely) with the message:
> 
> >Out of memory.  Exiting.
> 
> >Does anyone knows where does it come from?
> >And how I can manage to write down my data
> >in a file?
> 
> >Thank you in advance
> 
> >Tanguy Risset
> 
> Hello Tanguy,
> 
> unfortunately I can't help you with your problem. All I can say is that  
I
> had a similar problem with M. for Windows 2.2:
> 
> I tried to read a file of about 128 kB byte by byte. Mathematica read  
onl=
> y
> about 40 kB and stopped then without complaining. I realized it only
> because I wanted to process the data further and about 88 kB of them  
wher=
> e
> missing.
> 
> 
> Greetings,
> 
> 	Bjoern
> 

I suspect that these problems are unrelated.  The former (running out
of memory while writing a big expression) might be due to the fact that
Mathematica is trying to format the expression in one big chunk.  The
usual way to get around this problem is to write out the expression
in pieces.  The details of how you do that depend on the structure
of the expression, but unless the expression is naturally just one
big chunk, it usually isn't very difficult.  The other problem (reading
only part of a file under Windows) might mean that the file contained
an end-of-file character.  That problem can be solved by getting the
binary files package from MathSource, but without seeing your example
I can't say for sure if that is what is going on.

If you are a registered user of a supported version of Mathematica you
can send these questions to support at wri.com and we will be happy to
take a look at them.

Dave Withoff
Wolfram Research


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