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From: news@oasys.dt.navy.mil (USENET News System)
Newsgroups: comp.lang.fortran
Subject: Re: Array dilemma.
Message-ID: <5477@oasys.dt.navy.mil>
Date: 23 Jan 91 14:21:39 GMT
References: <quan.664590845@sol>
Reply-To: jwhite@dtoa3.dt.navy.mil (Joseph White)
Organization: David Taylor Research Center, Annapolis, MD
Lines: 51

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Sorry to post this, but it bounced when I tried to mail it (Host unknown)
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In article <quan.664590845@sol> quan@sol.surv.utas.oz (Stephen Quan) writes:
>I am currently on a project for surveyors and recently attempted to port
>the code from our Sun workstation to a PC.  Unfortunately, the original
>code needed double precision arrays of the order of 50000 elements or
>higher.
>
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[Stuff deleted]
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>Cause of problem      DOUBLE PRECISION BIG(3,50000)
>Synopsis of problem   compiler won't compile code for BIG is size 3x50000.
>Synopsis 2            PC won't load executable when BIG is size 3x4000.
>Synopsis 3            Seems to runs ok, when BIG is size 3x3000.
>Current Compiler      Microsoft Fortran.
>Current Size of EXE   About 150K (for both Synopsis 2 and 3).
>
>Question 1            Will F77L handle this problem?
>Question 2            Does F77L allocated space for arrays in the EXE?
>                      - Will I get a larger EXE file? (somewhat 600K?).
>Question 3            Is there a compiler that would solve this problem?
>
>There is little chance that I can push the department to get an F77L/EM,
>but I would be interested if that or any other compiler would solve my
>problem.  If all fails, I probably replaced the array with random
>accessing a large file instead.
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Hello;
    I can't directly answer any of your questions, but I might be able
to provide some insight to your problem.  To have an Double Precision
array that is (3,50000) would require:
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   (3 * 50000)elements * 8bytes/element = 1,200,000 bytes = 1,171.875Kbytes
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This is the amount of memory required to hold that array in memory,
since a PC can only access 640 Kbytes, there is not enough memory to
hold your array im memory let alone the rest of your program.  The only
way I can see out of your problem, other than the file approach you
mention is to get a 386 machine and a compiler that would create a protected
mode program.
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Sorry I couldn't help you more, but I wanted to share some insight into
your problem
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Joe White
jwhite@dtoa3.dt.navy.mil
David Taylor Research Center, Annapolis MD
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