From:	jasonp AT Glue DOT umd DOT edu (Jason Stratos Papadopoulos)
Newsgroups:	comp.os.msdos.djgpp
Subject:	need help handling enormous size arrays
Date:	5 Feb 1997 04:09:50 GMT
Organization:	University of Maryland, College Park
Lines:	18
Message-ID:	<5d916e$c1e@hecate.umd.edu>
NNTP-Posting-Host:	taylor.isr.umd.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hello. I'm writing a homebrew arbitrary precision arithmetic package,
and was coding up a multiply that uses fast Fourier transforms. Everything
is nice and fast up to array (of doubles) size 2^14, but from 2^15 on
the computation time hits a brick wall! Before this point (2^10,11,12,etc)
a given power of 2 only takes a bit more than twice as long as the one
before. The program does no memory management, and I need to work with
array sizes perhaps as large as 2^18 or 2^19. 

Am I not doing somethng vital? My hard drive isn't thrashing so it's
not a virtual memory problem; For the record, I have 16 megs of ram
and about 20 or 30 megs of free HD space; I'm using a Win95 DOS box
for dpmi.

Please don't flame me for missing the obvious...I'm an amateur at
high-powered scientific computing.

Thanks in advance,
jasonp

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