Message-ID: <32FA4C2E.740F@pobox.oleane.com>
Date: Thu, 06 Feb 1997 22:25:02 +0100
From: Francois Charton <deef AT pobox DOT oleane DOT com>
Organization: CCMSA
MIME-Version: 1.0
To: Jason Stratos Papadopoulos <jasonp AT Glue DOT umd DOT edu>
CC: djgpp AT delorie DOT com
Subject: Re: need help handling enormous size arrays
References: <5d916e$c1e AT hecate DOT umd DOT edu> <32f90055 DOT 22691415 AT news DOT ox DOT ac DOT uk> <5dbvte$hq2 AT hecate DOT umd DOT edu>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Jason Stratos Papadopoulos wrote:
> 
> PS: How *do* you make an FFT that's cache friendly? It could probably
> help me a lot.

There is an algorithm for memory local FFT (fft of data which do not fit 
in memory) in Numerical Recipes in C 2nd edition (Cambridge University 
Pres), paragraph 12.6. 

Also, for FFT of numbers close to the size of your machine memory, beware 
of malloc() : it rounds the data it needs *plus some small header size*  
to the higher power of two : so malloc'ing 2^N bytes always uses 2^(N+1) 
bytes...

Francois