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GSL 1.6: patch for gauss.c -- CORRECTION + TIMING


The patch to randist/gauss.c that I sent out at

    Date: Wed, 26 Jan 2005 17:29:26 -0500

has a fatal C++'ism creeping is.  Please replace

      y = abs(v) - t;

by

      y = fabs(v) - t;

Sorry about that!

I did a timing test using the default basic RNG with gcc -O2
optimization on a Linux Pentium 866 MHz machine.  The results are:

    GSL polar method: 640 ns
    Old ratio method: 630 ns
    New ratio method: 380 ns

So Leva's bounds give a nice speed up by about 1.6 over the raw ratio
method and the polar method.  Perhaps gsl_ran_gaussian_ratio_method
should be the default routine for normal deviates?

A PostScript on knuthran.  With Knuth's latest recommendations, knuthran
passes all the "Die Hard" tests and so qualifies as a major league RNG
(?).  (This is the raw RNG that I use.)

-- 
Charles Karney <ckarney@sarnoff.com>
Sarnoff Corporation, Princeton, NJ 08543-5300

URL: http://charles.karney.info
Tel: +1 609 734 2312
Fax: +1 609 734 2323


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