From 7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 Mon Sep 17 00:00:00 2001 From: Eric Andersen Date: Thu, 22 Nov 2001 14:04:29 +0000 Subject: Totally rework the math library, this time based on the MacOs X math library (which is itself based on the math lib from FreeBSD). -Erik --- libm/float/log10f.c | 129 ---------------------------------------------------- 1 file changed, 129 deletions(-) delete mode 100644 libm/float/log10f.c (limited to 'libm/float/log10f.c') diff --git a/libm/float/log10f.c b/libm/float/log10f.c deleted file mode 100644 index 6cb2e4d87..000000000 --- a/libm/float/log10f.c +++ /dev/null @@ -1,129 +0,0 @@ -/* log10f.c - * - * Common logarithm - * - * - * - * SYNOPSIS: - * - * float x, y, log10f(); - * - * y = log10f( x ); - * - * - * - * DESCRIPTION: - * - * Returns logarithm to the base 10 of x. - * - * The argument is separated into its exponent and fractional - * parts. The logarithm of the fraction is approximated by - * - * log(1+x) = x - 0.5 x**2 + x**3 P(x). - * - * - * - * ACCURACY: - * - * Relative error: - * arithmetic domain # trials peak rms - * IEEE 0.5, 2.0 100000 1.3e-7 3.4e-8 - * IEEE 0, MAXNUMF 100000 1.3e-7 2.6e-8 - * - * In the tests over the interval [0, MAXNUM], the logarithms - * of the random arguments were uniformly distributed over - * [-MAXL10, MAXL10]. - * - * ERROR MESSAGES: - * - * log10f singularity: x = 0; returns -MAXL10 - * log10f domain: x < 0; returns -MAXL10 - * MAXL10 = 38.230809449325611792 - */ - -/* -Cephes Math Library Release 2.1: December, 1988 -Copyright 1984, 1987, 1988 by Stephen L. Moshier -Direct inquiries to 30 Frost Street, Cambridge, MA 02140 -*/ - -#include -static char fname[] = {"log10"}; - -/* Coefficients for log(1+x) = x - x**2/2 + x**3 P(x)/Q(x) - * 1/sqrt(2) <= x < sqrt(2) - */ -static float P[] = { - 7.0376836292E-2, --1.1514610310E-1, - 1.1676998740E-1, --1.2420140846E-1, - 1.4249322787E-1, --1.6668057665E-1, - 2.0000714765E-1, --2.4999993993E-1, - 3.3333331174E-1 -}; - - -#define SQRTH 0.70710678118654752440 -#define L102A 3.0078125E-1 -#define L102B 2.48745663981195213739E-4 -#define L10EA 4.3359375E-1 -#define L10EB 7.00731903251827651129E-4 - -static float MAXL10 = 38.230809449325611792; - -float frexpf(float, int *), polevlf(float, float *, int); - -float log10f(float xx) -{ -float x, y, z; -int e; - -x = xx; -/* Test for domain */ -if( x <= 0.0 ) - { - if( x == 0.0 ) - mtherr( fname, SING ); - else - mtherr( fname, DOMAIN ); - return( -MAXL10 ); - } - -/* separate mantissa from exponent */ - -x = frexpf( x, &e ); - -/* logarithm using log(1+x) = x - .5x**2 + x**3 P(x) */ - -if( x < SQRTH ) - { - e -= 1; - x = 2.0*x - 1.0; - } -else - { - x = x - 1.0; - } - - -/* rational form */ -z = x*x; -y = x * ( z * polevlf( x, P, 8 ) ); -y = y - 0.5 * z; /* y - 0.5 * x**2 */ - -/* multiply log of fraction by log10(e) - * and base 2 exponent by log10(2) - */ -z = (x + y) * L10EB; /* accumulate terms in order of size */ -z += y * L10EA; -z += x * L10EA; -x = e; -z += x * L102B; -z += x * L102A; - - -return( z ); -} -- cgit v1.2.3