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/cbrtf.c | 119 ----------------------------------------------------- 1 file changed, 119 deletions(-) delete mode 100644 libm/float/cbrtf.c (limited to 'libm/float/cbrtf.c') diff --git a/libm/float/cbrtf.c b/libm/float/cbrtf.c deleted file mode 100644 index ca9b433d9..000000000 --- a/libm/float/cbrtf.c +++ /dev/null @@ -1,119 +0,0 @@ -/* cbrtf.c - * - * Cube root - * - * - * - * SYNOPSIS: - * - * float x, y, cbrtf(); - * - * y = cbrtf( x ); - * - * - * - * DESCRIPTION: - * - * Returns the cube root of the argument, which may be negative. - * - * Range reduction involves determining the power of 2 of - * the argument. A polynomial of degree 2 applied to the - * mantissa, and multiplication by the cube root of 1, 2, or 4 - * approximates the root to within about 0.1%. Then Newton's - * iteration is used to converge to an accurate result. - * - * - * - * ACCURACY: - * - * Relative error: - * arithmetic domain # trials peak rms - * IEEE 0,1e38 100000 7.6e-8 2.7e-8 - * - */ - /* cbrt.c */ - -/* -Cephes Math Library Release 2.2: June, 1992 -Copyright 1984, 1987, 1988, 1992 by Stephen L. Moshier -Direct inquiries to 30 Frost Street, Cambridge, MA 02140 -*/ - - -#include - -static float CBRT2 = 1.25992104989487316477; -static float CBRT4 = 1.58740105196819947475; - - -float frexpf(float, int *), ldexpf(float, int); - -float cbrtf( float xx ) -{ -int e, rem, sign; -float x, z; - -x = xx; -if( x == 0 ) - return( 0.0 ); -if( x > 0 ) - sign = 1; -else - { - sign = -1; - x = -x; - } - -z = x; -/* extract power of 2, leaving - * mantissa between 0.5 and 1 - */ -x = frexpf( x, &e ); - -/* Approximate cube root of number between .5 and 1, - * peak relative error = 9.2e-6 - */ -x = (((-0.13466110473359520655053 * x - + 0.54664601366395524503440 ) * x - - 0.95438224771509446525043 ) * x - + 1.1399983354717293273738 ) * x - + 0.40238979564544752126924; - -/* exponent divided by 3 */ -if( e >= 0 ) - { - rem = e; - e /= 3; - rem -= 3*e; - if( rem == 1 ) - x *= CBRT2; - else if( rem == 2 ) - x *= CBRT4; - } - - -/* argument less than 1 */ - -else - { - e = -e; - rem = e; - e /= 3; - rem -= 3*e; - if( rem == 1 ) - x /= CBRT2; - else if( rem == 2 ) - x /= CBRT4; - e = -e; - } - -/* multiply by power of 2 */ -x = ldexpf( x, e ); - -/* Newton iteration */ -x -= ( x - (z/(x*x)) ) * 0.333333333333; - -if( sign < 0 ) - x = -x; -return(x); -} -- cgit v1.2.3