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Diffstat (limited to 'libm/float/cbrtf.c')
| -rw-r--r-- | libm/float/cbrtf.c | 119 | 
1 files changed, 0 insertions, 119 deletions
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 <math.h> - -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); -}  | 
