diff options
Diffstat (limited to 'sysdeps/libm-ieee754/s_cbrtf.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_cbrtf.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_cbrtf.c b/sysdeps/libm-ieee754/s_cbrtf.c new file mode 100644 index 0000000000..a2b3c8106c --- /dev/null +++ b/sysdeps/libm-ieee754/s_cbrtf.c @@ -0,0 +1,84 @@ +/* s_cbrtf.c -- float version of s_cbrt.c. + * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. + */ + +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: s_cbrtf.c,v 1.4 1995/05/10 20:46:51 jtc Exp $"; +#endif + +#include "math.h" +#include "math_private.h" + +/* cbrtf(x) + * Return cube root of x + */ +#ifdef __STDC__ +static const unsigned +#else +static unsigned +#endif + B1 = 709958130, /* B1 = (84+2/3-0.03306235651)*2**23 */ + B2 = 642849266; /* B2 = (76+2/3-0.03306235651)*2**23 */ + +#ifdef __STDC__ +static const float +#else +static float +#endif +C = 5.4285717010e-01, /* 19/35 = 0x3f0af8b0 */ +D = -7.0530611277e-01, /* -864/1225 = 0xbf348ef1 */ +E = 1.4142856598e+00, /* 99/70 = 0x3fb50750 */ +F = 1.6071428061e+00, /* 45/28 = 0x3fcdb6db */ +G = 3.5714286566e-01; /* 5/14 = 0x3eb6db6e */ + +#ifdef __STDC__ + float __cbrtf(float x) +#else + float __cbrtf(x) + float x; +#endif +{ + float r,s,t; + int32_t hx; + u_int32_t sign; + u_int32_t high; + + GET_FLOAT_WORD(hx,x); + sign=hx&0x80000000; /* sign= sign(x) */ + hx ^=sign; + if(hx>=0x7f800000) return(x+x); /* cbrt(NaN,INF) is itself */ + if(hx==0) + return(x); /* cbrt(0) is itself */ + + SET_FLOAT_WORD(x,hx); /* x <- |x| */ + /* rough cbrt to 5 bits */ + if(hx<0x00800000) /* subnormal number */ + {SET_FLOAT_WORD(t,0x4b800000); /* set t= 2**24 */ + t*=x; GET_FLOAT_WORD(high,t); SET_FLOAT_WORD(t,high/3+B2); + } + else + SET_FLOAT_WORD(t,hx/3+B1); + + + /* new cbrt to 23 bits */ + r=t*t/x; + s=C+r*t; + t*=G+F/(s+E+D/s); + + /* retore the sign bit */ + GET_FLOAT_WORD(high,t); + SET_FLOAT_WORD(t,high|sign); + return(t); +} +weak_alias (__cbrtf, cbrtf) |