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Diffstat (limited to 'src/math/s_cbrt.c')
-rw-r--r-- | src/math/s_cbrt.c | 77 |
1 files changed, 0 insertions, 77 deletions
diff --git a/src/math/s_cbrt.c b/src/math/s_cbrt.c deleted file mode 100644 index 8adcb191..00000000 --- a/src/math/s_cbrt.c +++ /dev/null @@ -1,77 +0,0 @@ -/* @(#)s_cbrt.c 5.1 93/09/24 */ -/* - * ==================================================== - * 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. - * ==================================================== - */ - -#include <math.h> -#include "math_private.h" - -/* cbrt(x) - * Return cube root of x - */ -static const uint32_t - B1 = 715094163, /* B1 = (682-0.03306235651)*2**20 */ - B2 = 696219795; /* B2 = (664-0.03306235651)*2**20 */ - -static const double -C = 5.42857142857142815906e-01, /* 19/35 = 0x3FE15F15, 0xF15F15F1 */ -D = -7.05306122448979611050e-01, /* -864/1225 = 0xBFE691DE, 0x2532C834 */ -E = 1.41428571428571436819e+00, /* 99/70 = 0x3FF6A0EA, 0x0EA0EA0F */ -F = 1.60714285714285720630e+00, /* 45/28 = 0x3FF9B6DB, 0x6DB6DB6E */ -G = 3.57142857142857150787e-01; /* 5/14 = 0x3FD6DB6D, 0xB6DB6DB7 */ - -double -cbrt(double x) -{ - int32_t hx; - double r,s,t=0.0,w; - uint32_t sign; - uint32_t high,low; - - GET_HIGH_WORD(hx,x); - sign=hx&0x80000000; /* sign= sign(x) */ - hx ^=sign; - if(hx>=0x7ff00000) return(x+x); /* cbrt(NaN,INF) is itself */ - GET_LOW_WORD(low,x); - if((hx|low)==0) - return(x); /* cbrt(0) is itself */ - - SET_HIGH_WORD(x,hx); /* x <- |x| */ - /* rough cbrt to 5 bits */ - if(hx<0x00100000) /* subnormal number */ - {SET_HIGH_WORD(t,0x43500000); /* set t= 2**54 */ - t*=x; GET_HIGH_WORD(high,t); SET_HIGH_WORD(t,high/3+B2); - } - else - SET_HIGH_WORD(t,hx/3+B1); - - - /* new cbrt to 23 bits, may be implemented in single precision */ - r=t*t/x; - s=C+r*t; - t*=G+F/(s+E+D/s); - - /* chopped to 20 bits and make it larger than cbrt(x) */ - GET_HIGH_WORD(high,t); - INSERT_WORDS(t,high+0x00000001,0); - - - /* one step newton iteration to 53 bits with error less than 0.667 ulps */ - s=t*t; /* t*t is exact */ - r=x/s; - w=t+t; - r=(r-t)/(w+r); /* r-s is exact */ - t=t+t*r; - - /* retore the sign bit */ - GET_HIGH_WORD(high,t); - SET_HIGH_WORD(t,high|sign); - return(t); -} |