#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_cbrt.c,v 1.8 1995/05/10 20:46:49 jtc Exp $";
#endif
#include "math.h"
#include "math_private.h"
#ifdef __STDC__
static const u_int32_t
#else
static u_int32_t
#endif
B1 = 715094163,
B2 = 696219795;
#ifdef __STDC__
static const double
#else
static double
#endif
C = 5.42857142857142815906e-01,
D = -7.05306122448979611050e-01,
E = 1.41428571428571436819e+00,
F = 1.60714285714285720630e+00,
G = 3.57142857142857150787e-01;
#ifdef __STDC__
double cbrt(double x)
#else
double cbrt(x)
double x;
#endif
{
int32_t hx;
double r,s,t=0.0,w;
u_int32_t sign;
u_int32_t high,low;
GET_HIGH_WORD(hx,x);
sign=hx&0x80000000;
hx ^=sign;
if(hx>=0x7ff00000) return(x+x);
GET_LOW_WORD(low,x);
if((hx|low)==0)
return(x);
SET_HIGH_WORD(x,hx);
if(hx<0x00100000)
{SET_HIGH_WORD(t,0x43500000);
t*=x; GET_HIGH_WORD(high,t); SET_HIGH_WORD(t,high/3+B2);
}
else
SET_HIGH_WORD(t,hx/3+B1);
r=t*t/x;
s=C+r*t;
t*=G+F/(s+E+D/s);
GET_HIGH_WORD(high,t);
INSERT_WORDS(t,high+0x00000001,0);
s=t*t;
r=x/s;
w=t+t;
r=(r-t)/(w+r);
t=t+t*r;
GET_HIGH_WORD(high,t);
SET_HIGH_WORD(t,high|sign);
return(t);
}
#ifdef notdef
#ifdef __STDC__
float cbrtf(float x)
#else
float cbrtf(x)
float x;
#endif
{
return (float)cbrt( x );
}
#endif