k_tan.c File Reference

#include "math_libm.h"
#include "math_private.h"

Include dependency graph for k_tan.c:

Go to the source code of this file.

Functions
double attribute_hidden	__kernel_tan (double x, double y, int iy)

Variables
static const double	one = 1.00000000000000000000e+00
static const double	pio4 = 7.85398163397448278999e-01
static const double	pio4lo = 3.06161699786838301793e-17
static const double	T []

Function Documentation

double attribute_hidden __kernel_tan	(	double	x,
		double	y,
		int	iy
	)

Definition at line 69 of file k_tan.c.

References fabs(), GET_HIGH_WORD, GET_LOW_WORD, one, pio4, pio4lo, SET_LOW_WORD, and T.

Referenced by tan().

{
        double z,r,v,w,s;
        int32_t ix,hx;
        GET_HIGH_WORD(hx,x);
        ix = hx&0x7fffffff;     /* high word of |x| */
        if(ix<0x3e300000)                       /* x < 2**-28 */
            {if((int)x==0) {                    /* generate inexact */
                u_int32_t low;
                GET_LOW_WORD(low,x);
                if(((ix|low)|(iy+1))==0) return one/fabs(x);
                else return (iy==1)? x: -one/x;
            }
            }
        if(ix>=0x3FE59428) {                    /* |x|>=0.6744 */
            if(hx<0) {x = -x; y = -y;}
            z = pio4-x;
            w = pio4lo-y;
            x = z+w; y = 0.0;
        }
        z       =  x*x;
        w       =  z*z;
    /* Break x^5*(T[1]+x^2*T[2]+...) into
     *    x^5(T[1]+x^4*T[3]+...+x^20*T[11]) +
     *    x^5(x^2*(T[2]+x^4*T[4]+...+x^22*[T12]))
     */
        r = T[1]+w*(T[3]+w*(T[5]+w*(T[7]+w*(T[9]+w*T[11]))));
        v = z*(T[2]+w*(T[4]+w*(T[6]+w*(T[8]+w*(T[10]+w*T[12])))));
        s = z*x;
        r = y + z*(s*(r+v)+y);
        r += T[0]*s;
        w = x+r;
        if(ix>=0x3FE59428) {
            v = (double)iy;
            return (double)(1-((hx>>30)&2))*(v-2.0*(x-(w*w/(w+v)-r)));
        }
        if(iy==1) return w;
        else {          /* if allow error up to 2 ulp,
                           simply return -1.0/(x+r) here */
     /*  compute -1.0/(x+r) accurately */
            double a,t;
            z  = w;
            SET_LOW_WORD(z,0);
            v  = r-(z - x);     /* z+v = r+x */
            t = a  = -1.0/w;    /* a = -1.0/w */
            SET_LOW_WORD(t,0);
            s  = 1.0+t*z;
            return t+a*(s+t*v);
        }
}

Variable Documentation

const double one = 1.00000000000000000000e+00

static

Definition at line 50 of file k_tan.c.

Referenced by __kernel_tan().

const double pio4 = 7.85398163397448278999e-01

static

Definition at line 51 of file k_tan.c.

Referenced by __kernel_tan().

const double pio4lo = 3.06161699786838301793e-17

static

Definition at line 52 of file k_tan.c.

Referenced by __kernel_tan().

const double T[]

static

Initial value:

  {
  3.33333333333334091986e-01, 
  1.33333333333201242699e-01, 
  5.39682539762260521377e-02, 
  2.18694882948595424599e-02, 
  8.86323982359930005737e-03, 
  3.59207910759131235356e-03, 
  1.45620945432529025516e-03, 
  5.88041240820264096874e-04, 
  2.46463134818469906812e-04, 
  7.81794442939557092300e-05, 
  7.14072491382608190305e-05, 
 -1.85586374855275456654e-05, 
  2.59073051863633712884e-05, 
}

Definition at line 53 of file k_tan.c.

Referenced by __kernel_tan(), and runAdder().