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glibc  2.9
Functions
e_hypotl.c File Reference
#include "math.h"
#include "math_private.h"

Go to the source code of this file.

Functions

long double __ieee754_hypotl (long double x, long double y)

Function Documentation

long double __ieee754_hypotl ( long double  x,
long double  y 
)

Definition at line 58 of file e_hypotl.c.

{
       long double a,b,t1,t2,y1,y2,w;
       int64_t j,k,ha,hb;

       GET_LDOUBLE_MSW64(ha,x);
       ha &= 0x7fffffffffffffffLL;
       GET_LDOUBLE_MSW64(hb,y);
       hb &= 0x7fffffffffffffffLL;
       if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
       SET_LDOUBLE_MSW64(a,ha);    /* a <- |a| */
       SET_LDOUBLE_MSW64(b,hb);    /* b <- |b| */
       if((ha-hb)>0x78000000000000LL) {return a+b;} /* x/y > 2**120 */
       k=0;
       if(ha > 0x5f3f000000000000LL) {    /* a>2**8000 */
          if(ha >= 0x7fff000000000000LL) {       /* Inf or NaN */
              u_int64_t low;
              w = a+b;                    /* for sNaN */
              GET_LDOUBLE_LSW64(low,a);
              if(((ha&0xffffffffffffLL)|low)==0) w = a;
              GET_LDOUBLE_LSW64(low,b);
              if(((hb^0x7fff000000000000LL)|low)==0) w = b;
              return w;
          }
          /* scale a and b by 2**-9600 */
          ha -= 0x2580000000000000LL;
          hb -= 0x2580000000000000LL;     k += 9600;
          SET_LDOUBLE_MSW64(a,ha);
          SET_LDOUBLE_MSW64(b,hb);
       }
       if(hb < 0x20bf000000000000LL) {    /* b < 2**-8000 */
           if(hb <= 0x0000ffffffffffffLL) {      /* subnormal b or 0 */
               u_int64_t low;
              GET_LDOUBLE_LSW64(low,b);
              if((hb|low)==0) return a;
              t1=0;
              SET_LDOUBLE_MSW64(t1,0x7ffd000000000000LL); /* t1=2^16382 */
              b *= t1;
              a *= t1;
              k -= 16382;
           } else {         /* scale a and b by 2^9600 */
               ha += 0x2580000000000000LL;       /* a *= 2^9600 */
              hb += 0x2580000000000000LL; /* b *= 2^9600 */
              k -= 9600;
              SET_LDOUBLE_MSW64(a,ha);
              SET_LDOUBLE_MSW64(b,hb);
           }
       }
    /* medium size a and b */
       w = a-b;
       if (w>b) {
           t1 = 0;
           SET_LDOUBLE_MSW64(t1,ha);
           t2 = a-t1;
           w  = __ieee754_sqrtl(t1*t1-(b*(-b)-t2*(a+t1)));
       } else {
           a  = a+a;
           y1 = 0;
           SET_LDOUBLE_MSW64(y1,hb);
           y2 = b - y1;
           t1 = 0;
           SET_LDOUBLE_MSW64(t1,ha+0x0001000000000000LL);
           t2 = a - t1;
           w  = __ieee754_sqrtl(t1*y1-(w*(-w)-(t1*y2+t2*b)));
       }
       if(k!=0) {
           u_int64_t high;
           t1 = 1.0L;
           GET_LDOUBLE_MSW64(high,t1);
           SET_LDOUBLE_MSW64(t1,high+(k<<48));
           return t1*w;
       } else return w;
}

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