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00013 #if defined(LIBM_SCCS) && !defined(lint)
00014 static char rcsid[] = "$NetBSD: e_hypot.c,v 1.9 1995/05/12 04:57:27 jtc Exp $";
00015 #endif
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00049 #include "math.h"
00050 #include "mathP.h"
00051
00052 #ifdef __STDC__
00053 double __ieee754_hypot(double x, double y)
00054 #else
00055 double __ieee754_hypot(x,y)
00056 double x, y;
00057 #endif
00058 {
00059 double a=x,b=y,t1,t2,y1,y2,w;
00060 int32_t j,k,ha,hb;
00061
00062 GET_HIGH_WORD(ha,x);
00063 ha &= 0x7fffffff;
00064 GET_HIGH_WORD(hb,y);
00065 hb &= 0x7fffffff;
00066 if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
00067 SET_HIGH_WORD(a,ha);
00068 SET_HIGH_WORD(b,hb);
00069 if((ha-hb)>0x3c00000) {return a+b;}
00070 k=0;
00071 if(ha > 0x5f300000) {
00072 if(ha >= 0x7ff00000) {
00073 u_int32_t low;
00074 w = a+b;
00075 GET_LOW_WORD(low,a);
00076 if(((ha&0xfffff)|low)==0) w = a;
00077 GET_LOW_WORD(low,b);
00078 if(((hb^0x7ff00000)|low)==0) w = b;
00079 return w;
00080 }
00081
00082 ha -= 0x25800000; hb -= 0x25800000; k += 600;
00083 SET_HIGH_WORD(a,ha);
00084 SET_HIGH_WORD(b,hb);
00085 }
00086 if(hb < 0x20b00000) {
00087 if(hb <= 0x000fffff) {
00088 u_int32_t low;
00089 GET_LOW_WORD(low,b);
00090 if((hb|low)==0) return a;
00091 t1=0;
00092 SET_HIGH_WORD(t1,0x7fd00000);
00093 b *= t1;
00094 a *= t1;
00095 k -= 1022;
00096 } else {
00097 ha += 0x25800000;
00098 hb += 0x25800000;
00099 k -= 600;
00100 SET_HIGH_WORD(a,ha);
00101 SET_HIGH_WORD(b,hb);
00102 }
00103 }
00104
00105 w = a-b;
00106 if (w>b) {
00107 t1 = 0;
00108 SET_HIGH_WORD(t1,ha);
00109 t2 = a-t1;
00110 w = __ieee754_sqrt(t1*t1-(b*(-b)-t2*(a+t1)));
00111 } else {
00112 a = a+a;
00113 y1 = 0;
00114 SET_HIGH_WORD(y1,hb);
00115 y2 = b - y1;
00116 t1 = 0;
00117 SET_HIGH_WORD(t1,ha+0x00100000);
00118 t2 = a - t1;
00119 w = __ieee754_sqrt(t1*y1-(w*(-w)-(t1*y2+t2*b)));
00120 }
00121 if(k!=0) {
00122 u_int32_t high;
00123 t1 = 1.0;
00124 GET_HIGH_WORD(high,t1);
00125 SET_HIGH_WORD(t1,high+(k<<20));
00126 return t1*w;
00127 } else return w;
00128 }