67 lines
1.2 KiB
C
67 lines
1.2 KiB
C
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#include "libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double hypotl(long double x, long double y)
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{
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return hypot(x, y);
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}
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#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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#if LDBL_MANT_DIG == 64
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#define SPLIT (0x1p32L+1)
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#elif LDBL_MANT_DIG == 113
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#define SPLIT (0x1p57L+1)
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#endif
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static void sq(long double *hi, long double *lo, long double x)
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{
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long double xh, xl, xc;
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xc = x*SPLIT;
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xh = x - xc + xc;
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xl = x - xh;
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*hi = x*x;
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*lo = xh*xh - *hi + 2*xh*xl + xl*xl;
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}
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long double hypotl(long double x, long double y)
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{
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union ldshape ux = {x}, uy = {y};
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int ex, ey;
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long double hx, lx, hy, ly, z;
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ux.i.se &= 0x7fff;
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uy.i.se &= 0x7fff;
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if (ux.i.se < uy.i.se) {
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ex = uy.i.se;
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ey = ux.i.se;
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x = uy.f;
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y = ux.f;
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} else {
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ex = ux.i.se;
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ey = uy.i.se;
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x = ux.f;
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y = uy.f;
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}
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if (ex == 0x7fff && isinf(y))
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return y;
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if (ex == 0x7fff || y == 0)
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return x;
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if (ex - ey > LDBL_MANT_DIG)
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return x + y;
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z = 1;
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if (ex > 0x3fff+8000) {
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z = 0x1p10000L;
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x *= 0x1p-10000L;
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y *= 0x1p-10000L;
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} else if (ey < 0x3fff-8000) {
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z = 0x1p-10000L;
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x *= 0x1p10000L;
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y *= 0x1p10000L;
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}
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sq(&hx, &lx, x);
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sq(&hy, &ly, y);
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return z*sqrtl(ly+lx+hy+hx);
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}
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#endif
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