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Justine Tunney 2020-06-15 07:18:57 -07:00
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libc/math/atan2l.c Normal file
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/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2l.c */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*
*/
/*
* See comments in atan2.c.
* Converted to long double by David Schultz <das@FreeBSD.ORG>.
*/
#include "libc/math/__invtrigl.h"
#include "libc/math/libm.h"
#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
long double atan2l(long double y, long double x) { return atan2(y, x); }
#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
long double atan2l(long double y, long double x) {
union ldshape ux, uy;
long double z;
int m, ex, ey;
if (isnan(x) || isnan(y)) return x + y;
if (x == 1) return atanl(y);
ux.f = x;
uy.f = y;
ex = ux.i.se & 0x7fff;
ey = uy.i.se & 0x7fff;
m = 2 * (ux.i.se >> 15) | uy.i.se >> 15;
if (y == 0) {
switch (m) {
case 0:
case 1:
return y; /* atan(+-0,+anything)=+-0 */
case 2:
return 2 * pio2_hi; /* atan(+0,-anything) = pi */
case 3:
return -2 * pio2_hi; /* atan(-0,-anything) =-pi */
}
}
if (x == 0) return m & 1 ? -pio2_hi : pio2_hi;
if (ex == 0x7fff) {
if (ey == 0x7fff) {
switch (m) {
case 0:
return pio2_hi / 2; /* atan(+INF,+INF) */
case 1:
return -pio2_hi / 2; /* atan(-INF,+INF) */
case 2:
return 1.5 * pio2_hi; /* atan(+INF,-INF) */
case 3:
return -1.5 * pio2_hi; /* atan(-INF,-INF) */
}
} else {
switch (m) {
case 0:
return 0.0; /* atan(+...,+INF) */
case 1:
return -0.0; /* atan(-...,+INF) */
case 2:
return 2 * pio2_hi; /* atan(+...,-INF) */
case 3:
return -2 * pio2_hi; /* atan(-...,-INF) */
}
}
}
if (ex + 120 < ey || ey == 0x7fff) return m & 1 ? -pio2_hi : pio2_hi;
/* z = atan(|y/x|) without spurious underflow */
if ((m & 2) && ey + 120 < ex) /* |y/x| < 0x1p-120, x<0 */
z = 0.0;
else
z = atanl(fabsl(y / x));
switch (m) {
case 0:
return z; /* atan(+,+) */
case 1:
return -z; /* atan(-,+) */
case 2:
return 2 * __pio2_hi - (z - 2 * pio2_lo); /* atan(+,-) */
default: /* case 3 */
return (z - 2 * __pio2_lo) - 2 * pio2_hi; /* atan(-,-) */
}
}
#endif