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authormrb0nk500 <b0nk@b0nk.xyz>2023-02-02 17:29:19 -0400
committermrb0nk500 <b0nk@b0nk.xyz>2023-02-03 13:27:06 -0400
commitf2eabdb6257c09cf2890dac5e9737912728542af (patch)
tree3b46f6787185d65605651a0f48776dc9779ce648 /src/MSL_C.PPCEABI.bare.H/k_tan.c
parenteef1dd840b7cecac28c2e6b0574707b90a37d4e7 (diff)
global: Add rest of Dolphin SDK proper, add MSL, and MetroTRK
Finally, it links properly.
Diffstat (limited to 'src/MSL_C.PPCEABI.bare.H/k_tan.c')
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+/* @(#)k_tan.c 1.2 95/01/04 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/* __kernel_tan( x, y, k )
+ * kernel tan function on [-pi/4, pi/4], pi/4 ~ 0.7854
+ * Input x is assumed to be bounded by ~pi/4 in magnitude.
+ * Input y is the tail of x.
+ * Input k indicates whether tan (if k=1) or
+ * -1/tan (if k= -1) is returned.
+ *
+ * Algorithm
+ * 1. Since tan(-x) = -tan(x), we need only to consider positive x.
+ * 2. if x < 2^-28 (hx<0x3e300000 0), return x with inexact if x!=0.
+ * 3. tan(x) is approximated by a odd polynomial of degree 27 on
+ * [0,0.67434]
+ * 3 27
+ * tan(x) ~ x + T1*x + ... + T13*x
+ * where
+ *
+ * |tan(x) 2 4 26 | -59.2
+ * |----- - (1+T1*x +T2*x +.... +T13*x )| <= 2
+ * | x |
+ *
+ * Note: tan(x+y) = tan(x) + tan'(x)*y
+ * ~ tan(x) + (1+x*x)*y
+ * Therefore, for better accuracy in computing tan(x+y), let
+ * 3 2 2 2 2
+ * r = x *(T2+x *(T3+x *(...+x *(T12+x *T13))))
+ * then
+ * 3 2
+ * tan(x+y) = x + (T1*x + (x *(r+y)+y))
+ *
+ * 4. For x in [0.67434,pi/4], let y = pi/4 - x, then
+ * tan(x) = tan(pi/4-y) = (1-tan(y))/(1+tan(y))
+ * = 1 - 2*(tan(y) - (tan(y)^2)/(1+tan(y)))
+ */
+
+#include "fdlibm.h"
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+ one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
+ pio4 = 7.85398163397448278999e-01, /* 0x3FE921FB, 0x54442D18 */
+ pio4lo = 3.06161699786838301793e-17, /* 0x3C81A626, 0x33145C07 */
+ T[] = {
+ 3.33333333333334091986e-01, /* 0x3FD55555, 0x55555563 */
+ 1.33333333333201242699e-01, /* 0x3FC11111, 0x1110FE7A */
+ 5.39682539762260521377e-02, /* 0x3FABA1BA, 0x1BB341FE */
+ 2.18694882948595424599e-02, /* 0x3F9664F4, 0x8406D637 */
+ 8.86323982359930005737e-03, /* 0x3F8226E3, 0xE96E8493 */
+ 3.59207910759131235356e-03, /* 0x3F6D6D22, 0xC9560328 */
+ 1.45620945432529025516e-03, /* 0x3F57DBC8, 0xFEE08315 */
+ 5.88041240820264096874e-04, /* 0x3F4344D8, 0xF2F26501 */
+ 2.46463134818469906812e-04, /* 0x3F3026F7, 0x1A8D1068 */
+ 7.81794442939557092300e-05, /* 0x3F147E88, 0xA03792A6 */
+ 7.14072491382608190305e-05, /* 0x3F12B80F, 0x32F0A7E9 */
+ -1.85586374855275456654e-05, /* 0xBEF375CB, 0xDB605373 */
+ 2.59073051863633712884e-05, /* 0x3EFB2A70, 0x74BF7AD4 */
+};
+
+#ifdef __STDC__
+double __kernel_tan(double x, double y, _INT32 iy)
+#else
+double __kernel_tan(x, y, iy)
+double x, y;
+_INT32 iy;
+#endif
+{
+ double z, r, v, w, s;
+ _INT32 ix, hx;
+ hx = __HI(x); /* high word of x */
+ ix = hx & 0x7fffffff; /* high word of |x| */
+ if (ix < 0x3e300000) /* x < 2**-28 */
+ {
+ if ((_INT32)x == 0) { /* generate inexact */
+ if (((ix | __LO(x)) | (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;
+ __LO(z) = 0;
+ v = r - (z - x); /* z+v = r+x */
+ t = a = -1.0 / w; /* a = -1.0/w */
+ __LO(t) = 0;
+ s = 1.0 + t * z;
+ return t + a * (s + t * v);
+ }
+}