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Diffstat (limited to 'lib/mlibc/options/ansi/musl-generic-math/__tan.c')
| -rw-r--r-- | lib/mlibc/options/ansi/musl-generic-math/__tan.c | 110 |
1 files changed, 0 insertions, 110 deletions
diff --git a/lib/mlibc/options/ansi/musl-generic-math/__tan.c b/lib/mlibc/options/ansi/musl-generic-math/__tan.c deleted file mode 100644 index 8019844..0000000 --- a/lib/mlibc/options/ansi/musl-generic-math/__tan.c +++ /dev/null @@ -1,110 +0,0 @@ -/* origin: FreeBSD /usr/src/lib/msun/src/k_tan.c */ -/* - * ==================================================== - * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved. - * - * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice - * is preserved. - * ==================================================== - */ -/* __tan( x, y, k ) - * kernel tan function on ~[-pi/4, pi/4] (except on -0), pi/4 ~ 0.7854 - * Input x is assumed to be bounded by ~pi/4 in magnitude. - * Input y is the tail of x. - * Input odd indicates whether tan (if odd = 0) or -1/tan (if odd = 1) is returned. - * - * Algorithm - * 1. Since tan(-x) = -tan(x), we need only to consider positive x. - * 2. Callers must return tan(-0) = -0 without calling here since our - * odd polynomial is not evaluated in a way that preserves -0. - * Callers may do the optimization tan(x) ~ x for tiny x. - * 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 "libm.h" - -static const double T[] = { - 3.33333333333334091986e-01, /* 3FD55555, 55555563 */ - 1.33333333333201242699e-01, /* 3FC11111, 1110FE7A */ - 5.39682539762260521377e-02, /* 3FABA1BA, 1BB341FE */ - 2.18694882948595424599e-02, /* 3F9664F4, 8406D637 */ - 8.86323982359930005737e-03, /* 3F8226E3, E96E8493 */ - 3.59207910759131235356e-03, /* 3F6D6D22, C9560328 */ - 1.45620945432529025516e-03, /* 3F57DBC8, FEE08315 */ - 5.88041240820264096874e-04, /* 3F4344D8, F2F26501 */ - 2.46463134818469906812e-04, /* 3F3026F7, 1A8D1068 */ - 7.81794442939557092300e-05, /* 3F147E88, A03792A6 */ - 7.14072491382608190305e-05, /* 3F12B80F, 32F0A7E9 */ - -1.85586374855275456654e-05, /* BEF375CB, DB605373 */ - 2.59073051863633712884e-05, /* 3EFB2A70, 74BF7AD4 */ -}, -pio4 = 7.85398163397448278999e-01, /* 3FE921FB, 54442D18 */ -pio4lo = 3.06161699786838301793e-17; /* 3C81A626, 33145C07 */ - -double __tan(double x, double y, int odd) -{ - double_t z, r, v, w, s, a; - double w0, a0; - uint32_t hx; - int big, sign; - - GET_HIGH_WORD(hx,x); - big = (hx&0x7fffffff) >= 0x3FE59428; /* |x| >= 0.6744 */ - if (big) { - sign = hx>>31; - if (sign) { - x = -x; - y = -y; - } - x = (pio4 - x) + (pio4lo - y); - 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) + s*T[0]; - w = x + r; - if (big) { - s = 1 - 2*odd; - v = s - 2.0 * (x + (r - w*w/(w + s))); - return sign ? -v : v; - } - if (!odd) - return w; - /* -1.0/(x+r) has up to 2ulp error, so compute it accurately */ - w0 = w; - SET_LOW_WORD(w0, 0); - v = r - (w0 - x); /* w0+v = r+x */ - a0 = a = -1.0 / w; - SET_LOW_WORD(a0, 0); - return a0 + a*(1.0 + a0*w0 + a0*v); -} |