summaryrefslogtreecommitdiff
path: root/lib/mlibc/options/ansi/musl-generic-math/__tan.c
diff options
context:
space:
mode:
authorIan Moffett <ian@osmora.org>2024-03-07 17:28:52 -0500
committerIan Moffett <ian@osmora.org>2024-03-07 18:24:51 -0500
commitf5e48e94a2f4d4bbd6e5628c7f2afafc6dbcc459 (patch)
tree93b156621dc0303816b37f60ba88051b702d92f6 /lib/mlibc/options/ansi/musl-generic-math/__tan.c
parentbd5969fc876a10b18613302db7087ef3c40f18e1 (diff)
build: Build mlibc + add distclean target
Signed-off-by: Ian Moffett <ian@osmora.org>
Diffstat (limited to 'lib/mlibc/options/ansi/musl-generic-math/__tan.c')
-rw-r--r--lib/mlibc/options/ansi/musl-generic-math/__tan.c110
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);
-}