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git.proxmox.com Git - mirror_edk2.git/blob - StdLib/LibC/Math/s_tan.c
1 /* @(#)s_tan.c 5.1 93/09/24 */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
10 * ====================================================
12 #include <LibConfig.h>
13 #include <sys/EfiCdefs.h>
14 #if defined(LIBM_SCCS) && !defined(lint)
15 __RCSID("$NetBSD: s_tan.c,v 1.10 2002/05/26 22:01:58 wiz Exp $");
19 * Return tangent function of x.
22 * __kernel_tan ... tangent function on [-pi/4,pi/4]
23 * __ieee754_rem_pio2 ... argument reduction routine
26 * Let S,C and T denote the sin, cos and tan respectively on
27 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
28 * in [-pi/4 , +pi/4], and let n = k mod 4.
31 * n sin(x) cos(x) tan(x)
32 * ----------------------------------------------------------
37 * ----------------------------------------------------------
40 * Let trig be any of sin, cos, or tan.
41 * trig(+-INF) is NaN, with signals;
42 * trig(NaN) is that NaN;
45 * TRIG(x) returns trig(x) nearly rounded
49 #include "math_private.h"
62 if(ix
<= 0x3fe921fb) return __kernel_tan(x
,z
,1);
64 /* tan(Inf or NaN) is NaN */
65 else if (ix
>=0x7ff00000) return x
-x
; /* NaN */
67 /* argument reduction needed */
69 n
= __ieee754_rem_pio2(x
,y
);
70 return __kernel_tan(y
[0],y
[1],1-((n
&1)<<1)); /* 1 -- n even