2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
9 * ====================================================
13 * Return tangent function of x.
16 * __kernel_tan ... tangent function on [-pi/4,pi/4]
17 * __ieee754_rem_pio2 ... argument reduction routine
20 * Let S,C and T denote the sin, cos and tan respectively on
21 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
22 * in [-pi/4 , +pi/4], and let n = k mod 4.
25 * n sin(x) cos(x) tan(x)
26 * ----------------------------------------------------------
31 * ----------------------------------------------------------
34 * Let trig be any of sin, cos, or tan.
35 * trig(+-INF) is NaN, with signals;
36 * trig(NaN) is that NaN;
39 * TRIG(x) returns trig(x) nearly rounded
45 #define INLINE_REM_PIO2
46 #include "math_private.h"
47 #include "e_rem_pio2.c"
60 if(ix <= 0x3fe921fb) {
61 if(ix<0x3e400000) /* x < 2**-27 */
62 if((int)x==0) return x; /* generate inexact */
63 return __kernel_tan(x,z,1);
66 /* tan(Inf or NaN) is NaN */
67 else if (ix>=0x7ff00000) return x-x; /* NaN */
69 /* argument reduction needed */
71 n = __ieee754_rem_pio2(x,y);
72 return __kernel_tan(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even
77 #if (LDBL_MANT_DIG == 53)
78 __weak_reference(tan, tanl);