1 /* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */
3 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
4 * Optimized by Bruce D. Evans.
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
14 * ====================================================
19 /* Small multiples of pi/2 rounded to double precision. */
21 t1pio2
= 1*M_PI_2
, /* 0x3FF921FB, 0x54442D18 */
22 t2pio2
= 2*M_PI_2
, /* 0x400921FB, 0x54442D18 */
23 t3pio2
= 3*M_PI_2
, /* 0x4012D97C, 0x7F3321D2 */
24 t4pio2
= 4*M_PI_2
; /* 0x401921FB, 0x54442D18 */
32 GET_FLOAT_WORD(ix
, x
);
36 if (ix
<= 0x3f490fda) { /* |x| ~<= pi/4 */
37 if (ix
< 0x39800000) { /* |x| < 2**-12 */
38 /* raise inexact if x!=0 and underflow if subnormal */
39 FORCE_EVAL(ix
< 0x00800000 ? x
/0x1p
120f
: x
+0x1p
120f
);
44 if (ix
<= 0x407b53d1) { /* |x| ~<= 5*pi/4 */
45 if (ix
<= 0x4016cbe3) /* |x| ~<= 3pi/4 */
46 return __tandf((sign
? x
+t1pio2
: x
-t1pio2
), 1);
48 return __tandf((sign
? x
+t2pio2
: x
-t2pio2
), 0);
50 if (ix
<= 0x40e231d5) { /* |x| ~<= 9*pi/4 */
51 if (ix
<= 0x40afeddf) /* |x| ~<= 7*pi/4 */
52 return __tandf((sign
? x
+t3pio2
: x
-t3pio2
), 1);
54 return __tandf((sign
? x
+t4pio2
: x
-t4pio2
), 0);
57 /* tan(Inf or NaN) is NaN */
61 /* argument reduction */
62 n
= __rem_pio2f(x
, &y
);
63 return __tandf(y
, n
&1);