s_tanf.c revision 97413 
1/* s_tanf.c -- float version of s_tan.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#ifndef lint
17static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_tanf.c 97413 2002-05-28 18:15:04Z alfred $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23float
24tanf(float x)
25{
26	float y[2],z=0.0;
27	int32_t n, ix;
28
29	GET_FLOAT_WORD(ix,x);
30
31    /* |x| ~< pi/4 */
32	ix &= 0x7fffffff;
33	if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
34
35    /* tan(Inf or NaN) is NaN */
36	else if (ix>=0x7f800000) return x-x;		/* NaN */
37
38    /* argument reduction needed */
39	else {
40	    n = __ieee754_rem_pio2f(x,y);
41	    return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
42							      -1 -- n odd */
43	}
44}
45