s_tanf.c revision 2117 
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[] = "$Id: s_tanf.c,v 1.2 1994/08/18 23:10:20 jtc Exp $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23#ifdef __STDC__
24	float tanf(float x)
25#else
26	float tanf(x)
27	float x;
28#endif
29{
30	float y[2],z=0.0;
31	int32_t n, ix;
32
33	GET_FLOAT_WORD(ix,x);
34
35    /* |x| ~< pi/4 */
36	ix &= 0x7fffffff;
37	if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
38
39    /* tan(Inf or NaN) is NaN */
40	else if (ix>=0x7f800000) return x-x;		/* NaN */
41
42    /* argument reduction needed */
43	else {
44	    n = __ieee754_rem_pio2f(x,y);
45	    return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
46							      -1 -- n odd */
47	}
48}
49