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s_tanf.c revision 1.5 
      1 /* s_tanf.c -- float version of s_tan.c.
      2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) 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 #include <sys/cdefs.h>
     17 #if defined(LIBM_SCCS) && !defined(lint)
     18 __RCSID("$NetBSD: s_tanf.c,v 1.5 1997/10/09 11:33:38 lukem Exp $");
     19 #endif
     20 
     21 #include "math.h"
     22 #include "math_private.h"
     23 
     24 #ifdef __STDC__
     25 	float tanf(float x)
     26 #else
     27 	float tanf(x)
     28 	float x;
     29 #endif
     30 {
     31 	float y[2],z=0.0;
     32 	int32_t n, ix;
     33 
     34 	GET_FLOAT_WORD(ix,x);
     35 
     36     /* |x| ~< pi/4 */
     37 	ix &= 0x7fffffff;
     38 	if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
     39 
     40     /* tan(Inf or NaN) is NaN */
     41 	else if (ix>=0x7f800000) return x-x;		/* NaN */
     42 
     43     /* argument reduction needed */
     44 	else {
     45 	    n = __ieee754_rem_pio2f(x,y);
     46 	    return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
     47 							      -1 -- n odd */
     48 	}
     49 }
     50