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gcc/libjava/java/lang/s_tan.c
Tom Tromey 0d16618c58 [multiple changes]
Fri May 28 22:20:03 1999  Anthony Green  <green@cygnus.com>
	* java/lang/fdlibm.h: Don't use __uint32_t.  Include mprec.h.
	* java/lang/e_log.c: Don't use __uint32_t.
1999-05-27  Eric Christopher <echristo@cygnus.com>
	* configure: Rebuilt
	* configure.in: Fixed ISO C9X and namespace collision with __uint32_t
	* acconfig.h: Rebuilt
	* include/config.h.in: Rebuilt
	* java/lang/mprec.h, java/lang/e_acos.c, java/lang/e_asin.c,
 	java/lang/e_atan2.c, java/lang/e_exp.c, java/lang/e_fmod.c,
 	e_log.c, java/lang/e_pow.c, java/lang/e_rem_pio2.c,
 	java/lang/e_remainder.c, java/lang/e_sqrt.c, java/lang/fdlibm.h,
 	k_tan.c, java/lang/mprec.h, java/lang/s_atan.c,
 	java/lang/s_ceil.c, java/lang/s_copysign.c, java/lang/s_fabs.c,
 	s_floor.c, java/lang/s_rint.c, java/lang/sf_rint.c: Fixed ISO C9X
 	and namespace collision with __uint32_t

From-SVN: r27729
1999-06-24 20:06:09 +00:00

115 lines
2.4 KiB
C

/* @(#)s_tan.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
FUNCTION
<<tan>>, <<tanf>>---tangent
INDEX
tan
INDEX
tanf
ANSI_SYNOPSIS
#include <math.h>
double tan(double <[x]>);
float tanf(float <[x]>);
TRAD_SYNOPSIS
#include <math.h>
double tan(<[x]>)
double <[x]>;
float tanf(<[x]>)
float <[x]>;
DESCRIPTION
<<tan>> computes the tangent of the argument <[x]>.
Angles are specified in radians.
<<tanf>> is identical, save that it takes and returns <<float>> values.
RETURNS
The tangent of <[x]> is returned.
PORTABILITY
<<tan>> is ANSI. <<tanf>> is an extension.
*/
/* tan(x)
* Return tangent function of x.
*
* kernel function:
* __kernel_tan ... tangent function on [-pi/4,pi/4]
* __ieee754_rem_pio2 ... argument reduction routine
*
* Method.
* Let S,C and T denote the sin, cos and tan respectively on
* [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
* in [-pi/4 , +pi/4], and let n = k mod 4.
* We have
*
* n sin(x) cos(x) tan(x)
* ----------------------------------------------------------
* 0 S C T
* 1 C -S -1/T
* 2 -S -C T
* 3 -C S -1/T
* ----------------------------------------------------------
*
* Special cases:
* Let trig be any of sin, cos, or tan.
* trig(+-INF) is NaN, with signals;
* trig(NaN) is that NaN;
*
* Accuracy:
* TRIG(x) returns trig(x) nearly rounded
*/
#include "fdlibm.h"
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
double tan(double x)
#else
double tan(x)
double x;
#endif
{
double y[2],z=0.0;
int32_t n,ix;
/* High word of x. */
GET_HIGH_WORD(ix,x);
/* |x| ~< pi/4 */
ix &= 0x7fffffff;
if(ix <= 0x3fe921fb) return __kernel_tan(x,z,1);
/* tan(Inf or NaN) is NaN */
else if (ix>=0x7ff00000) return x-x; /* NaN */
/* argument reduction needed */
else {
n = __ieee754_rem_pio2(x,y);
return __kernel_tan(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even
-1 -- n odd */
}
}
#endif /* _DOUBLE_IS_32BITS */