tan.c revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* INDENT OFF */
/*
* tan(x)
* Table look-up algorithm by K.C. Ng, November, 1989.
*
* kernel function:
* __k_tan ... tangent function on [-pi/4,pi/4]
* __rem_pio2 ... argument reduction routine
*/
/* INDENT ON */
#include "libm.h"
#include "libm_synonyms.h"
#include "libm_protos.h"
#include <math.h>
double
tan(double x) {
double y[2], z = 0.0;
int n, ix;
/* high word of x */
/* |x| ~< pi/4 */
ix &= 0x7fffffff;
if (ix <= 0x3fe921fb)
return (__k_tan(x, z, 0));
/* tan(Inf or NaN) is NaN */
else if (ix >= 0x7ff00000) {
#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
/* assumes sparc-like QNaN */
#else
return (x - x); /* NaN */
#endif
}
/* argument reduction needed */
else {
n = __rem_pio2(x, y);
}
}