xref: /illumos-gate/usr/src/lib/libm/common/R/__tanf.c (revision 25c28e83)
1*25c28e83SPiotr Jasiukajtis /*
2*25c28e83SPiotr Jasiukajtis  * CDDL HEADER START
3*25c28e83SPiotr Jasiukajtis  *
4*25c28e83SPiotr Jasiukajtis  * The contents of this file are subject to the terms of the
5*25c28e83SPiotr Jasiukajtis  * Common Development and Distribution License (the "License").
6*25c28e83SPiotr Jasiukajtis  * You may not use this file except in compliance with the License.
7*25c28e83SPiotr Jasiukajtis  *
8*25c28e83SPiotr Jasiukajtis  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*25c28e83SPiotr Jasiukajtis  * or http://www.opensolaris.org/os/licensing.
10*25c28e83SPiotr Jasiukajtis  * See the License for the specific language governing permissions
11*25c28e83SPiotr Jasiukajtis  * and limitations under the License.
12*25c28e83SPiotr Jasiukajtis  *
13*25c28e83SPiotr Jasiukajtis  * When distributing Covered Code, include this CDDL HEADER in each
14*25c28e83SPiotr Jasiukajtis  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*25c28e83SPiotr Jasiukajtis  * If applicable, add the following below this CDDL HEADER, with the
16*25c28e83SPiotr Jasiukajtis  * fields enclosed by brackets "[]" replaced with your own identifying
17*25c28e83SPiotr Jasiukajtis  * information: Portions Copyright [yyyy] [name of copyright owner]
18*25c28e83SPiotr Jasiukajtis  *
19*25c28e83SPiotr Jasiukajtis  * CDDL HEADER END
20*25c28e83SPiotr Jasiukajtis  */
21*25c28e83SPiotr Jasiukajtis 
22*25c28e83SPiotr Jasiukajtis /*
23*25c28e83SPiotr Jasiukajtis  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24*25c28e83SPiotr Jasiukajtis  */
25*25c28e83SPiotr Jasiukajtis /*
26*25c28e83SPiotr Jasiukajtis  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27*25c28e83SPiotr Jasiukajtis  * Use is subject to license terms.
28*25c28e83SPiotr Jasiukajtis  */
29*25c28e83SPiotr Jasiukajtis 
30*25c28e83SPiotr Jasiukajtis #include "libm.h"
31*25c28e83SPiotr Jasiukajtis 
32*25c28e83SPiotr Jasiukajtis /* INDENT OFF */
33*25c28e83SPiotr Jasiukajtis /*
34*25c28e83SPiotr Jasiukajtis  * float __k_tan(double x);
35*25c28e83SPiotr Jasiukajtis  * kernel (float) tan function on [-pi/4, pi/4], pi/4 ~ 0.785398164
36*25c28e83SPiotr Jasiukajtis  * Input x is in double and assumed to be bounded by ~pi/4 in magnitude.
37*25c28e83SPiotr Jasiukajtis  *
38*25c28e83SPiotr Jasiukajtis  * Constants:
39*25c28e83SPiotr Jasiukajtis  * The hexadecimal values are the intended ones for the following constants.
40*25c28e83SPiotr Jasiukajtis  * The decimal values may be used, provided that the compiler will convert
41*25c28e83SPiotr Jasiukajtis  * from decimal to binary accurately enough to produce the hexadecimal values
42*25c28e83SPiotr Jasiukajtis  * shown.
43*25c28e83SPiotr Jasiukajtis  */
44*25c28e83SPiotr Jasiukajtis 
45*25c28e83SPiotr Jasiukajtis static const double q[] = {
46*25c28e83SPiotr Jasiukajtis /* one */ 1.0,
47*25c28e83SPiotr Jasiukajtis /* P0 */  4.46066928428959230679140546271810308098793029785e-0003,
48*25c28e83SPiotr Jasiukajtis /* P1 */  4.92165316309189027066395283327437937259674072266e+0000,
49*25c28e83SPiotr Jasiukajtis /* P2 */ -7.11410648161473480044492134766187518835067749023e-0001,
50*25c28e83SPiotr Jasiukajtis /* P3 */  4.08549808374053391446523164631798863410949707031e+0000,
51*25c28e83SPiotr Jasiukajtis /* P4 */  2.50411070398050927821032018982805311679840087891e+0000,
52*25c28e83SPiotr Jasiukajtis /* P5 */  1.11492064560251158411574579076841473579406738281e+0001,
53*25c28e83SPiotr Jasiukajtis /* P6 */ -1.50565540968422650891511693771462887525558471680e+0000,
54*25c28e83SPiotr Jasiukajtis /* P7 */ -1.81484378878349295050043110677506774663925170898e+0000,
55*25c28e83SPiotr Jasiukajtis /* T0 */  3.333335997532835641297409611782510896641e-0001,
56*25c28e83SPiotr Jasiukajtis /* T1 */  2.999997598248363761541668282006867229939e+00,
57*25c28e83SPiotr Jasiukajtis };
58*25c28e83SPiotr Jasiukajtis /* INDENT ON */
59*25c28e83SPiotr Jasiukajtis 
60*25c28e83SPiotr Jasiukajtis #define	one q[0]
61*25c28e83SPiotr Jasiukajtis #define	P0 q[1]
62*25c28e83SPiotr Jasiukajtis #define	P1 q[2]
63*25c28e83SPiotr Jasiukajtis #define	P2 q[3]
64*25c28e83SPiotr Jasiukajtis #define	P3 q[4]
65*25c28e83SPiotr Jasiukajtis #define	P4 q[5]
66*25c28e83SPiotr Jasiukajtis #define	P5 q[6]
67*25c28e83SPiotr Jasiukajtis #define	P6 q[7]
68*25c28e83SPiotr Jasiukajtis #define	P7 q[8]
69*25c28e83SPiotr Jasiukajtis #define	T0 q[9]
70*25c28e83SPiotr Jasiukajtis #define	T1 q[10]
71*25c28e83SPiotr Jasiukajtis 
72*25c28e83SPiotr Jasiukajtis float
__k_tanf(double x,int n)73*25c28e83SPiotr Jasiukajtis __k_tanf(double x, int n) {
74*25c28e83SPiotr Jasiukajtis 	float ft = 0.0;
75*25c28e83SPiotr Jasiukajtis 	double z, w;
76*25c28e83SPiotr Jasiukajtis 	int ix;
77*25c28e83SPiotr Jasiukajtis 
78*25c28e83SPiotr Jasiukajtis 	ix = ((int *) &x)[HIWORD] & ~0x80000000;	/* ix = leading |x| */
79*25c28e83SPiotr Jasiukajtis 	/* small argument */
80*25c28e83SPiotr Jasiukajtis 	if (ix < 0x3f800000) {		/* if |x| < 0.0078125 = 2**-7 */
81*25c28e83SPiotr Jasiukajtis 		if (ix < 0x3f100000) {	/* if |x| < 2**-14 */
82*25c28e83SPiotr Jasiukajtis 			if ((int) x == 0) {	/* raise inexact if x != 0 */
83*25c28e83SPiotr Jasiukajtis 				ft = n == 0 ? (float) x : (float) (-one / x);
84*25c28e83SPiotr Jasiukajtis 			}
85*25c28e83SPiotr Jasiukajtis 			return (ft);
86*25c28e83SPiotr Jasiukajtis 		}
87*25c28e83SPiotr Jasiukajtis 		z = (x * T0) * (T1 + x * x);
88*25c28e83SPiotr Jasiukajtis 		ft = n == 0 ? (float) z : (float) (-one / z);
89*25c28e83SPiotr Jasiukajtis 		return (ft);
90*25c28e83SPiotr Jasiukajtis 	}
91*25c28e83SPiotr Jasiukajtis 	z = x * x;
92*25c28e83SPiotr Jasiukajtis 	w = ((P0 * x) * (P1 + z * (P2 + z)) * (P3 + z * (P4 + z)))
93*25c28e83SPiotr Jasiukajtis 		* (P5 + z * (P6 + z * (P7 + z)));
94*25c28e83SPiotr Jasiukajtis 	ft = n == 0 ? (float) w : (float) (-one / w);
95*25c28e83SPiotr Jasiukajtis 	return (ft);
96*25c28e83SPiotr Jasiukajtis }
97