1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #pragma weak tan = __tan 31 32 /* INDENT OFF */ 33 /* 34 * tan(x) 35 * Table look-up algorithm by K.C. Ng, November, 1989. 36 * 37 * kernel function: 38 * __k_tan ... tangent function on [-pi/4,pi/4] 39 * __rem_pio2 ... argument reduction routine 40 */ 41 /* INDENT ON */ 42 43 #include "libm.h" 44 #include "libm_synonyms.h" 45 #include "libm_protos.h" 46 #include <math.h> 47 48 double 49 tan(double x) { 50 double y[2], z = 0.0; 51 int n, ix; 52 53 /* high word of x */ 54 ix = ((int *) &x)[HIWORD]; 55 56 /* |x| ~< pi/4 */ 57 ix &= 0x7fffffff; 58 if (ix <= 0x3fe921fb) 59 return (__k_tan(x, z, 0)); 60 61 /* tan(Inf or NaN) is NaN */ 62 else if (ix >= 0x7ff00000) { 63 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) 64 return (ix >= 0x7ff80000 ? x : x - x); /* NaN */ 65 /* assumes sparc-like QNaN */ 66 #else 67 return (x - x); /* NaN */ 68 #endif 69 } 70 71 /* argument reduction needed */ 72 else { 73 n = __rem_pio2(x, y); 74 return (__k_tan(y[0], y[1], n & 1)); 75 } 76 } 77