1 /* $NetBSD: s_tanl.c,v 1.2 2024/02/23 13:42:01 christos Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-2-Clause 5 * 6 * Copyright (c) 2007 Steven G. Kargl 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice unmodified, this list of conditions, and the following 14 * disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 __RCSID("$NetBSD: s_tanl.c,v 1.2 2024/02/23 13:42:01 christos Exp $"); 33 34 /* 35 * Limited testing on pseudorandom numbers drawn within [0:4e8] shows 36 * an accuracy of <= 1.5 ULP where 247024 values of x out of 40 million 37 * possibles resulted in tan(x) that exceeded 0.5 ULP (ie., 0.6%). 38 */ 39 #include "namespace.h" 40 #include <float.h> 41 #ifdef __i386__ 42 #include <ieeefp.h> 43 #endif 44 45 #include "math.h" 46 #include "math_private.h" 47 48 #ifdef __weak_alias 49 __weak_alias(tanl, _tanl) 50 #endif 51 52 #ifdef __HAVE_LONG_DOUBLE 53 54 #if LDBL_MANT_DIG == 64 55 #include "../ld80/e_rem_pio2l.h" 56 #include "../ld80/k_tanl.c" 57 #elif LDBL_MANT_DIG == 113 58 #include "../ld128/e_rem_pio2l.h" 59 #include "../ld128/k_tanl.c" 60 #else 61 #error "Unsupported long double format" 62 #endif 63 64 long double 65 tanl(long double x) 66 { 67 union ieee_ext_u z; 68 int e0, s; 69 long double y[2]; 70 long double hi, lo; 71 72 z.extu_ld = x; 73 s = z.extu_sign; 74 z.extu_sign = 0; 75 76 /* If x = +-0 or x is subnormal, then tan(x) = x. */ 77 if (z.extu_exp == 0) 78 return (x); 79 80 /* If x = NaN or Inf, then tan(x) = NaN. */ 81 if (z.extu_exp == 32767) 82 return ((x - x) / (x - x)); 83 84 ENTERI(); 85 86 /* Optimize the case where x is already within range. */ 87 if (z.extu_ld < M_PI_4) { 88 hi = __kernel_tanl(z.extu_ld, 0, 0); 89 RETURNI(s ? -hi : hi); 90 } 91 92 e0 = __ieee754_rem_pio2l(x, y); 93 hi = y[0]; 94 lo = y[1]; 95 96 switch (e0 & 3) { 97 case 0: 98 case 2: 99 hi = __kernel_tanl(hi, lo, 0); 100 break; 101 case 1: 102 case 3: 103 hi = __kernel_tanl(hi, lo, 1); 104 break; 105 } 106 107 RETURNI(hi); 108 } 109 110 #else 111 112 long double 113 tanl(long double x) 114 { 115 return tan(x); 116 } 117 118 #endif 119