1 /* $NetBSD: s_tanl.c,v 1.3 2024/04/03 18:53:42 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 1.3 2024/04/03 18:53:42 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 42 #include "math.h" 43 #include "math_private.h" 44 45 #ifdef __weak_alias 46 __weak_alias(tanl, _tanl) 47 #endif 48 49 #ifdef __HAVE_LONG_DOUBLE 50 51 #if LDBL_MANT_DIG == 64 52 #include "../ld80/e_rem_pio2l.h" 53 #include "../ld80/k_tanl.c" 54 #elif LDBL_MANT_DIG == 113 55 #include "../ld128/e_rem_pio2l.h" 56 #include "../ld128/k_tanl.c" 57 #else 58 #error "Unsupported long double format" 59 #endif 60 61 long double 62 tanl(long double x) 63 { 64 union ieee_ext_u z; 65 int e0, s; 66 long double y[2]; 67 long double hi, lo; 68 69 z.extu_ld = x; 70 s = z.extu_sign; 71 z.extu_sign = 0; 72 73 /* If x = +-0 or x is subnormal, then tan(x) = x. */ 74 if (z.extu_exp == 0) 75 return (x); 76 77 /* If x = NaN or Inf, then tan(x) = NaN. */ 78 if (z.extu_exp == 32767) 79 return ((x - x) / (x - x)); 80 81 ENTERI(); 82 83 /* Optimize the case where x is already within range. */ 84 if (z.extu_ld < M_PI_4) { 85 hi = __kernel_tanl(z.extu_ld, 0, 0); 86 RETURNI(s ? -hi : hi); 87 } 88 89 e0 = __ieee754_rem_pio2l(x, y); 90 hi = y[0]; 91 lo = y[1]; 92 93 switch (e0 & 3) { 94 case 0: 95 case 2: 96 hi = __kernel_tanl(hi, lo, 0); 97 break; 98 case 1: 99 case 3: 100 hi = __kernel_tanl(hi, lo, 1); 101 break; 102 } 103 104 RETURNI(hi); 105 } 106 107 #else 108 109 long double 110 tanl(long double x) 111 { 112 return tan(x); 113 } 114 115 #endif 116