1 /*- 2 * Copyright (c) 2007 Steven G. Kargl 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "cdefs-compat.h" 28 //__FBSDID("$FreeBSD: src/lib/msun/src/s_cosl.c,v 1.3 2011/05/30 19:41:28 kargl Exp $"); 29 30 /* 31 * Limited testing on pseudorandom numbers drawn within [-2e8:4e8] shows 32 * an accuracy of <= 0.7412 ULP. 33 */ 34 35 #include <float.h> 36 #include <openlibm.h> 37 38 #include "math_private.h" 39 #if LDBL_MANT_DIG == 64 40 #include "../ld80/e_rem_pio2l.h" 41 #elif LDBL_MANT_DIG == 113 42 #include "../ld128/e_rem_pio2l.h" 43 #else 44 #error "Unsupported long double format" 45 #endif 46 47 DLLEXPORT long double 48 cosl(long double x) 49 { 50 union IEEEl2bits z; 51 int e0; 52 long double y[2]; 53 long double hi, lo; 54 55 z.e = x; 56 z.bits.sign = 0; 57 58 /* If x = +-0 or x is a subnormal number, then cos(x) = 1 */ 59 if (z.bits.exp == 0) 60 return (1.0); 61 62 /* If x = NaN or Inf, then cos(x) = NaN. */ 63 if (z.bits.exp == 32767) 64 return ((x - x) / (x - x)); 65 66 /* Optimize the case where x is already within range. */ 67 if (z.e < M_PI_4) 68 return (__kernel_cosl(z.e, 0)); 69 70 e0 = __ieee754_rem_pio2l(x, y); 71 hi = y[0]; 72 lo = y[1]; 73 74 switch (e0 & 3) { 75 case 0: 76 hi = __kernel_cosl(hi, lo); 77 break; 78 case 1: 79 hi = - __kernel_sinl(hi, lo, 1); 80 break; 81 case 2: 82 hi = - __kernel_cosl(hi, lo); 83 break; 84 case 3: 85 hi = __kernel_sinl(hi, lo, 1); 86 break; 87 } 88 89 return (hi); 90 } 91