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 <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 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 #ifdef __i386__ 37 #include <ieeefp.h> 38 #endif 39 40 #include "math.h" 41 #include "math_private.h" 42 #if LDBL_MANT_DIG == 64 43 #include "../ld80/e_rem_pio2l.h" 44 #elif LDBL_MANT_DIG == 113 45 #include "../ld128/e_rem_pio2l.h" 46 #else 47 #error "Unsupported long double format" 48 #endif 49 50 long double 51 cosl(long double x) 52 { 53 union IEEEl2bits z; 54 int e0; 55 long double y[2]; 56 long double hi, lo; 57 58 z.e = x; 59 z.bits.sign = 0; 60 61 /* If x = +-0 or x is a subnormal number, then cos(x) = 1 */ 62 if (z.bits.exp == 0) 63 return (1.0); 64 65 /* If x = NaN or Inf, then cos(x) = NaN. */ 66 if (z.bits.exp == 32767) 67 return ((x - x) / (x - x)); 68 69 ENTERI(); 70 71 /* Optimize the case where x is already within range. */ 72 if (z.e < M_PI_4) 73 RETURNI(__kernel_cosl(z.e, 0)); 74 75 e0 = __ieee754_rem_pio2l(x, y); 76 hi = y[0]; 77 lo = y[1]; 78 79 switch (e0 & 3) { 80 case 0: 81 hi = __kernel_cosl(hi, lo); 82 break; 83 case 1: 84 hi = - __kernel_sinl(hi, lo, 1); 85 break; 86 case 2: 87 hi = - __kernel_cosl(hi, lo); 88 break; 89 case 3: 90 hi = __kernel_sinl(hi, lo, 1); 91 break; 92 } 93 94 RETURNI(hi); 95 } 96