170Ssundar/* s_cosl.c -- long double version of s_cos.c. 270Ssundar * Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz. 370Ssundar */ 4877Sattila 570Ssundar/* 670Ssundar * ==================================================== 770Ssundar * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8877Sattila * 970Ssundar * Developed at SunPro, a Sun Microsystems, Inc. business. 1070Ssundar * Permission to use, copy, modify, and distribute this 1170Ssundar * software is freely granted, provided that this notice 1270Ssundar * is preserved. 1370Ssundar * ==================================================== 14877Sattila */ 1570Ssundar 1670Ssundar/* cosq(x) 1770Ssundar * Return cosine function of x. 18877Sattila * 1970Ssundar * kernel function: 2070Ssundar * __quadmath_kernel_sinq ... sine function on [-pi/4,pi/4] 2170Ssundar * __quadmath_kernel_cosq ... cosine function on [-pi/4,pi/4] 2270Ssundar * __quadmath_rem_pio2q ... argument reduction routine 2370Ssundar * 2469Ssundar * Method. 2569Ssundar * Let S,C and T denote the sin, cos and tan respectively on 2669Ssundar * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 2769Ssundar * in [-pi/4 , +pi/4], and let n = k mod 4. 2869Ssundar * We have 2969Ssundar * 3069Ssundar * n sin(x) cos(x) tan(x) 3169Ssundar * ---------------------------------------------------------- 3269Ssundar * 0 S C T 3369Ssundar * 1 C -S -1/T 3469Ssundar * 2 -S -C T 3569Ssundar * 3 -C S -1/T 3669Ssundar * ---------------------------------------------------------- 37 * 38 * Special cases: 39 * Let trig be any of sin, cos, or tan. 40 * trig(+-INF) is NaN, with signals; 41 * trig(NaN) is that NaN; 42 * 43 * Accuracy: 44 * TRIG(x) returns trig(x) nearly rounded 45 */ 46 47#include "quadmath-imp.h" 48 49__float128 cosq(__float128 x) 50{ 51 __float128 y[2],z=0; 52 int64_t n, ix; 53 54 /* High word of x. */ 55 GET_FLT128_MSW64(ix,x); 56 57 /* |x| ~< pi/4 */ 58 ix &= 0x7fffffffffffffffLL; 59 if(ix <= 0x3ffe921fb54442d1LL) 60 return __quadmath_kernel_cosq(x,z); 61 62 /* cos(Inf or NaN) is NaN */ 63 else if (ix>=0x7fff000000000000LL) { 64 if (ix == 0x7fff000000000000LL) { 65 GET_FLT128_LSW64(n,x); 66 if (n == 0) 67 errno = EDOM; 68 } 69 return x-x; 70 } 71 72 /* argument reduction needed */ 73 else { 74 n = __quadmath_rem_pio2q(x,y); 75 switch(n&3) { 76 case 0: return __quadmath_kernel_cosq(y[0],y[1]); 77 case 1: return -__quadmath_kernel_sinq(y[0],y[1],1); 78 case 2: return -__quadmath_kernel_cosq(y[0],y[1]); 79 default: 80 return __quadmath_kernel_sinq(y[0],y[1],1); 81 } 82 } 83} 84