| |
| /* |
| * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* sin(x) |
| * Return sine function of x. |
| * |
| * kernel function: |
| * __kernel_sin ... sine function on [-pi/4,pi/4] |
| * __kernel_cos ... cose function on [-pi/4,pi/4] |
| * __ieee754_rem_pio2 ... argument reduction routine |
| * |
| * Method. |
| * Let S,C and T denote the sin, cos and tan respectively on |
| * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 |
| * in [-pi/4 , +pi/4], and let n = k mod 4. |
| * We have |
| * |
| * n sin(x) cos(x) tan(x) |
| * ---------------------------------------------------------- |
| * 0 S C T |
| * 1 C -S -1/T |
| * 2 -S -C T |
| * 3 -C S -1/T |
| * ---------------------------------------------------------- |
| * |
| * Special cases: |
| * Let trig be any of sin, cos, or tan. |
| * trig(+-INF) is NaN, with signals; |
| * trig(NaN) is that NaN; |
| * |
| * Accuracy: |
| * TRIG(x) returns trig(x) nearly rounded |
| */ |
| |
| #include "fdlibm.h" |
| |
| #ifdef __STDC__ |
| double sin(double x) |
| #else |
| double sin(x) |
| double x; |
| #endif |
| { |
| double y[2],z=0.0; |
| int n, ix; |
| |
| /* High word of x. */ |
| ix = __HI(x); |
| |
| /* |x| ~< pi/4 */ |
| ix &= 0x7fffffff; |
| if(ix <= 0x3fe921fb) return __kernel_sin(x,z,0); |
| |
| /* sin(Inf or NaN) is NaN */ |
| else if (ix>=0x7ff00000) return x-x; |
| |
| /* argument reduction needed */ |
| else { |
| n = __ieee754_rem_pio2(x,y); |
| switch(n&3) { |
| case 0: return __kernel_sin(y[0],y[1],1); |
| case 1: return __kernel_cos(y[0],y[1]); |
| case 2: return -__kernel_sin(y[0],y[1],1); |
| default: |
| return -__kernel_cos(y[0],y[1]); |
| } |
| } |
| } |
