Mercurial > sdl-ios-xcode
view src/libm/s_sin.c @ 5204:523409574510
Added an OpenGL ES 2.0 renderer, contributed by itsnotabigtruck
This compiles, but it untested.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Sun, 06 Feb 2011 00:00:13 -0800 |
parents | dc1eb82ffdaa |
children |
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/* @(#)s_sin.c 5.1 93/09/24 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ #if defined(LIBM_SCCS) && !defined(lint) static const char rcsid[] = "$NetBSD: s_sin.c,v 1.7 1995/05/10 20:48:15 jtc Exp $"; #endif /* 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 "math.h" #include "math_private.h" libm_hidden_proto(sin) #ifdef __STDC__ double sin(double x) #else double sin(x) double x; #endif { double y[2], z = 0.0; int32_t n, ix; /* High word of x. */ GET_HIGH_WORD(ix, 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]); } } } libm_hidden_def(sin)