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 /* s_tanl.c -- long double version of s_tan.c. * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. */ /* @(#)s_tan.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. * ==================================================== */ /* tanq(x) * Return tangent function of x. * * kernel function: * __quadmath_kernel_tanq ... tangent function on [-pi/4,pi/4] * __quadmath_rem_pio2q ... 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 "quadmath-imp.h" __float128 tanq(__float128 x) { __float128 y[2],z=0; int64_t n, ix; /* High word of x. */ GET_FLT128_MSW64(ix,x); /* |x| ~< pi/4 */ ix &= 0x7fffffffffffffffLL; if(ix <= 0x3ffe921fb54442d1LL) return __quadmath_kernel_tanq(x,z,1); /* tanq(Inf or NaN) is NaN */ else if (ix>=0x7fff000000000000LL) { if (ix == 0x7fff000000000000LL) { GET_FLT128_LSW64(n,x); if (n == 0) errno = EDOM; } return x-x; /* NaN */ } /* argument reduction needed */ else { n = __quadmath_rem_pio2q(x,y); return __quadmath_kernel_tanq(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even -1 -- n odd */ } }