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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libquadmath/] [math/] [cosq.c] - Blame information for rev 792

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1 740 jeremybenn 
/* s_cosl.c -- long double version of s_cos.c.
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 * Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz.
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 */
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/*
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunPro, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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/* cosl(x)
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 * Return cosine function of x.
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 *
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 * kernel function:
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 *      __kernel_sinl           ... sine function on [-pi/4,pi/4]
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 *      __kernel_cosl           ... cosine function on [-pi/4,pi/4]
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 *      __ieee754_rem_pio2l     ... argument reduction routine
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 *
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 * Method.
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 *      Let S,C and T denote the sin, cos and tan respectively on
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 *      [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
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 *      in [-pi/4 , +pi/4], and let n = k mod 4.
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 *      We have
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 *
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 *          n        sin(x)      cos(x)        tan(x)
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 *     ----------------------------------------------------------
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 *          0          S           C             T
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 *          1          C          -S            -1/T
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 *          2         -S          -C             T
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 *          3         -C           S            -1/T
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 *     ----------------------------------------------------------
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 *
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 * Special cases:
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 *      Let trig be any of sin, cos, or tan.
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 *      trig(+-INF)  is NaN, with signals;
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 *      trig(NaN)    is that NaN;
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 *
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 * Accuracy:
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 *      TRIG(x) returns trig(x) nearly rounded
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 */
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#include "quadmath-imp.h"
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__float128
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cosq (__float128 x)
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{
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        __float128 y[2],z=0.0Q;
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        int64_t n, ix;
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    /* High word of x. */
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        GET_FLT128_MSW64(ix,x);
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    /* |x| ~< pi/4 */
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        ix &= 0x7fffffffffffffffLL;
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        if(ix <= 0x3ffe921fb54442d1LL)
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          return __quadmath_kernel_cosq(x,z);
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    /* cos(Inf or NaN) is NaN */
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        else if (ix>=0x7fff000000000000LL) {
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            if (ix == 0x7fff000000000000LL) {
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                GET_FLT128_LSW64(n,x);
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            }
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            return x-x;
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        }
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    /* argument reduction needed */
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        else {
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            n = __quadmath_rem_pio2q(x,y);
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            switch(n&3) {
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                case 0: return  __quadmath_kernel_cosq(y[0],y[1]);
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                case 1: return -__quadmath_kernel_sinq(y[0],y[1],1);
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                case 2: return -__quadmath_kernel_cosq(y[0],y[1]);
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                default:
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                        return  __quadmath_kernel_sinq(y[0],y[1],1);
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            }
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        }
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}

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