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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libquadmath/] [math/] [acoshq.c] - Blame information for rev 740

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1 740 jeremybenn
/* e_acoshl.c -- long double version of e_acosh.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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/* __ieee754_acoshl(x)
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 * Method :
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 *      Based on
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 *              acoshl(x) = logl [ x + sqrtl(x*x-1) ]
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 *      we have
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 *              acoshl(x) := logl(x)+ln2,       if x is large; else
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 *              acoshl(x) := logl(2x-1/(sqrtl(x*x-1)+x)) if x>2; else
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 *              acoshl(x) := log1pl(t+sqrtl(2.0*t+t*t)); where t=x-1.
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 *
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 * Special cases:
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 *      acoshl(x) is NaN with signal if x<1.
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 *      acoshl(NaN) is NaN without signal.
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 */
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#include "quadmath-imp.h"
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static const __float128
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one     = 1.0Q,
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ln2     = 0.6931471805599453094172321214581766Q;
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__float128
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acoshq (__float128 x)
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{
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        __float128 t;
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        uint64_t lx;
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        int64_t hx;
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        GET_FLT128_WORDS64(hx,lx,x);
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        if(hx<0x3fff000000000000LL) {           /* x < 1 */
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            return (x-x)/(x-x);
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        } else if(hx >=0x4035000000000000LL) {  /* x > 2**54 */
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            if(hx >=0x7fff000000000000LL) {     /* x is inf of NaN */
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                return x+x;
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            } else
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                return logq(x)+ln2;     /* acoshl(huge)=logl(2x) */
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        } else if(((hx-0x3fff000000000000LL)|lx)==0) {
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            return 0.0Q;                        /* acosh(1) = 0 */
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        } else if (hx > 0x4000000000000000LL) { /* 2**28 > x > 2 */
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            t=x*x;
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            return logq(2.0Q*x-one/(x+sqrtq(t-one)));
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        } else {                        /* 1<x<2 */
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            t = x-one;
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            return log1pq(t+sqrtq(2.0Q*t+t*t));
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        }
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}

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