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[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [newlib/] [libm/] [math/] [w_exp.c] - Blame information for rev 855

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1 148 jeremybenn
 
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/* @(#)w_exp.c 5.1 93/09/24 */
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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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/*
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FUNCTION
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        <<exp>>, <<expf>>---exponential
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INDEX
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        exp
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INDEX
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        expf
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ANSI_SYNOPSIS
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        #include <math.h>
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        double exp(double <[x]>);
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        float expf(float <[x]>);
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TRAD_SYNOPSIS
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        #include <math.h>
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        double exp(<[x]>);
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        double <[x]>;
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        float expf(<[x]>);
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        float <[x]>;
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DESCRIPTION
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        <<exp>> and <<expf>> calculate the exponential of <[x]>, that is,
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        @ifnottex
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        e raised to the power <[x]> (where e
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        @end ifnottex
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        @tex
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        $e^x$ (where $e$
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        @end tex
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        is the base of the natural system of logarithms, approximately 2.71828).
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        You can use the (non-ANSI) function <<matherr>> to specify
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        error handling for these functions.
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RETURNS
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        On success, <<exp>> and <<expf>> return the calculated value.
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        If the result underflows, the returned value is <<0>>.  If the
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        result overflows, the returned value is <<HUGE_VAL>>.  In
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        either case, <<errno>> is set to <<ERANGE>>.
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PORTABILITY
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        <<exp>> is ANSI C.  <<expf>> is an extension.
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*/
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/*
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 * wrapper exp(x)
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 */
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#include "fdlibm.h"
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#include <errno.h>
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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static const double
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#else
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static double
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#endif
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o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
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u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
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#ifdef __STDC__
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        double exp(double x)            /* wrapper exp */
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#else
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        double exp(x)                   /* wrapper exp */
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        double x;
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#endif
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{
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#ifdef _IEEE_LIBM
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        return __ieee754_exp(x);
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#else
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        double z;
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        struct exception exc;
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        z = __ieee754_exp(x);
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        if(_LIB_VERSION == _IEEE_) return z;
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        if(finite(x)) {
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            if(x>o_threshold) {
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                /* exp(finite) overflow */
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#ifndef HUGE_VAL
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#define HUGE_VAL inf
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                double inf = 0.0;
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                SET_HIGH_WORD(inf,0x7ff00000);  /* set inf to infinite */
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#endif
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                exc.type = OVERFLOW;
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                exc.name = "exp";
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                exc.err = 0;
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                exc.arg1 = exc.arg2 = x;
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                if (_LIB_VERSION == _SVID_)
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                  exc.retval = HUGE;
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                else
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                  exc.retval = HUGE_VAL;
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                if (_LIB_VERSION == _POSIX_)
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                  errno = ERANGE;
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                else if (!matherr(&exc)) {
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                        errno = ERANGE;
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                }
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                if (exc.err != 0)
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                   errno = exc.err;
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                return exc.retval;
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            } else if(x<u_threshold) {
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                /* exp(finite) underflow */
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                exc.type = UNDERFLOW;
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                exc.name = "exp";
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                exc.err = 0;
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                exc.arg1 = exc.arg2 = x;
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                exc.retval = 0.0;
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                if (_LIB_VERSION == _POSIX_)
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                  errno = ERANGE;
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                else if (!matherr(&exc)) {
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                        errno = ERANGE;
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                }
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                if (exc.err != 0)
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                   errno = exc.err;
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                return exc.retval;
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            }
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        }
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        return z;
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#endif
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */

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