Initial revision

From-SVN: r26263

libjava/java/lang/w_exp.c

@@ -0,0 +1,136 @@
+
+/* @(#)w_exp.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.
+ * ====================================================
+ */
+
+/*
+FUNCTION
+	<<exp>>, <<expf>>---exponential
+INDEX
+	exp
+INDEX
+	expf
+
+ANSI_SYNOPSIS
+	#include <math.h>
+	double exp(double <[x]>);
+	float expf(float <[x]>);
+
+TRAD_SYNOPSIS
+	#include <math.h>
+	double exp(<[x]>);
+	double <[x]>;
+
+	float expf(<[x]>);
+	float <[x]>;
+
+DESCRIPTION
+	<<exp>> and <<expf>> calculate the exponential of <[x]>, that is, 
+	@ifinfo
+	e raised to the power <[x]> (where e
+	@end ifinfo
+	@tex
+	$e^x$ (where $e$
+	@end tex
+	is the base of the natural system of logarithms, approximately 2.71828).
+
+	You can use the (non-ANSI) function <<matherr>> to specify
+	error handling for these functions.
+
+RETURNS
+	On success, <<exp>> and <<expf>> return the calculated value.
+	If the result underflows, the returned value is <<0>>.  If the
+	result overflows, the returned value is <<HUGE_VAL>>.  In
+	either case, <<errno>> is set to <<ERANGE>>.
+
+PORTABILITY
+	<<exp>> is ANSI C.  <<expf>> is an extension.
+
+*/
+
+/* 
+ * wrapper exp(x)
+ */
+
+#include "fdlibm.h"
+#include <errno.h>
+
+#ifndef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+o_threshold=  7.09782712893383973096e+02,  /* 0x40862E42, 0xFEFA39EF */
+u_threshold= -7.45133219101941108420e+02;  /* 0xc0874910, 0xD52D3051 */
+
+#ifdef __STDC__
+	double exp(double x)		/* wrapper exp */
+#else
+	double exp(x)			/* wrapper exp */
+	double x;
+#endif
+{
+#ifdef _IEEE_LIBM
+	return __ieee754_exp(x);
+#else
+	double z;
+	struct exception exc;
+	z = __ieee754_exp(x);
+	if(_LIB_VERSION == _IEEE_) return z;
+	if(finite(x)) {
+	    if(x>o_threshold) {
+		/* exp(finite) overflow */
+#ifndef HUGE_VAL
+#define HUGE_VAL inf
+	        double inf = 0.0;
+
+	        SET_HIGH_WORD(inf,0x7ff00000);	/* set inf to infinite */
+#endif
+		exc.type = OVERFLOW;
+		exc.name = "exp";
+		exc.err = 0;
+		exc.arg1 = exc.arg2 = x;
+		if (_LIB_VERSION == _SVID_)
+		  exc.retval = HUGE;
+		else
+		  exc.retval = HUGE_VAL;
+		if (_LIB_VERSION == _POSIX_)
+		  errno = ERANGE;
+		else if (!matherr(&exc)) {
+			errno = ERANGE;
+		}
+	        if (exc.err != 0)
+	           errno = exc.err;
+	        return exc.retval; 
+	    } else if(x<u_threshold) {
+		/* exp(finite) underflow */
+		exc.type = UNDERFLOW;
+		exc.name = "exp";
+		exc.err = 0;
+		exc.arg1 = exc.arg2 = x;
+		exc.retval = 0.0;
+		if (_LIB_VERSION == _POSIX_)
+		  errno = ERANGE;
+		else if (!matherr(&exc)) {
+			errno = ERANGE;
+		}
+	        if (exc.err != 0)
+	           errno = exc.err;
+	        return exc.retval; 
+	    } 
+	} 
+	return z;
+#endif
+}
+
+#endif /* defined(_DOUBLE_IS_32BITS) */