import newlib-2000-02-17 snapshot

1 files changed, 193 insertions, 0 deletions

diff --git a/newlib/libm/math/w_gamma.c b/newlib/libm/math/w_gamma.c
new file mode 100644
index 000000000..da0211555
--- /dev/null
+++ b/newlib/libm/math/w_gamma.c
@@ -0,0 +1,193 @@
+
+/* @(#)w_gamma.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
+        <<gamma>>, <<gammaf>>, <<lgamma>>, <<lgammaf>>, <<gamma_r>>,
+	<<gammaf_r>>, <<lgamma_r>>, <<lgammaf_r>>---logarithmic gamma
+	function
+INDEX
+gamma
+INDEX
+gammaf
+INDEX
+lgamma
+INDEX
+lgammaf
+INDEX
+gamma_r
+INDEX
+gammaf_r
+INDEX
+lgamma_r
+INDEX
+lgammaf_r
+
+ANSI_SYNOPSIS
+#include <math.h>
+double gamma(double <[x]>);
+float gammaf(float <[x]>);
+double lgamma(double <[x]>);
+float lgammaf(float <[x]>);
+double gamma_r(double <[x]>, int *<[signgamp]>);
+float gammaf_r(float <[x]>, int *<[signgamp]>);
+double lgamma_r(double <[x]>, int *<[signgamp]>);
+float lgammaf_r(float <[x]>, int *<[signgamp]>);
+
+TRAD_SYNOPSIS
+#include <math.h>
+double gamma(<[x]>)
+double <[x]>;
+float gammaf(<[x]>)
+float <[x]>;
+double lgamma(<[x]>)
+double <[x]>;
+float lgammaf(<[x]>)
+float <[x]>;
+double gamma_r(<[x]>, <[signgamp]>)
+double <[x]>;
+int <[signgamp]>;
+float gammaf_r(<[x]>, <[signgamp]>)
+float <[x]>;
+int <[signgamp]>;
+double lgamma_r(<[x]>, <[signgamp]>)
+double <[x]>;
+int <[signgamp]>;
+float lgammaf_r(<[x]>, <[signgamp]>)
+float <[x]>;
+int <[signgamp]>;
+
+DESCRIPTION
+<<gamma>> calculates 
+@tex
+$\mit ln\bigl(\Gamma(x)\bigr)$, 
+@end tex
+the natural logarithm of the gamma function of <[x]>.  The gamma function
+(<<exp(gamma(<[x]>))>>) is a generalization of factorial, and retains
+the property that  
+@ifinfo
+<<exp(gamma(N))>> is equivalent to <<N*exp(gamma(N-1))>>.
+@end ifinfo
+@tex
+$\mit \Gamma(N)\equiv N\times\Gamma(N-1)$.
+@end tex
+Accordingly, the results of the gamma function itself grow very
+quickly.  <<gamma>> is defined as 
+@tex
+$\mit ln\bigl(\Gamma(x)\bigr)$ rather than simply $\mit \Gamma(x)$
+@end tex
+@ifinfo
+the natural log of the gamma function, rather than the gamma function
+itself, 
+@end ifinfo
+to extend the useful range of results representable.
+
+The sign of the result is returned in the global variable <<signgam>>,
+which is declared in math.h.
+
+<<gammaf>> performs the same calculation as <<gamma>>, but uses and
+returns <<float>> values.
+
+<<lgamma>> and <<lgammaf>> are alternate names for <<gamma>> and
+<<gammaf>>.  The use of <<lgamma>> instead of <<gamma>> is a reminder
+that these functions compute the log of the gamma function, rather
+than the gamma function itself.
+
+The functions <<gamma_r>>, <<gammaf_r>>, <<lgamma_r>>, and
+<<lgammaf_r>> are just like <<gamma>>, <<gammaf>>, <<lgamma>>, and
+<<lgammaf>>, respectively, but take an additional argument.  This
+additional argument is a pointer to an integer.  This additional
+argument is used to return the sign of the result, and the global
+variable <<signgam>> is not used.  These functions may be used for
+reentrant calls (but they will still set the global variable <<errno>>
+if an error occurs).
+
+RETURNS
+Normally, the computed result is returned.  
+
+When <[x]> is a nonpositive integer, <<gamma>> returns <<HUGE_VAL>>
+and <<errno>> is set to <<EDOM>>.  If the result overflows, <<gamma>>
+returns <<HUGE_VAL>> and <<errno>> is set to <<ERANGE>>.
+
+You can modify this error treatment using <<matherr>>.
+
+PORTABILITY
+Neither <<gamma>> nor <<gammaf>> is ANSI C.  */
+
+/* double gamma(double x)
+ * Return the logarithm of the Gamma function of x.
+ *
+ * Method: call gamma_r
+ */
+
+#include "fdlibm.h"
+#include <reent.h>
+#include <errno.h>
+
+#ifndef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+	double gamma(double x)
+#else
+	double gamma(x)
+	double x;
+#endif
+{
+#ifdef _IEEE_LIBM
+	return __ieee754_gamma_r(x,&(_REENT->_new._reent._gamma_signgam));
+#else
+        double y;
+	struct exception exc;
+        y = __ieee754_gamma_r(x,&(_REENT->_new._reent._gamma_signgam));
+        if(_LIB_VERSION == _IEEE_) return y;
+        if(!finite(y)&&finite(x)) {
+#ifndef HUGE_VAL 
+#define HUGE_VAL inf
+	    double inf = 0.0;
+
+	    SET_HIGH_WORD(inf,0x7ff00000);	/* set inf to infinite */
+#endif
+	    exc.name = "gamma";
+	    exc.err = 0;
+	    exc.arg1 = exc.arg2 = x;
+            if (_LIB_VERSION == _SVID_)
+                exc.retval = HUGE;
+            else
+                exc.retval = HUGE_VAL;
+	    if(floor(x)==x&&x<=0.0) {
+		/* gamma(-integer) or gamma(0) */
+		exc.type = SING;
+		if (_LIB_VERSION == _POSIX_)
+		  errno = EDOM;
+		else if (!matherr(&exc)) {
+		  errno = EDOM;
+		}
+            } else {
+		/* gamma(finite) overflow */
+		exc.type = OVERFLOW;
+                if (_LIB_VERSION == _POSIX_)
+		  errno = ERANGE;
+                else if (!matherr(&exc)) {
+                  errno = ERANGE;
+                }
+            }
+	    if (exc.err != 0)
+	       errno = exc.err;
+	    return exc.retval; 
+        } else
+            return y;
+#endif
+}             
+
+#endif /* defined(_DOUBLE_IS_32BITS) */