libmatheval.git -

diff --git a/INSTALL b/INSTALL
index 7d1c323..a1e89e1 100644
--- a/INSTALL
+++ b/INSTALL

@@ -1,8 +1,8 @@

Installation Instructions

*************************

-Copyright (C) 1994, 1995, 1996, 1999, 2000, 2001, 2002, 2004, 2005,

-2006, 2007, 2008, 2009 Free Software Foundation, Inc.

+Copyright (C) 1994-1996, 1999-2002, 2004-2011 Free Software Foundation,

+Inc.

Copying and distribution of this file, with or without modification,

are permitted in any medium without royalty provided the copyright

@@ -226,6 +226,11 @@ order to use an ANSI C compiler:

and if that doesn't work, install pre-built binaries of GCC for HP-UX.

+ HP-UX `make' updates targets which have the same time stamps as

+their prerequisites, which makes it generally unusable when shipped

+generated files such as `configure' are involved. Use GNU `make'

+instead.

+

On OSF/1 a.k.a. Tru64, some versions of the default C compiler cannot

parse its `<wchar.h>' header file. The option `-nodtk' can be used as

a workaround. If GNU CC is not installed, it is therefore recommended

diff --git a/lib/xmath.c b/lib/xmath.c
index 1310b2f..1bd5f81 100644
--- a/lib/xmath.c
+++ b/lib/xmath.c

@@ -162,7 +162,7 @@ math_step(double x)

/*

* Calculate step function value.

*/

- return (x < 0) ? 0 : 1;

+ return MATH_ISNAN(x) ? x : ((x < 0) ? 0 : 1);

}

double

@@ -171,7 +171,7 @@ math_delta(double x)

/*

* Calculate delta function value.

*/

- return (x == 0) ? MATH_INFINITY : 0;

+ return MATH_ISNAN(x) ? x : ((x == 0) ? MATH_INFINITY : 0);

}

double

@@ -180,5 +180,5 @@ math_nandelta(double x)

/*

* Calculate modified delta function value.

*/

- return (x == 0) ? MATH_NAN : 0;

+ return MATH_ISNAN(x) ? x : ((x == 0) ? MATH_NAN : 0);

}

diff --git a/lib/xmath.h b/lib/xmath.h
index 921e442..4a54db1 100644
--- a/lib/xmath.h
+++ b/lib/xmath.h

@@ -48,6 +48,12 @@

#define MATH_NAN (0.0/0.0)

#endif

+#ifdef isnan

+#define MATH_ISNAN(x) isnan(x)

+#else

+#define MATH_ISNAN(x) ((x) != (x))

+#endif

+

/* Calculate cotangent of value x. */

double math_cot(double x);