** $Id$
**
** Copyright (c) 2002 Robert B. Quattlebaum Jr.
+** Copyright (c) 2008 Chris Moore
**
** This package is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public License as
#include <functional>
+#include "hermite"
+
/* === M A C R O S ========================================================= */
//#ifndef _EPSILON
//#define _EPSILON 0.0000001
//#endif
-#define ETL_FIXED_DERIVATIVE 1
-
/* === T Y P E D E F S ===================================================== */
/* === C L A S S E S & S T R U C T S ======================================= */
typename T::result_type
operator()(const typename T::argument_type &x)const
{
-#ifdef ETL_FIXED_DERIVATIVE
return (func(x+epsilon)-func(x))/epsilon;
-#else
- return (func(x)-func(x+epsilon))/epsilon;
-#endif
+ }
+};
+
+template <typename T>
+class derivative<hermite<T> > : public std::unary_function<typename hermite<T>::argument_type,typename hermite<T>::result_type>
+{
+ hermite<T> func;
+public:
+ explicit derivative(const hermite<T> &x):func(x) { }
+
+ typename hermite<T>::result_type
+ operator()(const typename hermite<T>::argument_type &x)const
+ {
+ T a = func[0], b = func[1], c = func[2], d = func[3];
+ typename hermite<T>::argument_type y(1-x);
+ return ((b-a)*y*y + (c-b)*x*y*2 + (d-c)*x*x) * 3;
}
};