add a linear function of space

NumLib/Function/SpatialFunctionLinear.h

+/**
+ * \author Norihiro Watanabe
+ * \date   2013-08-13
+ *
+ * \copyright
+ * Copyright (c) 2013, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#ifndef SPATIALFUNCTIONLINEAR_H_
+#define SPATIALFUNCTIONLINEAR_H_
+
+#include "MathLib/LinearFunction.h"
+#include "TemplateSpatialFunction.h"
+
+namespace NumLib
+{
+
+/// Linear function of space
+typedef TemplateSpatialFunction<MathLib::LinearFunction<double, 3> > SpatialFunctionLinear;
+
+}
+
+#endif /* SPATIALFUNCTIONLINEAR_H_ */

NumLib/Function/TemplateSpatialFunction.h

+/**
+ * \author Norihiro Watanabe
+ * \date   2013-08-13
+ *
+ * \copyright
+ * Copyright (c) 2013, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#ifndef TEMPLATESPATIALFUNCTION_H_
+#define TEMPLATESPATIALFUNCTION_H_
+
+#include "ISpatialFunction.h"
+
+namespace NumLib
+{
+
+/**
+ * Template class to relate pure mathematical functions with ISpatialFunction
+ *
+ * @tparam T_FUNCTION Function object which takes "double const* const" as an argument.
+ */
+template <class T_FUNCTION>
+class TemplateSpatialFunction : public ISpatialFunction
+{
+public:
+	/**
+	 * Constructor
+	 * @param f  a function object
+	 */
+	TemplateSpatialFunction(const T_FUNCTION &f)
+	: _f(f) {}
+
+	/**
+	 * evaluate a function
+	 * @param pnt  a point object
+	 * @return evaluated value
+	 */
+	virtual double operator()(const GeoLib::Point& pnt) const
+	{
+		return _f(pnt.getCoords());
+	}
+
+private:
+	/// a function object
+	const T_FUNCTION _f;
+};
+
+}
+
+#endif /* TEMPLATESPATIALFUNCTION_H_ */