- added folder InterpolationAlgorithms within the folder MathLib

- added class template LinearIntervalInterpolation

MathLib/CMakeLists.txt

@@ -2,6 +2,9 @@
 GET_SOURCE_FILES(SOURCES_MATHLIB)
 SET ( SOURCES ${SOURCES_MATHLIB})
 
+GET_SOURCE_FILES(SOURCES_INTERPOLATIONALGORITHMS InterpolationAlgorithms)
+SET ( SOURCES ${SOURCES} ${SOURCES_INTERPOLATIONALGORITHMS})
+
 GET_SOURCE_FILES(SOURCES_LINALG LinAlg)
 SET ( SOURCES ${SOURCES} ${SOURCES_LINALG})
 

MathLib/InterpolationAlgorithms/LinearIntervalInterpolation.h

+/*
+ * @file LinearIntervalInterpolation.h
+ *
+ *  Created on: May 22, 2012
+ *      Author: fischeth
+ */
+
+#ifndef LINEARINTERVALINTERPOLATION_H_
+#define LINEARINTERVALINTERPOLATION_H_
+
+#include <stdexcept>
+
+namespace MathLib {
+
+/**
+ * @brief Class (template) LinearIntervalInterpolation is a functional object performing
+ * an interval mapping \f$f: [a,b] \to [c,d]\f$.
+ *
+ * Input numeric type has to be a floating point type and must behave well under the
+ * operations addition, subtraction, multiplication and division. Let \f$a, b, c, d\f$
+ * objects supporting the mentioned operations. Under the condition
+ * \f$a \neq b\f$ an instance of the class computes a value within the interval
+ * \f$[c, d]\f$, i.e., \f$f: [a,b] \to [c,d]\f$.
+ */
+template <typename NUMERIC_TYPE>
+class LinearIntervalInterpolation {
+public:
+	/**
+	 * Constructor of class template for a linear map \f$y = m \cdot x + n\f$.
+	 * Under the prerequisite \f$a \neq b\f$ it initializes the coefficients
+	 * \f$m\f$ and \f$n\f$ in a correct way.
+	 * @param a first endpoint of the first interval
+	 * @param b second endpoint of the first interval
+	 * @param c first endpoint of the second interval
+	 * @param d second endpoint of the second interval
+	 */
+	LinearIntervalInterpolation(NUMERIC_TYPE a, NUMERIC_TYPE b, NUMERIC_TYPE c, NUMERIC_TYPE d);
+	/**
+	 * Method computes the value at point \f$x\f$ obtained by linear interpolation.
+	 * @param x the point the interpolation value is searched for
+	 * @return the interpolation value at point \f$x\f$
+	 */
+	inline NUMERIC_TYPE operator() (NUMERIC_TYPE x) const;
+
+private:
+	/**
+	 * the slope of the linear map
+	 */
+	NUMERIC_TYPE _m;
+	/**
+	 * the offset of the linear map for \f$x\f$ equals zero
+	 */
+	NUMERIC_TYPE _n;
+};
+
+template <typename NUMERIC_TYPE>
+LinearIntervalInterpolation<NUMERIC_TYPE>::LinearIntervalInterpolation(NUMERIC_TYPE a, NUMERIC_TYPE b,
+				NUMERIC_TYPE c, NUMERIC_TYPE d) :
+	_m (d-c), _n(0.0)
+{
+	if (b == a) {
+		throw std::runtime_error("LinearIntervalInterpolation::LinearIntervalInterpolation: a == b, empty interval");
+	}
+	_m /= (b-a);
+	_n = c - _m * a;
+}
+
+template <typename NUMERIC_TYPE>
+inline NUMERIC_TYPE LinearIntervalInterpolation<NUMERIC_TYPE>::operator() (NUMERIC_TYPE x) const
+{
+	return _m * x + _n;
+}
+
+} // end namespace MathLib
+
+#endif /* LINEARINTERPOLATION_H_ */