renamed DE::Engine::CalculateError to DE::Engine::TestFitness

added ErrorAccumulator to aid in calculating RMSE
converted piecewiseapprox.cpp and polyapprox.cpp to use new pure virtual method name and ErrorAccumulator

de.h

@@ -23,12 +23,35 @@ namespace DE
 		void SetRange(unsigned int i, double minimum, double maximum);
 		void SetRange(const Vector<DIM>& minimum, const Vector<DIM>& maximum);
 		
-		virtual double CalculateError(const double testcase[DIM], bool& stop) = 0;
+		virtual double TestFitness(const double testcase[DIM], bool& stop) = 0;
 
 		void Reset();
 		bool Solve(unsigned int maxgenerations = 1000000000);
 		bool RunOneGeneration();
 
+	public:
+
+		// helper class for accumulating error and calculating
+		// root mean square error
+		class ErrorAccumulator
+		{
+		public:
+			ErrorAccumulator();
+			virtual ~ErrorAccumulator();
+
+			void Clear();
+			void AddTestCase(double expected, double actual);
+			double GetRMSE();
+
+		private:
+
+			void CalculateError();
+
+			unsigned int num_tests;         // # of test cases
+			double       sum_error_squared; // sum of error^2
+			double       error_rmse;        // root mean square error (-1 == "dirty" flag)
+		};
+
 	private:
 
 		// randomly select unique individuals

de.inl

@@ -207,7 +207,7 @@ bool DE::Engine<DIM,POPSIZE>::RunOneGeneration()
 		MakeTrial_randtobest1exp(candidate,trial);
 
 		// determine fitness of trial individual
-		double trialfitness = CalculateError(trial,success);
+		double trialfitness = TestFitness(trial,success);
 
 		// see if the trial improved current candidate in population
 		if ( trialfitness < fitness[candidate] )
@@ -448,5 +448,55 @@ inline void DE::Engine<DIM,POPSIZE>::MakeTrial_rand2bin(unsigned int candidate,
 	return;
 }
 
+
+
+
+template <unsigned int DIM, unsigned int POPSIZE>
+inline DE::Engine<DIM,POPSIZE>::ErrorAccumulator::ErrorAccumulator()
+{
+	Clear();
+}
+
+template <unsigned int DIM, unsigned int POPSIZE>
+inline DE::Engine<DIM,POPSIZE>::ErrorAccumulator::~ErrorAccumulator()
+{
+	// empty
+}
+
+template <unsigned int DIM, unsigned int POPSIZE>
+inline void DE::Engine<DIM,POPSIZE>::ErrorAccumulator::Clear()
+{
+	num_tests         = 0;
+	sum_error_squared = 0.0;
+	error_rmse        = 0.0; // initial error == zero
+}
+
+template <unsigned int DIM, unsigned int POPSIZE>
+inline void DE::Engine<DIM,POPSIZE>::ErrorAccumulator::AddTestCase(double expected, double actual)
+{
+	double e           = expected - actual; // compute error
+	sum_error_squared += e * e;             // add to sum of error^2
+	num_tests         += 1;                 // increment total test count
+	error_rmse         = -1.0;              // mark as dirty
+}
+
+template <unsigned int DIM, unsigned int POPSIZE>
+inline double DE::Engine<DIM,POPSIZE>::ErrorAccumulator::GetRMSE()
+{
+	if ( error_rmse < 0.0 ) // recalculate if set to "dirty"
+		CalculateError();
+
+	return error_rmse;
+}
+
+template <unsigned int DIM, unsigned int POPSIZE>
+inline void DE::Engine<DIM,POPSIZE>::ErrorAccumulator::CalculateError()
+{
+	// convert squared error to root mean squared error
+	error_rmse = sqrt(sum_error_squared / (double)num_tests);
+}
+
+
+
 #endif // __de_inl__
 

piecewiseapprox.cpp

@@ -39,37 +39,29 @@ class PolySearch: public DE::Engine<NUM_COEFFICIENTS>
 {
 	public:
 		// this method is called by the DE::Engine::Solve() to test a single DE individual
-		double CalculateError(const double testcase[NUM_COEFFICIENTS], bool& stop)
+		double TestFitness(const double testcase[NUM_COEFFICIENTS], bool& stop)
 		{
-			double       error      = 0.0;
-			unsigned int test_count = 0;
+			ErrorAccumulator e;
 
 			// accumulate squared error
 			for ( double i=-2.5;i<=2.5;i+=0.01 )
 			{
 				// test
-				double test   = CalculatePiecewise(i,NUM_COEFFICIENTS,testcase);
-				double actual = TargetFunction(i);
+				double actual   = CalculatePiecewise(i,NUM_COEFFICIENTS,testcase);
+				double expected = TargetFunction(i);
 
-				// accumulate error^2
-				double e = test - actual;
-				error += e * e;
-
-				// inc test count (divisor to get from SE to MSE)
-				test_count++;
+				// accumulate error
+				e.AddTestCase(expected,actual);
 			}
 
-			// convert SE to RMSE
-			error = sqrt(error / (double)test_count);
-
 			// set stop flag if the error is really low
-			if ( error < 0.0000001 )
+			if ( e.GetRMSE() < 0.0000001 )
 			{
 				stop = true;
 			}
 
 			// done
-			return error;
+			return e.GetRMSE();
 		}
 };
 

polyapprox.cpp

@@ -39,37 +39,29 @@ class PolySearch: public DE::Engine<NUM_COEFFICIENTS>
 {
 	public:
 		// this method is called by the DE::Engine::Solve() to test a single DE individual
-		double CalculateError(const double testcase[NUM_COEFFICIENTS], bool& stop)
+		double TestFitness(const double testcase[NUM_COEFFICIENTS], bool& stop)
 		{
-			double       error      = 0.0;
-			unsigned int test_count = 0;
+			ErrorAccumulator e;
 
 			// accumulate squared error
 			for ( double i=-1.25;i<=1.25;i+=0.001 )
 			{
 				// test
-				double test   = CalculatePolynomial(i,NUM_COEFFICIENTS,testcase);
-				double actual = TargetFunction(i);
+				double actual   = CalculatePolynomial(i,NUM_COEFFICIENTS,testcase);
+				double expected = TargetFunction(i);
 
-				// accumulate error^2
-				double e = test - actual;
-				error += e * e;
-
-				// inc test count (divisor to get from SE to MSE)
-				test_count++;
+				// accumulate error
+				e.AddTestCase(expected, actual);
 			}
 
-			// convert SE to RMSE
-			error = sqrt(error / (double)test_count);
-
 			// set stop flag if the error is really low
-			if ( error < 0.0000001 )
+			if ( e.GetRMSE() < 0.0000001 )
 			{
 				stop = true;
 			}
 
 			// done
-			return error;
+			return e.GetRMSE();
 		}
 };