Math::CubicSpline

- fixed input parameter checks and exception messages

src/ITABase/Math/Spline.cpp

@@ -19,18 +19,18 @@ CPiecewisePolynomial Math::CubicSpline(const std::vector<float>& vdSupportingPoi
 
 	if (vdSupportingPoints.size() != vdDataPoints.size())
 		ITA_EXCEPT_INVALID_PARAMETER("vdSupportingPoints and vdDataPoints need to have the same size");
-	if (vdSupportingPoints.size() < 2)
-		ITA_EXCEPT_INVALID_PARAMETER("vdSupportingPoints and vdDataPoints need to contain at least 3 elements");
+	if (vdSupportingPoints.size() < 4)
+		ITA_EXCEPT_INVALID_PARAMETER("vdSupportingPoints and vdDataPoints need to contain at least 4 elements");
 
 	//Calculate h_i, formular 1.27b
-	int iPolynomialOrder = 3;
-	int iPoints = vdSupportingPoints.size();
+	const int iPolynomialOrder = 3;
+	const int iPoints = vdSupportingPoints.size();
 	std::vector<float> vdH(iPoints - 1);
 
 	for (int i = 0; i < iPoints - 1; i++) {
 		vdH[i] = vdSupportingPoints[i + 1] - vdSupportingPoints[i];
-		if (vdH[i] < 0) {
-			ITA_EXCEPT_INVALID_PARAMETER("vdSupportingPoints needs to be sorted in ascending order");
+		if (vdH[i] <= 0) {
+			ITA_EXCEPT_INVALID_PARAMETER("vdSupportingPoints needs to be sorted in ascending order and not be duplicates");
 		}
 	}