ExtractLower() public method

Returns Matrix with only the values in the lower triangle (below main diagonal) intact. Puts 1.0's on diagonal and 0.0's in upper triangle
public ExtractLower ( ) : Matrix
return Matrix
Matrix Class Documentation
Beispiel #1
0
        public void Matrix_ExtractLowerComplicatedTest()
        {
            Matrix matrixA = new Matrix(4, 4);

            //Set up matrix A
            double[] columnOneOfMatrixA = { 3, 1, 2, 5 };
            double[] columnTwoOfMatrixA = { 7, 8, 1, 4 };
            double[] columnThreeOfMatrixA = { 2, 4, 9, 7 };
            double[] columnFourOfMatrixA = { 5, 2, 3, 1 };

            matrixA.SetColumn(0, columnOneOfMatrixA);
            matrixA.SetColumn(1, columnTwoOfMatrixA);
            matrixA.SetColumn(2, columnThreeOfMatrixA);
            matrixA.SetColumn(3, columnFourOfMatrixA);

            //The LUP Decomposition

            //Correct L Part
            Matrix correctLPartOfLUPDecomposition = new Matrix(4, 4);

            double[] columnOneOfLMatrix = { 1, 1, 2, 5 };
            double[] columnTwoOfLMatrix = { 0, 1, 1, 4 };
            double[] columnThreeOfLMatrix = { 0, 0, 1, 7 };
            double[] columnFourOfLMatrix = { 0, 0, 0, 1 };

            correctLPartOfLUPDecomposition.SetColumn(0, columnOneOfLMatrix);
            correctLPartOfLUPDecomposition.SetColumn(1, columnTwoOfLMatrix);
            correctLPartOfLUPDecomposition.SetColumn(2, columnThreeOfLMatrix);
            correctLPartOfLUPDecomposition.SetColumn(3, columnFourOfLMatrix);

            //Calculate L Part
            Matrix calculatedLPartOfLUPDecomposition = matrixA.ExtractLower();

            (calculatedLPartOfLUPDecomposition == correctLPartOfLUPDecomposition).Should().BeTrue();

        }