private static void TestClear()
        {
            var zero   = Matrix.CreateZero(LowerInvertible10by10.Order, LowerInvertible10by10.Order);
            var matrix = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);

            matrix.Clear();
            comparer.AssertEqual(zero, matrix);
        }
        private static void TestGetRow()
        {
            var matrix = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);

            for (int i = 0; i < LowerInvertible10by10.Order; ++i)
            {
                Vector rowExpected = DenseStrategies.GetRow(matrix, i);
                Vector rowComputed = matrix.GetRow(i);
                comparer.AssertEqual(rowExpected, rowComputed);
            }
        }
        private static void TestGetColumn()
        {
            var matrix = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);

            for (int j = 0; j < LowerInvertible10by10.Order; ++j)
            {
                Vector colExpected = DenseStrategies.GetColumn(matrix, j);
                Vector colComputed = matrix.GetColumn(j);
                comparer.AssertEqual(colExpected, colComputed);
            }
        }
        private static void TestArrayCopy()
        {
            // invertible
            var A1 = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);

            comparer.AssertEqual(LowerInvertible10by10.Matrix, A1.CopyToArray2D());

            // singular
            var A2 = TriangularLower.CreateFromArray(LowerSingular10by10.Matrix);

            comparer.AssertEqual(LowerSingular10by10.Matrix, A2.CopyToArray2D());
        }
        private static void TestMatrixVectorMultiplicationIntoResult(LinearAlgebraProviderChoice providers)
        {
            // The result vectors will first be set to some non zero values to make sure that the result overwrites
            // them instead of being added to them.

            TestSettings.RunMultiproviderTest(providers, delegate()
            {
                var A            = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);
                var x            = Vector.CreateFromArray(LowerInvertible10by10.Lhs);
                var bExpected    = Vector.CreateFromArray(LowerInvertible10by10.Rhs);
                Vector bComputed = Vector.CreateWithValue(A.NumRows, 1.0);
                A.MultiplyIntoResult(x, bComputed, false);
                comparer.AssertEqual(bExpected, bComputed);
            });
        }
        private static void TestTransposition()
        {
            // invertible
            var             A1 = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);
            var             A1TransposeExpected = MatrixOperations.Transpose(LowerInvertible10by10.Matrix);
            TriangularUpper A1TransposeComputed = A1.Transpose(false);

            comparer.AssertEqual(A1TransposeExpected, A1TransposeComputed.CopyToArray2D());

            // singular
            var             A2 = TriangularLower.CreateFromArray(LowerSingular10by10.Matrix);
            var             A2TransposeExpected = MatrixOperations.Transpose(LowerSingular10by10.Matrix);
            TriangularUpper A2TransposeComputed = A2.Transpose(false);

            comparer.AssertEqual(A2TransposeExpected, A2TransposeComputed.CopyToArray2D());
        }
        private static void TestMatrixVectorMultiplication(LinearAlgebraProviderChoice providers)
        {
            TestSettings.RunMultiproviderTest(providers, delegate()
            {
                // invertible
                var A1            = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);
                var x1            = Vector.CreateFromArray(LowerInvertible10by10.Lhs);
                var b1Expected    = Vector.CreateFromArray(LowerInvertible10by10.Rhs);
                Vector b1Computed = A1.Multiply(x1);
                comparer.AssertEqual(b1Expected, b1Computed);

                // singular
                var A2            = TriangularLower.CreateFromArray(LowerSingular10by10.Matrix);
                var x2            = Vector.CreateFromArray(LowerSingular10by10.Lhs);
                var b2Expected    = Vector.CreateFromArray(LowerSingular10by10.Rhs);
                Vector b2Computed = A2.Multiply(x1);
                comparer.AssertEqual(b2Expected, b2Computed);
            });
        }
        private static void TestSystemSolution(LinearAlgebraProviderChoice providers)
        {
            TestSettings.RunMultiproviderTest(providers, delegate()
            {
                // invertible
                var A1            = TriangularLower.CreateFromArray(LowerInvertible10by10.Matrix);
                var b1            = Vector.CreateFromArray(LowerInvertible10by10.Rhs);
                var x1Expected    = Vector.CreateFromArray(LowerInvertible10by10.Lhs);
                Vector x1Computed = A1.SolveLinearSystem(b1);
                comparer.AssertEqual(x1Expected, x1Computed);

                // singular
                var A2            = TriangularLower.CreateFromArray(LowerSingular10by10.Matrix);
                var b2            = Vector.CreateFromArray(LowerSingular10by10.Rhs);
                var x2Expected    = Vector.CreateFromArray(LowerSingular10by10.Lhs);
                Vector x2Computed = A2.SolveLinearSystem(b2);
                Assert.False(comparer.AreEqual(x2Expected, x2Computed));
            });
        }