mathnet-numerics/src/UnitTests/LinearAlgebraTests/Double/SparseMatrixTests.cs

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namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
{
	using System.Collections.Generic;
	using MbUnit.Framework;
    using LinearAlgebra.Double;

    public class SparseMatrixTests : MatrixTests
    {
        protected override Matrix CreateMatrix(int rows, int columns)
        {
            return new SparseMatrix(rows, columns);
        }

        protected override Matrix CreateMatrix(double[,] data)
        {
            return new SparseMatrix(data);
        }

        protected override Vector CreateVector(int size)
        {
            return new SparseVector(size);
        }

        protected override Vector CreateVector(double[] data)
        {
            return new SparseVector(data);
        }

        [Test]
        public void CanCreateMatrixFrom1DArray()
        {
            var testData = new Dictionary<string, Matrix>
                           {
                               { "Singular3x3", new SparseMatrix(3, 3, new double[] { 1, 1, 1, 1, 1, 1, 2, 2, 2 }) },
                               { "Square3x3", new SparseMatrix(3, 3, new[] { -1.1, 0.0, -4.4, -2.2, 1.1, 5.5, -3.3, 2.2, 6.6 }) },
                               { "Square4x4", new SparseMatrix(4, 4, new[] { -1.1, 0.0, 1.0, -4.4, -2.2, 1.1, 2.1, 5.5, -3.3, 2.2, 6.2, 6.6, -4.4, 3.3, 4.3, -7.7 }) },
                               { "Tall3x2", new SparseMatrix(3, 2, new[] { -1.1, 0.0, -4.4, -2.2, 1.1, 5.5 }) },
                               { "Wide2x3", new SparseMatrix(2, 3, new[] { -1.1, 0.0, -2.2, 1.1, -3.3, 2.2 }) }
                           };

            foreach (var name in testData.Keys)
            {
                Assert.AreEqual(TestMatrices[name], testData[name]);
            }
        }

        [Test, Ignore]
        public void MatrixFrom1DArrayIsReference()
        {
            // Sparse Matrix copies values from double[], but no remember reference. 
            var data = new double[] { 1, 1, 1, 1, 1, 1, 2, 2, 2 };
            var matrix = new SparseMatrix(3, 3, data);
            matrix[0, 0] = 10.0;
            Assert.AreEqual(10.0, data[0]);
        }

        [Test]
        public void MatrixFrom2DArrayIsCopy()
        {
            var matrix = new SparseMatrix(TestData2D["Singular3x3"]);
            matrix[0, 0] = 10.0;
            Assert.AreEqual(1.0, TestData2D["Singular3x3"][0, 0]);
        }

        [Test]
        [Row("Singular3x3")]
        [Row("Singular3x3")]
        [Row("Square3x3")]
        [Row("Square4x4")]
        [Row("Tall3x2")]
        [Row("Wide2x3")]
        public void CanCreateMatrixFrom2DArray(string name)
        {
            var matrix = new SparseMatrix(TestData2D[name]);
            for (var i = 0; i < TestData2D[name].GetLength(0); i++)
            {
                for (var j = 0; j < TestData2D[name].GetLength(1); j++)
                {
                    Assert.AreEqual(TestData2D[name][i, j], matrix[i, j]);
                }
            }
        }

        [Test]
        public void CanCreateMatrixWithUniformValues()
        {
            var matrix = new SparseMatrix(10, 10, 10.0);
            for (var i = 0; i < matrix.RowCount; i++)
            {
                for (var j = 0; j < matrix.ColumnCount; j++)
                {
                    Assert.AreEqual(matrix[i, j], 10.0);
                }
            }
        }

        [Test]
        public void CanCreateIdentity()
        {
            var matrix = SparseMatrix.Identity(5);
            for (var i = 0; i < matrix.RowCount; i++)
            {
                for (var j = 0; j < matrix.ColumnCount; j++)
                {
                    Assert.AreEqual(i == j ? 1.0 : 0.0, matrix[i, j]);
                }
            }
        }

        [Test]
        [Row(0)]
        [Row(-1)]
        [ExpectedArgumentException]
        public void IdentityFailsWithZeroOrNegativeOrder(int order)
        {
            SparseMatrix.Identity(order);
        }

        [Test]
        public void CanCreateHeavySparseMatrix()
        {
            var matrix = new SparseMatrix(500, 1000);
            var nonzero = 0;
            var rnd = new System.Random();

            for (int i = 0; i < matrix.RowCount; i++)
            {
                for (int j = 0; j < matrix.ColumnCount; j++ )
                {
                    var value = rnd.Next(10) * rnd.Next(10) * rnd.Next(10) * rnd.Next(10) * rnd.Next(10);
                    if (value != 0)
                    {
                        nonzero++;
                    }
                    matrix[i, j] = value;
                }
            }

            Assert.AreEqual(matrix.NonZerosCount, nonzero);
        }
    }
}