using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Azimuth.Approximation;
using Azimuth.SparseLinearAlgebra;
using Azimuth.DenseLinearAlgebra;

namespace Azimuth.UnitTests.SparseLinearAlgebra
{
    public class ColleagueMatrixTests : UnitTestSharp.TestFixture
    {
        public void x0()
        {
            var coefficients = new DenseVector(new Scalar[] { });

            var colleague = new ColleagueMatrix(coefficients);

            var roots = colleague.CalculateRealEigenvalues();

            CheckEqual(new Scalar[] { }, roots);
        }

        public void x1()
        {
            var coefficients = new DenseVector(new Scalar[] { 1, });

            var colleague = new ColleagueMatrix(coefficients);

            var roots = colleague.CalculateRealEigenvalues();

            CheckEqual(new Scalar[] { }, roots);
        }

        public void x2()
        {
            var coefficients = new DenseVector(new Scalar[] { 2, 1, });

            var colleague = new ColleagueMatrix(coefficients);

            var roots = colleague.CalculateRealEigenvalues();

            CheckEqual(new Scalar[] { -1, }, roots);
        }

        public void x3()
        {
            var coefficients = new DenseVector(new Scalar[] { 2, 1, 1 });

            var colleague = new ColleagueMatrix(coefficients);

            var roots = colleague.CalculateRealEigenvalues();

            CheckEqual(new Scalar[] { -0.5, 0 }, roots);
        }

        public void x5()
        {
            var coefficients = new DenseVector(new Scalar[] { 2, 1, 1, 1, 1, });

            var colleague = new ColleagueMatrix(coefficients);

            var roots = colleague.CalculateRealEigenvalues();

            var expectedRoots = new List<Scalar> {
                Math.Sqrt(2) / 2,
                -Math.Sqrt(2) / 2,
                -.25 * (1 + Math.Sqrt(5)),
                -.25 * (1 - Math.Sqrt(5))
            };
            expectedRoots.Sort();

            CheckEqual(expectedRoots, roots);
        }

        public void Quadratic()
        {
            Func<Scalar, Scalar> f = x => 2 * x * x - 9 * x + 10;

            var cheby = new Chebyshev(f, new Interval(-10, 10));

            var colleague = new ColleagueMatrix(cheby);

            var roots = colleague.CalculateRealEigenvalues();

            var expected = new Scalar[] { 2/10.0, 5 / 2.0 / 10.0 };

            CheckEqual(expected, roots);
        }
    }
}