using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Azimuth.RootFinding;

namespace Azimuth.UnitTests.RootFinding
{
    public class NewtonsMethodTests : UnitTestSharp.TestFixture
    {
        public void Basic()
        {
            Scalar root;
            var success = NewtonsMethod.FindRoot(x => Math.Cos(x), x => -Math.Sin(x), 1, out root);

            CheckEqual(EndingState.SUCCESS, success);

            CheckEqual(Math.PI / 2, root);
        }

        public void NegativeMaxIterations()
        {
            Scalar root;
            int evaluations = 0;
            CheckThrow(typeof(Exception));
            var success = NewtonsMethod.FindRoot(x => Math.Cos(x), x => -Math.Sin(x), 1, -1, out root, ref evaluations);
        }

        public void ZeroMaxIterations()
        {
            Scalar root;
            int evaluations = 0;
            CheckThrow(typeof(Exception));
            var success = NewtonsMethod.FindRoot(x => Math.Cos(x), x => -Math.Sin(x), 1, 0, out root, ref evaluations);
        }

        public void ZeroDerivative()
        {
            Scalar root;
            var success = NewtonsMethod.FindRoot(x => 1 - x * x, x => -2 * x, 0, out root);

            CheckEqual(EndingState.MALFORMED_INPUT, success);

            Check(Scalar.IsNaN(root));
        }

        public void Cycle()
        {
            Scalar root;
            int evaluations = 0;
            var success = NewtonsMethod.FindRoot(x => x*x*x-2*x+2, x => 3*x*x-2, 0, 64, out root, ref evaluations);

            CheckEqual(EndingState.MAX_ITERATIONS_EXCEEDED, success);

            Check(Scalar.IsNaN(root));
            CheckEqual(64, evaluations);
        }

        public void ExactHit()
        {
            Scalar root;
            int evaluations = 0;
            var success = NewtonsMethod.FindRoot(x => x, x => 0, 0, 64, out root, ref evaluations);

            CheckEqual(EndingState.SUCCESS, success);
            CheckEqual(0, root);
        }
    }
}