using System;

namespace Science.Mathematics.VectorCalculus
{
    public class JacobianDeterminant
    {
        private Function.ToLastType<double[],double[]> dela;
        private Function.ToLastType<double[],double> del;
        private double[] at1;
        public JacobianDeterminant(Function.ToLastType<double[], double[]> map, double[] at)
        {
            dela = map;
            at1 = at;
        }
        private PartialDerivative obj;
        private int comp;
        private MatrixSquare ma;
        public void Compute()
        {
            ma = new MatrixSquare(at1.Length);
            for (int i = 0; i < at1.Length; i++)
            {
                comp = i;
                del = new Function.ToLastType<double[], double>(OneComponent);
                obj = new PartialDerivative(del, at1);
                for (int j = 0; j < at1.Length; j++)
                {
                    obj.WithRespectTo = j;
                    obj.Compute();
                    ma[i,j] = obj.Result;
                }
            }
            result = ma.Determinant;
        }
        private double OneComponent(double[] u)
        {
            return dela(u)[comp];
        }
        private double result;
        public double[] At
        {
            set { at1 = value; }
        }
        public double Result
        {
            get { return result; }
        }  		
    }
}