using System;

namespace Science.Mathematics.VectorCalculus
{
    public class ChainRule
    {
        Function.ToLastType<double[], double[]> f;
        Function.ToLastType<double[], double[]> g;
        public ChainRule(Function.ToLastType<double[], double[]> functionRmToRp,
            Function.ToLastType<double[], double[]> functionRnToRm, double[] at)
        {
            f = functionRmToRp;
            g = functionRnToRm;
            x0 = at;
        }
        private double[] x0;
        public double[] At
        {
            get { return x0; }
            set { x0 = value; }
        }
        public void Compute()
        {
            MatrixOfPartialDerivatives obj = new MatrixOfPartialDerivatives(g, x0);
            obj.Compute();
            double[] y0 = g(x0);
            MatrixOfPartialDerivatives obj2 = new MatrixOfPartialDerivatives(f, y0);
            obj2.Compute();
            res = obj2.Result * obj.Result;
        }
        private Matrix res;
        public Matrix Result
        {
            get { return res; }
        }
    }
}