using System;

namespace Science.Mathematics.VectorCalculus
{
    public class Divergence
    {
        private Function.ToLastType<double[], double[]> func;
        private double res = 0.0;
        private double[] at1;
        private int n;
        public Divergence(Function.ToLastType<double[], double[]> f,
            double[] x)
        {
            n = f(x).Length;
            func = f;
            at1 = x;
        }
        public double[] At
        {
            set { at1 = value; } 
        }
        private int cp;
        public void Compute()
        {
           res = 0.0;
           Function.ToLastType<double[], double> part
               = new Function.ToLastType<double[], double>(comp);
           PartialDerivative obj; 
           for (int j = 0; j < n; j++)
           {
               cp = j;
               obj = new PartialDerivative(part, at1);
               obj.WithRespectTo = j;
               obj.Compute();
               res += obj.Result;
           } 
        }
        private double comp(double[] x)
        {
            return func(x)[cp];
        }
        public double Result
        {
            get { return res; }
        }
    }
}