方法返回不同类型的值

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

namespace consoleTest01
{
    public struct individuals
    {
        public double[] fitness;
        public double[,] chrom;

    }
    class Program
    {
        private static individuals getIndividuals()
        {
            individuals L = new individuals();
            L.fitness = new double[6];
            for (int i = 0; i < 6; i++)
            {
                L.fitness[i] = 0.1 * i;
            }

            L.chrom = new double[,] { { 1, 2, 3 }, { 1, 2, 3 }, { 1, 2, 3 }, { 1, 2, 3 }, { 1, 2, 3 }, { 1, 2, 3 } };
            return L;

        }
        static double[] SUM(double[] a, double[,] b, int c, int d, out double[,] e)
        {
            e = new double[c, d];
            for (int i = 0; i < c; i++)
                for (int j = 0; j < d; j++)
                {
                    e[i, j] = b[i, j];
                }
            return a;

        }
        static void Main(string[] args)
        {
            individuals L=getIndividuals();
            int i = 6;
            int j = 3;
            double[,] e=new double[i,j];
            var result = SUM(L.fitness,L.chrom,i,j, out e);
            foreach (double d in result)
            {
                Console.WriteLine(d);
            }
        }
        
    }
}