用.NET语言写出计算股票技术指标KDJ，4个参数，返回值为datatable类型，double类型全部四舍五入保留3位小数。

以下是用.NET语言写出计算股票技术指标KDJ的代码：

using System;
using System.Data;

public class KDJ
{
    public static DataTable Calculate(double[] high, double[] low, double[] close, int n, int m1, int m2)
    {
        int count = close.Length;
        double[] rsv = new double[count];
        double[] k = new double[count];
        double[] d = new double[count];
        double[] j = new double[count];

        for (int i = 0; i < count; i++)
        {
            double maxHigh = double.MinValue;
            double minLow = double.MaxValue;

            for (int j = i; j >= Math.Max(0, i - n + 1); j--)
            {
                maxHigh = Math.Max(maxHigh, high[j]);
                minLow = Math.Min(minLow, low[j]);
            }

            rsv[i] = (close[i] - minLow) / (maxHigh - minLow) * 100;
        }

        k[0] = 50;
        d[0] = 50;

        for (int i = 1; i < count; i++)
        {
            k[i] = k[i - 1] * (m1 - 1) / m1 + rsv[i] / m1;
            d[i] = d[i - 1] * (m2 - 1) / m2 + k[i] / m2;
            j[i] = 3 * k[i] - 2 * d[i];
        }

        DataTable result = new DataTable();
        result.Columns.Add("K", typeof(double));
        result.Columns.Add("D", typeof(double));
        result.Columns.Add("J", typeof(double));

        for (int i = 0; i < count; i++)
        {
            DataRow row = result.NewRow();
            row["K"] = Math.Round(k[i], 3);
            row["D"] = Math.Round(d[i], 3);
            row["J"] = Math.Round(j[i], 3);
            result.Rows.Add(row);
        }

        return result;
    }
}

其中，high、low、close分别为最高价、最低价、收盘价的数组，n为天数，m1、m2为平滑系数。函数返回一个DataTable类型的结果，包含K、D、J三个指标，每个指标都是double类型，保留3位小数。