数学计算公式

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/// <summary> /// 求出数据平均值,并保留三位小数 /// </summary> /// <param name="Valist">数据集合</param> /// <returns></returns> public static double average(List<double> Valist) {     double sum = 0;     foreach (double d in Valist)     {         sum = sum + d;     }     double revl = System.Math.Round(sum / Valist.Count, 3);     return revl; } /// <summary> /// 求数据集合标准差 /// </summary> /// <param name="ValList"></param> /// <returns></returns> public static double stdev(List<double> ValList) {     double avg = average(ValList);     double sumstdev = 0;     foreach (double d in ValList)     {         sumstdev = sumstdev + (d - avg) * (d - avg);     }     double stdeval = System.Math.Sqrt(sumstdev);     return System.Math.Round(stdeval, 3); } /// <summary> /// 相关系数,要求两个集合数量必须相同 /// </summary> /// <param name="array1">数组一</param> /// <param name="array2">数组二</param> /// <returns></returns> public double correl(List<double> array1, List<double> array2) {     //数组一     double avg1 = average(array1);     double stdev1 = stdev(array1);     //数组二     double avg2 = average(array2);     double stdev2 = stdev(array2);       double sum = 0;     for (int i = 0; i < array1.Count && i < array2.Count; i++)     {         sum = sum + ((array1[i] - avg1) / stdev1) * ((array2[i] - avg2) / stdev2);     }     return Math.Round(sum, 3); }