class cp
    {
        public double sum(double[] t)
        {
            double result = 0;
            foreach (double i in t)
            {
                result = result + i;
            }
            return result;
        }
cp mycp = new cp();
        PointF[] p = new PointF[8];
        double a, b, c, u, q;

        private double sumx(PointF[] tp)//求X的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = tp[i].X;
            }
            return mycp.sum(temp);
        }
        private double sumy(PointF[] tp)//Y的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = tp[i].Y;
            }
            return mycp.sum(temp);
        }
        private double sumx2(PointF[] tp)//求X2的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 2);  
            }
            return mycp.sum(temp);
        }
        private double sumx3(PointF[] tp)//求X3和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 3);
            }
            return mycp.sum(temp);
        }
        private double sumx4(PointF[] tp)//求X4的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 4);
            }
            return mycp.sum(temp);
        }
        private double sumxy(PointF[] tp)//求XY的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = tp[i].X * tp[i].Y;
            }
            return mycp.sum(temp);
        }
        private double sumx2y(PointF[] tp)//求X2Y的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 2) * tp[i].Y;
            }
            return mycp.sum(temp);
        }
        private void calculate()
        {
            int n = tidu.Length;
            double d, e, f, g, h;
            d = n * sumx2(p) - sumx(p) * sumx(p);
            e = n * sumx2y(p) - sumx2(p) * sumy(p);
            f = n * sumxy(p) - sumx(p) * sumy(p);
            g = n * sumx3(p) - sumx2(p) * sumx(p);
            h = n * sumx4(p) - sumx2(p) * sumx2(p);
            a = (d * e - f * g) / (h * d - g * g);
            b = (f - g * a) / d;
            c = (sumy(p) - a * sumx2(p) - b * sumx(p)) / n;
            u = -(b / (2 * a));
            q = Math.Sqrt(-1 / (2 * a));
            this.label4.Text = "a=" + a.ToString() + "\r\nb=" + b.ToString() + "\r\nc=" + c.ToString() + "\r\nu=" + u.ToString() + "\r\nq=" + q.ToString();
        }

怎么把上面的用类定义出来，哪位大侠帮帮忙！

class cp
你这个不是类吗？你还想怎么定义？

建议先看看资料什么的。

我想把下面的定义成类，看了一些资料，但是不会啊！

那你就重新定义一个类  然后把下面的代码放进该类就行了啊？？

我试了怎么有问题啊？

重新定义一个类放进去老是出现这样的错误：找不到类型或命名空间名称PointF，是否缺少using指令或程序集应用。

定义了之后怎么调用类啊？

PointF[] p = new PointF[8];
这是什么？抱你那个错误时因为PointF不是String[]一样  不可以自己写就用了

你是想把它PointF[] 定义成个类么？

1.在开始加上引用空间：using System.Drawing
2.程序最好这样写：

    class cp
    {
        public double sum(double[] t)
        {
            double result = 0;
            foreach (double i in t)
            {
                result = result + i;
            }
            return result;
        }

        public double sumx(PointF[] tp)//求X的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = tp[i].X;
            }
            return mycp.sum(temp);
        }
        public double sumy(PointF[] tp)//Y的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = tp[i].Y;
            }
            return mycp.sum(temp);
        }
        public double sumx2(PointF[] tp)//求X2的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 2);
            }
            return mycp.sum(temp);
        }
        public double sumx3(PointF[] tp)//求X3和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 3);
            }
            return mycp.sum(temp);
        }
        public double sumx4(PointF[] tp)//求X4的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 4);
            }
            return mycp.sum(temp);
        }
        public double sumxy(PointF[] tp)//求XY的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = tp[i].X * tp[i].Y;
            }
            return mycp.sum(temp);
        }
        public double sumx2y(PointF[] tp)//求X2Y的和
        {
            double[] temp = new double[tp.Length];
            for (int i = 0; i < tp.Length; i++)
            {
                temp[i] = Math.Pow(tp[i].X, 2) * tp[i].Y;
            }
            return mycp.sum(temp);
        }
    }

这个是定义计算的类，用的时候这样用：

            double d = 0;
            cp mycp=new cp();
            d = mycp.sumx2(1) - mycp.sumx(1) * mycp.sumx(1);
            ……

显得比较有条理。用的时候是在另一个所定义的类中的一个方法内。

明白了，谢谢！