namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            class hanshu
            {
                public double F(int x)
                {
                    const double a1=30.58;
                    const double b1=-110.7;
                    const double c1=27.96;
                    double f=a1*Math.Exp(-((x-b1)/c1)*((x-b1)/c1));
                }
            }
           
                    

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
           
           
  
           
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
           
        
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
           
        }

        private void button1_Click(object sender, EventArgs e)
        {
             hanshu qiangdu1=new hanshu();
             int x=Convert.ToInt32(textBox1.Text);
             double r1=qiangdu1.F(x);


             hanshu qiangdu2=new hanshu();
             int m=Convert.ToInt32(textBox2.Text);
             double r2=qiangdu1.F(m);


             hanshu qiangdu3=new hanshu();
             int n=Convert.ToInt32(textBox3.Text);
             double r3=qiangdu1.F(n);
     
            
            
            
            Graphics gra = this.pictureBox1.CreateGraphics();
            Pen pen = new Pen(Color.Pink);
            gra.DrawEllipse(pen, 10, 10, Convert.ToInt32(r1), Convert.ToInt32(r1));
            gra.DrawEllipse(pen, 20, 10,Convert.ToInt32(r2), Convert.ToInt32(r2));
            gra.DrawEllipse(pen, 10, 20,Convert.ToInt32(r3), Convert.ToInt32(r3));

        }
    }
}

错误    应输入 class、delegate、enum、interface 或 struct
错误    应输入类型、命名空间定义或文件尾   
错误    “WindowsFormsApplication1.Form1.hanshu.F(int)”: 并非所有的代码路径都返回值

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            hanshu qiangdu1 = new hanshu();
            int x = Convert.ToInt32(textBox1.Text);
            double r1 = qiangdu1.F(x);

            hanshu qiangdu2 = new hanshu();
            int m = Convert.ToInt32(textBox2.Text);
            double r2 = qiangdu1.F(m);

            hanshu qiangdu3 = new hanshu();
            int n = Convert.ToInt32(textBox3.Text);
            double r3 = qiangdu1.F(n);

            Graphics gra = this.pictureBox1.CreateGraphics();
            Pen pen = new Pen(Color.Pink);
            gra.DrawEllipse(pen, 10, 10, Convert.ToInt32(r1), Convert.ToInt32(r1));
            gra.DrawEllipse(pen, 20, 10, Convert.ToInt32(r2), Convert.ToInt32(r2));
            gra.DrawEllipse(pen, 10, 20, Convert.ToInt32(r3), Convert.ToInt32(r3));
        }
    }

    class hanshu
    {
        public double F(int x)
        {
            const double a1 = 30.58;
            const double b1 = -110.7;
            const double c1 = 27.96;
            double f = a1 * Math.Exp(-((x - b1) / c1) * ((x - b1) / c1));
            return f;
        }
    }
}

画不出来圆是为什么那？

试试楼上的

试了，还是不行

这个程序一共画了三个椭圆，坐标分别是picturebox1相对左上角坐标的10,10    20,10   10,20
正常画出来三个椭圆是相交的，DrawEllipse方法的第4，5个参数分别表示宽和高，因为传入的参数分别都为r1,r2,r3，宽高一样，所以画出来是圆形
但是hanshu类的F方法，也就是计算宽高的这个方法，那个公式没看明白，经测试，传入的大多数字，计算后宽高（半径）几乎都小于0或接近0，所以看不到
你在三个textbox内都输入-100，即传入-100参数给F方法，能得到宽高（半径）为26.41401931439983，可以看到画出来的圆（仅测试而已）