vidual studio中用c#写相关语句

求三个数中的最大值：
protected void Button1_Click(object sender, EventArgs e)
{ double x,maxnum;
protect double MaxValue(double num1,double num2,double num3)
{ double num1=double .Parse (TextNumber1.Text );
double num2=double. Parse (TextNumber2.Text );
double num3=double. Parse (TextNumber3.Text );
return x;
}
maxnum=MaxValue(num1,num2,num3);
lblResult.Text=Convert .ToString(maxnum);

    }

请各位大神帮忙看看哪错了，谢了!

方法里面没有比较三个数，而且return的x为null

 protected void Button1_Click(object sender, EventArgs e)
{
    double num1=double.Parse(TextNumber1.Text );
    double num2=double.Parse(TextNumber2.Text );
    double num3=double.Parse(TextNumber3.Text );
    lblResult.Text = Math.Max(Math.Max(num1, num2), num3).ToString();
}

直接用math.max方法啊。。

return x 并没有用