c# ZedGraph控件一个小问题

private void CreateGraph(ZedGraphControl zgc)
{
v = Convert.ToDouble(textBox1.Text);
// get a reference to the GraphPane
GraphPane myPane = zgc.GraphPane;

// Set the Titles
myPane.Title.Text = "抛物线";
myPane.XAxis.Title.Text = "落点";
myPane.YAxis.Title.Text = "高度";

// Make up some data arrays based on the Sine function
double x, y1;
PointPairList list1 = new PointPairList();
for (int i = 0; i < 36; i++)
{
x = (double)i + 5;
y1 = (double)i*Math.Sin(v)
list1.Add(x, y1);
}

LineItem myCurve = myPane.AddCurve("物体",
zgc.AxisChange();
}

ZedGraph是什么

GDI+不行么？？