正弦函数的绘制的一种方法。（坐标变换与放大）
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim G As Graphics
G = PictureBox1.CreateGraphics()
'移动坐标原点(那么原点下就变成了(20,pictruebox1.height\2))
G.TranslateTransform(20, PictureBox1.Height \ 2)
'绘制X轴与Y轴
'Y轴
G.DrawLine(Pens.Black, 20, -PictureBox1.Height \ 2, 20, PictureBox1.Height \ 2)
'X轴
G.DrawLine(Pens.Black, -20, 0, PictureBox1.Width, 0)
'正弦函数
Dim X, Y As Double
For X = 0 To 400 Step 0.002
Y = 60 * Math.Sin(2 * 3.1415926 * X / 200)
G.DrawLine(Pens.Blue, CInt(X), 0, CInt(X), CInt(Y))
Application.DoEvents()
Next
For X = 0 To 400 Step 0.002
Y = 60 * Math.Sin(2 * 3.1415926 * X / 200)
G.DrawLine(Pens.Red, CInt(X), 0, CInt(X), CInt(Y))
Application.DoEvents()
Next
End Sub
