Построить график функции

Public Class Form1
Dim Graph1 As Graphics
Dim Pen1 As New Pen(Color.Black, 2)
Dim Pen2 As New Pen(Color.Red, 2)
Dim brush1 As New SolidBrush(Color.Black)
Dim font1 As New Font("Arial", 10)
Dim X, Y, Z As Single
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Graph1 = Me.PictureBox1.CreateGraphics()
'Рисуем шкалу координат
'По оcи X
For X = -180 To 180 Step 90
Graph1.DrawString(X, font1, brush1, X + 180, 100)
Next X
'По оcи Y
For Y = -100 To 100 Step 50
Graph1.DrawString(Y / 50, font1, brush1, 180, 100 - Y)
Next Y
'Преобразование компьютерной системы координат в математическую
'Поворот оси Y
Graph1.ScaleTransform(1, -1)
'Сдвиг по осям X и Y
Graph1.TranslateTransform(180, -100)
'Рисование осей математической системы координат
'Ось X
Graph1.DrawLine(Pen1, -180, 0, 180, 0)
'Ось Y
Graph1.DrawLine(Pen1, 0, -100, 0, 100)
'Делаем засечки по осям координат
'По оси X
For X = -180 To 180 Step 90
Graph1.DrawLine(Pen1, X, -5, X, 5)
Next X
'По оси Y
For Y = -100 To 100 Step 50
Graph1.DrawLine(Pen1, -5, Y, 5, Y)
Next Y
End Sub
End Class