跪求大神解释下下列vb程序含义

Private Sub Command1_Click()
If ((IsNumeric(di.Text) = False) Or (IsNumeric(pc.Text) = False) Or (IsNumeric(power.Text) = False) Or (IsNumeric(xishu.Text) = False) Or (IsNumeric(c2.Text) = False)) Then
MsgBox "请确认输入的都是数字！"
Exit Sub
End If
tdex2 = 2
td.Text = Str(Val(di.Text) * Val(pc.Text))
tdex1 = Str(Val(power.Text) * tdex2)
tdex1 = Str(Val(tdex1) * Val(xishu.Text))
tdex1 = Str(Val(tdex1) - Val(power.Text))
If (Val(tdex1) = 0) Then
MsgBox "请确认输入的数据正确！"
Exit Sub
End If
td.Text = Str(Val(td.Text) / Val(tdex1))
td.Text = Str(Val(td.Text) + Val(c2.Text))
End Sub