Ragazzi qualcuno di voi mi spiegherebbe in modo chiaro e semplice come funziona questo programma? ci sono alcune cose che proprio non capisco...
sopratutto la session... che roba è e come funziona???
<%@ Page Language="VB" Strict="false" %>

<%@ Import Namespace="System.Drawing" %>
<%@ Import Namespace="System.Drawing.Imaging" %>


<script runat="server">
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
lbll.Text = "Calcolo della retta dei minimi quadrati "
Dim grafico As String = Me.Request.QueryString("grafico")
If grafico IsNot Nothing AndAlso grafico = "1" Then
creaGrafico()
End If
End Sub

Private valori(5, 5) As Double

Sub creaGrafico()

Dim I, Sx, Sy, Sxy, Sx2, m, q, n As Double
Dim y01, y02 As Double
Dim objBitmap As New Bitmap(200, 200)
Dim objGraphic As Graphics = Graphics.FromImage(objBitmap)
Dim whiteBrush As New SolidBrush(Color.White)
Dim redpen As New Pen(Color.Red, 2)
Dim blackPen As New Pen(Color.Black, 2)
If Me.Session("valori") Is Nothing Then
valori(1, 1) = Me.Request.Form("x1")
valori(1, 2) = Me.Request.Form("y1")
valori(2, 1) = Me.Request.Form("x2")
valori(2, 2) = Me.Request.Form("y2")
valori(3, 1) = Me.Request.Form("x3")
valori(3, 2) = Me.Request.Form("y3")
valori(4, 1) = Me.Request.Form("x4")
valori(4, 2) = Me.Request.Form("y4")
valori(5, 1) = Me.Request.Form("x5")
valori(5, 2) = Me.Request.Form("y5")

Else
valori = DirectCast(Me.Session("valori"), Double(,))
End If
n = 5
Sx = 0
Sy = 0
Sx2 = 0
Sxy = 0
For I = 1 To 5
valori(I, 3) = valori(I, 1) * valori(I, 1)
valori(I, 4) = valori(I, 1) * valori(I, 2)
Sx = Sx + valori(I, 1)
Sy = Sy + valori(I, 2)
Sx2 = Sx2 + valori(I, 3)
Sxy = Sxy + valori(I, 4)
Next I
m = (n * Sxy - Sx * Sy) / (n * Sx2 - (Sx) * (Sx))
q = (Sx2 * Sy - Sxy * Sx) / (n * Sx ^ 2 - (Sx) * (Sx))
If q > 0 Then
lbl2.Text = "Risultato : Y=" & m & "X+" & q
Else
lbl2.Text = "Risultato : Y=" & m & "X" & q
End If


y01 = 195 - q
y02 = 195 - ((195 * m) + q)
objGraphic.FillRectangle(whiteBrush, 0, 0, 200, 200)
objGraphic.DrawLine(blackPen, New Point(0, 195), New Point(195, 195))
objGraphic.DrawLine(blackPen, New Point(5, 5), New Point(5, 200))
objGraphic.DrawLine(redpen, New Point(5, y01), New Point(195, y02))

If Me.Session("valori") IsNot Nothing Then
Me.Session("valori") = Nothing

Dim grafico As String = Me.Request.QueryString("grafico")
If grafico IsNot Nothing AndAlso grafico = "1" Then
Response.ContentType = "image/gif"
objBitmap.Save(Response.OutputStream, ImageFormat.Gif)
Me.Response.End()
End If
Else
Me.Session("valori") = valori
Me.Literal1.Text = String.Format("[img]a1.aspx?grafico=1&{0}[/img]", DateTime.Now.Ticks)
End If
End Sub

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
creaGrafico()
End Sub

</script>

<html>
<body>
<form id="Form1" runat="server">



<asp:Label ID="lbll" runat="server" ForeColor="#0000FF" Font-Bold="true" /></p>
x1:
<asp:TextBox ID="x1" Columns="10" runat="server" Text="1" />
y1:
<asp:TextBox ID="y1" Columns="10" runat="server" Text="1" />

x2:
<asp:TextBox ID="x2" Columns="10" runat="server" Text="2" />
y2:
<asp:TextBox ID="y2" Columns="10" runat="server" Text="4" />

x3:
<asp:TextBox ID="x3" Columns="10" runat="server" Text="3" />
y3:
<asp:TextBox ID="y3" Columns="10" runat="server" Text="9" />

x4:
<asp:TextBox ID="x4" Columns="10" runat="server" Text="4" />
y4:
<asp:TextBox ID="y4" Columns="10" runat="server" Text="16" />

x5:
<asp:TextBox ID="x5" Columns="10" runat="server" Text="5" />
y5:
<asp:TextBox ID="y5" Columns="10" runat="server" Text="25" />

<asp:Button ID="Button1" runat="server" Text="Button" onClick="Button1_Click" />



<asp:Label ID="lbl2" runat="server" /></p>
<asp:Literal ID="Literal1" runat="server"></asp:Literal>
</form>
</body>
</html>
grazie mille a chiunque vorrà perdere del tempo a spiegarmelo!