Need Help with understanding line of code ( and what a certain placement of a comma means) Thanks VB.net and Mathmatica help ?

• To: mathgroup at smc.vnet.net
• Subject: [mg122097] Need Help with understanding line of code ( and what a certain placement of a comma means) Thanks VB.net and Mathmatica help ?
• From: Kane Avellano <avellano.kane at googlemail.com>
• Date: Thu, 13 Oct 2011 03:49:09 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Ok i was looking at the celestial Two-Body Problem  source code and
wanted it in Vb.net

http://demonstrations.wolfram.com/TheCelestialTwoBodyProblem/

\[CapitalTheta][\[Epsilon]_, R_, \[Alpha]_, t_] :=
Mod[\[Alpha] + \[Pi] + (\[Pi] Tan[.5 (\[Epsilon] + .0001)^.284 (M[\
\[Epsilon], R, t] - \[Pi])])/Tan[.5 (\[Epsilon] + .0001)^.284 \[Pi]],
2 \[Pi]]

and

M[\[Epsilon]_, R_, t_] :=
Mod[8 \[Pi] t ((1 + \[Epsilon])/R)^(3/2) , 2 \[Pi]]

what does the 2 Pi do as when i put it in vb i didn't include the 2 pi
as i didn't what it was doing

my vb code is ...

Public Class test2
Dim ee, r, a, angle, t, x1, y1, x2, y2, m As Decimal
Private Function calcr(ByVal ee As Decimal, ByVal r As Decimal,
ByVal a As Decimal, ByVal angle As Decimal)
Return ((1 - ee) * r) / (1 + ee * Cos(angle - a))
End Function
Private Function calcmass(ByVal ee As Decimal, ByVal r As Decimal,
ByVal t As Decimal)
Return Abs(8 * PI * t * ((1 + ee) / r) ^ (3 / 2))
End Function
Private Function calcangle(ByVal ee As Decimal, ByVal r As
Decimal, ByVal a As Decimal, ByVal t As Decimal)
Dim angleexample As Decimal

angleexample = Abs(a + PI + ((PI * Tan((0.5 * (ee + 0.0001) ^
(0.284)) * calcmass(ee, r, t) - PI) _
/ (Tan(0.5 * ((ee + 0.0001) ^ (0.284)) *
PI)))))
Return Abs(a + PI + ((PI * Tan((0.5 * (ee + 0.0001) ^ (0.284))
* calcmass(ee, r, t) - PI) _
/ (Tan(0.5 * ((ee + 0.0001) ^
(0.284)) * PI)))))
End Function
Private Sub planetorbits(ByVal m, ByVal ee, ByVal r, ByVal a)

End Sub
Private Function x(ByVal ee, ByVal r, ByVal a, ByVal t)
Return calcr(ee, r, a, calcangle(ee, r, a, t)) *
Cos(calcangle(ee, r, a, t))
End Function
Private Function y(ByVal ee, ByVal r, ByVal a, ByVal t)
Return calcr(ee, r, a, calcangle(ee, r, a, t)) *
Sin(calcangle(ee, r, a, t))
End Function

Private Sub plotplanets()
x1 = x(ee, r, a, t + (1 / 8) * (r / (1 + ee)) ^ (3 / 2))

y1 = y(ee, r, a, t + 1 / 8 * (r / (1 + ee)) ^ (3 / 2))

x2 = -m ^ -1 * x(ee, r, a, t + 1 / 8 * (r / (1 + ee)) ^ (3 /
2))

PictureBox2.Location = New Point(x1, y1)
PictureBox3.Location = New Point(x2, y2)

End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
m = 2
ee = 0.5
r = 10
a = PI / 4
t = 0
End Sub

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Timer1.Tick
t += 0.01
plotplanets()
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles Button1.Click
Timer1.Enabled = True
End Sub

Private Sub reset_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles reset.Click
t = 0
Timer1.Enabled = True
End Sub
End Class

But when it runs, it follow the pattern for the first run but speeds
up each time until its going so fast it stops and reverses

got any ideas what the 2 pi does or is it like a limit to reset at 2
pi

Thanks

Kane A

```

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