Imports System.Globalization

Module Module1

    Sub Main()

        REM ROCKET.BAS by Brian Tung

        Dim A As Double = 1.032     REM Earth gravity in light-years per year squared
        Dim D As Double

        Do
            Console.WriteLine("Distance in light-years (0-100 million)")
            Double.TryParse(Console.ReadLine, D)
            If D >= 0 And D <= 100000000 Then
                Exit Do
            Else
                Console.WriteLine("Distance must be between 0 and 100 million l-y")
            End If
        Loop

        Dim D1 As Double = D / 2
        Dim T As Double = Math.Sqrt(D1 * D1 + (2 * D1 / A))
        Dim X As Double = A * T
        Dim M As Integer = 1 REM Lines 110-180 compute inverse sinh
        If X < 0 Then M = -1
        Dim S As Double = Math.Log(Math.Abs(X) + 1)
        Dim S1 As Double = S + 1

        Do
            Dim X1 As Double = (Math.Exp(S) - Math.Exp(-S)) / 2 - Math.Abs(X)
            S1 = X1 / (Math.Exp(S) + Math.Exp(-S)) / 2
            S = S - S1
            If Math.Abs(S1) <= 0.0000001 Then Exit Do
        Loop

        Dim T1 As Double = 1 / A * S * M
        Dim V As Double = A * T / Math.Sqrt(1 + (A * T) * (A * T))
        Console.WriteLine("Time on Earth: {0} years", (2 * T).ToString("#########.###", CultureInfo.InvariantCulture))
        Console.WriteLine("Time on board: {0} years", (2 * T1).ToString("#########.###", CultureInfo.InvariantCulture))
        Dim Z As String = "Top speed: "
        Dim Z3 As String = "#.###"

        If D >= 1 Then
            Dim Z1 As Double = Int(2 * Math.Log(D) / Math.Log(10))
            If D >= 1 And D < 10000000 Then
                Dim Z2 As Integer = Z1
                Z3 = Z3 + StrDup(Z2, "#")
            End If
            If D >= 10000000 Then
                Z3 = Z3 + "#############"
            End If
        End If

        Z = Z + "{0} c"
        Console.WriteLine(Z, V.ToString(Z3, CultureInfo.InvariantCulture))
        Console.WriteLine("Press any key to exit...")
        Console.ReadKey()

        REM  APPEARED IN COMPUTERS IN
        REM  ASTRONOMY, SKY & TELESCOPE,
        REM  FEBRUARY 2002, PAGE 66

    End Sub

End Module