VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   4665
   ClientLeft      =   2655
   ClientTop       =   1740
   ClientWidth     =   5865
   LinkTopic       =   "Form1"
   ScaleHeight     =   4665
   ScaleWidth      =   5865
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   4080
      TabIndex        =   0
      Top             =   4080
      Width           =   1215
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
    'PROGRAM D6R4
    'Driver for routine RAN3
    'Calculates pi statistically using volume of unit n-sphere
    PI = 3.1415926
    Dim IY(3), YPROB(3)
    IDUM& = -1
    For I = 1 To 3
        IY(I) = 0
    Next I
    Print Tab(13); "Volume of unit n-sphere, n=2,3,4"
    Print Tab(5); "# points     PI         (4/3)*PI     (1/2)*PI^2"
    For J = 1 To 15
        For K = 2 ^ (J - 1) To 2 ^ J
            x1 = RAN3(IDUM&)
            x2 = RAN3(IDUM&)
            x3 = RAN3(IDUM&)
            x4 = RAN3(IDUM&)
            If (FNC(x1, x2, 0#, 0#) < 1#) Then IY(1) = IY(1) + 1
            If (FNC(x1, x2, x3, 0#) < 1#) Then IY(2) = IY(2) + 1
            If (FNC(x1, x2, x3, x4) < 1#) Then IY(3) = IY(3) + 1
        Next K
        For I = 1 To 3
            YPROB(I) = 1# * (2 ^ (I + 1)) * IY(I) / (2 ^ J)
        Next I
        Print Tab(5); 2 ^ J;
        For M = 1 To 3
            Print Tab(15 + (M - 1) * 14); Format$(YPROB(M), "#.#####0");
        Next M
    Next J
    Print Tab(5); "actual"; Tab(15); Format$(PI, "#.#####0");
    Print Tab(29); Format$(4# * PI / 3#, "#.#####0");
    Print Tab(43); Format$(0.5 * (PI ^ 2), "#.#####0")
End Sub
Function FNC(x1, x2, x3, x4)
    FNC = Sqr(x1 ^ 2 + x2 ^ 2 + x3 ^ 2 + x4 ^ 2)
End Function
Static Function RAN3(IDUM&)
    MBIG& = 1000000000: MSEED& = 161803398: MZ& = 0: FAC = 0.000000001
    Dim MA&(55)
    If IDUM& < 0 Or IFF = 0 Then
        IFF = 1
        MJ& = MSEED& - Abs(IDUM&)
        MJ& = MJ& - MBIG& * Int(MJ& / MBIG&)
        MA&(55) = MJ&
        MK& = 1
        For I = 1 To 54
            II = (21 * I) - 55 * Int((21 * I) / 55)
            MA&(II) = MK&
            MK& = MJ& - MK&
            If MK& < MZ& Then MK& = MK& + MBIG&
            MJ& = MA&(II)
        Next I
        For K = 1 To 4
            For I = 1 To 55
                MA&(I) = MA&(I) - MA&(1 + I + 30 - 55 * Int((I + 30) / 55))
                If MA&(I) < MZ& Then MA&(I) = MA&(I) + MBIG&
            Next I
        Next K
        INEXT = 0
        INEXTP = 31
        IDUM& = 1
    End If
    INEXT = INEXT + 1
    If INEXT = 56 Then INEXT = 1
    INEXTP = INEXTP + 1
    If INEXTP = 56 Then INEXTP = 1
    MJ& = MA&(INEXT) - MA&(INEXTP)
    If MJ& < MZ& Then MJ& = MJ& + MBIG&
    MA&(INEXT) = MJ&
    RAN3 = MJ& * FAC
End Function