VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   6690
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   7680
   LinkTopic       =   "Form1"
   ScaleHeight     =   6690
   ScaleWidth      =   7680
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   5760
      TabIndex        =   0
      Top             =   6120
      Width           =   1335
   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 D12R8
    'Driver for routine RZEXTR
    'Feed values from a rational function
    'Fn(x)=(1-x+x^3)/(x+1)^n
    NV = 4
    NUSE = 5
    Dim YEST(4), YZ(4), DY(4)
    For I = 1 To 10
        IEST = I
        XEST = 1# / CSng(I)
        DUM = 1# - XEST + XEST ^ 3
        For J = 1 To NV
            DUM = DUM / (XEST + 1#)
            YEST(J) = DUM
        Next J
        Call RZEXTR(IEST, XEST, YEST(), YZ(), DY(), NV, NUSE)
        Print Tab(5); "IEST= "; I; "   XEST= "; Format$(XEST, "#.###0")
        Print Tab(5); "Extrap. Function: ";
        For J = 1 To NV
            Print Tab(15 + J * 14); Format$(YZ(J), ".#####0");
        Next J
        Print Tab(5); "Extrap. Error: ";
        For J = 1 To NV
            Print Tab(15 + J * 14); Format$(DY(J), ".#####0");
        Next J
    Next I
    Print Tab(5); "Actual Values:"; Tab(29); "1.0";
    Print Tab(43); "1.0"; Tab(57); "1.0"; Tab(71); "1.0"
End Sub
Sub RZEXTR(IEST, XEST, YEST(), YZ(), DY(), NV, NUSE)
    Dim FX(7)
    Static X(11), D(10, 7)
    X(IEST) = XEST
    If IEST = 1 Then
        For J = 1 To NV
            YZ(J) = YEST(J)
            D(J, 1) = YEST(J)
            DY(J) = YEST(J)
        Next J
    Else
        M1 = IEST
        If NUSE < IEST Then M1 = NUSE
        For K = 1 To M1 - 1
            FX(K + 1) = X(IEST - K) / XEST
        Next K
        For J = 1 To NV
            YY = YEST(J)
            V = D(J, 1)
            C = YY
            D(J, 1) = YY
            For K = 2 To M1
                B1 = FX(K) * V
                B = B1 - C
                If B <> 0# Then
                    B = (C - V) / B
                    DDY = C * B
                    C = B1 * B
                Else
                    DDY = V
                End If
                If K <> M1 Then V = D(J, K)
                D(J, K) = DDY
                YY = YY + DDY
            Next K
            DY(J) = DDY
            YZ(J) = YY
        Next J
    End If
    Erase FX
End Sub