VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   5715
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   5460
   LinkTopic       =   "Form1"
   ScaleHeight     =   5715
   ScaleWidth      =   5460
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   3360
      TabIndex        =   0
      Top             =   4800
      Width           =   1455
   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 D4R1
    'Driver for routine GAMMLN
    PI = 3.1415926
    Open "D:\VB常用數值算法集\DATA\FNCVAL.DAT" For Input As #1
    Do
      Line Input #1, Text$
    Loop While Text$ <> "Gamma Function"
    Line Input #1, NVAL$
    NVAL = Val(NVAL$)
    Print Text$
    Print
    Print "    X       Actual      GAMMA(X)"
    For I = 1 To NVAL
        Line Input #1, DUM$
        X = Val(Mid(DUM$, 1, 4))
        ACTUAL = Val(Mid(DUM$, 8))
        If X > 0 Then
            If X >= 1 Then
                CALC = GAMMLN(X)
            Else
                CALC = GAMMLN(X + 1) - Log(X)
            End If
            Print Tab(4); Format$(X, "#0.0#");
            Print Tab(12); Format$(Log(ACTUAL), "##.000000");
            Print Tab(25); Format$(CALC, "##.000000")
        End If
    Next I
End Sub
Function GAMMLN(XX)
    Dim COF(6)
    COF(1) = 76.18009173
    COF(2) = -86.50532033
    COF(3) = 24.01409822
    COF(4) = -1.231739516
    COF(5) = 0.00120858003
    COF(6) = -0.00000536382
    STP = 2.50662827465
    HALF = 0.5
    ONE = 1#
    FPF = 5.5
    X = XX - ONE
    TMP = X + FPF
    TMP = (X + HALF) * Log(TMP) - TMP
    SER = ONE
    For J = 1 To 6
        X = X + ONE
        SER = SER + COF(J) / X
    Next J
    GAMMLN = TMP + Log(STP * SER)
End Function