d4r6.frm

来自「常用数值算法集哈」· FRM 代码 · 共 148 行

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   2700
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4395
   LinkTopic       =   "Form1"
   ScaleHeight     =   2700
   ScaleWidth      =   4395
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   2640
      TabIndex        =   0
      Top             =   2040
      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 D4R6
    'Driver for routine GAMMP
    Dim ACTUAL(5), X(5), A(5)
    ACTUAL(1) = 0.742026
    ACTUAL(2) = 0.989896
    ACTUAL(3) = 0.632121
    ACTUAL(4) = 0.993262
    ACTUAL(5) = 0.038732
    A(1) = 0.1
    A(2) = 0.1
    A(3) = 1#
    A(4) = 1#
    A(5) = 6#
    X(1) = 0.031623
    X(2) = 1.581139
    X(3) = 1#
    X(4) = 5#
    X(5) = 2.44949
    Print
    Print "     A       X        Actual    GAMMP(A,X)"
    For I = 1 To 5
        Print Tab(4); Format$(A(I), "#0.00");
        Print Tab(10); Format$(X(I), "#0.####00");
        Print Tab(22); Format$(ACTUAL(I), "0.000000");
        Print Tab(33); Format$(GAMMP(A(I), X(I)), "0.000000")
    Next I
End Sub
Function GAMMP(A, X)
    If X < 0# Or A <= 0# Then
        Print "PAUSE"
        Exit Function
    End If
    If X < A + 1# Then
        Call GSER(GAMSER, A, X, GLN)
        GAMMP = GAMSER
    Else
        Call GCF(GAMMCF, A, X, GLN)
        GAMMP = 1# - GAMMCF
    End If
End Function
Sub GSER(GAMSER, A, X, GLN)
    ITMAX = 100
    EPS = 0.0000003
    GLN = GAMMLN(A)
    If X <= 0# Then
        If X < 0# Then
            Print " PAUSE"
            Exit Sub
        End If
        GAMSER = 0#
        Exit Sub
    End If
    AP = A
    Sum = 1# / A
    DEL = Sum
    For N = 1 To ITMAX
        AP = AP + 1#
        DEL = DEL * X / AP
        Sum = Sum + DEL
        If Abs(DEL) < Abs(Sum) * EPS Then GoTo 1
    Next N
    Print "A too large, ITMAX too small"
1   GAMSER = Sum * Exp(-X + A * Log(X) - GLN)
End Sub
Sub GCF(GAMMCF, A, X, GLN)
    ITMAX = 100
    EPS = 0.0000003
    GLN = GAMMLN(A)
    GOLD = 0#
    A0 = 1#
    A1 = X
    B0 = 0#
    B1 = 1#
    FAC = 1#
    For N = 1 To ITMAX
        AN = N
        ANA = AN - A
        A0 = (A1 + A0 * ANA) * FAC
        B0 = (B1 + B0 * ANA) * FAC
        ANF = AN * FAC
        A1 = X * A0 + ANF * A1
        B1 = X * B0 + ANF * B1
        If A1 <> 0# Then
            FAC = 1# / A1
            G = B1 * FAC
            If Abs((G - GOLD) / G) < EPS Then GoTo 1
            GOLD = G
        End If
    Next N
    Print "A too large, ITMAX too small"
1   GAMMCF = Exp(-X + A * Log(X) - GLN) * G
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