d4r7.frm

来自「常用数值算法集哈」· FRM 代码 · 共 146 行

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   2745
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4185
   LinkTopic       =   "Form1"
   ScaleHeight     =   2745
   ScaleWidth      =   4185
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   2520
      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 D4R7
    'Driver for routine GAMMQ
    Dim ACTUAL(5), X(5), A(5)
    ACTUAL(1) = 0.161092
    ACTUAL(2) = 0.010104
    ACTUAL(3) = 0.367879
    ACTUAL(4) = 0.006738
    ACTUAL(5) = 0.961268
    A(1) = 0.1
    A(2) = 0.1
    A(3) = 1#
    A(4) = 1#
    A(5) = 6#
    X(1) = 0.116228
    X(2) = 1.581139
    X(3) = 1#
    X(4) = 5#
    X(5) = 2.44949
    Print
    Print "     A       X       Actual       GAMMQ(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$(ACTUAL(I), "0.000000");
        Print Tab(35); Format$(GAMMQ(A(I), X(I)), "0.000000")
    Next I
End Sub
Function GAMMQ(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)
        GAMMQ = 1# - GAMSER
    Else
        Call GCF(GAMMCF, A, X, GLN)
        GAMMQ = 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