gcf.txt

常用的数值算法的VB程序

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