rtflsp.txt

Visual Basic 常用数学算法集书中收录了所有代码

Function RTFLSP(X1, X2, XACC)
    MAXIT = 30
    FL = FUNC(X1)
    FH = FUNC(X2)
    If FL * FH > 0 Then
        Print "Root must be bracketed for false position"
    End If
    If FL < 0 Then
        XL = X1
        XH = X2
    Else
        XL = X2
        XH = X1
        SWAP = FL
        FL = FH
        FH = SWAP
    End If
    DX = XH - XL
    For J = 1 To MAXIT
        RTFLSP = XL + DX * FL / (FL - FH)
        F = FUNC(RTFLSP)
        If F < 0 Then
            DEL = XL - RTFLSP
            XL = RTFLSP
            FL = F
        Else
            DEL = XH - RTFLSP
            XH = RTFLSP
            FH = F
        End If
        DX = XH - XL
        If Abs(DEL) < XACC Or F = 0 Then Exit Function
    Next J
    Print "RTFLSP exceed maximum iterations"
End Function