mdian2.txt

用VB实现的数据的统计描述 包括分布的矩---均值、平均差、标准差、方差和中位数的搜索、均值与方差的显著性检验等

Sub MDIAN2(X(), N, XMED)
    BIG = 1E+30
    AFAC = 1.5
    AMP = 1.5
    A = 0.5 * (X(1) + X(N))
    EPS = Abs(X(N) - X(1))
    AP = BIG
    AM = -BIG
1   Sum = 0#
    SUMX = 0#
    NP = 0
    NM = 0
    XP = BIG
    XM = -BIG
    For J = 1 To N
        XX = X(J)
        If XX <> A Then
            If XX > A Then
                NP = NP + 1
                If XX < XP Then XP = XX
            ElseIf XX < A Then
                NM = NM + 1
                If XX > XM Then XM = XX
            End If
            DUM = 1# / (EPS + Abs(XX - A))
            Sum = Sum + DUM
            SUMX = SUMX + XX * DUM
        End If
    Next J
    If NP - NM >= 2 Then
        AM = A
        If SUMX / Sum - A < 0 Then
            BBB = 0
        Else
            BBB = SUMX / Sum - A
        End If
        AA = XP + BBB * AMP
        If AA > AP Then AA = 0.5 * (A + AP)
        EPS = AFAC * Abs(AA - A)
        A = AA
        GoTo 1
    ElseIf NM - NP >= 2 Then
        AP = A
        If SUMX / Sum - A < 0 Then
            BBB = SUMX / Sum - A
        Else
            BBB = 0
        End If
        AA = XM + BBB * AMP
        If AA < AM Then AA = 0.5 * (A + AM)
        EPS = AFAC * Abs(AA - A)
        A = AA
        GoTo 1
    Else
        If (N Mod 2) = 0 Then
            If NP = NM Then
                XMED = 0.5 * (XP + XM)
            ElseIf NP > NM Then
                XMED = 0.5 * (A + XP)
            Else
                XMED = 0.5 * (XM + A)
            End If
        Else
            If NP = NM Then
                XMED = A
            ElseIf NP > NM Then
                XMED = XP
            Else
                XMED = XM
            End If
        End If
    End If
End Sub