VB6中连续使用Randomize对后续随机数出现概率影响测试

'程序的思路是将a，b分别给一个0到num-1的随机数，循环多次，观察(a,b)的所有组合出现的次数，用来反映其出现的概率
'测试结果表明连续使用Randomize，出现的(a,b)组合并不是等概率的

Option Explicit

Sub Cal(ByVal num As Integer)
    Dim a, b, i, j, k, n, c() As Long
    ReDim c(num * num - 1)
    For i = 1 To 500000
        Randomize
        a = Int(Rnd * num)
        Randomize '此处注释后结果不同
        b = Int(Rnd * num)
        n = 0
        For j = 0 To num - 1
            If a = j Then
                For k = 0 To num - 1
                    If b = k Then
                        GoTo f
                    End If
                    n = n + 1
                Next k
            End If
            n = n + num
        Next j
f:
        c(n) = c(n) + 1
    Next i
    For i = 0 To num * num - 1
        Debug.Print c(i),
    Next i
    Debug.Print
End Sub

Private Sub Command1_Click()
    Call Cal(3)
End Sub