VBA随机数在模拟

Question

我想创建一个棒球赛季后模拟器，看看有多少坏的投手影响球队的夺冠赔率。所以我基本上创建为淘汰赛模拟器（3轮，第一个是最好的5，接下来的两个是最好的7）。我能看到多少，如果他每间距第三场比赛，他减少了10％胜算一个SP会伤害球队。

为了确保我这样做的写，我第一次跑我的模拟没有任何调整，每场比赛两队将有获胜的几率为50％。（团队将因此拥有赢得世界的12.5％的机会在3轮季后赛中），但是，我一直高于12.5。

我有一个感觉问题是与Rnd函数，所以我玩了一下（增加了一个函数，试图改变时间等），现在我的模拟出来是< 12.5％。然后我试图排除麻烦，并注意到在每一轮中都没有赢得50％的时间......这是每次我重新运行模拟时的情况（第一轮比第一轮有47％的成功，然后是第二轮51 ％，那么第三轮58％......那么接下来的运行将返回46％，52％，59％。

难道我做错了什么，或者这只是事情的RND功能是不是在处理大？

Public Function wRandomNumber(lowerbound, upperbound, Optional rndType = 1) As Double 
Dim rndVariable As Double 
'Const ms As Double = 0.000000011574 

Randomize Timer 
'Application.Wait Now + ms * 1 
rndVariable = Rnd 
If rndType = 1 Then 
    wRandomNumber = Int((upperbound - lowerbound + 1) * rndVariable + lowerbound) 
ElseIf rndType = 2 Then 
    If (upperbound - lowerbound + 1) * rndVariable + lowerbound <= upperbound Then 
     wRandomNumber = (upperbound - lowerbound + 1) * rndVariable + lowerbound 
    Else 
     Do While (upperbound - lowerbound + 1) * rndVariable + lowerbound > upperbound 
      rndVariable = Rnd 
      If (upperbound - lowerbound + 1) * rndVariable + lowerbound <= upperbound Then 
       wRandomNumber = (upperbound - lowerbound + 1) * rndVariable + lowerbound 
      End If 
     Loop 
    End If 
End If 
End Function 

Public Sub Playoff_sim() 

Dim game_num As Integer 
Dim lds_wins_stros As Integer 
Dim lds_loss_stros As Integer 
Dim lcs_wins_stros As Integer 
Dim lcs_loss_stros As Integer 
Dim ws_wins_stros As Integer 
Dim ws_loss_stros As Integer 
Dim p As Double 
Dim outcome1 As Single 
Dim outcome2 As Single 
Dim outcome3 As Single 
Dim i As Double 
Dim iter As Double 
Dim CHAMPS As Double 
Dim Loser As Double 
Dim p_bad As Double 
Dim p_norm As Double 
Dim lds_champs As Double 
Dim lcs_champs As Double 
Dim r As Double 
Const ms As Double = 0.000000011574 

iter = 100000 
CHAMPS = 0 
Loser = 0 
lds_champs = 0 
lcs_champs = 0 
p_bad = 0.5 
p_norm = 0.5 
r = 0 
For i = 1 To iter 

game_num = 1 
lds_wins_stros = 0 
lds_loss_stros = 0 
lcs_wins_stros = 0 
lcs_loss_stros = 0 
ws_loss_stros = 0 
ws_wins_stros = 0 

Do Until lds_wins_stros = 3 Or lds_loss_stros = 3 

outcome1 = wRandomNumber(0, 1, 2) 
    If game_num = 3 Then 
     p = p_bad 
    Else 
     p = p_norm 
    End If 

    If p > outcome1 Then 
     lds_wins_stros = lds_wins_stros + 1 
    Else 
     lds_loss_stros = lds_loss_stros + 1 
    End If 
    r = r + 1 
    'Worksheets("Playoff_Sim").Cells(r, 15).Value = outcome1 

game_num = game_num + 1 
Loop 

If lds_wins_stros = 3 Then 

    outcome2 = wRandomNumber(0, 1, 2) 
    lds_champs = 1 + lds_champs 
    Do Until lcs_wins_stros = 4 Or lcs_loss_stros = 4 

    If game_num = 3 Or 6 Or 9 Or 12 Or 15 Or 18 Or 21 Then 
     p = p_bad 
    Else 
     p = p_norm 
    End If 

    If p > outcome2 Then 
     lcs_wins_stros = lcs_wins_stros + 1 
    Else 
     lcs_loss_stros = lcs_loss_stros + 1 
    End If 

    game_num = game_num + 1 

    Loop 

    If lcs_wins_stros = 4 Then 
     lcs_champs = lcs_champs + 1 

     outcome3 = wRandomNumber(0, 1, 2) 
     Do Until ws_wins_stros = 4 Or ws_loss_stros = 4 

      If game_num = 3 Or 6 Or 9 Or 12 Or 15 Or 18 Or 21 Then 
       p = p_bad 
      Else 
       p = p_norm 
      End If 

      If p > outcome3 Then 
       ws_wins_stros = ws_wins_stros + 1 
      Else 
       ws_loss_stros = ws_loss_stros + 1 
      End If 
     'r = r + 1 
     game_num = game_num + 1 
     'Worksheets("Playoff_Sim").Cells(r, 15).Value = outcome3 
     Loop 

     If ws_wins_stros = 4 Then 
      CHAMPS = CHAMPS + 1 
     Else 
      Loser = Loser + 1 
     End If 

    Else 
     Loser = Loser + 1 
    End If 

Else 
    Loser = Loser + 1 
End If 

Next i 

Worksheets("Playoff_Sim").Cells(2, 1).Value = CHAMPS 
Worksheets("Playoff_Sim").Cells(2, 2).Value = Loser 
Worksheets("Playoff_Sim").Cells(2, 3).Value = lds_champs 
Worksheets("Playoff_Sim").Cells(2, 4).Value = lcs_champs 

结束子

Answer 1

的问题是不只是在随机数（其可以由@ASH的建议来解决使用Application.RandBetween），但也是逻辑你的模拟。两次重复的代码片段

If game_num = 3 Or 6 Or 9 Or 12 Or 15 Or 18 Or 21 Then 
    p = p_bad 
Else 
    p = p_norm 
End If 

相当于单行p = p_bad。这是因为条件game_num = 3 Or 6 Or 9 Or 12 Or 15 Or 18 Or 21结果始终为True，因为你只比较game_num到3但随后迫使VBA使用Or运营商，他们来解释其余的数字（6,9,15,18,21）为True。相反，只是这样做：

If game_num Mod 3 = 0 Then 
    p = p_bad 
Else 
    p = p_norm 
End If 

可能还有其他问题，尽管这应该足以让你开始。