[英]Calling MS Excel function from MS Access VBA
我正在使用MS Access應用程序,其中一部分使用Beta Distribution功能。 由於MS Access沒有自己的Beta Distribution函數,我正在使用從MS Excel調用BetaDist函數。 我已經在MS Excel中測試了代碼,它似乎運行成功。 在MS Access中,代碼工作正常並生成正確的結果,但Access所花費的時間非常高於Excel所用的時間。 我發布了使用BetaDist函數的代碼部分,也是代碼中最慢的部分。 我想減少Access所花費的時間。 任何幫助表示贊賞。
使用BetaDist的Code的一部分:
For i = 1 To UBound(arrBetaParam)
If arrBetaParam(i).Alpha <= 0 Or arrBetaParam(i).Beta <= 0 Or tryOutValue > arrBetaParam(i).ExpValue Then
dblTempEP = 0
Else
If tryOutValue > arrBetaParam(i).LastKnownGoodValue Then
dblTempEP = 0
Else
dblTempEP = 1
End If
Dim bt As Double
bt = -1
On Error Resume Next
bt = Excel.WorksheetFunction.BetaDist(tryOutValue, arrBetaParam(i).Alpha, arrBetaParam(i).Beta, 0, arrBetaParam(i).ExpValue)
tj = bt
If bt > -1 Then
If bt > 1 Then bt = 1
If bt < 0 Then bt = 0
arrBetaParam(i).LastKnownGoodValue = tryOutValue
dblTempEP = 1 - bt
End If
On Error GoTo 0
End If
OEP = OEP + dblTempEP * arrBetaParam(i).Rate
'sumRate = sumRate + arrBetaParam(i).Rate
Next
由於必須打開Excel
應用程序,您的代碼可能需要很長時間。
BetaDist實現起來並不復雜。 為什么不在Acces VBA中創建VBA功能。 這是公式:
f(x) = B(alpha,beta)-1 xalpha-1(1-x)beta-1
在這里,我發現了一個不錯 但是沒有測試它:
Option Explicit
Const n As Long = 200 ' increase for accuracy, decrease for speed
Public aa As Double
Public bb As Double
Function BetaDist1(x As Double, a As Double, b As Double)
Dim d1 As Double
Dim d2 As Double
Dim n1 As Long
Dim n2 As Long
aa = a
bb = b
n1 = x * n
n2 = n - n1
d1 = SimpsonInt(0, x, n1)
d2 = SimpsonInt(x, 1, n2)
BetaDist1 = d1 / (d1 + d2)
End Function
Function SimpsonInt(ti As Double, tf As Double, ByVal n As Long) As Double
' shg 2006
' Returns the integral of Func (below) from ti to tf _
using Composite Simpson's Rule over n intervals
Dim i As Double ' index
Dim dH As Double ' step size
Dim dOdd As Double ' sum of Func(i), i = 1, 3, 5, 7, ... n-1, i.e., n/2 values
Dim dEvn As Double ' sum of Func(i), i = 2, 4, 6, ... n-2 i.e., n/2 - 1 values
' 1 + (n/2) + (n/2 - 1) + 1 = n+1 function evaluations
If n < 1 Then Exit Function
If n And 1 Then n = n + 1 ' n must be even
dH = (tf - ti) / n
For i = 1 To n - 1 Step 2
dOdd = dOdd + Func(ti + i * dH)
Next i
For i = 2 To n - 2 Step 2
dEvn = dEvn + Func(ti + i * dH)
Next i
SimpsonInt = (Func(ti) + 4# * dOdd + 2# * dEvn + Func(tf)) * dH / 3# ' weighted sum
End Function
Function Func(t As Double) As Double
Func = t ^ (aa - 1) * (1 - t) ^ (bb - 1)
End Function
你可以這樣做:
Dim xls As Excel.Application
Set xls = New Excel.Application
' Begin loop.
bt = xls.WorksheetFunction.BetaDist(tryOutValue, arrBetaParam(i).Alpha, arrBetaParam(i).Beta, 0, arrBetaParam(i).ExpValue)
' End loop.
xls.Quit
Set xls = Nothing
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