VBA корень поиска корыто бисекция

Question

Мой код VBA продолжает возвращать значение 0, когда я знаю, что корни моей функции не 0.

Это довольно простой код, но я не могу отладить. Любая идея, откуда эта ошибка может возникнуть?

Option Explicit 

Public Function Bisect(ByVal xlow As Double, ByVal xhigh As Double) As Double 

Dim i As Integer 
Dim xmid As Double 

xmid = (xlow + xhigh)/2 

For i = 1 To 100 

If f(xlow) * f(xmid) < 0 Then 
    xhigh = xmid 
    xmid = (xlow + xhigh)/2 
Else 
    xlow = xmid 
    xmid = (xlow + xhigh)/2 
End If 

Next i 

Bisect = xmid 

End Function 

Function f(ByVal x As Double, Optional ByRef inputArray As Range) As Variant 

Dim ca0 As Double 
Dim v0 As Double 
Dim k As Double 
Dim e As Double 
Dim ac As Double 
Dim L As Double 

inputArray(2, 2) = ca0 
inputArray(3, 2) = v0 
inputArray(4, 2) = k 
inputArray(5, 2) = e 
inputArray(6, 2) = ac 
inputArray(7, 2) = L 

f(x) = (v0/(k * ca0 * ac)) * ((2 * e * (1 + e) * Log(1 - x)) + (e^2 * x) + (((1 + e)^2 * x)/(1 - x))) - L 

End Function 

Answer 1

Может быть, вы пытаетесь назначить inputarray пустыми переменными?

На мой взгляд, это должно быть:

ca0 = inputArray(2, 2) 
v0 = inputArray(3, 2) 

И так далее.

Я предполагаю

f(x) = (v0/(k * ca0 * ac)) * ((2 * e * (1 + e) * Log(1 - x)) + (e^2 * x) + (((1 + e)^2 * x)/(1 - x))) - L 

Должно быть

f = (v0/(k * ca0 * ac)) * ((2 * e * (1 + e) * Log(1 - x)) + (e^2 * x) + (((1 + e)^2 * x)/(1 - x))) - L 

Answer 2

' i Think you want to take those constant values from cells presentin the sheet 

Function f(ByVal x As Double) As Variant 


Dim inputArray As Range 

Dim ca0 As Double 
Dim v0 As Double 
Dim k As Double 
Dim e As Double 
Dim ac As Double 
Dim L As Double 

' i Think you want to take values from cells in the sheet 

ca0 = ActiveSheet.Cells(2, 2).Value 
v0 = ActiveSheet.Cells(3, 2).Value 
k = ActiveSheet.Cells(4, 2).Value 
e = ActiveSheet.Cells(5, 2).Value 
ac = ActiveSheet.Cells(6, 2).Value 
L = ActiveSheet.Cells(7, 2).Value