Excel VBA error 438 : object doesn't support this property or method - vba

Question

Please help , this is my first try to code something useful by VBA and I am self-learning now. And I got that above error . Please help
Sub Bezier()
Dim C As Double, k As Integer, ansx As Double, ansy As Double, t As Double, n As Integer
n = 3
For i = 0 To 100
t = i * 0.01
ansx = 0
ansy = 0
For k = 0 To n
C = (WorksheetFunction.Fact(n) / WorksheetFunction.Fact(k)) / WorksheetFunction.Fact(n - k)
ansx = ansx + Cells(k + 2, 1).Value * C * WorksheetFunction.Power(t, k) * WorksheetFunction.Power(1 - t, n - k)
ansy = ansy + Cells(k + 2, 2).Value * C * WorksheetFunction.Power(t, k) * WorksheetFunction.Power(1 - t, n - k)
Next
Cells(i + 2, 6).Value = ansx
Cells(i + 2, 7).Value = ansy
Next
End Sub

Answer 1

First of all, you should know, that some of functions, used on the worksheet, have limitations. So my point is avoid of using them in VBA, if it is not necessary.
For example, function POWER() returns error on attempt to raise a zero to zero. An alternative is to use 0 ^ 0 combination, which is exactly doing the same, but looks more simply and operates without such error. But also there is no embedded alternative in VBA to the FACT() function, so you can use it, or simply add your own function factor() - it's uppon your choise.
If you just have started learning VBA, I would recomend you to use Option Explicit. It will help you to find out, which variables are not defined, and sometimes to avoid errors related to variable names missprint.
Here is your code, fixed and a little bit optimized:
Option Explicit' It is an option that turns on check for every used variable to be defined before execution. If this option is not defined, your code below will find undefined variables and define them when they are used. Good practice is to use this option, because it helps you, for example to prevent missprinting errors in variable names.
Sub Bezier()
Dim C as Double , t As Double
Dim k As Long, n As Long, i As Long
n = 3
For i = 0 To 100
t = i * 0.01
Cells(i + 2, 6) = 0
Cells(i + 2, 7) = 0
For k = 0 To n
C = (WorksheetFunction.Fact(n) / WorksheetFunction.Fact(k)) / WorksheetFunction.Fact(n - k)
Cells(i + 2, 6) = Cells(i + 2, 6).Value + Cells(k + 2, 1).Value * C * (t ^ k) * ((1 - t) ^ (n - k))
Cells(i + 2, 7) = Cells(i + 2, 7).Value + Cells(k + 2, 2).Value * C * (t ^ k) * ((1 - t) ^ (n - k))
Next
Next
End Sub
UPDATE
Here are some examples of factorial calculations.
Public Function fnFact(number) ' a simple cycle example of Factorial function
Dim tmp As Long ' new temporary variable to keep the "number" variable unchanged
tmp = number
fnFact = number
While tmp > 1
tmp = tmp - 1
fnFact = fnFact * tmp
Wend
End Function
Public Function fnFactR(number) ' a simple example of recursive function for Factorial calculation
If number > 0 Then
fnFactR = fnFactR(number - 1) * number ' function calls itself to continue calculations
Else
fnFactR = 1 ' function returns {1} when calculations are over
End If
End Function
Sub Factor_test() 'RUN ME TO TEST ALL THE FACTORIAL FUNCTIONS
Dim number As Long
number = 170 ' change me to find Factorial for a different value
MsgBox "Cycle Factorial:" & vbNewLine & number & "!= " & fnFact(number)
MsgBox "WorksheetFunction Factorial:" & vbNewLine & number & "!= " & WorksheetFunction.Fact(number)
MsgBox "Recursive Factorial:" & vbNewLine & number & "!= " & fnFactR(number)
End Sub
All those functions are available to calculate Factorial only for numbers before 170 inclusively, because of large result value.
So for my PC the limitation for WorksheetFunction.Fact() function is also 170.
Let me know, if your PC has different limitation for this function, - it's quite interesting thing. :)
UPDATE2
It is recomended to use Long data type instead of Integer each type when integer (or whole number) variable is needed. Long is slightly faster, it has much wider limitations and costs no additional memory. Here are proof links:
1. MSDN:The Integer, Long, and Byte Data Types
2. ozgrid.com:Long Vs Integer
3. pcreview.co.uk:VBA code optimization - why using long instead of integer?
Thanks for #Ioannis and #chris neilsen for the information about Long data type and proof links!
Good luck in your further VBA actions!

Answer 2

I can't find a pow method on the WorksheetFunction object. There is a Power method though. Perhaps you meant that?