Prevent recalculations of User Defined Functions used in named ranges - arrays

Question

I have three UDF's:
Private Function IsInArray(stringToBeFound As Variant, arr As Variant) As Boolean
IsInArray = Not IsError(Application.Match(stringToBeFound, arr, 0))
End Function
This function checks if something is in the array.
Private Function data_to_array(data As Range)
Dim arrArray As Variant
Dim cell As Range
Dim z As Integer
z = 0
ReDim arrArray(1 To data.Cells.Count)
For Each cell In data
z = z + 1
arrArray(z) = cell.Value
Next cell
data_to_array = arrArray
End Function
This function extracts selected range values and puts them into an array.
Private Function plot_vals(data As Variant, custom_arr As Variant)
Dim arrPlot As Variant
ReDim arrPlot(1 To UBound(data)) As Variant
Dim c As Integer
Dim cl As Integer
cl = 0
For c = 1 To UBound(data)
cl = cl + 1
If IsInArray(cl, custom_arr) Then
arrPlot(cl) = data(cl)
Else
arrPlot(cl) = CVErr(xlErrNA)
End If
Next c
plot_vals = arrPlot
End Function
The last UDF loops through the data array from second UDF and if index/position of value in data_array is in custom_array, then it returns its value. Otherwise it puts an error into an array.
Data looks like this:
These functions are used like this in Excel:
data_to_array(A1:A5) - this UDF creates an array(1 to 5) with values from cells A1:A5.
plot_vals(data_to_array(A1:A5), {1,5}) - this UDF creates an array(1 to 5), and uses second argument to retrieve first and fifth values while putting errors in the other indexes. The result is array of for example: {5,error,error,error,1}
If I used the function on above data like this: plot_vals(data_to_array(A1:A5), {1,2}) then the result would be an array {5,4,error,error,error}
That plot_vals UDF is used in named range and that named range is used to plot values on chart.
Data is stored in named range myData and the function in second named range is used like this:
plot_vals(myData,{1,5}).
Everything works, I can plot it on chart, all is good but when the named ranges are used on charts, every time I change something in my workbook all functions are recalculated like... 10 times each one, instead of once. It causes Excel to slow down/freeze if those functions are used many times. I have tried to search about function volatility and how to turn it off (it should be turned off by default?), but nothing seems to be working and I do not know how to stop that from happening. I have tried to recreate this in Excel using standard Excel functions in named ranges, but I cannot find a correct function to do what I want. UDF is exactly what I need.
When these named ranges are NOT used in charts then nothing happens, but as soon as I use the named range on chart then it recalculates everything on even a minor change of a workbook. Minor change meaning - copying / pasting / adding rows etc.
How can I stop that from happening? How to recalculate UDF's only once?
EDIT on further research:
I have tried the potential solutions provided by Charles Williams:
https://fastexcel.wordpress.com/2011/11/25/writing-efficient-vba-udfs-part-7-udfs-calculated-multiple-times/
His potential solutions do not change anything.
I have also tried using Sheet_Change event, changing calculations to manual and then back to automatic. It helps but it clears the clipboard (unacceptable) and it causes issues with my other macros, so it is a "no-go" solution.
It is also worth noting, that as soon as the chart is deleted and the UDF's remain in named ranges, everything is working nice and smooth. But when those named ranges are in chart series formulas, everything is recalculating 100's of times.

Answer 1

Aside from trying to fix the basic problem of how many times your functions get called, you can partially address the slow-down by optimizing the basic performance:
Application.Match is relatively slow unless the data being searched in on a worksheet
Reading a range into an array is slower than reading the whole range at once using its .Value (assuming range is a single area)
So:
Sub PerfTester()
Const ARR_SZ As Long = 10
Dim arr(1 To ARR_SZ), i, n, t, v, m
'populate a test array
For i = 1 To ARR_SZ
arr(i) = i
Next i
t = Timer
For n = 1 To 100000
v = Round(Rnd * ARR_SZ, 0)
m = IsInArray(v, arr) 'using match
Next n
Debug.Print Timer - t '~ 1.7 sec
t = Timer
For n = 1 To 100000
v = Round(Rnd * ARR_SZ, 0)
m = IsInArray2(v, arr) 'using a loop
Next n
Debug.Print Timer - t '~0.11 sec
t = Timer
For n = 1 To 100000
v = data_to_array(Range("A1:A50")) 'using cell-by-cell
Next n
Debug.Print Timer - t '~ 11.5 sec
t = Timer
For n = 1 To 100000
v = data_to_array2(Range("A1:A50")) 'using single read from range
Next n
Debug.Print Timer - t '~ 2.8 sec
End Sub
Private Function IsInArray(stringToBeFound As Variant, arr As Variant) As Boolean
IsInArray = Not IsError(Application.Match(stringToBeFound, arr, 0))
End Function
Private Function IsInArray2(stringToBeFound As Variant, arr As Variant) As Boolean
Dim i
For i = LBound(arr) To UBound(arr)
If arr(i) = stringToBeFound Then
IsInArray2 = True
Exit For
End If
Next i
End Function
Private Function data_to_array(data As Range)
Dim arrArray As Variant, cell As Range, z As Integer
z = 0
ReDim arrArray(1 To data.Cells.Count)
For Each cell In data
z = z + 1
arrArray(z) = cell.Value
Next cell
data_to_array = arrArray
End Function
Private Function data_to_array2(data As Range)
Dim arrArray As Variant, cell As Range, z As Long, v
v = data.Value
ReDim arrArray(1 To UBound(v, 1))
For z = 1 To UBound(v, 1)
arrArray = v(z, 1)
Next z
data_to_array2 = arrArray
End Function

Answer 2

You should be able to prevent unnecessary additional calculations by including
Application.EnableEvent = False
Application.Calculation = xlManual
at the start of your functions and
Application.EnableEvents = True
Application.Calculation = xlAutomatic
at the end of your functions. This prevents your spreadsheet from attempting to update and recalculate whenever you make a minor change. If you feel it necessary, you can add
Worksheet.Calculate
at some point in your code to force a recalculation of the current sheet.