Convert cell formula to VBA

[Oxalate]

Hello, is there a hero to help me convert a cell formula to VBA code with a custom function?
The cell formula takes 2 selected values and calculates the difference between them, and then shows the result as "xx % difference".
The difference is always calculated in regards to the higher value:

(higher value - lower value)/higher value * 100 %
So the funktion has to check which vaule is higher and then do the calculation.

The problem is that in the cell there is not always just a number (that would be easy), but sometimes the cell is made of text and numbers e.g. "< LOQ (0.05)", so the formula has to "extract" the number and then calculate further. I have made a cell function but its really long and i have to adjust the cell reference multiple times.
Could someone please make a custom named VBA function where I select the cells and excel does the rest, for example =difference(A1,A2).

This is the function (of course any function that works will be ok too):

IF(OR(A1="< limit ",A2="< limit "),"Value close to or at limit",IFERROR(IF(A1>=A2,ROUND((((A1-A2)/A1)*100),0)&" % Difference",ROUND((((A2-A1)/A2)*100),0)&" % Difference"),IF(--MID(A1,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A1),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A1,".",0),",",0),ROW($1:$100),1)))>=--MID(A2,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A2),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A2,".",0),",",0),ROW($1:$100),1))),ROUND((((--MID(A1,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A1),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A1,".",0),",",0),ROW($1:$100),1)))---MID(A2,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A2),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A2,".",0),",",0),ROW($1:$100),1))))/--MID(A1,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A1),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A1,".",0),",",0),ROW($1:$100),1))))*100),0)&" % Difference",ROUND((((--MID(A2,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A2),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A2,".",0),",",0),ROW($1:$100),1)))---MID(A1,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A1),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A1,".",0),",",0),ROW($1:$100),1))))/--MID(A2,MIN(IFERROR(FIND({0,1,2,3,4,5,6,7,8,9,".",","},A2),"")),COUNT(--MID(SUBSTITUTE(SUBSTITUTE(A2,".",0),",",0),ROW($1:$100),1))))*100),0)&" % Difference")))

Thank you in advance.

 

[wideboydixon]

Book1
	A	B	C
1	< LOQ(0.05)	0.06	16.67 % difference
2	7	5	28.57 % difference
3	0.5 0.6	0.7	#ERROR
4	< limit	3	Value close to or at limit
5	100	99	1.00 % difference
Sheet1

Cell Formulas
Range	Formula
C1	=GetDifference(A1,B1)

Private regex As Object
Public Function GetDifference(range1 As Range, range2 As Range) As String

Dim matches1 As Object
Dim matches2 As Object
Dim value1 As Double
Dim value2 As Double
Dim diffValue As Double

' Set up the object
If regex Is Nothing Then Set regex = CreateObject("VBScript.RegExp")

' Check for special condition
If Left$(range1.Value, 7) = "< limit" Or Left$(range2.Value, 7) = "< limit" Then
    GetDifference = "Value close to or at limit"
    Exit Function
End If

' Find the numbers in the ranges
With regex
    .Pattern = "([\d\.,]+)"
    .Global = True
    Set matches1 = .Execute(range1.Value)
    Set matches2 = .Execute(range2.Value)
End With

' Check there's only one number
If matches1.Count <> 1 Or matches2.Count <> 1 Then
    GetDifference = "#ERROR"
    Exit Function
End If

' Get the values
value1 = CDbl(matches1(0).Value)
value2 = CDbl(matches2(0).Value)

' Calculate the % difference
If value1 > value2 Then
    diffValue = (value1 - value2) / value1 * 100
Else
    diffValue = (value2 - value1) / value2 * 100
End If

' Format the result
GetDifference = Format$(diffValue, "0.00") & " % difference"

End Function

WBD