diff --git a/FractionStringConverter.vb b/FractionStringConverter.vb
index ed4ccfa..c3ff96d 100644
--- a/FractionStringConverter.vb
+++ b/FractionStringConverter.vb
@@ -89,7 +89,7 @@ Public Module FractionStringConverter
    End Function
 
    ' riceve la stringa sorgente e restituisce la nuova strunga in formato decimale (senza eseguire conversioni di unità)
-   Public Function StringFractionToStringDecimal(sVal As String, ByRef sValConverted As String) As Boolean
+   Public Function OldStringFractionToStringDecimal(sVal As String, ByRef sValConverted As String) As Boolean
       Dim dVal As Double = 0
       Dim bNegativeValue As Boolean = False
       ' dato in ingresso: sVal = 2'3"23/32
@@ -182,31 +182,82 @@ Public Module FractionStringConverter
       End If
    End Function
 
-   Public Function MyStringFractionToStringDecimal(sVal As String, ByRef sValConverted As String) As Boolean
-      Dim sPattern As String = "(-?) *(\d+ */? *\d*')? *(\d* */? *\d+-)? *(\d+ */? *\d* *"")?(\d+ */? *\d*)?"
+   Public Function StringFractionToStringDecimal(sVal As String, ByRef sValConverted As String) As Boolean
+      sValConverted = sVal
+      ' (-?) *(\d */? *\d*')? *(\d* */? *\d+-)? *(\d */? *\d* *""?)? *(\d */? *\d*)?
+      Dim sPattern As String = "(-?) *(\d */? *\d*')?( *(?(?=\d+ */ *\d+)\d+ */ *\d+|\d+)""?)*"
       Dim MyMatchCollection As MatchCollection = Regex.Matches(sVal, sPattern)
 
       For Each MyMatch As Match In MyMatchCollection
-         ' Loop over captures.
+         Dim bValueExists As Boolean = False
+         Dim bNegative As Boolean = False
+         Dim dFeet As Double = 0
+         Dim bFeet As Boolean = True
+         Dim dInch As Double = 0
+         Dim bInch As Boolean = True
+         Dim dFraction As Double = 0
+         Dim bFraction As Boolean = True
+         Dim sCurrValue As String = String.Empty
+         Dim sCurrValueConverted As String = String.Empty
+         Dim dCurrValueConverted As Double = 0
 
-         For Each MyGroup As Capture In MyMatch.Captures
+         For GroupIndex As Integer = 0 To MyMatch.Groups.Count - 1
+            Dim MyGroup As Group = MyMatch.Groups(GroupIndex)
             Dim sGroupVal As String = MyGroup.Value
-            Select Case MyGroup.Index
-               Case 1
-                  ' riconosco il segno "-" ad inizio stringa
-               Case 2
-                  ' riconosco il valore di Feet " ' "
-               Case 3
-                  ' ...?...
-               Case 4
-                  ' riconosco il valore di Inch " "" "
-               Case 5
-                  ' riconosco il valore di frazione
-            End Select
-
+            ' verifico che il gruppo non sia vuoto
+            If Not String.IsNullOrEmpty(sGroupVal) Or Not String.IsNullOrWhiteSpace(sGroupVal) Then
+               Select Case GroupIndex
+                  Case 0
+                     ' se il valore è vuoto allora passo a prossimo Match
+                     If String.IsNullOrEmpty(sGroupVal.Trim) Or String.IsNullOrWhiteSpace(sGroupVal.Trim) Then
+                        Exit For
+                     End If
+                     ' salvo il valore del membro dell'espressione che deve essere valutato
+                     sCurrValue = sGroupVal
+                     bValueExists = True
+                  Case 1
+                     ' riconosco il segno "-" ad inizio stringa
+                     bNegative = True
+                  Case 2
+                     ' riconosco il valore di Feet " ' "
+                     sGroupVal = sGroupVal.Replace("'"c, "")
+                     bFeet = StringToDouble(sGroupVal, dFeet)
+                  Case 3
+                     For CaptureIndex As Integer = 0 To MyGroup.Captures.Count - 1
+                        Dim MyCapture As Capture = MyGroup.Captures(CaptureIndex)
+                        Dim sCapture As String = MyCapture.Value
+                        Select Case CaptureIndex
+                           Case 0
+                              ' riconosco il valore in pollici
+                              sCapture = sCapture.Replace(""""c, "")
+                              bInch = StringToDouble(sCapture, dInch)
+                           Case 1
+                              ' riconosco il valore di frazione
+                              bFraction = StringToDouble(sCapture, dFraction)
+                        End Select
+                     Next
+               End Select
+            End If
          Next
-      Next
 
+         If bValueExists And bFeet And bInch And bFraction Then
+            ' ricavo il valore decimale
+            dCurrValueConverted = dFeet * 12 + dInch + dFraction
+            If bNegative Then dCurrValueConverted = -dCurrValueConverted
+            sCurrValueConverted = DoubleToString(dCurrValueConverted, 4)
+            ' sostituisco il valore calcolato nell'espressione iniziale
+            Dim nStartIndex As Integer = sValConverted.IndexOf(sCurrValue)
+            sValConverted = sValConverted.Remove(nStartIndex, sCurrValue.Count).Insert(nStartIndex, sCurrValueConverted)
+         End If
+         ' passo allavalutazione del prossimo membro dell'espressione
+      Next
+      Dim dValueConverted As Double = 0
+      If StringToDouble(sValConverted, dValueConverted) Then
+         sValConverted = DoubleToString(dValueConverted, 4)
+      Else
+         ' Errore lettura stringa: sCurrVal non è convertibile
+         Return False
+      End If
       Return True
    End Function