private const string PatternForReplace = @"((\d+)[.,](\d+))";
        private Regex rgx = new Regex(PatternForReplace, RegexOptions.Compiled);
        private static CultureInfo cultureInfo = CultureInfo.CreateSpecificCulture("en-EN");
        private static NumberStyles numberStyles = NumberStyles.AllowDecimalPoint;

        private static string CapText(Match m)
        {
            var matchString = m.ToString().Replace(",",".");

            double dummy;
            if (double.TryParse(matchString, numberStyles, cultureInfo, out dummy))
                return matchString + "m";
            else
                return matchString;
        }

var matchString = m.ToString().Replace(",",".");