Accord.Math.Optimization.QuadraticObjectiveFunction.parseString C# (CSharp) Method

        private static Dictionary<Tuple<string, string>, double> parseString(string f, CultureInfo culture)
        {
            f = f.Replace("*", String.Empty).Replace(" ", String.Empty);

            var terms = new Dictionary<Tuple<string, string>, double>();

            Regex replaceQuad = new Regex(@"([a-zA-Z])(²)");
            f = replaceQuad.Replace(f, "$1$1");


            string separator = culture.NumberFormat.NumberDecimalSeparator;

            Regex r = new Regex(@"[\-\+]?[\s]*((\d*\" + separator + @"{0,1}\d+)|[a-zA-Z][²]?)+");
            Regex number = new Regex(@"\d*\" + separator + @"{0,1}\d+");
            Regex symbol = new Regex(@"[a-zA-Z]");


            MatchCollection matches = r.Matches(f, 0);

            foreach (Match m in matches)
            {
                string term = m.Value;

                double scalar = (term[0] == '-') ? -1 : 1;

                // Extract value
                MatchCollection coeff = number.Matches(term);

                foreach (Match c in coeff)
                    scalar *= Double.Parse(c.Value, culture);

                // Extract symbols
                MatchCollection symbols = symbol.Matches(term);

                if (symbols.Count == 1)
                    terms.Add(Tuple.Create(symbols[0].Value, (string)null), scalar);
                else if (symbols.Count == 2)
                    terms.Add(Tuple.Create(symbols[0].Value, symbols[1].Value), scalar);
                else
                    terms.Add(Tuple.Create((string)null, (string)null), scalar);
            }

            return terms;
        }