MightyLittleGeodesy.Positions.WGS84Position.ParseValueFromDmString C# (CSharp) Method

        private double ParseValueFromDmString(string value, char positiveChar)
        {
            if (string.IsNullOrEmpty(value))
            {
                return double.MinValue;
            }

            var direction = value[0];
            value = value.Substring(1).Trim();

            var index = value.IndexOf("º", StringComparison.Ordinal);
            var degree = value.Substring(0, index);
            value = value.Substring(index + 1).Trim();

            var minutes = value.Substring(0, value.IndexOf("'", StringComparison.Ordinal));

            double retVal = double.Parse(degree);
            retVal += double.Parse(minutes, CultureInfo.InvariantCulture) / 60;

            if (retVal > 90)
            {
               return double.MinValue;
            }

            if (direction == positiveChar || direction == '-')
            {
                retVal *= -1;
            }

            return retVal;
        }