//public string Representation { get; set; }

        public DisplacementVector(string displacementVectorFormat)
        {
            if (RegexPatterns.DisplacementVector.IsMatch(displacementVectorFormat))
            {
                var pairs  = displacementVectorFormat.Split(new string[] { "|" }, StringSplitOptions.RemoveEmptyEntries);
                var top    = new Expression(pairs[0]);
                var bottom = new Expression(pairs[1]);
                DispVector = new TopBottom <Expression, Expression>(top, bottom);
            }
            else
            {
                throw new ArgumentException("Must use proper format");
            }
        }
 public DisplacementVector(TopBottom <Expression, Expression> value)
 {
     DispVector = value;
 }
 public DisplacementVector(Expression horizontal, Expression vertical)
 {
     DispVector = new TopBottom <Expression, Expression>(horizontal, vertical);
 }