// V(x + y) = V(x) + V(y)
protected override Expression VisitSum(Sum A)
{
return Sum.New(A.Terms.Select(i => Visit(i)));
}
protected override Expression VisitSum(Sum A)
{
return Sum.New(A.Terms.Select(i => Visit(i)).Where(i => !i.EqualsZero()));
}
protected override Expression VisitSum(Sum A)
{
return EvaluateSum(A.Terms.SelectMany(i => Sum.TermsOf(Visit(i))));
}
protected override string VisitSum(Sum A)
{
int pr = Parser.Precedence(Operator.Add);
StringBuilder s = new StringBuilder();
s.Append(Visit(A.Terms.First(), pr));
foreach (Expression i in A.Terms.Skip(1))
{
string si = Visit(i, pr);
if (si[0] != '-')
s.Append("+");
s.Append(si);
}
return s.ToString();
}
public Expression Solve(Expression x)
{
return(Unary.Negate(Sum.New(this.Where(i => !i.Key.Equals(x)).Select(i => Product.New(i.Key, i.Value)))) / this[x]);
}
// Expression operators.
public static LazyExpression operator +(LazyExpression L, LazyExpression R)
{
return(new LazyExpression(Sum.New(L.value, R.value)));
}
public static LazyExpression operator -(LazyExpression L, LazyExpression R)
{
return(new LazyExpression(Sum.New(L.value, Unary.Negate(R.value))));
}