protected override Expression VisitPower(Power P)
{
Expression L = Visit(P.Left);
Expression R = Visit(P.Right);
if (R.IsInteger())
{
// Transform (x*y)^z => x^z*y^z if z is an integer.
Product M = L as Product;
if (!ReferenceEquals(M, null))
{
return(Visit(Product.New(M.Terms.Select(i => Power.New(i, R)))));
}
}
// Transform (x^y)^z => x^(y*z) if z is an integer.
Power LP = L as Power;
if (!ReferenceEquals(LP, null))
{
L = LP.Left;
R = Visit(Product.New(P.Right, LP.Right));
}
// Handle identities.
Real?LR = AsReal(L);
if (EqualsZero(LR))
{
return(0);
}
if (EqualsOne(LR))
{
return(1);
}
Real?RR = AsReal(R);
if (EqualsZero(RR))
{
return(1);
}
if (EqualsOne(RR))
{
return(L);
}
// Evaluate result.
if (LR != null && RR != null)
{
return(Constant.New(LR.Value ^ RR.Value));
}
else
{
return(Power.New(L, R));
}
}
/// <summary>
/// If x is of the form a^n where n is an integer, return n and replace x with a.
/// </summary>
/// <param name="x"></param>
/// <returns></returns>
public static int IntegralExponentOf(Expression x)
{
Expression n = ExponentOf(x);
if (n.IsInteger())
{
return((int)(Real)n);
}
return(1);
}
public override bool Contains(Expression x)
{
return(x.IsInteger());
}