showrecursive(id,p[,ord]); id any object of basering, p= product of
variables and ord=string (any allowed ordstr)
Display:
display 'id' in a recursive format as a polynomial in the variables
occurring in p with coefficients in the remaining variables. This is
done by mapping to a ring with parameters [and ordering 'ord',
if a 3rd argument is present (default: ord="dp")] and applying
procedure 'show'