The call type(expr, ratpoly(K, v)) checks to see if expr is a rational function in the variables v with coefficients in the domain K.

A typical calling sequence would be type(a, ratpoly(integer, x)) which tests to see if a is a rational polynomial in x over the integers.

The variable(s) v can be a single indeterminate or a list or set of indeterminates.  If v is omitted, then it defaults to a list of all indeterminates of type name in expr.

The domain specification K is a type name such as integer or algnum (algebraic number). If the domain specification is omitted, then it defaults to type constant.