The call type(expr, radalgnum) checks if expr is an algebraic number in RootOf or radical notation.

An algebraic number is defined as either a rational number, a root of a univariate polynomial with algebraic number coefficients, specified by a RootOf, or an n-th root of an algebraic number. A sum, product, or quotient of these is also an algebraic number.

For example, both   and RootOf(z^2-2, z) are of type radalgnum.