The input expression e is assumed to be a polynomial expressed in terms of a Chebyshev basis .

First the expression e is collected in 'T'. Then the terms in the collected polynomial expression are sorted in ``Chebyshev order'';  i.e. the  basis polynomials are ordered in ascending order with respect to the first argument.

If some basis polynomials  have non-numeric first argument then ordering will be attempted using the ``is'' predicate. If that is not successful then ordering is performed only with respect to numeric first arguments (other terms are left as trailing terms).

Note that chebsort is a destructive operation because it invokes the Maple sort function (see ?sort);  i.e. the input expression is sorted ``in-place''.

The command with(numapprox,chebsort) allows the use of the abbreviated form of this command.