Usage:
<l_dual0 d J f
Given an integer d, compute
J = (x1^d, ..., xn^d), and
f = x1^(d-1).x2^(d-1)...xn^(d-1)
where the variables in the current ring are x1, ..., xn.
Parameters:
d = an integer expression.
Output values:
J = a 1xn matrix
f = a 1x1 matrix.
This script is used in "<l_from_dual" and "<l_to_dual". The current
ring may be a quotient ring.