WeylClosure -- Weyl closure of an ideal

Let $D$ be the Weyl algebra with generators $x_1,\dots,x_n$ and $\partial_1,\dots,\partial_n$ over a field $K$ of characteristic zero, and denote $R = K(x_1..x_n)<\partial_1..\partial_n>$, the ring of differential operators with rational function coefficients. The Weyl closure of an ideal $I$ in $D$ is the intersection of the extended ideal $R I$ with $D$. It consists of all operators which vanish on the common holomorphic solutions of $D$ and is thus analogous to the radical operation on a commutative ideal.

The partial Weyl closure of $I$ with respect to a polynomial $f$ is the intersection of the extended ideal $D[f^{-1}] I$ with $D$.

The Weyl closure is computed by localizing $D/I$ with respect to a polynomial $f$ vanishing on the singular locus, and computing the kernel of the map $D \to D/I \to (D/I)[f^{-1}]$.

The ideal I should be of finite holonomic rank, which can be tested manually by using the function holonomicRank. The Weyl closure of non-finite rank ideals or arbitrary submodules has not been implemented.