DIndexQ

• DIndexQ[expr] gives True if expr is a valid directional-index.
• DIndexQ[expr, vbundle] gives True if expr is a valid directional-index belonging to vbundle or to a subvbundle of vbundle.

• A directional index always has head Dir and a single free index, which can be either covariant or contravariant.
• There is an internal check on the validity of the ultraindex of the expression.
• See: Section 2.4.
• See also: CDIndexQ, GIndexQ.
• New in version 0.
• Last update: 24-IX-2007 for version 0.9.3 of xTensor`.

Created by Mathematica  (May 16, 2008)