FindFreeIndices

• FindFreeIndices[expr] gives an IndexList with the (order not kept) free indices of expr, throwing an error if they are not homogeneous in all terms of expr.

• FindFreeIndices always returns a list of indices with head IndexList, to avoid confusion with the notation for basis and component indices.
• Indices in expressions with free ultraindices and indices in Scalar expressions or scalar-functions are not found.
• FindFreeIndices has attribute HoldFirst, and hence requires very often the use of Evaluate.
• Only abstract and basis indices can be free.
• See: Section 2.7.
• See also: FindIndices, FindDummyIndices, FindBlockedIndices.
• New in version 0.
• Last update: 15-V-2008 for version 0.9.5 of xTensor`.

Created by Mathematica  (May 16, 2008)