# ImplicitIndex

Indicates that an object carries indices which are not written out.

Indicates that the object carries implicit indices, e.g. for objects
representing matrices or vectors. Such objects will not be moved
through each other, i.e. they are mutually noncommuting.{M,A}::ImplicitIndex;
ex:=M A;
sort_product(_);

\(\displaystyle{}\text{Attached property ImplicitIndex to }(M, A).\)

\(\displaystyle{}M A\)

\(\displaystyle{}M A\)

Without the

`ImplicitIndex`

property, `sort_product`

would have freely moved the objects through each other.
For more information on how to use matrices and vectors with implicit
indices, see

`expand`

.