SymbolicIdentityArray

represents an n₁×n₂×…×n₁×n₂×… array with elements a_{i₁,i₂,…,j₁,j₂,…} equal to 1 if all i_kj_k, and 0 otherwise.

Details

Valid dimension specifications n_i in SymbolicIdentityArray[{n₁,n₂,…}] are positive integers. It is also possible to work with symbolic dimension specifications.
SymbolicIdentityArray may be produced by differentiation involving ArraySymbol objects.
For an array a=SymbolicIdentityArray[{n₁,n₂,…}] with positive integer dimension specifications n_i, Normal[a] converts a to an explicit array. SparseArray[a] converts a to a SparseArray.

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The derivative of a symbolic array variable with respect to itself is a SymbolicIdentityArray:

Create a SymbolicIdentityArray with explicit numeric dimensions:

Convert a to an explicit array:

Convert a to a SparseArray:

Arithmetic operations:

Array operations:

SymbolicIdentityArray gives a symbolic representation of the array:

Use Normal to convert a to an explicit array:

IdentityMatrix[n] gives an explicit version of SymbolicIdentityArray[{n}]:

The derivative of a symbolic array variable with respect to itself is a SymbolicIdentityArray:

SymbolicIdentityArray objects are identity elements for ArrayDot:

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