The n×nn\times nn×n identity matrix InI_nIn is the n×nn\times nn×n matrix whose entries (aij)(a_{ij})(aij) are such that aij=1a_{ij}=1aij=1 when i=ji=ji=j and 000 otherwise. That is, aij=δija_{ij} = \delta_{ij}aij=δij where δij\delta_{ij}δij is the Kronecker delta.
Wikidata ID: Q193794