Identity matrix

In linear algebra, the identity matrix of size n is the n × n square matrix with ones on the main diagonal and zeros elsewhere. It is denoted by In, or simply by I if the size is immaterial or can be trivially determined by the context. The term unit matrix has also been widely used, but the term identity matrix is now standard. The term unit matrix is ambiguous, because it is also used for a matrix of ones and for any unit of the ring of all n×n matrices. When A is m×n, it is a property of matrix multiplication that The identity matrix can also be written using the Kronecker delta notation:

Identity matrix

In linear algebra, the identity matrix of size n is the n × n square matrix with ones on the main diagonal and zeros elsewhere. It is denoted by In, or simply by I if the size is immaterial or can be trivially determined by the context. The term unit matrix has also been widely used, but the term identity matrix is now standard. The term unit matrix is ambiguous, because it is also used for a matrix of ones and for any unit of the ring of all n×n matrices. When A is m×n, it is a property of matrix multiplication that The identity matrix can also be written using the Kronecker delta notation: