Mathematics    

The Identity Matrix

Generally accepted mathematical notation uses the capital letter I to denote identity matrices, matrices of various sizes with ones on the main diagonal and zeros elsewhere. These matrices have the property that AI = A and IA = A whenever the dimensions are compatible. The original version of MATLAB could not use I for this purpose because it did not distinguish between upper and lowercase letters and i already served double duty as a subscript and as the complex unit. So an English language pun was introduced. The function

returns an m-by-n rectangular identity matrix and eye(n) returns an n-by-n square identity matrix.


 Matrix Multiplication The Kronecker Tensor Product