Kind of like a unit vector, but it's a matrix.
For example, if the notation is $A_{ij}$, then this matrix has all zero elements, except $a_{ij} = 1$.
Is there a common notation/term for this kind of matrix?
The goal is to write something like: for a matrix $B$, then $B + A_{12}$ gives the same matrix but one element at $(1,2)$ is incremented.
Is there a better notation for this goal?
Thanks!
You could use any letter you want to use for a single-entry matrix, as long as you define it, but $e$ is a nice choice (e.g., $e_{12}$), since $e$ is often used for basis vectors, and the single-entry matrices form a basis of matrices as a vector space.