Let A be a symmetric n x n matrix.

Two m x n matrices are row equivalent if and only if they have the same row space.

Let A be a complex n x n matrix, with entries .

Here is the n by n matrix of second derivatives evaluated at the minimum of the function.

We would also like to mention the best circuit known for the permanent of an n by n matrix.

Let A be an n x n matrix.

In general, the direct sum of n matrices is:

Let A be an m x n matrix and b an m-dimensional vector.

Let A be the given n x n matrix.

This is usually referred to as the "full ring of n by n matrices".