Singular matrix

A singular matrix is a square matrix that does not have an inverse. In other words, if A is a singular matrix, then there does not exist a matrix B such that AB = BA = I, where I is the identity matrix. An intuitive way to think of a singular matrix is that it has "redundant" or "dependent" rows or columns, such that they can be expressed as linear combinations of the other rows or columns. Singular matrices are also sometimes referred to as degenerate matrices.