Packed storage matrix

A packed storage matrix, also known as packed matrix, is a term used in programming for representing an $$m\times n$$ matrix. It is a more compact way than an m-by-n rectangular array by exploiting a special structure of the matrix.

Typical examples of matrices that can take advantage of packed storage include:
 * symmetric or hermitian matrix
 * Triangular matrix
 * Banded matrix.

Code examples (Fortran)
Both of the following storage schemes are used extensively in BLAS and LAPACK.

An example of packed storage for Hermitian matrix:

An example of packed storage for banded matrix: