** Next:** Unit Triangular Matrices
** Up:** Matrix Storage Schemes
** Previous:** Band Storage
** Contents**
** Index**

##

Tridiagonal and Bidiagonal Matrices

An unsymmetric
tridiagonal matrix of order *n* is stored in
three one-dimensional arrays, one of length *n* containing the
diagonal elements, and two of length *n*-1 containing the
subdiagonal and superdiagonal elements in elements **1:***n*-1.

A symmetric tridiagonal or
bidiagonal matrix is stored in
two one-dimensional arrays, one of length *n* containing the
diagonal elements, and one of length *n*-1 containing the
off-diagonal elements. (EISPACK routines store the off-diagonal
elements in elements **2:***n* of a vector of length *n*.)

*Susan Blackford*

*1999-10-01*