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In [[mathematics]], a '''bidiagonal matrix''' is a [[banded matrix]] with non-zero entries along the main diagonal and ''either'' the diagonal above or the diagonal below. This means there are exactly two non zero diagonals in the matrix.
In [[mathematics]], a '''bidiagonal matrix''' is a [[banded matrix]] with non-zero entries along the main diagonal and ''either'' the diagonal above or the diagonal below. This means there are exactly two non-zero diagonals in the matrix.


When the diagonal above the main diagonal has the non-zero entries the matrix is '''upper bidiagonal'''. When the diagonal below the main diagonal has the non-zero entries the matrix is '''lower bidiagonal'''.
When the diagonal above the main diagonal has the non-zero entries the matrix is '''upper bidiagonal'''. When the diagonal below the main diagonal has the non-zero entries the matrix is '''lower bidiagonal'''.
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* [[List of matrices]]
* [[List of matrices]]
* [[LAPACK]]
* [[LAPACK]]
* [[Hessenberg form]] The Hessenberg form is similar, but has more non zero diagonal lines than 2.
* [[Hessenberg form]] The Hessenberg form is similar, but has more non-zero diagonal lines than 2.


==References==
==References==

Revision as of 02:00, 25 February 2022

In mathematics, a bidiagonal matrix is a banded matrix with non-zero entries along the main diagonal and either the diagonal above or the diagonal below. This means there are exactly two non-zero diagonals in the matrix.

When the diagonal above the main diagonal has the non-zero entries the matrix is upper bidiagonal. When the diagonal below the main diagonal has the non-zero entries the matrix is lower bidiagonal.

For example, the following matrix is upper bidiagonal:

and the following matrix is lower bidiagonal:

Usage

One variant of the QR algorithm starts with reducing a general matrix into a bidiagonal one,[1] and the Singular value decomposition uses this method as well.

Bidiagonalization

See also

References

  • Stewart, G. W. (2001) Matrix Algorithms, Volume II: Eigensystems. Society for Industrial and Applied Mathematics. ISBN 0-89871-503-2.
  1. ^ Bochkanov Sergey Anatolyevich. ALGLIB User Guide - General Matrix operations - Singular value decomposition . ALGLIB Project. 2010-12-11. URL:http://www.alglib.net/matrixops/general/svd.php. Accessed: 2010-12-11. (Archived by WebCite at https://www.webcitation.org/5utO4iSnR)