# Routines for Estimating the Condition Number

This section describes the LAPACK routines for estimating the condition number of a matrix. The condition number is used for analyzing the errors in the solution of a system of linear equations (see Error Analysis). Since the condition number may be arbitrarily large when the matrix is nearly singular, the routines actually compute the reciprocal condition number.

- ?gecon
  Estimates the reciprocal of the condition number of a general matrix in the 1-norm or the infinity-norm.
- ?gbcon
  Estimates the reciprocal of the condition number of a band matrix in the 1-norm or the infinity-norm.
- ?gtcon
  Estimates the reciprocal of the condition number of a tridiagonal matrix using the factorization computed by ?gttrf.
- ?pocon
  Estimates the reciprocal of the condition number of a symmetric (Hermitian) positive-definite matrix.
- ?ppcon
  Estimates the reciprocal of the condition number of a packed symmetric (Hermitian) positive-definite matrix.
- ?pbcon
  Estimates the reciprocal of the condition number of a symmetric (Hermitian) positive-definite band matrix.
- ?ptcon
  Estimates the reciprocal of the condition number of a symmetric (Hermitian) positive-definite tridiagonal matrix.
- ?sycon
  Estimates the reciprocal of the condition number of a symmetric matrix.
- ?hecon
  Estimates the reciprocal of the condition number of a Hermitian matrix.
- ?spcon
  Estimates the reciprocal of the condition number of a packed symmetric matrix.
- ?hpcon
  Estimates the reciprocal of the condition number of a packed Hermitian matrix.
- ?trcon
  Estimates the reciprocal of the condition number of a triangular matrix.
- ?tpcon
  Estimates the reciprocal of the condition number of a packed triangular matrix.
- ?tbcon
  Estimates the reciprocal of the condition number of a triangular band matrix.

Parent topic: Computational Routines