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.
• ?syconv
  Converts a symmetric matrix given by a triangular matrix factorization into two matrices and vice versa.
• ?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.