dpocon (l)  Linux Man Pages
dpocon: estimates the reciprocal of the condition number (in the 1norm) of a real symmetric positive definite matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPOTRF
Command to display dpocon
manual in Linux: $ man l dpocon
NAME
DPOCON  estimates the reciprocal of the condition number (in the 1norm) of a real symmetric positive definite matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPOTRF
SYNOPSIS
 SUBROUTINE DPOCON(

UPLO, N, A, LDA, ANORM, RCOND, WORK, IWORK,
INFO )

CHARACTER
UPLO

INTEGER
INFO, LDA, N

DOUBLE
PRECISION ANORM, RCOND

INTEGER
IWORK( * )

DOUBLE
PRECISION A( LDA, * ), WORK( * )
PURPOSE
DPOCON estimates the reciprocal of the condition number (in the
1norm) of a real symmetric positive definite matrix using the
Cholesky factorization A = U**T*U or A = L*L**T computed by DPOTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
ARGUMENTS
 UPLO (input) CHARACTER*1

= aqUaq: Upper triangle of A is stored;
= aqLaq: Lower triangle of A is stored.
 N (input) INTEGER

The order of the matrix A. N >= 0.
 A (input) DOUBLE PRECISION array, dimension (LDA,N)

The triangular factor U or L from the Cholesky factorization
A = U**T*U or A = L*L**T, as computed by DPOTRF.
 LDA (input) INTEGER

The leading dimension of the array A. LDA >= max(1,N).
 ANORM (input) DOUBLE PRECISION

The 1norm (or infinitynorm) of the symmetric matrix A.
 RCOND (output) DOUBLE PRECISION

The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
estimate of the 1norm of inv(A) computed in this routine.
 WORK (workspace) DOUBLE PRECISION array, dimension (3*N)

 IWORK (workspace) INTEGER array, dimension (N)

 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
Pages related to dpocon
 dpocon (3)
 dpoequ (l)  computes row and column scalings intended to equilibrate a symmetric positive definite matrix A and reduce its condition number (with respect to the twonorm)
 dpoequb (l)  computes row and column scalings intended to equilibrate a symmetric positive definite matrix A and reduce its condition number (with respect to the twonorm)
 dporfs (l)  improves the computed solution to a system of linear equations when the coefficient matrix is symmetric positive definite,
 dporfsx (l)  DPORFSX improve the computed solution to a system of linear equations when the coefficient matrix is symmetric positive definite, and provides error bounds and backward error estimates for the solution
 dposv (l)  computes the solution to a real system of linear equations A * X = B,
 dposvx (l)  uses the Cholesky factorization A = U**T*U or A = L*L**T to compute the solution to a real system of linear equations A * X = B,
 dposvxx (l)  DPOSVXX use the Cholesky factorization A = U**T*U or A = L*L**T to compute the solution to a double precision system of linear equations A * X = B, where A is an NbyN symmetric positive definite matrix and X and B are NbyNRHS matrices