sgecon (l)  Linux Manuals
sgecon: estimates the reciprocal of the condition number of a general real matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by SGETRF
NAME
SGECON  estimates the reciprocal of the condition number of a general real matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by SGETRFSYNOPSIS
 SUBROUTINE SGECON(
 NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO )
 CHARACTER NORM
 INTEGER INFO, LDA, N
 REAL ANORM, RCOND
 INTEGER IWORK( * )
 REAL A( LDA, * ), WORK( * )
PURPOSE
SGECON estimates the reciprocal of the condition number of a general real matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by SGETRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed asRCOND
ARGUMENTS
 NORM (input) CHARACTER*1

Specifies whether the 1norm condition number or the
infinitynorm condition number is required:
= aq1aq or aqOaq: 1norm;
= aqIaq: Infinitynorm.  N (input) INTEGER
 The order of the matrix A. N >= 0.
 A (input) REAL array, dimension (LDA,N)
 The factors L and U from the factorization A = P*L*U as computed by SGETRF.
 LDA (input) INTEGER
 The leading dimension of the array A. LDA >= max(1,N).
 ANORM (input) REAL
 If NORM = aq1aq or aqOaq, the 1norm of the original matrix A. If NORM = aqIaq, the infinitynorm of the original matrix A.
 RCOND (output) REAL
 The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
 WORK (workspace) REAL array, dimension (4*N)
 IWORK (workspace) INTEGER array, dimension (N)
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value