# sgecon(3) [centos man page]

sgecon.f(3) LAPACK sgecon.f(3)NAME

sgecon.f-SYNOPSIS

Functions/Subroutines subroutine sgecon (NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO) SGECONFunction/Subroutine Documentation subroutine sgecon (characterNORM, integerN, real, dimension( lda, * )A, integerLDA, realANORM, realRCOND, real, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO) SGECON Purpose: SGECON estimates the reciprocal of the condition number of a general real matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by SGETRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / ( norm(A) * norm(inv(A)) ). Parameters: NORM NORM is CHARACTER*1 Specifies whether the 1-norm condition number or the infinity-norm condition number is required: = '1' or 'O': 1-norm; = 'I': Infinity-norm. N N is INTEGER The order of the matrix A. N >= 0. A A is REAL array, dimension (LDA,N) The factors L and U from the factorization A = P*L*U as computed by SGETRF. LDA LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). ANORM ANORM is REAL If NORM = '1' or 'O', the 1-norm of the original matrix A. If NORM = 'I', the infinity-norm of the original matrix A. RCOND RCOND is REAL The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))). WORK WORK is REAL array, dimension (4*N) IWORK IWORK is INTEGER array, dimension (N) INFO INFO is INTEGER = 0: successful exit < 0: if INFO =, the i-th argument had an illegal value Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: November 2011 Definition at line 124 of file sgecon.f.-iAuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 sgecon.f(3)

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SGECON(l)) SGECON(l)NAME

SGECON - estimate the reciprocal of the condition number of a general real matrix A, in either the 1-norm or the infinity-norm, 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 1-norm or the infinity-norm, using the LU factorization computed by SGETRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / ( norm(A) * norm(inv(A)) ).ARGUMENTS

NORM (input) CHARACTER*1 Specifies whether the 1-norm condition number or the infinity-norm condition number is required: = '1' or 'O': 1-norm; = 'I': Infinity-norm. 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 = '1' or 'O', the 1-norm of the original matrix A. If NORM = 'I', the infinity-norm 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 =, the i-th argument had an illegal value-iLAPACK version 3.015 June 2000 SGECON(l)