SRC/sgbcon.f(3)            Library Functions Manual            SRC/sgbcon.f(3)

NAME
       SRC/sgbcon.f

SYNOPSIS
   Functions/Subroutines
       subroutine sgbcon (norm, n, kl, ku, ab, ldab, ipiv, anorm, rcond, work,
           iwork, info)
           SGBCON

Function/Subroutine Documentation
   subroutine sgbcon (character norm, integer n, integer kl, integer ku, real,
       dimension( ldab, * ) ab, integer ldab, integer, dimension( * ) ipiv,
       real anorm, real rcond, real, dimension( * ) work, integer, dimension(
       * ) iwork, integer info)
       SGBCON

       Purpose:


            SGBCON estimates the reciprocal of the condition number of a real
            general band matrix A, in either the 1-norm or the infinity-norm,
            using the LU factorization computed by SGBTRF.

            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.

           KL

                     KL is INTEGER
                     The number of subdiagonals within the band of A.  KL >= 0.

           KU

                     KU is INTEGER
                     The number of superdiagonals within the band of A.  KU >= 0.

           AB

                     AB is REAL array, dimension (LDAB,N)
                     Details of the LU factorization of the band matrix A, as
                     computed by SGBTRF.  U is stored as an upper triangular band
                     matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and
                     the multipliers used during the factorization are stored in
                     rows KL+KU+2 to 2*KL+KU+1.

           LDAB

                     LDAB is INTEGER
                     The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.

           IPIV

                     IPIV is INTEGER array, dimension (N)
                     The pivot indices; for 1 <= i <= N, row i of the matrix was
                     interchanged with row IPIV(i).

           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 (3*N)

           IWORK

                     IWORK is INTEGER array, dimension (N)

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0: if INFO = -i, the i-th argument had an illegal value

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 144 of file sgbcon.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                 SRC/sgbcon.f(3)