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

NAME
       SRC/spbcon.f

SYNOPSIS
   Functions/Subroutines
       subroutine spbcon (uplo, n, kd, ab, ldab, anorm, rcond, work, iwork,
           info)
           SPBCON

Function/Subroutine Documentation
   subroutine spbcon (character uplo, integer n, integer kd, real, dimension(
       ldab, * ) ab, integer ldab, real anorm, real rcond, real, dimension( *
       ) work, integer, dimension( * ) iwork, integer info)
       SPBCON

       Purpose:


            SPBCON estimates the reciprocal of the condition number (in the
            1-norm) of a real symmetric positive definite band matrix using the
            Cholesky factorization A = U**T*U or A = L*L**T computed by SPBTRF.

            An estimate is obtained for norm(inv(A)), and the reciprocal of the
            condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).

       Parameters
           UPLO

                     UPLO is CHARACTER*1
                     = 'U':  Upper triangular factor stored in AB;
                     = 'L':  Lower triangular factor stored in AB.

           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           KD

                     KD is INTEGER
                     The number of superdiagonals of the matrix A if UPLO = 'U',
                     or the number of subdiagonals if UPLO = 'L'.  KD >= 0.

           AB

                     AB is REAL array, dimension (LDAB,N)
                     The triangular factor U or L from the Cholesky factorization
                     A = U**T*U or A = L*L**T of the band matrix A, stored in the
                     first KD+1 rows of the array.  The j-th column of U or L is
                     stored in the j-th column of the array AB as follows:
                     if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j;
                     if UPLO ='L', AB(1+i-j,j)    = L(i,j) for j<=i<=min(n,j+kd).

           LDAB

                     LDAB is INTEGER
                     The leading dimension of the array AB.  LDAB >= KD+1.

           ANORM

                     ANORM is REAL
                     The 1-norm (or infinity-norm) of the symmetric band matrix A.

           RCOND

                     RCOND is REAL
                     The reciprocal of the condition number of the matrix A,
                     computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
                     estimate of the 1-norm of inv(A) computed in this routine.

           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 130 of file spbcon.f.

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

LAPACK                          Version 3.12.0                 SRC/spbcon.f(3)