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

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