TESTING/LIN/sgbt01.f(3)

NAME
TESTING/LIN/sgbt01.f

SYNOPSIS

  Functions/Subroutines
subroutine sgbt01 (m, n, kl, ku, a, lda, afac, ldafac, ipiv, work, resid)
SGBT01

Function/Subroutine Documentation

  subroutine sgbt01 (integer m, integer n, integer kl, integer ku, real, dimension( lda, * ) a, integer lda, real, dimension( ldafac, * ) afac, integer ldafac, integer, dimension( * ) ipiv, real, dimension( * ) work, real resid)

SGBT01

Purpose:

    !>
    !> SGBT01 reconstructs a band matrix A from its L*U factorization and
    !> computes the residual:
    !>    norm(L*U - A) / ( N * norm(A) * EPS ),
    !> where EPS is the machine epsilon.
    !>
    !> The expression L*U - A is computed one column at a time, so A and
    !> AFAC are not modified.
    !>

Parameters
    M

    !>          M is INTEGER
    !>          The number of rows of the matrix A.  M >= 0.
    !>

    N

    !>          N is INTEGER
    !>          The number of columns 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.
    !>

    A

    !>          A is REAL array, dimension (LDA,N)
    !>          The original matrix A in band storage, stored in rows 1 to
    !>          KL+KU+1.
    !>

    LDA

    !>          LDA is INTEGER.
    !>          The leading dimension of the array A.  LDA >= max(1,KL+KU+1).
    !>

    AFAC

    !>          AFAC is REAL array, dimension (LDAFAC,N)
    !>          The factored form of the matrix A.  AFAC contains the banded
    !>          factors L and U from the L*U factorization, 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.  See SGBTRF for further details.
    !>

    LDAFAC

    !>          LDAFAC is INTEGER
    !>          The leading dimension of the array AFAC.
    !>          LDAFAC >= max(1,2*KL*KU+1).
    !>

    IPIV

    !>          IPIV is INTEGER array, dimension (min(M,N))
    !>          The pivot indices from SGBTRF.
    !>

    WORK

    !>          WORK is REAL array, dimension (2*KL+KU+1)
    !>

    RESID

    !>          RESID is REAL
    !>          norm(L*U - A) / ( N * norm(A) * EPS )
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 124 of file sgbt01.f.

Author

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