TESTING/LIN/dgbt01.f(3)

NAME
TESTING/LIN/dgbt01.f

SYNOPSIS

  Functions/Subroutines
subroutine dgbt01 (m, n, kl, ku, a, lda, afac, ldafac, ipiv, work, resid)
DGBT01

Function/Subroutine Documentation

  subroutine dgbt01 (integer m, integer n, integer kl, integer ku, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldafac, * ) afac, integer ldafac, integer, dimension( * ) ipiv, double precision, dimension( * ) work, double precision resid)

DGBT01

Purpose:

     DGBT01 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 DOUBLE PRECISION 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 DOUBLE PRECISION 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
              DGBTRF.  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 DGBTRF 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 DGBTRF.

    WORK

              WORK is DOUBLE PRECISION array, dimension (2*KL+KU+1)

    RESID

              RESID is DOUBLE PRECISION
              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 dgbt01.f.

Author

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