dla_gbrcond.f(3)

NAME
dla_gbrcond.f -

SYNOPSIS

  Functions/Subroutines
DOUBLE PRECISION function DLA_GBRCOND (TRANS, N, KL, KU, AB, LDAB, AFB, LDAFB, IPIV, CMODE, C, INFO, WORK, IWORK)
DLA_GBRCOND

Function/Subroutine Documentation

  DOUBLE PRECISION function DLA_GBRCOND (CHARACTERTRANS, INTEGERN, INTEGERKL, INTEGERKU, DOUBLE PRECISION, dimension( ldab, * )AB, INTEGERLDAB, DOUBLE PRECISION, dimension( ldafb, * )AFB, INTEGERLDAFB, INTEGER, dimension( * )IPIV, INTEGERCMODE, DOUBLE PRECISION, dimension( * )C, INTEGERINFO, DOUBLE PRECISION, dimension( * )WORK, INTEGER, dimension( * )IWORK)

DLA_GBRCOND

Purpose:

        DLA_GBRCOND Estimates the Skeel condition number of  op(A) * op2(C)
        where op2 is determined by CMODE as follows
        CMODE =  1    op2(C) = C
        CMODE =  0    op2(C) = I
        CMODE = -1    op2(C) = inv(C)
        The Skeel condition number  cond(A) = norminf( |inv(A)||A| )
        is computed by computing scaling factors R such that
        diag(R)*A*op2(C) is row equilibrated and computing the standard
        infinity-norm condition number.

Parameters:
    TRANS

              TRANS is CHARACTER*1
         Specifies the form of the system of equations:
           = 'N':  A * X = B     (No transpose)
           = 'T':  A**T * X = B  (Transpose)
           = 'C':  A**H * X = B  (Conjugate Transpose = Transpose)

    N

              N is INTEGER
         The number of linear equations, i.e., 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 DOUBLE PRECISION array, dimension (LDAB,N)
         On entry, the matrix A in band storage, in rows 1 to KL+KU+1.
         The j-th column of A is stored in the j-th column of the
         array AB as follows:
         AB(KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+kl)

    LDAB

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

    AFB

              AFB is DOUBLE PRECISION array, dimension (LDAFB,N)
         Details of the LU factorization of the band matrix A, 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.

    LDAFB

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

    IPIV

              IPIV is INTEGER array, dimension (N)
         The pivot indices from the factorization A = P*L*U
         as computed by DGBTRF; row i of the matrix was interchanged
         with row IPIV(i).

    CMODE

              CMODE is INTEGER
         Determines op2(C) in the formula op(A) * op2(C) as follows:
         CMODE =  1    op2(C) = C
         CMODE =  0    op2(C) = I
         CMODE = -1    op2(C) = inv(C)

    C

              C is DOUBLE PRECISION array, dimension (N)
         The vector C in the formula op(A) * op2(C).

    INFO

              INFO is INTEGER
           = 0:  Successful exit.
         i > 0:  The ith argument is invalid.

    WORK

              WORK is DOUBLE PRECISION array, dimension (5*N).
         Workspace.

    IWORK

              IWORK is INTEGER array, dimension (N).
         Workspace.

Author:
    Univ'. of Tennessee

    Univ'. of California Berkeley

    Univ'. of Colorado Denver

    NAG Ltd'.

Date:
    November 2011

Definition at line 169 of file dla_gbrcond.f'.

Author

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