Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3 - solves the real quasi-triangular system   op(T)*p = scale*c, if LREAL = .TRUE

SYNOPSIS

       SUBROUTINE DLAQTR( LTRAN, LREAL, N, T, LDT, B, W, SCALE, X, WORK, INFO )

           LOGICAL        LREAL, LTRAN

           INTEGER        INFO, LDT, N

           DOUBLE         PRECISION SCALE, W

           DOUBLE         PRECISION B( * ), T( LDT, * ), WORK( * ), X( * )

PURPOSE

       DLAQTR solves the real quasi-triangular system
        or the complex quasi-triangular systems
                   op(T + iB)*(p+iq) = scale*(c+id),  if LREAL = .FALSE.
        in real arithmetic, where T is upper quasi-triangular.
        If LREAL = .FALSE., then the first diagonal block of T must be
        1 by 1, B is the specially structured matrix
                       B = [ b(1) b(2) ... b(n) ]
                           [       w            ]
                           [           w        ]
                           [              .     ]
                           [                 w  ]
        op(A) = A or A**T, A**T denotes the transpose of
        matrix A.
        On input, X = [ c ].  On output, X = [ p ].
                      [ d ]                  [ q ]
        This subroutine is designed for the condition number estimation
        in routine DTRSNA.

ARGUMENTS

        LTRAN   (input) LOGICAL
                On entry, LTRAN specifies the option of conjugate transpose:
                = .FALSE.,    op(T+i*B) = T+i*B,
                = .TRUE.,     op(T+i*B) = (T+i*B)**T.

        LREAL   (input) LOGICAL
                On entry, LREAL specifies the input matrix structure:
                = .FALSE.,    the input is complex
                = .TRUE.,     the input is real

        N       (input) INTEGER
                On entry, N specifies the order of T+i*B. N >= 0.

        T       (input) DOUBLE PRECISION array, dimension (LDT,N)
                On entry, T contains a matrix in Schur canonical form.
                If LREAL = .FALSE., then the first diagonal block of T mu
                be 1 by 1.

        LDT     (input) INTEGER
                The leading dimension of the matrix T. LDT >= max(1,N).

        B       (input) DOUBLE PRECISION array, dimension (N)
                On entry, B contains the elements to form the matrix
                B as described above.
                If LREAL = .TRUE., B is not referenced.

        W       (input) DOUBLE PRECISION
                On entry, W is the diagonal element of the matrix B.
                If LREAL = .TRUE., W is not referenced.

        SCALE   (output) DOUBLE PRECISION
                On exit, SCALE is the scale factor.

        X       (input/output) DOUBLE PRECISION array, dimension (2*N)
                On entry, X contains the right hand side of the system.
                On exit, X is overwritten by the solution.

        WORK    (workspace) DOUBLE PRECISION array, dimension (N)

        INFO    (output) INTEGER
                On exit, INFO is set to
                0: successful exit.
                1: the some diagonal 1 by 1 block has been perturbed by
                a small number SMIN to keep nonsingularity.
                2: the some diagonal 2 by 2 block has been perturbed by
                a small number in DLALN2 to keep nonsingularity.
                NOTE: In the interests of speed, this routine does not
                check the inputs for errors.

 LAPACK auxiliary routine (version 3.3.1)   April 2011                            DLAQTR(3lapack)