dgemlq.f(3)

NAME
dgemlq.f

SYNOPSIS

  Functions/Subroutines
subroutine dgemlq (side, trans, m, n, k, a, lda, t, tsize, c, ldc, work, lwork, info)
DGEMLQ

Function/Subroutine Documentation

  subroutine dgemlq (character side, character trans, integer m, integer n, integer k, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) t, integer tsize, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( * ) work, integer lwork, integer info)

DGEMLQ

Purpose:

         DGEMLQ overwrites the general real M-by-N matrix C with
                        SIDE = 'L'     SIDE = 'R'
        TRANS = 'N':      Q * C          C * Q
        TRANS = 'T':      Q**T * C       C * Q**T
        where Q is a real orthogonal matrix defined as the product
        of blocked elementary reflectors computed by short wide LQ
        factorization (DGELQ)

Parameters
    SIDE

              SIDE is CHARACTER*1
              = 'L': apply Q or Q**T from the Left;
              = 'R': apply Q or Q**T from the Right.

    TRANS

              TRANS is CHARACTER*1
              = 'N':  No transpose, apply Q;
              = 'T':  Transpose, apply Q**T.

    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 C. N >= 0.

    K

              K is INTEGER
              The number of elementary reflectors whose product defines
              the matrix Q.
              If SIDE = 'L', M >= K >= 0;
              if SIDE = 'R', N >= K >= 0.

    A

              A is DOUBLE PRECISION array, dimension
                                   (LDA,M) if SIDE = 'L',
                                   (LDA,N) if SIDE = 'R'
              Part of the data structure to represent Q as returned by DGELQ.

    LDA

              LDA is INTEGER
              The leading dimension of the array A. LDA >= max(1,K).

    T

              T is DOUBLE PRECISION array, dimension (MAX(5,TSIZE)).
              Part of the data structure to represent Q as returned by DGELQ.

    TSIZE

              TSIZE is INTEGER
              The dimension of the array T. TSIZE >= 5.

    C

              C is DOUBLE PRECISION array, dimension (LDC,N)
              On entry, the M-by-N matrix C.
              On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.

    LDC

              LDC is INTEGER
              The leading dimension of the array C. LDC >= max(1,M).

    WORK

             (workspace) DOUBLE PRECISION array, dimension (MAX(1,LWORK))

    LWORK

              LWORK is INTEGER
              The dimension of the array WORK.
              If LWORK = -1, then a workspace query is assumed. The routine
              only calculates the size of the WORK array, returns this
              value as WORK(1), and no error message related to WORK
              is issued by XERBLA.

    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.

Further Details

     These details are particular for this LAPACK implementation. Users should not
     take them for granted. These details may change in the future, and are not likely
     true for another LAPACK implementation. These details are relevant if one wants
     to try to understand the code. They are not part of the interface.
     In this version,
              T(2): row block size (MB)
              T(3): column block size (NB)
              T(6:TSIZE): data structure needed for Q, computed by
                               DLASWLQ or DGELQT
      Depending on the matrix dimensions M and N, and row and column
      block sizes MB and NB returned by ILAENV, DGELQ will use either
      DLASWLQ (if the matrix is wide-and-short) or DGELQT to compute
      the LQ factorization.
      This version of DGEMLQ will use either DLAMSWLQ or DGEMLQT to
      multiply matrix Q by another matrix.
      Further Details in DLAMSWLQ or DGEMLQT.

Definition at line 169 of file dgemlq.f.

Author

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