SRC/zgemqr.f(3)            Library Functions Manual            SRC/zgemqr.f(3)

NAME
       SRC/zgemqr.f

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

Function/Subroutine Documentation
   subroutine zgemqr (character side, character trans, integer m, integer n,
       integer k, complex*16, dimension( lda, * ) a, integer lda, complex*16,
       dimension( * ) t, integer tsize, complex*16, dimension( ldc, * ) c,
       integer ldc, complex*16, dimension( * ) work, integer lwork, integer
       info)
       ZGEMQR

       Purpose:


           !>
           !> ZGEMQR overwrites the general real M-by-N matrix C with
           !>
           !>                      SIDE = 'L'     SIDE = 'R'
           !>      TRANS = 'N':      Q * C          C * Q
           !>      TRANS = 'T':      Q**H * C       C * Q**H
           !>
           !> where Q is a complex unitary matrix defined as the product
           !> of blocked elementary reflectors computed by tall skinny
           !> QR factorization (ZGEQR)
           !>
           !>

       Parameters
           SIDE

           !>          SIDE is CHARACTER*1
           !>          = 'L': apply Q or Q**H from the Left;
           !>          = 'R': apply Q or Q**H from the Right.
           !>

           TRANS

           !>          TRANS is CHARACTER*1
           !>          = 'N':  No transpose, apply Q;
           !>          = 'C':  Conjugate transpose, apply Q**H.
           !>

           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 COMPLEX*16 array, dimension (LDA,K)
           !>          Part of the data structure to represent Q as returned by ZGEQR.
           !>

           LDA

           !>          LDA is INTEGER
           !>          The leading dimension of the array A.
           !>          If SIDE = 'L', LDA >= max(1,M);
           !>          if SIDE = 'R', LDA >= max(1,N).
           !>

           T

           !>          T is COMPLEX*16 array, dimension (MAX(5,TSIZE)).
           !>          Part of the data structure to represent Q as returned by ZGEQR.
           !>

           TSIZE

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

           C

           !>          C is COMPLEX*16 array, dimension (LDC,N)
           !>          On entry, the M-by-N matrix C.
           !>          On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
           !>

           LDC

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

           WORK

           !>          (workspace) COMPLEX*16 array, dimension (MAX(1,LWORK))
           !>          On exit, if INFO = 0, WORK(1) returns the minimal LWORK.
           !>

           LWORK

           !>          LWORK is INTEGER
           !>          The dimension of the array WORK. LWORK >= 1.
           !>          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
           !>                           ZLATSQR or ZGEQRT
           !>
           !>  Depending on the matrix dimensions M and N, and row and column
           !>  block sizes MB and NB returned by ILAENV, ZGEQR will use either
           !>  ZLATSQR (if the matrix is tall-and-skinny) or ZGEQRT to compute
           !>  the QR factorization.
           !>  This version of ZGEMQR will use either ZLAMTSQR or ZGEMQRT to
           !>  multiply matrix Q by another matrix.
           !>  Further Details in ZLAMTSQR or ZGEMQRT.
           !>
           !>

       Definition at line 173 of file zgemqr.f.

Author
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LAPACK                          Version 3.12.0                 SRC/zgemqr.f(3)