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

NAME
       SRC/sgemqr.f

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

Function/Subroutine Documentation
   subroutine sgemqr (character side, character trans, integer m, integer n,
       integer k, real, dimension( lda, * ) a, integer lda, real, dimension( *
       ) t, integer tsize, real, dimension( ldc, * ) c, integer ldc, real,
       dimension( * ) work, integer lwork, integer info)
       SGEMQR

       Purpose:


            SGEMQR 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 tall skinny
            QR factorization (SGEQR)

       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 REAL array, dimension (LDA,K)
                     Part of the data structure to represent Q as returned by SGEQR.

           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 REAL array, dimension (MAX(5,TSIZE)).
                     Part of the data structure to represent Q as returned by SGEQR.

           TSIZE

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

           C

                     C is REAL 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) REAL 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
                                      SLATSQR or SGEQRT

             Depending on the matrix dimensions M and N, and row and column
             block sizes MB and NB returned by ILAENV, SGEQR will use either
             SLATSQR (if the matrix is tall-and-skinny) or SGEQRT to compute
             the QR factorization.
             This version of SGEMQR will use either SLAMTSQR or SGEMQRT to
             multiply matrix Q by another matrix.
             Further Details in SLAMTSQR or SGEMQRT.

       Definition at line 172 of file sgemqr.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                 SRC/sgemqr.f(3)