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

NAME

       LAPACK-3 - generates an M-by-N real matrix Q with orthonormal columns,

SYNOPSIS

       SUBROUTINE DORGQR( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )

           INTEGER        INFO, K, LDA, LWORK, M, N

           DOUBLE         PRECISION A( LDA, * ), TAU( * ), WORK( * )

PURPOSE

       DORGQR generates an M-by-N real matrix Q with orthonormal columns,
        which is defined as the first N columns of a product of K elementary
        reflectors of order M
              Q  =  H(1) H(2) . . . H(k)
        as returned by DGEQRF.

ARGUMENTS

        M       (input) INTEGER
                The number of rows of the matrix Q. M >= 0.

        N       (input) INTEGER
                The number of columns of the matrix Q. M >= N >= 0.

        K       (input) INTEGER
                The number of elementary reflectors whose product defines the
                matrix Q. N >= K >= 0.

        A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
                On entry, the i-th column must contain the vector which
                defines the elementary reflector H(i), for i = 1,2,...,k, as
                returned by DGEQRF in the first k columns of its array
                argument A.
                On exit, the M-by-N matrix Q.

        LDA     (input) INTEGER
                The first dimension of the array A. LDA >= max(1,M).

        TAU     (input) DOUBLE PRECISION array, dimension (K)
                TAU(i) must contain the scalar factor of the elementary
                reflector H(i), as returned by DGEQRF.

        WORK    (workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK))
                On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

        LWORK   (input) INTEGER
                The dimension of the array WORK. LWORK >= max(1,N).
                For optimum performance LWORK >= N*NB, where NB is the
                optimal blocksize.
                If LWORK = -1, then a workspace query is assumed; the routine
                only calculates the optimal size of the WORK array, returns
                this value as the first entry of the WORK array, and no error
                message related to LWORK is issued by XERBLA.

        INFO    (output) INTEGER
                = 0:  successful exit
                < 0:  if INFO = -i, the i-th argument has an illegal value

 LAPACK routine (version 3.2)               April 2011                            DORGQR(3lapack)