ESMF_DORGQR Subroutine

subroutine ESMF_DORGQR(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

\brief \b ESMF_DORGQR \htmlonly Download ESMF_DORGQR + dependencies [TGZ] [ZIP] [TXT] \endhtmlonly \par Purpose:

\verbatim

ESMF_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 ESMF_DGEQRF. \endverbatim \param[in] M \verbatim M is INTEGER The number of rows of the matrix Q. M >= 0. \endverbatim

\param[in] N \verbatim N is INTEGER The number of columns of the matrix Q. M >= N >= 0. \endverbatim

\param[in] K \verbatim K is INTEGER The number of elementary reflectors whose product defines the matrix Q. N >= K >= 0. \endverbatim

\param[in,out] A \verbatim A is 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 ESMF_DGEQRF in the first k columns of its array argument A. On exit, the M-by-N matrix Q. \endverbatim

\param[in] LDA \verbatim LDA is INTEGER The first dimension of the array A. LDA >= max(1,M). \endverbatim

\param[in] TAU \verbatim TAU is DOUBLE PRECISION array, dimension (K) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by ESMF_DGEQRF. \endverbatim

\param[out] WORK \verbatim WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. \endverbatim

\param[in] LWORK \verbatim LWORK is 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 ESMF_XERBLA.

\endverbatim

\param[out] INFO \verbatim INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument has an illegal value \endverbatim \author Univ. of Tennessee \author Univ. of California Berkeley \author Univ. of Colorado Denver \author NAG Ltd. \date December 2016 \ingroup doubleOTHERcomputational

Arguments