ESMF_DORM2L Subroutine

subroutine ESMF_DORM2L(SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, INFO)

\brief \b ESMF_DORM2L multiplies a general matrix by the orthogonal matrix from a QL factorization determined by sgeqlf (unblocked algorithm). \htmlonly Download ESMF_DORM2L + dependencies [TGZ] [ZIP] [TXT] \endhtmlonly \par Purpose:

\verbatim

ESMF_DORM2L overwrites the general real m by n matrix C with

  Q * C  if SIDE = 'L' and TRANS = 'N', or

  Q**T * C  if SIDE = 'L' and TRANS = 'T', or

  C * Q  if SIDE = 'R' and TRANS = 'N', or

  C * Q**T if SIDE = 'R' and TRANS = 'T',

where Q is a real orthogonal matrix defined as the product of k elementary reflectors

  Q = H(k) . . . H(2) H(1)

as returned by DGEQLF. Q is of order m if SIDE = ‘L’ and of order n if SIDE = ‘R’. \endverbatim \param[in] SIDE \verbatim SIDE is CHARACTER1 = ‘L’: apply Q or QT from the Left = ‘R’: apply Q or Q*T from the Right \endverbatim

\param[in] TRANS \verbatim TRANS is CHARACTER1 = ‘N’: apply Q (No transpose) = ‘T’: apply Q*T (Transpose) \endverbatim

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

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

\param[in] K \verbatim 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. \endverbatim

\param[in] A \verbatim A is DOUBLE PRECISION array, dimension (LDA,K) The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,…,k, as returned by DGEQLF in the last k columns of its array argument A. A is modified by the routine but restored on exit. \endverbatim

\param[in] LDA \verbatim LDA is INTEGER The leading dimension of the array A. If SIDE = ‘L’, LDA >= max(1,M); if SIDE = ‘R’, LDA >= max(1,N). \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 DGEQLF. \endverbatim

\param[in,out] C \verbatim C is DOUBLE PRECISION array, dimension (LDC,N) On entry, the m by n matrix C. On exit, C is overwritten by QC or QTC or CQT or CQ. \endverbatim

\param[in] LDC \verbatim LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M). \endverbatim

\param[out] WORK \verbatim WORK is DOUBLE PRECISION array, dimension (N) if SIDE = ‘L’, (M) if SIDE = ‘R’ \endverbatim

\param[out] INFO \verbatim INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had 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