ESMF_DORGHR Subroutine

subroutine ESMF_DORGHR(N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)

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

\verbatim

ESMF_DORGHR generates a real orthogonal matrix Q which is defined as the product of IHI-ILO elementary reflectors of order N, as returned by ESMF_DGEHRD:

Q = H(ilo) H(ilo+1) . . . H(ihi-1). \endverbatim \param[in] N \verbatim N is INTEGER The order of the matrix Q. N >= 0. \endverbatim

\param[in] ILO \verbatim ILO is INTEGER \endverbatim

\param[in] IHI \verbatim IHI is INTEGER

     ILO and IHI must have the same values as in the previous call
     of ESMF_DGEHRD. Q is equal to the unit matrix except in the
     submatrix Q(ilo+1:ihi,ilo+1:ihi).
     1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.

\endverbatim

\param[in,out] A \verbatim A is DOUBLE PRECISION array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by ESMF_DGEHRD. On exit, the N-by-N orthogonal matrix Q. \endverbatim

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

\param[in] TAU \verbatim TAU is DOUBLE PRECISION array, dimension (N-1) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by ESMF_DGEHRD. \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 >= IHI-ILO. For optimum performance LWORK >= (IHI-ILO)*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 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