\brief \b ESMF_DLAQP2 \htmlonly Download ESMF_DLAQP2 + dependencies [TGZ] [ZIP] [TXT] \endhtmlonly \par Purpose:
\verbatim
ESMF_DLAQP2 computes a QR factorization with column pivoting of the block A(OFFSET+1:M,1:N). The block A(1:OFFSET,1:N) is accordingly pivoted, but not factorized. \endverbatim \param[in] M \verbatim M is INTEGER The number of rows of the matrix A. M >= 0. \endverbatim
\param[in] N \verbatim N is INTEGER The number of columns of the matrix A. N >= 0. \endverbatim
\param[in] OFFSET \verbatim OFFSET is INTEGER The number of rows of the matrix A that must be pivoted but no factorized. OFFSET >= 0. \endverbatim
\param[in,out] A \verbatim A is DOUBLE PRECISION array, dimension (LDA,N) On entry, the M-by-N matrix A. On exit, the upper triangle of block A(OFFSET+1:M,1:N) is the triangular factor obtained; the elements in block A(OFFSET+1:M,1:N) below the diagonal, together with the array TAU, represent the orthogonal matrix Q as a product of elementary reflectors. Block A(1:OFFSET,1:N) has been accordingly pivoted, but no factorized. \endverbatim
\param[in] LDA \verbatim LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M). \endverbatim
\param[in,out] JPVT \verbatim JPVT is INTEGER array, dimension (N) On entry, if JPVT(i) .ne. 0, the i-th column of A is permuted to the front of AP (a leading column); if JPVT(i) = 0, the i-th column of A is a free column. On exit, if JPVT(i) = k, then the i-th column of AP was the k-th column of A. \endverbatim
\param[out] TAU \verbatim TAU is DOUBLE PRECISION array, dimension (min(M,N)) The scalar factors of the elementary reflectors. \endverbatim
\param[in,out] VN1 \verbatim VN1 is DOUBLE PRECISION array, dimension (N) The vector with the partial column norms. \endverbatim
\param[in,out] VN2 \verbatim VN2 is DOUBLE PRECISION array, dimension (N) The vector with the exact column norms. \endverbatim
\param[out] WORK \verbatim WORK is DOUBLE PRECISION array, dimension (N) \endverbatim \author Univ. of Tennessee \author Univ. of California Berkeley \author Univ. of Colorado Denver \author NAG Ltd. \date November 2011 \ingroup doubleOTHERauxiliary \par Contributors:
G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain X. Sun, Computer Science Dept., Duke University, USA \n Partial column norm updating strategy modified on April 2011 Z. Drmac and Z. Bujanovic, Dept. of Mathematics, University of Zagreb, Croatia. \par References:
LAPACK Working Note 176 \htmlonly [PDF] \endhtmlonly
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| integer | :: | M | ||||
| integer | :: | N | ||||
| integer | :: | OFFSET | ||||
| double precision | :: | A(LDA,*) | ||||
| integer | :: | LDA | ||||
| integer | :: | JPVT(*) | ||||
| double precision | :: | TAU(*) | ||||
| double precision | :: | VN1(*) | ||||
| double precision | :: | VN2(*) | ||||
| double precision | :: | WORK(*) |