.. SPDX-FileCopyrightText: 2019-2020 Intel Corporation .. .. SPDX-License-Identifier: CC-BY-4.0 .. _onemkl_lapack_orgqr: orgqr ===== Generates the real orthogonal matrix :math:Q of the QR factorization formed by :ref:onemkl_lapack_geqrf. .. container:: section .. rubric:: Description orgqr supports the following precisions. .. list-table:: :header-rows: 1 * - T * - float * - double The routine generates the whole or part of :math:m \times m orthogonal matrix :math:Q of the QR factorization formed by the routine :ref:onemkl_lapack_geqrf. Usually :math:Q is determined from the QR factorization of an m by p matrix :math:A with :math:m \ge p. To compute the whole matrix :math:Q, use: :: oneapi::mkl::lapack::orgqr(queue, m, m, p, a, lda, tau, scratchpad, scratchpad_size) To compute the leading :math:p columns of :math:Q (which form an orthonormal basis in the space spanned by the columns of :math:A): :: oneapi::mkl::lapack::orgqr(queue, m, p, p, a, lda, tau, scratchpad, scratchpad_size) To compute the matrix :math:Q^{k} of the QR factorization of leading :math:k columns of the matrix :math:A: :: oneapi::mkl::lapack::orgqr(queue, m, m, k, a, lda, tau, scratchpad, scratchpad_size) To compute the leading :math:k columns of :math:Q^{k} (which form an orthonormal basis in the space spanned by leading :math:k columns of the matrix :math:A): :: oneapi::mkl::lapack::orgqr(queue, m, k, k, a, lda, tau, scratchpad, scratchpad_size) orgqr (Buffer Version) ---------------------- .. container:: section .. rubric:: Syntax .. code-block:: cpp namespace oneapi::mkl::lapack { void orgqr(cl::sycl::queue &queue, std::int64_t m, std::int64_t n, std::int64_t k, cl::sycl::buffer &a, std::int64_t lda, cl::sycl::buffer &tau, cl::sycl::buffer &scratchpad, std::int64_t scratchpad_size) } .. container:: section .. rubric:: Input Parameters queue The queue where the routine should be executed. m The number of rows in the matrix :math:A (:math:0 \le m). n The number of columns in the matrix :math:A (:math:0 \le n \le m). k The number of elementary reflectors whose product defines the matrix :math:Q (:math:0 \le k \le n). a The buffer a as returned by :ref:onemkl_lapack_geqrf. lda The leading dimension of a (:math:\text{lda} \le m). tau The buffer tau as returned by :ref:onemkl_lapack_geqrf. scratchpad_size Size of scratchpad memory as a number of floating point elements of type T. Size should not be less than the value returned by :ref:onemkl_lapack_orgqr_scratchpad_size function. .. container:: section .. rubric:: Output Parameters a Overwritten by :math:n leading columns of the :math:m \times m orthogonal matrix :math:Q. scratchpad Buffer holding scratchpad memory to be used by routine for storing intermediate results. .. container:: section .. rubric:: Throws This routine shall throw the following exceptions if the associated condition is detected. An implementation may throw additional implementation-specific exception(s) in case of error conditions not covered here. :ref:oneapi::mkl::host_bad_alloc :ref:oneapi::mkl::device_bad_alloc :ref:oneapi::mkl::unimplemented :ref:oneapi::mkl::unsupported_device :ref:oneapi::mkl::lapack::invalid_argument :ref:oneapi::mkl::lapack::computation_error Exception is thrown in case of problems during calculations. The info code of the problem can be obtained by info() method of exception object: If :math:\text{info}=-i, the :math:i-th parameter had an illegal value. If info equals to value passed as scratchpad size, and detail() returns non zero, then passed scratchpad is of insufficient size, and required size should not be less than value return by detail() method of exception object. orgqr (USM Version) ---------------------- .. container:: section .. rubric:: Syntax .. code-block:: cpp namespace oneapi::mkl::lapack { cl::sycl::event orgqr(cl::sycl::queue &queue, std::int64_t m, std::int64_t n, std::int64_t k, T *a, std::int64_t lda, T *tau, T *scratchpad, std::int64_t scratchpad_size, const std::vector &events = {}) } .. container:: section .. rubric:: Input Parameters queue The queue where the routine should be executed. m The number of rows in the matrix :math:A (:math:0 \le m). n The number of columns in the matrix :math:A (:math:0 \le n \le m). k The number of elementary reflectors whose product defines the matrix :math:Q (:math:0 \le k \le n). a The pointer to a as returned by :ref:onemkl_lapack_geqrf. lda The leading dimension of a (:math:\text{lda} \le m). tau The pointer to tau as returned by :ref:onemkl_lapack_geqrf. scratchpad_size Size of scratchpad memory as a number of floating point elements of type T. Size should not be less than the value returned by :ref:onemkl_lapack_orgqr_scratchpad_size function. events List of events to wait for before starting computation. Defaults to empty list. .. container:: section .. rubric:: Output Parameters a Overwritten by :math:n leading columns of the :math:m \times m orthogonal matrix :math:Q. scratchpad Pointer to scratchpad memory to be used by routine for storing intermediate results. .. container:: section .. rubric:: Throws This routine shall throw the following exceptions if the associated condition is detected. An implementation may throw additional implementation-specific exception(s) in case of error conditions not covered here. :ref:oneapi::mkl::host_bad_alloc :ref:oneapi::mkl::device_bad_alloc :ref:oneapi::mkl::unimplemented :ref:oneapi::mkl::unsupported_device :ref:oneapi::mkl::lapack::invalid_argument :ref:oneapi::mkl::lapack::computation_error Exception is thrown in case of problems during calculations. The info code of the problem can be obtained by info() method of exception object: If :math:\text{info}=-i, the :math:i-th parameter had an illegal value. If info equals to value passed as scratchpad size, and detail() returns non zero, then passed scratchpad is of insufficient size, and required size should not be less than value return by detail() method of exception object. .. container:: section .. rubric:: Return Values Output event to wait on to ensure computation is complete. **Parent topic:** :ref:onemkl_lapack-linear-equation-routines