.. _onemkl_blas_her2: her2 ==== Computes a rank-2 update of a Hermitian matrix. .. _onemkl_blas_her2_description: .. rubric:: Description The ``her2`` routines compute two scalar-vector-vector products and add them to a Hermitian matrix. The operation is defined as: .. math:: A \leftarrow alpha*x*y^H + conjg(alpha)*y*x^H + A where: ``alpha`` is a scalar, ``A`` is an ``n``-by-``n`` Hermitian matrix, ``x`` and ``y`` are vectors or length ``n``. ``her2`` supports the following precisions. .. list-table:: :header-rows: 1 * - T * - ``std::complex`` * - ``std::complex`` .. _onemkl_blas_her2_buffer: her2 (Buffer Version) --------------------- .. rubric:: Syntax .. code-block:: cpp namespace oneapi::mkl::blas::column_major { void her2(sycl::queue &queue, onemkl::uplo upper_lower, std::int64_t n, T alpha, sycl::buffer &x, std::int64_t incx, sycl::buffer &y, std::int64_t incy, sycl::buffer &a, std::int64_t lda) } .. code-block:: cpp namespace oneapi::mkl::blas::row_major { void her2(sycl::queue &queue, onemkl::uplo upper_lower, std::int64_t n, T alpha, sycl::buffer &x, std::int64_t incx, sycl::buffer &y, std::int64_t incy, sycl::buffer &a, std::int64_t lda) } .. container:: section .. rubric:: Input Parameters queue The queue where the routine should be executed. upper_lower Specifies whether ``A`` is upper or lower triangular. See :ref:`onemkl_datatypes` for more details. n Number of columns of ``A``. Must be at least zero. alpha Scaling factor for the matrix-vector product. x Buffer holding input vector ``x``. The buffer must be of size at least (1 + (``n`` - 1)*abs(``incx``)). See :ref:`matrix-storage` for more details. incx Stride of vector ``x``. y Buffer holding input/output vector ``y``. The buffer must be of size at least (1 + (``n`` - 1)*abs(``incy``)). See :ref:`matrix-storage` for more details. incy Stride of vector ``y``. a Buffer holding input matrix ``A``. Must have size at least ``lda``\ \*\ ``n``. See :ref:`matrix-storage` for more details. lda Leading dimension of matrix ``A``. Must be at least ``n``, and positive. .. container:: section .. rubric:: Output Parameters a Buffer holding the updated upper triangular part of the Hermitian matrix ``A`` if ``upper_lower``\ \=\ ``upper``, or the updated lower triangular part of the Hermitian matrix ``A`` if ``upper_lower``\ \=\ ``lower``. The imaginary parts of the diagonal elements are set to zero. .. _onemkl_blas_her2_usm: her2 (USM Version) ------------------ .. rubric:: Syntax .. code-block:: cpp namespace oneapi::mkl::blas::column_major { sycl::event her2(sycl::queue &queue, onemkl::uplo upper_lower, std::int64_t n, T alpha, const T *x, std::int64_t incx, const T *y, std::int64_t incy, T *a, std::int64_t lda, const std::vector &dependencies = {}) } .. code-block:: cpp namespace oneapi::mkl::blas::row_major { sycl::event her2(sycl::queue &queue, onemkl::uplo upper_lower, std::int64_t n, T alpha, const T *x, std::int64_t incx, const T *y, std::int64_t incy, T *a, std::int64_t lda, const std::vector &dependencies = {}) } .. container:: section .. rubric:: Input Parameters queue The queue where the routine should be executed. upper_lower Specifies whether ``A`` is upper or lower triangular. See :ref:`onemkl_datatypes` for more details. n Number of columns of ``A``. Must be at least zero. alpha Scaling factor for the matrix-vector product. x Pointer to input vector ``x``. The array holding input vector ``x`` must be of size at least (1 + (``n`` - 1)*abs(``incx``)). See :ref:`matrix-storage` for more details. incx Stride of vector ``x``. y Pointer to input/output vector ``y``. The array holding input/output vector ``y`` must be of size at least (1 + (``n`` - 1)*abs(``incy``)). See :ref:`matrix-storage` for more details. incy Stride of vector ``y``. a Pointer to input matrix ``A``. The array holding input matrix ``A`` must have size at least ``lda``\ \*\ ``n``. See :ref:`matrix-storage` for more details. lda Leading dimension of matrix ``A``. Must be at least ``n``, and positive. dependencies List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies. .. container:: section .. rubric:: Output Parameters a Pointer to the updated upper triangular part of the Hermitian matrix ``A`` if ``upper_lower``\ \=\ ``upper``, or the updated lower triangular part of the Hermitian matrix ``A`` if ``upper_lower``\ \=\ ``lower``. The imaginary parts of the diagonal elements are set to zero. .. container:: section .. rubric:: Return Values Output event to wait on to ensure computation is complete. **Parent topic:** :ref:`blas-level-2-routines`