.. _onemkl_blas_dot:

dot
===

Computes the ``dot`` product of two real vectors.

Description
***********

The ``dot`` routines perform a dot product between two vectors. 
The operation is defined as:

.. math::

      \mathrm{result} = \sum_{i=1}^n X_i Y_i

``dot`` supports the following precisions:

.. list-table::
   :header-rows: 1

   * -  T
     -  T_res
   * -  ``float``
     -  ``float``
   * -  ``double``
     -  ``double``
   * -  ``float``
     -  ``double``

.. note::
   For mixed precision version (inputs are float while result is double), ``dot`` product is computed with double precision.


dot (Buffer Version)
********************

Syntax
------

.. code-block:: cpp

   namespace oneapi::mkl::blas::column_major {
       void dot(sycl::queue &queue,
                std::int64_t n,
                sycl::buffer<T,1> &x,
                std::int64_t incx,
                sycl::buffer<T,1> &y,
                std::int64_t incy,
                sycl::buffer<T_res,1> &result)
   }

.. code-block:: cpp

   namespace oneapi::mkl::blas::row_major {
       void dot(sycl::queue &queue,
                std::int64_t n,
                sycl::buffer<T,1> &x,
                std::int64_t incx,
                sycl::buffer<T,1> &y,
                std::int64_t incy,
                sycl::buffer<T_res,1> &result)
   }

Input Parameters
----------------

queue
   The queue where the routine should be executed.

n
   Number of elements in vectors ``x`` and ``y``.

x
   Buffer holding input vector ``x``. Size of the buffer must be at least
   (1 + (``n`` – 1)*abs(``incx``)). See :ref:`matrix-storage` for
   more details.

incx
   Stride of vector ``x``.

y
   Buffer holding input vector y. Size of the buffer must be at least
   (1 + (``n`` – 1)*abs(``incy``)). See :ref:`matrix-storage` for
   more details.

incy
   Stride of vector ``y``.

Output Parameters
-----------------

result
   Buffer where the result (a scalar) will be stored.


dot (USM Version)
*****************

Syntax
------

.. code-block:: cpp

   namespace oneapi::mkl::blas::column_major {
       sycl::event dot(sycl::queue &queue,
                       std::int64_t n,
                       const T *x,
                       std::int64_t incx,
                       const T *y,
                       std::int64_t incy,
                       T_res *result,
                       const std::vector<sycl::event> &dependencies = {})
   }

.. code-block:: cpp

   namespace oneapi::mkl::blas::row_major {
       sycl::event dot(sycl::queue &queue,
                       std::int64_t n,
                       const T *x,
                       std::int64_t incx,
                       const T *y,
                       std::int64_t incy,
                       T_res *result,
                       const std::vector<sycl::event> &dependencies = {})
   }

Input Parameters
----------------

queue
   The queue where the routine should be executed.

n
   Number of elements in vectors ``x`` and ``y``.

x
   Pointer to input vector ``x``. Size of the array holding vector ``x`` must be least (1 + (``n`` – 1)*abs(``incx``)). See :ref:`matrix-storage` for more details.

incx
   Stride of vector ``x``.

y
   Pointer to input vector ``y``. Size of the array holding vector ``y`` must be at least (1 + (``n`` – 1)*abs(``incy``)). See :ref:`matrix-storage` for more details.

incy
   Stride of vector ``y``.

dependencies
   List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters
-----------------

result
   Pointer to where the result (a scalar) will be stored.

Return Values
-------------

Output event to wait on to ensure computation is complete.