.. _copysign:

copysign
========

Computes the element-wise copy of vector ``a`` elements with the sign of vector ``b`` elements.


.. contents::
    :local:
    :depth: 1

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

The ``copysign(a,b)`` function returns the first vector argument elements
with the sign changed to match the sign of the second vector
argument's corresponding elements.

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

   * -  Argument 1
     -  Argument 2
     -  Result
     -  Error Code
   * -  any value
     -  positive value
     -  +any value
     -   
   * -  any value
     -  negative value
     -  -any value
     -   

The ``copysign(a,b)`` function does not generate any errors.


API
***


Syntax
------

**Buffer API**


.. code-block:: cpp

   namespace oneapi::mkl::vm {

   sycl::event copysign(sycl::queue & exec_queue,
         std::int64_t n,
         sycl::buffer<T> & a,
         sycl::buffer<T> & b,
         sycl::buffer<T> & y,
         oneapi::mkl::vm::mode mode = oneapi::mkl::vm::mode::not_defined);

   }

.. code-block:: cpp

   namespace oneapi::mkl::vm {

   sycl::event copysign(sycl::queue & exec_queue,
         sycl::buffer<T> & a,
         oneapi::mkl::slice sa,
         sycl::buffer<T> & b,
         oneapi::mkl::slice sb,
         sycl::buffer<T> & y,
         oneapi::mkl::slice sy,
         oneapi::mkl::vm::mode mode = oneapi::mkl::vm::mode::not_defined);

   }

**USM API**

.. code-block:: cpp

   namespace oneapi::mkl::vm {

   sycl::event copysign(sycl::queue & exec_queue,
         std::int64_t n,
         T const * a,
         T const * b,
         T * y,
         std::vector<cl::sycl::event> const & depends = {},
         oneapi::mkl::vm::mode mode = oneapi::mkl::vm::mode::not_defined);

   }

.. code-block:: cpp

   namespace oneapi::mkl::vm {

   sycl::event copysign(sycl::queue & exec_queue,
         T const * a,
         oneapi::mkl::slice sa,
         T const * b,
         oneapi::mkl::slice sb,
         T * y,
         oneapi::mkl::slice sy,
         std::vector<cl::sycl::event> const & depends = {},
         oneapi::mkl::vm::mode mode = oneapi::mkl::vm::mode::not_defined);

   }


``copysign`` supports the following precisions and devices:


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

   * -  T
     -  Devices supported
   * -  ``float``
     -  Host, CPU, and GPU
   * -  ``double``
     -  Host, CPU, and GPU


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

**Buffer API**


exec_queue
   The queue where the routine should be executed.


n
   Specifies the number of elements to be calculated.


a
   The buffer containing the 1st input vector.


sa
   Slice selector for ``a``. See :ref:`data-types` for a description of the |O-MKL| slice type.


b
   The buffer containing the 2nd input vector.


sb
   Slice selector for ``b``. See :ref:`data-types` for a description of the |O-MKL| slice type.


sy
   Slice selector for ``y``. See :ref:`data-types` for a description of the |O-MKL| slice type.


mode
   Overrides the global VM mode setting for this function call. See :ref:`set_mode` function for possible values and their description. This is an optional parameter. The default value is ``mode::not_defined``.


**USM API**


exec_queue
   The queue where the routine should be executed.


n
   Specifies the number of elements to be calculated.


a
   Pointer to the 1st input vector.


sa
   Slice selector for ``a``. See :ref:`data-types` for a description of the |O-MKL| slice type.


b
   Pointer to the 2nd input vector.


sb
   Slice selector for ``b``. See :ref:`data-types` for a description of the |O-MKL| slice type.


sy
   Slice selector for ``y``. See :ref:`data-types` for a description of the |O-MKL| slice type.


depends
   Vector of dependent events (to wait for input data to be ready). This is an optional parameter. The default is an empty vector.


mode
   Overrides the global VM mode setting for this function call. See the :ref:`set_mode` function for possible values and their description. This is an optional parameter. The default value is ``mode::not_defined``.


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

**Buffer API**


y
   The buffer containing the output vector.


return value (event)
   Computation end event.


**USM API**


y
   Pointer to the output vector.


return value (event)
   Computation end event.


Examples
********

An example of how to use ``copysign`` can be found in the |O-MKL|
installation directory, under:

.. code-block::

   examples/dpcpp/vml/source/vcopysign.cpp