.. _modf:

modf
====


Computes the element-wise truncated integral and remaining fractional parts of vector elements.


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

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

The ``modf(a)`` function computes a truncated integer value and the
remaining fraction part for each vector element.


.. math::

   a_i \geq 0,
   \begin{cases}
      y_i = \lfloor a_i \rfloor \\
      z_i = a_i - \lfloor a_i \rfloor
   \end{cases}

.. math::

   a_i < 0,
   \begin{cases}
      y_i = \lceil a_i \rceil \\
      z_i = a_i - \lceil a_i \rceil
   \end{cases}


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

   * -  Argument
     -  Result 1
     -  Result 2
     -  Error Code
   * -  +0
     -  +0
     -  +0
     -   
   * -  -0
     -  -0
     -  -0
     -   
   * -  +\ :math:`\infty`
     -  +\ :math:`\infty`
     -  +0
     -   
   * -  -\ :math:`\infty`
     -  -\ :math:`\infty`
     -  -0
     -   
   * -  SNAN
     -  QNAN
     -  QNAN
     -   
   * -  QNAN
     -  QNAN
     -  QNAN
     -   




The ``modf`` function does not generate any errors.


API
***


Syntax
------

**Buffer API**


.. code-block:: cpp

   namespace oneapi::mkl::vm {

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

   }

.. code-block:: cpp

   namespace oneapi::mkl::vm {

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

   }


**USM API**

.. code-block:: cpp

   namespace oneapi::mkl::vm {

   sycl::event modf(sycl::queue & exec_queue,
         std::int64_t n,
         T const * a,
         T * y,
         T * z,
         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 modf(sycl::queue & exec_queue,
         T const * a,
         oneapi::mkl::slice sa,
         T * y,
         oneapi::mkl::slice sy,
         T * z,
         oneapi::mkl::slice sz,
         std::vector<cl::sycl::event> const & depends = {},
         oneapi::mkl::vm::mode mode = oneapi::mkl::vm::mode::not_defined);

   }



``modf`` 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 input vector.


sa
   Slice selector for ``a``. 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.


sz
   Slice selector for ``z``. 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 input vector.


sa
   Slice selector for ``a``. 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.


sz
   Slice selector for ``z``. 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 for truncated integer values.


z
   The buffer containing the output vector for remaining fraction parts.


return value (event)
   Computation end event.


**USM API**


y
   Pointer to the output vector for truncated integer values.


z
   Pointer to the output vector for remaining fraction parts.


return value (event)
   Computation end event.


Examples
********

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


.. code-block::

   examples/dpcpp/vml/source/vmodf.cpp