.. SPDX-FileCopyrightText: 2019-2020 Intel Corporation
..
.. SPDX-License-Identifier: CC-BY-4.0

.. _onemath_vm_tgamma:

tgamma
======


.. container::


   Computes the gamma function of vector elements.


   .. container:: section


      .. rubric:: Syntax
         :class: sectiontitle


      Buffer API:


      .. code-block:: cpp


            namespace oneapi::math::vm {

            sycl::event tgamma(
                    sycl::queue& exec_queue,
                    std::int64_t n,
                    sycl::buffer<T,1>& a,
                    sycl::buffer<T,1>& y,
                    oneapi::math::vm::mode mode = oneapi::math::vm::mode::not_defined,
                    oneapi::math::vm::error_handler<T> errhandler = {});

            } // namespace oneapi::math::vm



      USM API:


      .. code-block:: cpp


            namespace oneapi::math::vm {

            sycl::event tgamma(
                    sycl::queue& exec_queue,
                    std::int64_t n,
                    const T *a,
                    T* y,
                    std::vector<sycl::event> const & depends = {},
                    oneapi::math::vm::mode mode = oneapi::math::vm::mode::not_defined,
                    oneapi::math::vm::error_handler<T> errhandler = {});

            } // namespace oneapi::math::vm



      ``tgamma`` supports the following precisions.


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

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




.. container:: section


   .. rubric:: Description
      :class: sectiontitle


   The tgamma(a) function computes the gamma function for elements of
   the input vector ``a`` and writes them to the output vector ``y``.
   Precision overflow thresholds for the tgamma function are beyond the
   scope of this document. If the result does not meet the target
   precision, the function raises sets the VM status code to
   oneapi::math::vm::status::sing.


   .. container:: tablenoborder


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

         * - Argument
           - Result
           - Status code
         * - +0
           - +∞
           - ``oneapi::math::vm::status::sing``
         * - -0
           - -∞
           - ``oneapi::math::vm::status::sing``
         * - negative integer
           - QNAN
           - ``oneapi::math::vm::status::errdom``
         * - -∞
           - QNAN
           - ``oneapi::math::vm::status::errdom``
         * - +∞
           - +∞
           -  
         * - a > overflow
           - +∞
           - ``oneapi::math::vm::status::sing``
         * - QNAN
           - QNAN
           -  
         * - SNAN
           - QNAN
           -  




.. container:: section


   .. rubric:: Input Parameters
      :class: sectiontitle


   Buffer API:


   exec_queue
      The queue where the routine should be executed.


   n
      Specifies the number of elements to be calculated.


   a
      The buffer ``a`` containing input vector of size ``n``.


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


   errhandler
      Sets local error handling mode for this function call. See the
      :ref:`onemath_vm_create_error_handler`
      function for arguments and their descriptions. This is an optional
      parameter. The local error handler is disabled by default.


   USM API:


   exec_queue
      The queue where the routine should be executed.


   n
      Specifies the number of elements to be calculated.


   a
      Pointer ``a`` to the input vector of size ``n``.


   depends
      Vector of dependent events (to wait for input data to be ready).


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


   errhandler
      Sets local error handling mode for this function call. See the
      :ref:`onemath_vm_create_error_handler`
      function for arguments and their descriptions. This is an optional
      parameter. The local error handler is disabled by default.


.. container:: section


   .. rubric:: Output Parameters
      :class: sectiontitle


   Buffer API:


   y
      The buffer ``y`` containing the output vector of size ``n``.


   USM API:


   y
      Pointer ``y`` to the output vector of size ``n``.


   return value (event)
      Event, signifying availability of computed output and status code(s).

.. container:: section


    .. rubric:: Exceptions
        :class: sectiontitle

    For list of generated exceptions please refer to  :ref:`onemath_vm_exceptions`


.. container:: familylinks


   .. container:: parentlink

      **Parent topic:** :ref:`onemath_vm_mathematical_functions`