.. _getri_batch-usm-strided-version:

getri_batch (USM Strided Version)
=================================


Computes the batch of inverses of an LU-factored general matrices
determined by ``getrf_batch`` (USM stride version) function. This routine
belongs to the ``oneapi::mkl::lapack`` namespace.


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

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

The routine computes the inverses ``A``\ :sub:`1`-1 of a general
matrices ``A``\ :sub:`1`. Before calling this routine, call
:ref:`getrf_batch-usm-strided-version` function
to factorize ``A``\ :sub:`1`.


API
***


Syntax
------

.. code-block:: cpp

   namespace oneapi::mkl::lapack {
     cl::sycl::event getri_batch(cl::sycl::queue &queue,
     std::int64_t n,
     T *a,
    std::int64_t lda,
    std::int64_t stride_a,
    std::int64_t *ipiv,
    std::int64_t stride_ipiv,
    std::int64_t batch_size,
    T *scratchpad,
    std::int64_t scratchpad_size,
    const std::vector<cl::sycl::event> &events = {})
   }

Function supports the following precisions and devices.

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

   * -  T
     -  Devices supported
   * -  ``float``
     -  Host, CPU, and GPU
   * -  ``double``
     -  Host, CPU, and GPU
   * -  ``std::complex<float>``
     -  Host, CPU, and GPU
   * -  ``std::complex<double>``
     -  Host, CPU, and GPU


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

queue
   Device queue where calculations will be performed.


n
   The order of the matrices ``A``\ :sub:`i` (``0 ≤ n``).


a
   Result of the :ref:`getrf_batch-usm-strided-version`
   function


lda
   The leading dimension of ``A``\ :sub:`i` (``n`` ≤ ``lda``).


stride_a
   The stride between the beginnings of matrices ``A``\ :sub:`i`
   inside the batch array ``a``.


ipiv
   The array as returned by :ref:`getrf_batch-usm-strided-version`.


stride_ipiv
   The stride between the beginnings of arrays ``ipiv``\ :sub:`i`
   inside the array ``ipiv``.


batch_size
   Specifies the number of problems in a batch.


scratchpad
   Scratchpad memory to be used by routine for storing intermediate
   results.


scratchpad_size
   Size of scratchpad memory as a number of floating point elements
   of type ``T``. Size should not be less than the value returned by
   stride version of :ref:`getri_batch_scratchpad_size-strided-version`
   function.


events
   List of events to wait for before starting computation. Defaults
   to empty list.


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

a
   Overwritten by the n-by-n matrices ``A``\ :sub:`i`\ :sup:`-1`.


Exceptions
----------

.. tabularcolumns:: |\Y{0.3}|\Y{0.7}|

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

   * - Exception
     - Description

   * -     ``mkl::lapack::batch_exception``
     -     This exception is thrown when problems occur during    calculations. You can obtain the info code of the problem using the   info() method of the exception object:

           If   ``info = -n``, the ``n``-th parameter had an illegal   value.

           If ``info`` equals the value passed as   scratchpad size, and detail() returns non-zero, then the passed   scratchpad is of insufficient size, and the required size should be   not less then value returned by the detail() method of the exception   object.


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

Output event to wait on to ensure computation is complete.