TheRock/rocm-libraries/projects/rocsparse/library/include/internal/generic/rocsparse_spilu0.h

/*! \file */
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#ifndef ROCSPARSE_SPILU0_H
#define ROCSPARSE_SPILU0_H

#include "../../rocsparse-types.h"
#include "rocsparse/rocsparse-export.h"

#ifdef __cplusplus
extern "C" {
#endif

/*! \ingroup generic_module
 *  \brief Get buffer size for incomplete LU factorization with 0 fill-ins and no pivoting.
*  \details
*  \p rocsparse_spilu0_buffer_size returns the size of the non-persistent buffer
*  that is required by \ref rocsparse_spilu0, and must be allocated by the user.
*
*  \note
*  This function is non-blocking and executed asynchronously with respect to the host.
*  It can return before the actual computation has finished.
*
*  \note
*  This routine supports execution in a hipGraph context.
*
*  \note
*  Supported formats are \ref rocsparse_format_csr and \ref rocsparse_format_bsr.
*
*  @param[in]
*  handle       handle to the rocSPARSE library context queue.
*  @param[in]
*  spilu0_descr Spilu0 descriptor.
*  @param[in]
*  A            descriptor of the matrix to factorize.
*  @param[in]
*  P            descriptor of the factorization.
*  @param[in]
*  spilu0_stage stage for the Spilu0 computation.
*  @param[out]
*  p_buffer_size_in_bytes  number of bytes of the buffer.
*  @param[out]
*  p_error      error descriptor created if the returned status is not \ref rocsparse_status_success. A null pointer can be passed if the user is not interested in obtaining an error descriptor.
*
*  \retval rocsparse_status_success the operation completed successfully.
*  \retval rocsparse_status_invalid_handle the library context was not initialized.
*  \retval rocsparse_status_not_implemented the sparse format is invalid or the preconditioner \p P is not identical to the matrix to factorize \p A.
*  \retval rocsparse_status_invalid_value the \p spilu0_stage value is invalid.
*  \retval rocsparse_status_invalid_pointer \p spilu0_descr, \p A, \p P, or \p p_buffer_size_in_bytes pointer is invalid.
*/
ROCSPARSE_EXPORT
rocsparse_status rocsparse_spilu0_buffer_size(rocsparse_handle            handle,
                                              rocsparse_spilu0_descr      spilu0_descr,
                                              rocsparse_const_spmat_descr A,
                                              rocsparse_const_spmat_descr P,
                                              rocsparse_spilu0_stage      spilu0_stage,
                                              size_t*                     p_buffer_size_in_bytes,
                                              rocsparse_error*            p_error);

/*! \ingroup generic_module
   *  \brief Incomplete LU factorization with 0 fill-ins and no pivoting.
   *
   *  \details
   *  \p rocsparse_spilu0 computes the incomplete LU factorization with 0 fill-ins and no
   *  pivoting of a sparse \f$m \times m\f$ matrix \f$A\f$, such that
   *  \f[
   *    A \approx LU
   *  \f]
*  where the lower triangular matrix \f$L\f$ and the upper triangular matrix \f$U\f$ are computed using:
*  \f[
*    \begin{array}{ll}
*        L_{ij} = \frac{1}{U_{jj}}(A_{ij} - \sum_{k=0}^{j-1}L_{ik} \times U_{kj}), & \text{if i > j} \\
*        U_{ij} = (A_{ij} - \sum_{k=0}^{j-1}L_{ik} \times U_{kj}), & \text{if i <= j}
*    \end{array}
*  \f]
*  for each entry found in the matrix \f$A\f$.
*
*  Performing the above operation requires two stages, the stage \ref rocsparse_spilu0_stage_analysis and the stage \ref rocsparse_spilu0_stage_compute.
*  The stage \ref rocsparse_spilu0_stage_analysis is required to perform the stage \ref rocsparse_spilu0_stage_compute and only needs to be called once for a given sparse matrix \f$A\f$, while the stage \ref rocsparse_spilu0_stage_compute can be repeatedly used with different matrices \f$A\f$ that have the same sparsity pattern.
*
*  \p rocsparse_spilu0 supports the following
*  data types for \p A : \ref rocsparse_datatype_f32_r, \ref rocsparse_datatype_f64_r, \ref rocsparse_datatype_f32_c, and \ref rocsparse_datatype_f64_c.
*
*  \note The descriptor \p spilu0_descr needs to be configured with \ref rocsparse_spilu0_set_input.
*  \note The sparse matrix formats currently supported are \ref rocsparse_format_csr and \ref rocsparse_format_bsr.
*
*  \note
*  the \ref rocsparse_spilu0_stage_compute stage is non-blocking
*  and executed asynchronously with respect to the host. It can return before the actual computation has finished.
*  The \ref rocsparse_spilu0_stage_analysis stage is blocking with respect to the host.
*
*  \note
*  Only the \ref rocsparse_spilu0_stage_compute stage
*  supports execution in a hipGraph context. The \ref rocsparse_spilu0_stage_analysis stage does not support hipGraph.
*
*  \note
*  This routine only supports uniform batched computation, that is, same sparsity pattern but batched values of the matrices.
*
*  @param[in]
*  handle       handle to the rocSPARSE library context queue.
*  @param[in]
*  spilu0_descr Spilu0 descriptor.
*  @param[in]
*  A            descriptor of the matrix to factorize.
*  @param[out]
*  P            descriptor of the factorization.
*  @param[in]
*  spilu0_stage stage for the Spilu0 computation.
*  @param[in]
*  buffer_size_in_bytes  number of bytes of the buffer.
*  @param[in]
*  buffer       buffer allocated by the user.
*  @param[out]
*  p_error      error descriptor created if the returned status is not \ref rocsparse_status_success. A null pointer can be passed if an error descriptor is not required.
*
*  \retval rocsparse_status_success the operation completed successfully.
*  \retval rocsparse_status_invalid_handle the library context was not initialized.
*  \retval rocsparse_status_not_implemented the sparse format is invalid or the preconditioner \p P is not identical to the matrix to factorize \p A.
*  \retval rocsparse_status_invalid_value the \p spilu0_stage value is invalid.
*  \retval rocsparse_status_invalid_pointer \p spilu0_descr, \p A, \p P, or \p buffer_size_in_bytes pointer is invalid.
*
*  \par Example
*  \snippet example_rocsparse_spilu0.cpp doc example
*/
ROCSPARSE_EXPORT
rocsparse_status rocsparse_spilu0(rocsparse_handle            handle,
                                  rocsparse_spilu0_descr      spilu0_descr,
                                  rocsparse_const_spmat_descr A,
                                  rocsparse_spmat_descr       P,
                                  rocsparse_spilu0_stage      spilu0_stage,
                                  size_t                      buffer_size_in_bytes,
                                  void*                       buffer,
                                  rocsparse_error*            p_error);

#ifdef __cplusplus
}
#endif
#endif