/*! \file */
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#ifndef ROCSPARSE_SPILDLT0_H
#define ROCSPARSE_SPILDLT0_H

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

#ifdef __cplusplus
extern "C" {
#endif

/*! \ingroup generic_module
 *  \brief Incomplete \f$LDL^H\f$ factorization with 0 fill-ins and no pivoting.
 *  \details
 *  \p rocsparse_spildlt0_buffer_size returns the size of the non-persistent buffer
 *  that is required by \ref rocsparse_spildlt0 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 format is \ref rocsparse_format_csr.
 *
 *  \note
 *  This routine only supports uniform strided batched computation, that is, the same sparsity pattern but strided batched values of the matrices.
 *
 *  @param[in]
 *  handle          handle to the rocSPARSE library context queue.
 *  @param[in]
 *  spildlt0_descr  SpILDLT0 descriptor.
 *  @param[in]
 *  A               descriptor of the matrix to factorize.
 *  @param[in]
 *  P               descriptor of the factorization. In-place \p P = \p A is allowed.
 *  @param[in]
 *  spildlt0_stage  stage for the SpILDLT0 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 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 spildlt0_stage value is invalid.
 *  \retval rocsparse_status_invalid_pointer \p spildlt0_descr, \p A, \p P, or \p p_buffer_size_in_bytes pointer is invalid.
 */
ROCSPARSE_EXPORT
rocsparse_status rocsparse_spildlt0_buffer_size(rocsparse_handle            handle,
                                                rocsparse_spildlt0_descr    spildlt0_descr,
                                                rocsparse_const_spmat_descr A,
                                                rocsparse_const_spmat_descr P,
                                                rocsparse_spildlt0_stage    spildlt0_stage,
                                                size_t*                     p_buffer_size_in_bytes,
                                                rocsparse_error*            p_error);

/*! \ingroup generic_module
 *  \brief Incomplete \f$LDL^H\f$ factorization with 0 fill-ins and no pivoting.
 *
 *  \details
 *  \p rocsparse_spildlt0 computes the incomplete \f$LDL^H\f$ factorization with 0 fill-ins
 *  and no pivoting of a sparse \f$m \times m\f$ Hermitian (or symmetric for real types)
 *  matrix \f$A\f$, such that
 *  \f[
 *    A \approx L D L^H
 *  \f]
 *  where \f$L\f$ is unit lower triangular and \f$D\f$ is a real diagonal matrix.
 *
 *  The diagonal entries of \f$D\f$ are computed as:
 *  \f[
 *    D_i = \mathrm{real}(A_{ii}) - \sum_{k<i} |L_{ik}|^2 D_k
 *  \f]
 *  and the off-diagonal entries of \f$L\f$ as:
 *  \f[
 *    L_{ij} = \frac{1}{D_j} \left( A_{ij} - \sum_{k<j} L_{ik} D_k \overline{L_{jk}} \right)
 *  \f]
 *  for each entry found in the lower triangular part of the matrix \f$A\f$.
 *
 *  Performing the above operation requires two stages, the stage \ref rocsparse_spildlt0_stage_analysis and the stage \ref rocsparse_spildlt0_stage_compute.
 *  The stage \ref rocsparse_spildlt0_stage_analysis is required to perform the stage \ref rocsparse_spildlt0_stage_compute and only needs to be called once for a given sparse matrix \f$A\f$, while the stage \ref rocsparse_spildlt0_stage_compute can be repeatedly used with different matrices \f$A\f$ that have the same sparsity pattern.
 *
 *  The factorization overwrites the values array of \p P with \f$L + D - I\f$: the strict
 *  lower-triangular entries hold \f$L\f$ (its unit diagonal is implicit), and the diagonal
 *  entries hold the real diagonal \f$D\f$.
 *
 *  \p rocsparse_spildlt0 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 spildlt0_descr needs to be configured with \ref rocsparse_spildlt0_set_input.
 *
 *  \note
 *  The sparse matrix format currently supported is \ref rocsparse_format_csr.
 *
 *  \note
 *  the \ref rocsparse_spildlt0_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_spildlt0_stage_analysis stage is blocking with respect to the host.
 *
 *  \note
 *  Only the \ref rocsparse_spildlt0_stage_compute stage
 *  supports execution in a hipGraph context. The \ref rocsparse_spildlt0_stage_analysis stage does not support hipGraph.
 *
 *  \note
 *  This routine only supports uniform strided batched computation, that is, the same sparsity pattern but strided batched values of the matrices.
 *
 *  @param[in]
 *  handle          handle to the rocSPARSE library context queue.
 *  @param[in]
 *  spildlt0_descr  SpILDLT0 descriptor.
 *  @param[in]
 *  A               descriptor of the matrix to factorize.
 *  @param[out]
 *  P               descriptor of the factorization. In-place \p P = \p A is allowed.
 *  @param[in]
 *  spildlt0_stage  stage for the SpILDLT0 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 spildlt0_stage value is invalid.
 *  \retval rocsparse_status_invalid_pointer \p spildlt0_descr, \p A, \p P, or \p buffer_size_in_bytes pointer is invalid.
 *
 *  \par Example
 *  \snippet example_rocsparse_spildlt0.cpp doc example
 */
ROCSPARSE_EXPORT
rocsparse_status rocsparse_spildlt0(rocsparse_handle            handle,
                                    rocsparse_spildlt0_descr    spildlt0_descr,
                                    rocsparse_const_spmat_descr A,
                                    rocsparse_spmat_descr       P,
                                    rocsparse_spildlt0_stage    spildlt0_stage,
                                    size_t                      buffer_size_in_bytes,
                                    void*                       buffer,
                                    rocsparse_error*            p_error);

#ifdef __cplusplus
}
#endif
#endif