// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

//

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//   used to endorse or promote products derived from this software without

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// Author: sameeragarwal@google.com (Sameer Agarwal)

#include "ceres/lapack.h"

#include "ceres/internal/port.h"

#include "ceres/linear_solver.h"

#include "glog/logging.h"

// C interface to the LAPACK Cholesky factorization and triangular solve.

extern "C" void dpotrf_(char* uplo,

                       int* n,

                       double* a,

                       int* lda,

                       int* info);

extern "C" void dpotrs_(char* uplo,

                        int* n,

                        int* nrhs,

                        double* a,

                        int* lda,

                        double* b,

                        int* ldb,

                        int* info);

extern "C" void dgels_(char* uplo,

                       int* m,

                       int* n,

                       int* nrhs,

                       double* a,

                       int* lda,

                       double* b,

                       int* ldb,

                       double* work,

                       int* lwork,

                       int* info);

namespace ceres {

namespace internal {

LinearSolverTerminationType LAPACK::SolveInPlaceUsingCholesky(

    int num_rows,

    const double* in_lhs,

    double* rhs_and_solution,

    std::string* message) {

#ifdef CERES_NO_LAPACK

  LOG(FATAL) << "Ceres was built without a BLAS library.";

  return LINEAR_SOLVER_FATAL_ERROR;

#else

  char uplo = 'L';

  int n = num_rows;

  int info = 0;

  int nrhs = 1;

  double* lhs = const_cast<double*>(in_lhs);

  dpotrf_(&uplo, &n, lhs, &n, &info;;

  if (info < 0) {

    LOG(FATAL) << "Congratulations, you found a bug in Ceres."

               << "Please report it."

               << "LAPACK::dpotrf fatal error."

               << "Argument: " << -info << " is invalid.";

    return LINEAR_SOLVER_FATAL_ERROR;

  }

  if (info > 0) {

    *message =

        StringPrintf(

            "LAPACK::dpotrf numerical failure. "

             "The leading minor of order %d is not positive definite.", info);

    return LINEAR_SOLVER_FAILURE;

  }

  dpotrs_(&uplo, &n, &nrhs, lhs, &n, rhs_and_solution, &n, &info;;

  if (info < 0) {

    LOG(FATAL) << "Congratulations, you found a bug in Ceres."

               << "Please report it."

               << "LAPACK::dpotrs fatal error."

               << "Argument: " << -info << " is invalid.";

    return LINEAR_SOLVER_FATAL_ERROR;

  }

  *message = "Success";

  return LINEAR_SOLVER_SUCCESS;

#endif

}

int LAPACK::EstimateWorkSizeForQR(int num_rows, int num_cols) {

#ifdef CERES_NO_LAPACK

  LOG(FATAL) << "Ceres was built without a LAPACK library.";

  return -1;

#else

  char trans = 'N';

  int nrhs = 1;

  int lwork = -1;

  double work;

  int info = 0;

  dgels_(&trans,

         &num_rows,

         &num_cols,

         &nrhs,

         NULL,

         &num_rows,

         NULL,

         &num_rows,

         &work,

         &lwork,

         &info;;

  if (info < 0) {

    LOG(FATAL) << "Congratulations, you found a bug in Ceres."

               << "Please report it."

               << "LAPACK::dgels fatal error."

               << "Argument: " << -info << " is invalid.";

  }

  return static_cast<int>(work);

#endif

}

LinearSolverTerminationType LAPACK::SolveInPlaceUsingQR(

    int num_rows,

    int num_cols,

    const double* in_lhs,

    int work_size,

    double* work,

    double* rhs_and_solution,

    std::string* message) {

#ifdef CERES_NO_LAPACK

  LOG(FATAL) << "Ceres was built without a LAPACK library.";

  return LINEAR_SOLVER_FATAL_ERROR;

#else

  char trans = 'N';

  int m = num_rows;

  int n = num_cols;

  int nrhs = 1;

  int lda = num_rows;

  int ldb = num_rows;

  int info = 0;

  double* lhs = const_cast<double*>(in_lhs);

  dgels_(&trans,

         &m,

         &n,

         &nrhs,

         lhs,

         &lda,

         rhs_and_solution,

         &ldb,

         work,

         &work_size,

         &info;;

  if (info < 0) {

    LOG(FATAL) << "Congratulations, you found a bug in Ceres."

               << "Please report it."

               << "LAPACK::dgels fatal error."

               << "Argument: " << -info << " is invalid.";

  }

  *message = "Success.";

  return LINEAR_SOLVER_SUCCESS;

#endif

}

}  // namespace internal

}  // namespace ceres