// Ceres Solver - A fast non-linear least squares minimizer
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// Author: sameeragarwal@google.com (Sameer Agarwal)
//
// Wrappers around Eigen's dense Cholesky factorization
// routines. Normally, if CERES_USE_LDLT_FOR_EIGEN_CHOLESKY is not
// defined Eigen's LLT factorization is used, which is faster than the
// LDLT factorization, however on ARM the LLT factorization seems to
// give significantly worse results than LDLT and we are forced to use
// LDLT instead.
//
// These wrapper functions provide a level of indirection to deal with
// this switching and hide it from the rest of the code base.

#ifndef CERES_INTERNAL_ARRAY_UTILS_H_
#define CERES_INTERNAL_ARRAY_UTILS_H_

#include "ceres/internal/eigen.h"

namespace ceres {
namespace internal {

// Invert a matrix using Eigen's dense Cholesky factorization. values
// and inverse_values can point to the same array.
Eigen::ComputationInfo
InvertUpperTriangularUsingCholesky(int size,
                                   const double* values,
                                   double* inverse_values);

// Solve a linear system using Eigen's dense Cholesky
// factorization. rhs_values and solution can point to the same array.
Eigen::ComputationInfo
SolveUpperTriangularUsingCholesky(int size,
                                  const double* lhs,
                                  const double* rhs,
                                  double* solution);

}  // namespace internal
}  // namespace ceres

#endif  // CERES_INTERNAL_ARRAY_UTILS_H_