ceres之求解器

ceres之求解器

// TODO(keir): Considerably expand the explanations of each solver type.
enum LinearSolverType {
  // These solvers are for general rectangular systems formed from the
  // normal equations A'A x = A'b. They are direct solvers and do not
  // assume any special problem structure.

  // Solve the normal equations using a dense Cholesky solver; based
  // on Eigen.
  DENSE_NORMAL_CHOLESKY,

  // Solve the normal equations using a dense QR solver; based on
  // Eigen.
  DENSE_QR,

  // Solve the normal equations using a sparse cholesky solver; requires
  // SuiteSparse or CXSparse.
  SPARSE_NORMAL_CHOLESKY,

  // Specialized solvers, specific to problems with a generalized
  // bi-partitite structure.

  // Solves the reduced linear system using a dense Cholesky solver;
  // based on Eigen.
  DENSE_SCHUR,

  // Solves the reduced linear system using a sparse Cholesky solver;
  // based on CHOLMOD.
  SPARSE_SCHUR,

  // Solves the reduced linear system using Conjugate Gradients, based
  // on a new Ceres implementation.  Suitable for large scale
  // problems.
  ITERATIVE_SCHUR,

  // Conjugate gradients on the normal equations.
  CGNR
};