internal/ceres/parameter_block.h

// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
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// Author: keir@google.com (Keir Mierle)

#ifndef CERES_INTERNAL_PARAMETER_BLOCK_H_
#define CERES_INTERNAL_PARAMETER_BLOCK_H_

#include <cstdlib>
#include <glog/logging.h>
#include "ceres/array_utils.h"
#include "ceres/integral_types.h"
#include "ceres/internal/eigen.h"
#include "ceres/internal/port.h"
#include "ceres/internal/scoped_ptr.h"
#include "ceres/local_parameterization.h"

namespace ceres {
namespace internal {

class ProblemImpl;

// The parameter block encodes the location of the user's original value, and
// also the "current state" of the parameter. The evaluator uses whatever is in
// the current state of the parameter when evaluating. This is inlined since the
// methods are performance sensitive.
//
// The class is not thread-safe, unless only const methods are called. The
// parameter block may also hold a pointer to a local parameterization; the
// parameter block does not take ownership of this pointer, so the user is
// responsible for the proper disposal of the local parameterization.
class ParameterBlock {
 public:
  ParameterBlock(double* user_state, int size) {
    Init(user_state, size, NULL);
  }
  ParameterBlock(double* user_state,
                 int size,
                 LocalParameterization* local_parameterization) {
    Init(user_state, size, local_parameterization);
  }

  // The size of the parameter block.
  int Size() const { return size_; }

  // Manipulate the parameter state.
  bool SetState(const double* x) {
    CHECK(x != NULL)
        << "Tried to set the state of constant parameter "
        << "with user location " << user_state_;
    CHECK(!is_constant_)
        << "Tried to set the state of constant parameter "
        << "with user location " << user_state_;

    state_ = x;
    return UpdateLocalParameterizationJacobian();
  }

  // Copy the current parameter state out to x. This is "GetState()" rather than
  // simply "state()" since it is actively copying the data into the passed
  // pointer.
  void GetState(double *x) const {
    if (x != state_) {
      memcpy(x, state_, sizeof(*state_) * size_);
    }
  }

  // Direct pointers to the current state.
  const double* state() const { return state_; }
  const double* user_state() const { return user_state_; }
  double* mutable_user_state() { return user_state_; }
  LocalParameterization* local_parameterization() const {
    return local_parameterization_;
  }
  LocalParameterization* mutable_local_parameterization() {
    return local_parameterization_;
  }

  // Set this parameter block to vary or not.
  void SetConstant() { is_constant_ = true; }
  void SetVarying() { is_constant_ = false; }
  bool IsConstant() const { return is_constant_; }

  // This parameter block's index in an array.
  int index() const { return index_; }
  void set_index(int index) { index_ = index; }

  // This parameter offset inside a larger state vector.
  int state_offset() const { return state_offset_; }
  void set_state_offset(int state_offset) { state_offset_ = state_offset; }

  // This parameter offset inside a larger delta vector.
  int delta_offset() const { return delta_offset_; }
  void set_delta_offset(int delta_offset) { delta_offset_ = delta_offset; }

  // Methods relating to the parameter block's parameterization.

  // The local to global jacobian. Returns NULL if there is no local
  // parameterization for this parameter block. The returned matrix is row-major
  // and has Size() rows and  LocalSize() columns.
  const double* LocalParameterizationJacobian() const {
    return local_parameterization_jacobian_.get();
  }

  int LocalSize() const {
    return (local_parameterization_ == NULL)
        ? size_
        : local_parameterization_->LocalSize();
  }

  // Set the parameterization. The parameterization can be set exactly once;
  // multiple calls to set the parameterization to different values will crash.
  // It is an error to pass NULL for the parameterization. The parameter block
  // does not take ownership of the parameterization.
  void SetParameterization(LocalParameterization* new_parameterization) {
    CHECK(new_parameterization != NULL) << "NULL parameterization invalid.";
    CHECK(new_parameterization->GlobalSize() == size_)
        << "Invalid parameterization for parameter block. The parameter block "
        << "has size " << size_ << " while the parameterization has a global "
        << "size of " << new_parameterization->GlobalSize() << ". Did you "
        << "accidentally use the wrong parameter block or parameterization?";
    if (new_parameterization != local_parameterization_) {
      CHECK(local_parameterization_ == NULL)
          << "Can't re-set the local parameterization; it leads to "
          << "ambiguous ownership.";
      local_parameterization_ = new_parameterization;
      local_parameterization_jacobian_.reset(
          new double[local_parameterization_->GlobalSize() *
                     local_parameterization_->LocalSize()]);
      CHECK(UpdateLocalParameterizationJacobian())
          "Local parameterization Jacobian computation failed"
          "for x: " << ConstVectorRef(state_, Size()).transpose();
    } else {
      // Ignore the case that the parameterizations match.
    }
  }

  // Generalization of the addition operation. This is the same as
  // LocalParameterization::Plus() but uses the parameter's current state
  // instead of operating on a passed in pointer.
  bool Plus(const double *x, const double* delta, double* x_plus_delta) {
    if (local_parameterization_ == NULL) {
      VectorRef(x_plus_delta, size_) = ConstVectorRef(x, size_) +
                                       ConstVectorRef(delta,  size_);
      return true;
    }
    return local_parameterization_->Plus(x, delta, x_plus_delta);
  }

 private:
  void Init(double* user_state,
            int size,
            LocalParameterization* local_parameterization) {
    user_state_ = user_state;
    size_ = size;
    is_constant_ = false;
    state_ = user_state_;

    local_parameterization_ = NULL;
    if (local_parameterization != NULL) {
      SetParameterization(local_parameterization);
    }

    index_ = -1;
    state_offset_ = -1;
    delta_offset_ = -1;
  }

  bool UpdateLocalParameterizationJacobian() {
    if (local_parameterization_ == NULL) {
      return true;
    }

    // Update the local to global Jacobian. In some cases this is
    // wasted effort; if this is a bottleneck, we will find a solution
    // at that time.

    const int jacobian_size = Size() * LocalSize();
    InvalidateArray(jacobian_size,
                    local_parameterization_jacobian_.get());
    if (!local_parameterization_->ComputeJacobian(
            state_,
            local_parameterization_jacobian_.get())) {
      LOG(WARNING) << "Local parameterization Jacobian computation failed"
          "for x: " << ConstVectorRef(state_, Size()).transpose();
      return false;
    }

    if (!IsArrayValid(jacobian_size, local_parameterization_jacobian_.get())) {
      LOG(WARNING) << "Local parameterization Jacobian computation returned"
                   << "an invalid matrix for x: "
                   << ConstVectorRef(state_, Size()).transpose()
                   << "\n Jacobian matrix : "
                   << ConstMatrixRef(local_parameterization_jacobian_.get(),
                                     Size(),
                                     LocalSize());
      return false;
    }
    return true;
  }

  double* user_state_;
  int size_;
  bool is_constant_;
  LocalParameterization* local_parameterization_;

  // The "state" of the parameter. These fields are only needed while the
  // solver is running. While at first glance using mutable is a bad idea, this
  // ends up simplifying the internals of Ceres enough to justify the potential
  // pitfalls of using "mutable."
  mutable const double* state_;
  mutable scoped_array<double> local_parameterization_jacobian_;

  // The index of the parameter. This is used by various other parts of Ceres to
  // permit switching from a ParameterBlock* to an index in another array.
  int32 index_;

  // The offset of this parameter block inside a larger state vector.
  int32 state_offset_;

  // The offset of this parameter block inside a larger delta vector.
  int32 delta_offset_;

  // Necessary so ProblemImpl can clean up the parameterizations.
  friend class ProblemImpl;
};

}  // namespace internal
}  // namespace ceres

#endif  // CERES_INTERNAL_PARAMETER_BLOCK_H_