295 lines
11 KiB
C++
295 lines
11 KiB
C++
/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010, Georgia Tech Research Corporation,
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* Atlanta, Georgia 30332-0415
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* All Rights Reserved
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* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
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* See LICENSE for the license information
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* -------------------------------------------------------------------------- */
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/**
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* NonlinearOptimizer-inl.h
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* This is a template definition file, include it where needed (only!)
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* so that the appropriate code is generated and link errors avoided.
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* @brief: Encapsulates nonlinear optimization state
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* @Author: Frank Dellaert
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* Created on: Sep 7, 2009
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*/
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#pragma once
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#include <iostream>
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#include <boost/tuple/tuple.hpp>
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#include <gtsam/base/cholesky.h>
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#include <gtsam/nonlinear/NonlinearOptimizer.h>
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#define INSTANTIATE_NONLINEAR_OPTIMIZER(G,C) \
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template class NonlinearOptimizer<G,C>;
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using namespace std;
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namespace gtsam {
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/* ************************************************************************* */
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template<class G, class C, class L, class S, class W>
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NonlinearOptimizer<G, C, L, S, W>::NonlinearOptimizer(shared_graph graph,
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shared_values values, shared_ordering ordering, shared_parameters parameters) :
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graph_(graph), values_(values), error_(graph->error(*values)), ordering_(ordering),
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parameters_(parameters), iterations_(0),
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dimensions_(new vector<size_t>(values->dims(*ordering))),
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structure_(new VariableIndex(*graph->symbolic(*values, *ordering))) {
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if (!graph) throw std::invalid_argument(
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"NonlinearOptimizer constructor: graph = NULL");
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if (!values) throw std::invalid_argument(
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"NonlinearOptimizer constructor: values = NULL");
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if (!ordering) throw std::invalid_argument(
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"NonlinearOptimizer constructor: ordering = NULL");
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}
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/* ************************************************************************* */
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// FIXME: remove this constructor
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template<class G, class C, class L, class S, class W>
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NonlinearOptimizer<G, C, L, S, W>::NonlinearOptimizer(shared_graph graph,
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shared_values values, shared_ordering ordering,
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shared_solver spcg_solver, shared_parameters parameters) :
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graph_(graph), values_(values), error_(graph->error(*values)), ordering_(ordering),
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parameters_(parameters), iterations_(0),
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dimensions_(new vector<size_t>(values->dims(*ordering))),
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spcg_solver_(spcg_solver) {
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if (!graph) throw std::invalid_argument(
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"NonlinearOptimizer constructor: graph = NULL");
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if (!values) throw std::invalid_argument(
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"NonlinearOptimizer constructor: values = NULL");
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if (!spcg_solver) throw std::invalid_argument(
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"NonlinearOptimizer constructor: spcg_solver = NULL");
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}
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/* ************************************************************************* */
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// One iteration of Gauss Newton
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/* ************************************************************************* */
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template<class G, class C, class L, class S, class W>
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NonlinearOptimizer<G, C, L, S, W> NonlinearOptimizer<G, C, L, S, W>::iterate() const {
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Parameters::verbosityLevel verbosity = parameters_->verbosity_ ;
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// FIXME: get rid of spcg solver
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shared_solver solver;
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if (spcg_solver_) { // special case for SPCG
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spcg_solver_->replaceFactors(linearize());
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solver = spcg_solver_;
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} else { // normal case
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solver = createSolver();
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}
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VectorValues delta = *solver->optimize();
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// maybe show output
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if (verbosity >= Parameters::DELTA) delta.print("delta");
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// take old values and update it
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shared_values newValues(new C(values_->expmap(delta, *ordering_)));
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// maybe show output
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if (verbosity >= Parameters::VALUES) newValues->print("newValues");
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NonlinearOptimizer newOptimizer = newValues_(newValues);
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if (verbosity >= Parameters::ERROR) cout << "error: " << newOptimizer.error_ << endl;
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return newOptimizer;
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}
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/* ************************************************************************* */
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template<class G, class C, class L, class S, class W>
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NonlinearOptimizer<G, C, L, S, W> NonlinearOptimizer<G, C, L, S, W>::gaussNewton() const {
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static W writer(error_);
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if (error_ < parameters_->sumError_ ) {
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if ( parameters_->verbosity_ >= Parameters::ERROR)
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cout << "Exiting, as error = " << error_
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<< " < sumError (" << parameters_->sumError_ << ")" << endl;
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return *this;
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}
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// linearize, solve, update
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NonlinearOptimizer next = iterate();
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writer.write(next.error_);
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// check convergence
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bool converged = gtsam::check_convergence(*parameters_, error_, next.error_);
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// return converged state or iterate
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if (converged) return next;
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else return next.gaussNewton();
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}
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/* ************************************************************************* */
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// Iteratively try to do tempered Gauss-Newton steps until we succeed.
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// Form damped system with given lambda, and return a new, more optimistic
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// optimizer if error decreased or iterate with a larger lambda if not.
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// TODO: in theory we can't infinitely recurse, but maybe we should put a max.
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// Reminder: the parameters are Graph type $G$, Values class type $T$,
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// linear system class $L$, the non linear solver type $S$, and the writer type $W$
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template<class G, class T, class L, class S, class W>
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NonlinearOptimizer<G, T, L, S, W> NonlinearOptimizer<G, T, L, S, W>::try_lambda(const L& linearSystem) {
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const Parameters::verbosityLevel verbosity = parameters_->verbosity_ ;
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const Parameters::LambdaMode lambdaMode = parameters_->lambdaMode_ ;
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const double factor = parameters_->lambdaFactor_ ;
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double lambda = parameters_->lambda_ ;
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if( lambdaMode >= Parameters::CAUTIOUS) throw runtime_error("CAUTIOUS mode not working yet, please use BOUNDED.");
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double next_error = error_;
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shared_values next_values = values_;
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// Keep increasing lambda until we make make progress
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while(true) {
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if (verbosity >= Parameters::TRYLAMBDA) cout << "trying lambda = " << lambda << endl;
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// add prior-factors
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// TODO: replace this dampening with a backsubstitution approach
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typename L::shared_ptr dampedSystem(new L(linearSystem));
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{
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double sigma = 1.0 / sqrt(lambda);
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dampedSystem->reserve(dampedSystem->size() + dimensions_->size());
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// for each of the variables, add a prior
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for(Index j=0; j<dimensions_->size(); ++j) {
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size_t dim = (*dimensions_)[j];
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Matrix A = eye(dim);
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Vector b = zero(dim);
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SharedDiagonal model = noiseModel::Isotropic::Sigma(dim,sigma);
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typename L::sharedFactor prior(new JacobianFactor(j, A, b, model));
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dampedSystem->push_back(prior);
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}
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}
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if (verbosity >= Parameters::DAMPED) dampedSystem->print("damped");
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// Create a new solver using the damped linear system
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// FIXME: remove spcg specific code
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if (spcg_solver_) spcg_solver_->replaceFactors(dampedSystem);
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shared_solver solver = (spcg_solver_) ? spcg_solver_ : shared_solver(
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new S(dampedSystem, structure_, parameters_->useQR_));
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// Try solving
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try {
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VectorValues delta = *solver->optimize();
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if (verbosity >= Parameters::TRYDELTA) delta.print("delta");
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// update values
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shared_values newValues(new T(values_->expmap(delta, *ordering_)));
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// create new optimization state with more adventurous lambda
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double error = graph_->error(*newValues);
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if (verbosity >= Parameters::TRYLAMBDA) cout << "next error = " << error << endl;
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if( error <= error_ ) {
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next_values = newValues;
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next_error = error;
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lambda /= factor;
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break;
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}
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else {
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// Either we're not cautious, or the same lambda was worse than the current error.
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// The more adventurous lambda was worse too, so make lambda more conservative
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// and keep the same values.
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if(lambdaMode >= Parameters::BOUNDED && lambda >= 1.0e5) {
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break;
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} else {
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lambda *= factor;
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}
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}
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} catch(const NegativeMatrixException& e) {
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cout << "Negative matrix, increasing lambda" << endl;
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// Either we're not cautious, or the same lambda was worse than the current error.
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// The more adventurous lambda was worse too, so make lambda more conservative
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// and keep the same values.
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if(lambdaMode >= Parameters::BOUNDED && lambda >= 1.0e5) {
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break;
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} else {
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lambda *= factor;
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}
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} catch(...) {
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throw;
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}
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} // end while
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return newValuesErrorLambda_(next_values, next_error, lambda);
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}
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/* ************************************************************************* */
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// One iteration of Levenberg Marquardt
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// Reminder: the parameters are Graph type $G$, Values class type $T$,
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// linear system class $L$, the non linear solver type $S$, and the writer type $W$
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template<class G, class T, class L, class S, class W>
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NonlinearOptimizer<G, T, L, S, W> NonlinearOptimizer<G, T, L, S, W>::iterateLM() {
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const Parameters::verbosityLevel verbosity = parameters_->verbosity_ ;
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const double lambda = parameters_->lambda_ ;
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// show output
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if (verbosity >= Parameters::VALUES) values_->print("values");
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if (verbosity >= Parameters::ERROR) cout << "error: " << error_ << endl;
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if (verbosity >= Parameters::LAMBDA) cout << "lambda = " << lambda << endl;
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// linearize all factors once
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boost::shared_ptr<L> linear(new L(*graph_->linearize(*values_, *ordering_)));
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if (verbosity >= Parameters::LINEAR) linear->print("linear");
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// try lambda steps with successively larger lambda until we achieve descent
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if (verbosity >= Parameters::LAMBDA) cout << "Trying Lambda for the first time" << endl;
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return try_lambda(*linear);
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}
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/* ************************************************************************* */
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// Reminder: the parameters are Graph type $G$, Values class type $T$,
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// linear system class $L$, the non linear solver type $S$, and the writer type $W$
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template<class G, class T, class L, class S, class W>
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NonlinearOptimizer<G, T, L, S, W> NonlinearOptimizer<G, T, L, S, W>::levenbergMarquardt() {
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// Initialize
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bool converged = false;
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const Parameters::verbosityLevel verbosity = parameters_->verbosity_ ;
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// check if we're already close enough
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if (error_ < parameters_->sumError_) {
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if ( verbosity >= Parameters::ERROR )
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cout << "Exiting, as sumError = " << error_ << " < " << parameters_->sumError_ << endl;
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return *this;
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}
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// for the case that maxIterations_ = 0
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iterations_ = 1;
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if (iterations_ >= parameters_->maxIterations_)
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return *this;
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// Iterative loop that implements Levenberg-Marquardt
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while (true) {
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double previous_error = error_;
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// do one iteration of LM
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NonlinearOptimizer next = iterateLM();
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error_ = next.error_;
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values_ = next.values_;
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parameters_ = next.parameters_;
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// check convergence
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// TODO: move convergence checks here and incorporate in verbosity levels
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// TODO: build into iterations somehow as an instance variable
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converged = gtsam::check_convergence(*parameters_, previous_error, error_);
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if(iterations_ >= parameters_->maxIterations_ || converged == true) {
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if (verbosity >= Parameters::VALUES) values_->print("final values");
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if (verbosity >= Parameters::ERROR) cout << "final error: " << error_ << endl;
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if (verbosity >= Parameters::LAMBDA) cout << "final lambda = " << lambda() << endl;
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return *this;
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}
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iterations_++;
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}
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}
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}
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