93 lines
3.5 KiB
C++
93 lines
3.5 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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* SubgraphSolver-inl.h
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*
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* Created on: Jan 17, 2010
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* Author: nikai
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* Description: subgraph preconditioning conjugate gradient solver
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*/
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#pragma once
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#include <boost/tuple/tuple.hpp>
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#include <gtsam/linear/SubgraphSolver.h>
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#include <gtsam/linear/iterative-inl.h>
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#include <gtsam/inference/graph-inl.h>
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#include <gtsam/inference/FactorGraph-inl.h>
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using namespace std;
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namespace gtsam {
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/* ************************************************************************* */
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template<class Graph, class Values>
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SubgraphSolver<Graph, Values>::SubgraphSolver(const Graph& G, const Values& theta0) {
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initialize(G,theta0);
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}
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/* ************************************************************************* */
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template<class Graph, class Values>
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void SubgraphSolver<Graph, Values>::initialize(const Graph& G, const Values& theta0) {
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// generate spanning tree
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PredecessorMap<Key> tree = gtsam::findMinimumSpanningTree<Graph, Key, Constraint>(G);
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// split the graph
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if (verbose_) cout << "generating spanning tree and split the graph ...";
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gtsam::split<Graph,Key,Constraint>(G, tree, T_, C_) ;
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if (verbose_) cout << ",with " << T_.size() << " and " << C_.size() << " factors" << endl;
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// make the ordering
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list<Key> keys = predecessorMap2Keys(tree);
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ordering_ = boost::shared_ptr<Ordering>(new Ordering(list<Symbol>(keys.begin(), keys.end())));
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// Add a HardConstraint to the root, otherwise the root will be singular
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Key root = keys.back();
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T_.addHardConstraint(root, theta0[root]);
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// compose the approximate solution
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theta_bar_ = composePoses<Graph, Constraint, Pose, Values> (T_, tree, theta0[root]);
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}
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/* ************************************************************************* */
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template<class Graph, class Values>
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boost::shared_ptr<SubgraphPreconditioner> SubgraphSolver<Graph, Values>::linearize(const Graph& G, const Values& theta_bar) const {
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SubgraphPreconditioner::sharedFG Ab1 = T_.linearize(theta_bar, *ordering_);
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SubgraphPreconditioner::sharedFG Ab2 = C_.linearize(theta_bar, *ordering_);
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#ifdef TIMING
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SubgraphPreconditioner::sharedBayesNet Rc1;
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SubgraphPreconditioner::sharedValues xbar;
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#else
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GaussianFactorGraph sacrificialAb1 = *Ab1; // duplicate !!!!!
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SubgraphPreconditioner::sharedBayesNet Rc1 = Inference::Eliminate(sacrificialAb1) ;
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SubgraphPreconditioner::sharedValues xbar = gtsam::optimize_(*Rc1);
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#endif
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// TODO: there does not seem to be a good reason to have Ab1_
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// It seems only be used to provide an ordering for creating sparse matrices
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return boost::shared_ptr<SubgraphPreconditioner>(new SubgraphPreconditioner(Ab1, Ab2, Rc1, xbar));
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}
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/* ************************************************************************* */
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template<class Graph, class Values>
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VectorValues SubgraphSolver<Graph, Values>::optimize(SubgraphPreconditioner& system) const {
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VectorValues zeros = system.zero();
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// Solve the subgraph PCG
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VectorValues ybar = conjugateGradients<SubgraphPreconditioner, VectorValues,
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Errors> (system, zeros, verbose_, epsilon_, epsilon_abs_, maxIterations_);
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VectorValues xbar = system.x(ybar);
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return xbar;
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}
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}
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