mirror of
https://github.com/ceres-solver/ceres-solver.git
synced 2026-08-30 00:50:37 +08:00
Darius Rueckert
4247d420fa
This patch adds the 'Expression' class, which is a fundamental building block of automatic code generation. The expressions can be used as scalar types for cost functors as well as Jets. Dynamic branching is not yet supported. Change-Id: I8c61bee5c307e0eec20fd39382683ea90f720dff
86 lines
3.3 KiB
C++
86 lines
3.3 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2019 Google Inc. All rights reserved.
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// http://code.google.com/p/ceres-solver/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// Author: darius.rueckert@fau.de (Darius Rueckert)
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#include "ceres/internal/expression_graph.h"
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#include "glog/logging.h"
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namespace ceres {
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namespace internal {
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static ExpressionGraph* expression_pool = nullptr;
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void StartRecordingExpressions() {
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CHECK(expression_pool == nullptr)
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<< "Expression recording must be stopped before calling "
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"StartRecordingExpressions again.";
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expression_pool = new ExpressionGraph;
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}
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ExpressionGraph StopRecordingExpressions() {
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CHECK(expression_pool)
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<< "Expression recording hasn't started yet or you tried "
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"to stop it twice.";
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ExpressionGraph result = std::move(*expression_pool);
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delete expression_pool;
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expression_pool = nullptr;
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return result;
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}
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ExpressionGraph* GetCurrentExpressionGraph() { return expression_pool; }
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Expression& ExpressionGraph::CreateExpression(ExpressionType type) {
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auto id = expressions_.size();
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Expression expr(type, id);
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expressions_.push_back(expr);
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return expressions_.back();
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}
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bool ExpressionGraph::DependsOn(ExpressionId A, ExpressionId B) const {
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// Depth first search on the expression graph
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// Equivalent Recursive Implementation:
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// if (A.DirectlyDependsOn(B)) return true;
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// for (auto p : A.params_) {
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// if (pool[p.id].DependsOn(B, pool)) return true;
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// }
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std::vector<ExpressionId> stack = ExpressionForId(A).arguments_;
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while (!stack.empty()) {
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auto top = stack.back();
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stack.pop_back();
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if (top == B) {
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return true;
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}
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auto& expr = ExpressionForId(top);
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stack.insert(stack.end(), expr.arguments_.begin(), expr.arguments_.end());
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}
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return false;
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}
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} // namespace internal
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} // namespace ceres
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