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https://github.com/ceres-solver/ceres-solver.git
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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
93 lines
3.9 KiB
C++
93 lines
3.9 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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#ifndef CERES_PUBLIC_EXPRESSION_TREE_H_
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#define CERES_PUBLIC_EXPRESSION_TREE_H_
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#include <vector>
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#include "expression.h"
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namespace ceres {
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namespace internal {
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// A directed, acyclic, unconnected graph containing all expressions of a
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// program.
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//
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// The expression graph is stored linear in the expressions_ array. The order is
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// identical to the execution order. Each expression can have multiple children
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// and multiple parents.
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// A is child of B <=> B has A as a parameter <=> B.DirectlyDependsOn(A)
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// A is parent of B <=> A has B as a parameter <=> A.DirectlyDependsOn(B)
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class ExpressionGraph {
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public:
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// Creates an expression and adds it to expressions_.
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// The returned reference will be invalid after this function is called again.
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Expression& CreateExpression(ExpressionType type);
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// Checks if A depends on B.
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// -> B is a descendant of A
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bool DependsOn(ExpressionId A, ExpressionId B) const;
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Expression& ExpressionForId(ExpressionId id) { return expressions_[id]; }
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const Expression& ExpressionForId(ExpressionId id) const {
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return expressions_[id];
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}
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int Size() const { return expressions_.size(); }
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private:
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// All Expressions are referenced by an ExpressionId. The ExpressionId is the
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// index into this array. Each expression has a list of ExpressionId as
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// arguments. These references form the graph.
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std::vector<Expression> expressions_;
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};
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// After calling this method, all operations on 'ExpressionRef' objects will be
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// recorded into an ExpressionGraph. You can obtain this graph by calling
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// StopRecordingExpressions.
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//
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// Performing expression operations before calling StartRecordingExpressions or
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// calling StartRecodring. twice is an error.
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void StartRecordingExpressions();
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// Stops recording and returns all expressions that have been executed since the
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// call to StartRecordingExpressions. The internal ExpressionGraph will be
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// invalidated and a second consecutive call to this method results in an error.
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ExpressionGraph StopRecordingExpressions();
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// Returns a pointer to the active expression tree.
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// Normal users should not use this functions.
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ExpressionGraph* GetCurrentExpressionGraph();
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} // namespace internal
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} // namespace ceres
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#endif
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