internal/ceres/solver_test.cc - ceres-solver - Git at Google

 // Ceres Solver - A fast non-linear least squares minimizer
 // Copyright 2022 Google Inc. All rights reserved.
 // http://ceres-solver.org/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are met:
 //
 // * Redistributions of source code must retain the above copyright notice,
 //   this list of conditions and the following disclaimer.
 // * Redistributions in binary form must reproduce the above copyright notice,
 //   this list of conditions and the following disclaimer in the documentation
 //   and/or other materials provided with the distribution.
 // * Neither the name of Google Inc. nor the names of its contributors may be
 //   used to endorse or promote products derived from this software without
 //   specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.
 //
 // Author: sameeragarwal@google.com (Sameer Agarwal)

 #include "ceres/solver.h"

 #include <cmath>
 #include <limits>
 #include <memory>
 #include <vector>

 #include "ceres/autodiff_cost_function.h"
 #include "ceres/evaluation_callback.h"
 #include "ceres/local_parameterization.h"
 #include "ceres/manifold.h"
 #include "ceres/problem.h"
 #include "ceres/problem_impl.h"
 #include "ceres/sized_cost_function.h"
 #include "gtest/gtest.h"

 namespace ceres::internal {

 using std::string;

 TEST(SolverOptions, DefaultTrustRegionOptionsAreValid) {
   Solver::Options options;
   options.minimizer_type = TRUST_REGION;
   string error;
   EXPECT_TRUE(options.IsValid(&error)) << error;
 }

 TEST(SolverOptions, DefaultLineSearchOptionsAreValid) {
   Solver::Options options;
   options.minimizer_type = LINE_SEARCH;
   string error;
   EXPECT_TRUE(options.IsValid(&error)) << error;
 }

 struct QuadraticCostFunctor {
   template <typename T>
   bool operator()(const T* const x, T* residual) const {
     residual[0] = T(5.0) - *x;
     return true;
   }

   static CostFunction* Create() {
     return new AutoDiffCostFunction<QuadraticCostFunctor, 1, 1>(
         new QuadraticCostFunctor);
   }
 };

 struct RememberingCallback : public IterationCallback {
   explicit RememberingCallback(double* x) : calls(0), x(x) {}
   CallbackReturnType operator()(const IterationSummary& summary) final {
     x_values.push_back(*x);
     return SOLVER_CONTINUE;
   }
   int calls;
   double* x;
   std::vector<double> x_values;
 };

 struct NoOpEvaluationCallback : EvaluationCallback {
   void PrepareForEvaluation(bool evaluate_jacobians,
                             bool new_evaluation_point) final {
     (void)evaluate_jacobians;
     (void)new_evaluation_point;
   }
 };

 TEST(Solver, UpdateStateEveryIterationOptionNoEvaluationCallback) {
   double x = 50.0;
   const double original_x = x;

   Problem::Options problem_options;
   Problem problem(problem_options);
   problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &x);

   Solver::Options options;
   options.linear_solver_type = DENSE_QR;

   RememberingCallback callback(&x);
   options.callbacks.push_back(&callback);

   Solver::Summary summary;

   int num_iterations;

   // First: update_state_every_iteration=false, evaluation_callback=nullptr.
   Solve(options, &problem, &summary);
   num_iterations =
       summary.num_successful_steps + summary.num_unsuccessful_steps;
   EXPECT_GT(num_iterations, 1);
   for (double value : callback.x_values) {
     EXPECT_EQ(50.0, value);
   }

   // Second: update_state_every_iteration=true, evaluation_callback=nullptr.
   x = 50.0;
   options.update_state_every_iteration = true;
   callback.x_values.clear();
   Solve(options, &problem, &summary);
   num_iterations =
       summary.num_successful_steps + summary.num_unsuccessful_steps;
   EXPECT_GT(num_iterations, 1);
   EXPECT_EQ(original_x, callback.x_values[0]);
   EXPECT_NE(original_x, callback.x_values[1]);
 }

 TEST(Solver, UpdateStateEveryIterationOptionWithEvaluationCallback) {
   double x = 50.0;
   const double original_x = x;

   Problem::Options problem_options;
   NoOpEvaluationCallback evaluation_callback;
   problem_options.evaluation_callback = &evaluation_callback;

   Problem problem(problem_options);
   problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &x);

   Solver::Options options;
   options.linear_solver_type = DENSE_QR;
   RememberingCallback callback(&x);
   options.callbacks.push_back(&callback);

   Solver::Summary summary;

   int num_iterations;

   // First: update_state_every_iteration=true, evaluation_callback=!nullptr.
   x = 50.0;
   options.update_state_every_iteration = true;
   callback.x_values.clear();
   Solve(options, &problem, &summary);
   num_iterations =
       summary.num_successful_steps + summary.num_unsuccessful_steps;
   EXPECT_GT(num_iterations, 1);
   EXPECT_EQ(original_x, callback.x_values[0]);
   EXPECT_NE(original_x, callback.x_values[1]);

   // Second: update_state_every_iteration=false, evaluation_callback=!nullptr.
   x = 50.0;
   options.update_state_every_iteration = false;
   callback.x_values.clear();
   Solve(options, &problem, &summary);
   num_iterations =
       summary.num_successful_steps + summary.num_unsuccessful_steps;
   EXPECT_GT(num_iterations, 1);
   EXPECT_EQ(original_x, callback.x_values[0]);
   EXPECT_NE(original_x, callback.x_values[1]);
 }

 TEST(Solver, CantMixEvaluationCallbackWithInnerIterations) {
   double x = 50.0;
   double y = 60.0;

   Problem::Options problem_options;
   NoOpEvaluationCallback evaluation_callback;
   problem_options.evaluation_callback = &evaluation_callback;

   Problem problem(problem_options);
   problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &x);
   problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &y);

   Solver::Options options;
   options.use_inner_iterations = true;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, FAILURE);

   options.use_inner_iterations = false;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
 }

 // The parameters must be in separate blocks so that they can be individually
 // set constant or not.
 struct Quadratic4DCostFunction {
   template <typename T>
   bool operator()(const T* const x,
                   const T* const y,
                   const T* const z,
                   const T* const w,
                   T* residual) const {
     // A 4-dimension axis-aligned quadratic.
     residual[0] = T(10.0) - *x + T(20.0) - *y + T(30.0) - *z + T(40.0) - *w;
     return true;
   }

   static CostFunction* Create() {
     return new AutoDiffCostFunction<Quadratic4DCostFunction, 1, 1, 1, 1, 1>(
         new Quadratic4DCostFunction);
   }
 };

 // A cost function that simply returns its argument.
 class UnaryIdentityCostFunction : public SizedCostFunction<1, 1> {
  public:
   bool Evaluate(double const* const* parameters,
                 double* residuals,
                 double** jacobians) const final {
     residuals[0] = parameters[0][0];
     if (jacobians != nullptr && jacobians[0] != nullptr) {
       jacobians[0][0] = 1.0;
     }
     return true;
   }
 };

 TEST(Solver, TrustRegionProblemHasNoParameterBlocks) {
   Problem problem;
   Solver::Options options;
   options.minimizer_type = TRUST_REGION;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_EQ(summary.message,
             "Function tolerance reached. "
             "No non-constant parameter blocks found.");
 }

 TEST(Solver, LineSearchProblemHasNoParameterBlocks) {
   Problem problem;
   Solver::Options options;
   options.minimizer_type = LINE_SEARCH;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_EQ(summary.message,
             "Function tolerance reached. "
             "No non-constant parameter blocks found.");
 }

 TEST(Solver, TrustRegionProblemHasZeroResiduals) {
   Problem problem;
   double x = 1;
   problem.AddParameterBlock(&x, 1);
   Solver::Options options;
   options.minimizer_type = TRUST_REGION;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_EQ(summary.message,
             "Function tolerance reached. "
             "No non-constant parameter blocks found.");
 }

 TEST(Solver, LineSearchProblemHasZeroResiduals) {
   Problem problem;
   double x = 1;
   problem.AddParameterBlock(&x, 1);
   Solver::Options options;
   options.minimizer_type = LINE_SEARCH;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_EQ(summary.message,
             "Function tolerance reached. "
             "No non-constant parameter blocks found.");
 }

 TEST(Solver, TrustRegionProblemIsConstant) {
   Problem problem;
   double x = 1;
   problem.AddResidualBlock(new UnaryIdentityCostFunction, nullptr, &x);
   problem.SetParameterBlockConstant(&x);
   Solver::Options options;
   options.minimizer_type = TRUST_REGION;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_EQ(summary.initial_cost, 1.0 / 2.0);
   EXPECT_EQ(summary.final_cost, 1.0 / 2.0);
 }

 TEST(Solver, LineSearchProblemIsConstant) {
   Problem problem;
   double x = 1;
   problem.AddResidualBlock(new UnaryIdentityCostFunction, nullptr, &x);
   problem.SetParameterBlockConstant(&x);
   Solver::Options options;
   options.minimizer_type = LINE_SEARCH;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_EQ(summary.initial_cost, 1.0 / 2.0);
   EXPECT_EQ(summary.final_cost, 1.0 / 2.0);
 }

 #if defined(CERES_NO_SUITESPARSE)
 TEST(Solver, SparseNormalCholeskyNoSuiteSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = SUITE_SPARSE;
   options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, SparseSchurNoSuiteSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = SUITE_SPARSE;
   options.linear_solver_type = SPARSE_SCHUR;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }
 #endif

 #if defined(CERES_NO_CXSPARSE)
 TEST(Solver, SparseNormalCholeskyNoCXSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = CX_SPARSE;
   options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, SparseSchurNoCXSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = CX_SPARSE;
   options.linear_solver_type = SPARSE_SCHUR;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }
 #endif

 #if defined(CERES_NO_ACCELERATE_SPARSE)
 TEST(Solver, SparseNormalCholeskyNoAccelerateSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = ACCELERATE_SPARSE;
   options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, SparseSchurNoAccelerateSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = ACCELERATE_SPARSE;
   options.linear_solver_type = SPARSE_SCHUR;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }
 #else
 TEST(Solver, DynamicSparseNormalCholeskyUnsupportedWithAccelerateSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = ACCELERATE_SPARSE;
   options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
   options.dynamic_sparsity = true;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }
 #endif

 #if !defined(CERES_USE_EIGEN_SPARSE)
 TEST(Solver, SparseNormalCholeskyNoEigenSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = EIGEN_SPARSE;
   options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, SparseSchurNoEigenSparse) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = EIGEN_SPARSE;
   options.linear_solver_type = SPARSE_SCHUR;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }
 #endif

 TEST(Solver, SparseNormalCholeskyNoSparseLibrary) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = NO_SPARSE;
   options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, SparseSchurNoSparseLibrary) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = NO_SPARSE;
   options.linear_solver_type = SPARSE_SCHUR;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, IterativeSchurWithClusterJacobiPerconditionerNoSparseLibrary) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = NO_SPARSE;
   options.linear_solver_type = ITERATIVE_SCHUR;
   // Requires SuiteSparse.
   options.preconditioner_type = CLUSTER_JACOBI;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver,
      IterativeSchurWithClusterTridiagonalPerconditionerNoSparseLibrary) {
   Solver::Options options;
   options.sparse_linear_algebra_library_type = NO_SPARSE;
   options.linear_solver_type = ITERATIVE_SCHUR;
   // Requires SuiteSparse.
   options.preconditioner_type = CLUSTER_TRIDIAGONAL;
   string message;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, IterativeLinearSolverForDogleg) {
   Solver::Options options;
   options.trust_region_strategy_type = DOGLEG;
   string message;
   options.linear_solver_type = ITERATIVE_SCHUR;
   EXPECT_FALSE(options.IsValid(&message));

   options.linear_solver_type = CGNR;
   EXPECT_FALSE(options.IsValid(&message));
 }

 TEST(Solver, LinearSolverTypeNormalOperation) {
   Solver::Options options;
   options.linear_solver_type = DENSE_QR;

   string message;
   EXPECT_TRUE(options.IsValid(&message));

   options.linear_solver_type = DENSE_NORMAL_CHOLESKY;
   EXPECT_TRUE(options.IsValid(&message));

   options.linear_solver_type = DENSE_SCHUR;
   EXPECT_TRUE(options.IsValid(&message));

   options.linear_solver_type = SPARSE_SCHUR;
 #if defined(CERES_NO_SUITESPARSE) && defined(CERES_NO_CXSPARSE) && \
     !defined(CERES_USE_EIGEN_SPARSE)
   EXPECT_FALSE(options.IsValid(&message));
 #else
   EXPECT_TRUE(options.IsValid(&message));
 #endif

   options.linear_solver_type = ITERATIVE_SCHUR;
   EXPECT_TRUE(options.IsValid(&message));
 }

 template <int kNumResiduals, int... Ns>
 class DummyCostFunction : public SizedCostFunction<kNumResiduals, Ns...> {
  public:
   bool Evaluate(double const* const* parameters,
                 double* residuals,
                 double** jacobians) const override {
     for (int i = 0; i < kNumResiduals; ++i) {
       residuals[i] = kNumResiduals * kNumResiduals + i;
     }

     return true;
   }
 };

 TEST(Solver, FixedCostForConstantProblem) {
   double x = 1.0;
   Problem problem;
   problem.AddResidualBlock(new DummyCostFunction<2, 1>(), nullptr, &x);
   problem.SetParameterBlockConstant(&x);
   const double expected_cost = 41.0 / 2.0;  // 1/2 * ((4 + 0)^2 + (4 + 1)^2)
   Solver::Options options;
   Solver::Summary summary;
   Solve(options, &problem, &summary);
   EXPECT_TRUE(summary.IsSolutionUsable());
   EXPECT_EQ(summary.fixed_cost, expected_cost);
   EXPECT_EQ(summary.initial_cost, expected_cost);
   EXPECT_EQ(summary.final_cost, expected_cost);
   EXPECT_EQ(summary.iterations.size(), 0);
 }

 struct LinearCostFunction {
   template <typename T>
   bool operator()(const T* x, const T* y, T* residual) const {
     residual[0] = T(10.0) - *x;
     residual[1] = T(5.0) - *y;
     return true;
   }
   static CostFunction* Create() {
     return new AutoDiffCostFunction<LinearCostFunction, 2, 1, 1>(
         new LinearCostFunction);
   }
 };

 TEST(Solver, ZeroSizedLocalParameterizationHoldsParameterBlockConstant) {
   double x = 0.0;
   double y = 1.0;
   Problem problem;
   problem.AddResidualBlock(LinearCostFunction::Create(), nullptr, &x, &y);
   problem.SetParameterization(&y, new SubsetParameterization(1, {0}));
   EXPECT_TRUE(problem.IsParameterBlockConstant(&y));

   Solver::Options options;
   options.function_tolerance = 0.0;
   options.gradient_tolerance = 0.0;
   options.parameter_tolerance = 0.0;
   Solver::Summary summary;
   Solve(options, &problem, &summary);

   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_NEAR(x, 10.0, 1e-7);
   EXPECT_EQ(y, 1.0);
 }

 TEST(Solver, ZeroSizedManifoldHoldsParameterBlockConstant) {
   double x = 0.0;
   double y = 1.0;
   Problem problem;
   problem.AddResidualBlock(LinearCostFunction::Create(), nullptr, &x, &y);
   problem.SetManifold(&y, new SubsetManifold(1, {0}));
   EXPECT_TRUE(problem.IsParameterBlockConstant(&y));

   Solver::Options options;
   options.function_tolerance = 0.0;
   options.gradient_tolerance = 0.0;
   options.parameter_tolerance = 0.0;
   Solver::Summary summary;
   Solve(options, &problem, &summary);

   EXPECT_EQ(summary.termination_type, CONVERGENCE);
   EXPECT_NEAR(x, 10.0, 1e-7);
   EXPECT_EQ(y, 1.0);
 }

 }  // namespace ceres::internal
	// Ceres Solver - A fast non-linear least squares minimizer
	// Copyright 2022 Google Inc. All rights reserved.
	// http://ceres-solver.org/
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are met:
	//
	// * Redistributions of source code must retain the above copyright notice,
	// this list of conditions and the following disclaimer.
	// * Redistributions in binary form must reproduce the above copyright notice,
	// this list of conditions and the following disclaimer in the documentation
	// and/or other materials provided with the distribution.
	// * Neither the name of Google Inc. nor the names of its contributors may be
	// used to endorse or promote products derived from this software without
	// specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	// POSSIBILITY OF SUCH DAMAGE.
	//
	// Author: sameeragarwal@google.com (Sameer Agarwal)

	#include "ceres/solver.h"

	#include <cmath>
	#include <limits>
	#include <memory>
	#include <vector>

	#include "ceres/autodiff_cost_function.h"
	#include "ceres/evaluation_callback.h"
	#include "ceres/local_parameterization.h"
	#include "ceres/manifold.h"
	#include "ceres/problem.h"
	#include "ceres/problem_impl.h"
	#include "ceres/sized_cost_function.h"
	#include "gtest/gtest.h"

	namespace ceres::internal {

	using std::string;

	TEST(SolverOptions, DefaultTrustRegionOptionsAreValid) {
	Solver::Options options;
	options.minimizer_type = TRUST_REGION;
	string error;
	EXPECT_TRUE(options.IsValid(&error)) << error;
	}

	TEST(SolverOptions, DefaultLineSearchOptionsAreValid) {
	Solver::Options options;
	options.minimizer_type = LINE_SEARCH;
	string error;
	EXPECT_TRUE(options.IsValid(&error)) << error;
	}

	struct QuadraticCostFunctor {
	template <typename T>
	bool operator()(const T* const x, T* residual) const {
	residual[0] = T(5.0) - *x;
	return true;
	}

	static CostFunction* Create() {
	return new AutoDiffCostFunction<QuadraticCostFunctor, 1, 1>(
	new QuadraticCostFunctor);
	}
	};

	struct RememberingCallback : public IterationCallback {
	explicit RememberingCallback(double* x) : calls(0), x(x) {}
	CallbackReturnType operator()(const IterationSummary& summary) final {
	x_values.push_back(*x);
	return SOLVER_CONTINUE;
	}
	int calls;
	double* x;
	std::vector<double> x_values;
	};

	struct NoOpEvaluationCallback : EvaluationCallback {
	void PrepareForEvaluation(bool evaluate_jacobians,
	bool new_evaluation_point) final {
	(void)evaluate_jacobians;
	(void)new_evaluation_point;
	}
	};

	TEST(Solver, UpdateStateEveryIterationOptionNoEvaluationCallback) {
	double x = 50.0;
	const double original_x = x;

	Problem::Options problem_options;
	Problem problem(problem_options);
	problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &x);

	Solver::Options options;
	options.linear_solver_type = DENSE_QR;

	RememberingCallback callback(&x);
	options.callbacks.push_back(&callback);

	Solver::Summary summary;

	int num_iterations;

	// First: update_state_every_iteration=false, evaluation_callback=nullptr.
	Solve(options, &problem, &summary);
	num_iterations =
	summary.num_successful_steps + summary.num_unsuccessful_steps;
	EXPECT_GT(num_iterations, 1);
	for (double value : callback.x_values) {
	EXPECT_EQ(50.0, value);
	}

	// Second: update_state_every_iteration=true, evaluation_callback=nullptr.
	x = 50.0;
	options.update_state_every_iteration = true;
	callback.x_values.clear();
	Solve(options, &problem, &summary);
	num_iterations =
	summary.num_successful_steps + summary.num_unsuccessful_steps;
	EXPECT_GT(num_iterations, 1);
	EXPECT_EQ(original_x, callback.x_values[0]);
	EXPECT_NE(original_x, callback.x_values[1]);
	}

	TEST(Solver, UpdateStateEveryIterationOptionWithEvaluationCallback) {
	double x = 50.0;
	const double original_x = x;

	Problem::Options problem_options;
	NoOpEvaluationCallback evaluation_callback;
	problem_options.evaluation_callback = &evaluation_callback;

	Problem problem(problem_options);
	problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &x);

	Solver::Options options;
	options.linear_solver_type = DENSE_QR;
	RememberingCallback callback(&x);
	options.callbacks.push_back(&callback);

	Solver::Summary summary;

	int num_iterations;

	// First: update_state_every_iteration=true, evaluation_callback=!nullptr.
	x = 50.0;
	options.update_state_every_iteration = true;
	callback.x_values.clear();
	Solve(options, &problem, &summary);
	num_iterations =
	summary.num_successful_steps + summary.num_unsuccessful_steps;
	EXPECT_GT(num_iterations, 1);
	EXPECT_EQ(original_x, callback.x_values[0]);
	EXPECT_NE(original_x, callback.x_values[1]);

	// Second: update_state_every_iteration=false, evaluation_callback=!nullptr.
	x = 50.0;
	options.update_state_every_iteration = false;
	callback.x_values.clear();
	Solve(options, &problem, &summary);
	num_iterations =
	summary.num_successful_steps + summary.num_unsuccessful_steps;
	EXPECT_GT(num_iterations, 1);
	EXPECT_EQ(original_x, callback.x_values[0]);
	EXPECT_NE(original_x, callback.x_values[1]);
	}

	TEST(Solver, CantMixEvaluationCallbackWithInnerIterations) {
	double x = 50.0;
	double y = 60.0;

	Problem::Options problem_options;
	NoOpEvaluationCallback evaluation_callback;
	problem_options.evaluation_callback = &evaluation_callback;

	Problem problem(problem_options);
	problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &x);
	problem.AddResidualBlock(QuadraticCostFunctor::Create(), nullptr, &y);

	Solver::Options options;
	options.use_inner_iterations = true;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, FAILURE);

	options.use_inner_iterations = false;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	}

	// The parameters must be in separate blocks so that they can be individually
	// set constant or not.
	struct Quadratic4DCostFunction {
	template <typename T>
	bool operator()(const T* const x,
	const T* const y,
	const T* const z,
	const T* const w,
	T* residual) const {
	// A 4-dimension axis-aligned quadratic.
	residual[0] = T(10.0) - x + T(20.0) - y + T(30.0) - z + T(40.0) - w;
	return true;
	}

	static CostFunction* Create() {
	return new AutoDiffCostFunction<Quadratic4DCostFunction, 1, 1, 1, 1, 1>(
	new Quadratic4DCostFunction);
	}
	};

	// A cost function that simply returns its argument.
	class UnaryIdentityCostFunction : public SizedCostFunction<1, 1> {
	public:
	bool Evaluate(double const* const* parameters,
	double* residuals,
	double** jacobians) const final {
	residuals[0] = parameters[0][0];
	if (jacobians != nullptr && jacobians[0] != nullptr) {
	jacobians[0][0] = 1.0;
	}
	return true;
	}
	};

	TEST(Solver, TrustRegionProblemHasNoParameterBlocks) {
	Problem problem;
	Solver::Options options;
	options.minimizer_type = TRUST_REGION;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_EQ(summary.message,
	"Function tolerance reached. "
	"No non-constant parameter blocks found.");
	}

	TEST(Solver, LineSearchProblemHasNoParameterBlocks) {
	Problem problem;
	Solver::Options options;
	options.minimizer_type = LINE_SEARCH;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_EQ(summary.message,
	"Function tolerance reached. "
	"No non-constant parameter blocks found.");
	}

	TEST(Solver, TrustRegionProblemHasZeroResiduals) {
	Problem problem;
	double x = 1;
	problem.AddParameterBlock(&x, 1);
	Solver::Options options;
	options.minimizer_type = TRUST_REGION;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_EQ(summary.message,
	"Function tolerance reached. "
	"No non-constant parameter blocks found.");
	}

	TEST(Solver, LineSearchProblemHasZeroResiduals) {
	Problem problem;
	double x = 1;
	problem.AddParameterBlock(&x, 1);
	Solver::Options options;
	options.minimizer_type = LINE_SEARCH;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_EQ(summary.message,
	"Function tolerance reached. "
	"No non-constant parameter blocks found.");
	}

	TEST(Solver, TrustRegionProblemIsConstant) {
	Problem problem;
	double x = 1;
	problem.AddResidualBlock(new UnaryIdentityCostFunction, nullptr, &x);
	problem.SetParameterBlockConstant(&x);
	Solver::Options options;
	options.minimizer_type = TRUST_REGION;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_EQ(summary.initial_cost, 1.0 / 2.0);
	EXPECT_EQ(summary.final_cost, 1.0 / 2.0);
	}

	TEST(Solver, LineSearchProblemIsConstant) {
	Problem problem;
	double x = 1;
	problem.AddResidualBlock(new UnaryIdentityCostFunction, nullptr, &x);
	problem.SetParameterBlockConstant(&x);
	Solver::Options options;
	options.minimizer_type = LINE_SEARCH;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_EQ(summary.initial_cost, 1.0 / 2.0);
	EXPECT_EQ(summary.final_cost, 1.0 / 2.0);
	}

	#if defined(CERES_NO_SUITESPARSE)
	TEST(Solver, SparseNormalCholeskyNoSuiteSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = SUITE_SPARSE;
	options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, SparseSchurNoSuiteSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = SUITE_SPARSE;
	options.linear_solver_type = SPARSE_SCHUR;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}
	#endif

	#if defined(CERES_NO_CXSPARSE)
	TEST(Solver, SparseNormalCholeskyNoCXSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = CX_SPARSE;
	options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, SparseSchurNoCXSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = CX_SPARSE;
	options.linear_solver_type = SPARSE_SCHUR;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}
	#endif

	#if defined(CERES_NO_ACCELERATE_SPARSE)
	TEST(Solver, SparseNormalCholeskyNoAccelerateSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = ACCELERATE_SPARSE;
	options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, SparseSchurNoAccelerateSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = ACCELERATE_SPARSE;
	options.linear_solver_type = SPARSE_SCHUR;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}
	#else
	TEST(Solver, DynamicSparseNormalCholeskyUnsupportedWithAccelerateSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = ACCELERATE_SPARSE;
	options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
	options.dynamic_sparsity = true;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}
	#endif

	#if !defined(CERES_USE_EIGEN_SPARSE)
	TEST(Solver, SparseNormalCholeskyNoEigenSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = EIGEN_SPARSE;
	options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, SparseSchurNoEigenSparse) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = EIGEN_SPARSE;
	options.linear_solver_type = SPARSE_SCHUR;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}
	#endif

	TEST(Solver, SparseNormalCholeskyNoSparseLibrary) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = NO_SPARSE;
	options.linear_solver_type = SPARSE_NORMAL_CHOLESKY;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, SparseSchurNoSparseLibrary) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = NO_SPARSE;
	options.linear_solver_type = SPARSE_SCHUR;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, IterativeSchurWithClusterJacobiPerconditionerNoSparseLibrary) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = NO_SPARSE;
	options.linear_solver_type = ITERATIVE_SCHUR;
	// Requires SuiteSparse.
	options.preconditioner_type = CLUSTER_JACOBI;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver,
	IterativeSchurWithClusterTridiagonalPerconditionerNoSparseLibrary) {
	Solver::Options options;
	options.sparse_linear_algebra_library_type = NO_SPARSE;
	options.linear_solver_type = ITERATIVE_SCHUR;
	// Requires SuiteSparse.
	options.preconditioner_type = CLUSTER_TRIDIAGONAL;
	string message;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, IterativeLinearSolverForDogleg) {
	Solver::Options options;
	options.trust_region_strategy_type = DOGLEG;
	string message;
	options.linear_solver_type = ITERATIVE_SCHUR;
	EXPECT_FALSE(options.IsValid(&message));

	options.linear_solver_type = CGNR;
	EXPECT_FALSE(options.IsValid(&message));
	}

	TEST(Solver, LinearSolverTypeNormalOperation) {
	Solver::Options options;
	options.linear_solver_type = DENSE_QR;

	string message;
	EXPECT_TRUE(options.IsValid(&message));

	options.linear_solver_type = DENSE_NORMAL_CHOLESKY;
	EXPECT_TRUE(options.IsValid(&message));

	options.linear_solver_type = DENSE_SCHUR;
	EXPECT_TRUE(options.IsValid(&message));

	options.linear_solver_type = SPARSE_SCHUR;
	#if defined(CERES_NO_SUITESPARSE) && defined(CERES_NO_CXSPARSE) && \
	!defined(CERES_USE_EIGEN_SPARSE)
	EXPECT_FALSE(options.IsValid(&message));
	#else
	EXPECT_TRUE(options.IsValid(&message));
	#endif

	options.linear_solver_type = ITERATIVE_SCHUR;
	EXPECT_TRUE(options.IsValid(&message));
	}

	template <int kNumResiduals, int... Ns>
	class DummyCostFunction : public SizedCostFunction<kNumResiduals, Ns...> {
	public:
	bool Evaluate(double const* const* parameters,
	double* residuals,
	double** jacobians) const override {
	for (int i = 0; i < kNumResiduals; ++i) {
	residuals[i] = kNumResiduals * kNumResiduals + i;
	}

	return true;
	}
	};

	TEST(Solver, FixedCostForConstantProblem) {
	double x = 1.0;
	Problem problem;
	problem.AddResidualBlock(new DummyCostFunction<2, 1>(), nullptr, &x);
	problem.SetParameterBlockConstant(&x);
	const double expected_cost = 41.0 / 2.0; // 1/2 * ((4 + 0)^2 + (4 + 1)^2)
	Solver::Options options;
	Solver::Summary summary;
	Solve(options, &problem, &summary);
	EXPECT_TRUE(summary.IsSolutionUsable());
	EXPECT_EQ(summary.fixed_cost, expected_cost);
	EXPECT_EQ(summary.initial_cost, expected_cost);
	EXPECT_EQ(summary.final_cost, expected_cost);
	EXPECT_EQ(summary.iterations.size(), 0);
	}

	struct LinearCostFunction {
	template <typename T>
	bool operator()(const T* x, const T* y, T* residual) const {
	residual[0] = T(10.0) - *x;
	residual[1] = T(5.0) - *y;
	return true;
	}
	static CostFunction* Create() {
	return new AutoDiffCostFunction<LinearCostFunction, 2, 1, 1>(
	new LinearCostFunction);
	}
	};

	TEST(Solver, ZeroSizedLocalParameterizationHoldsParameterBlockConstant) {
	double x = 0.0;
	double y = 1.0;
	Problem problem;
	problem.AddResidualBlock(LinearCostFunction::Create(), nullptr, &x, &y);
	problem.SetParameterization(&y, new SubsetParameterization(1, {0}));
	EXPECT_TRUE(problem.IsParameterBlockConstant(&y));

	Solver::Options options;
	options.function_tolerance = 0.0;
	options.gradient_tolerance = 0.0;
	options.parameter_tolerance = 0.0;
	Solver::Summary summary;
	Solve(options, &problem, &summary);

	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_NEAR(x, 10.0, 1e-7);
	EXPECT_EQ(y, 1.0);
	}

	TEST(Solver, ZeroSizedManifoldHoldsParameterBlockConstant) {
	double x = 0.0;
	double y = 1.0;
	Problem problem;
	problem.AddResidualBlock(LinearCostFunction::Create(), nullptr, &x, &y);
	problem.SetManifold(&y, new SubsetManifold(1, {0}));
	EXPECT_TRUE(problem.IsParameterBlockConstant(&y));

	Solver::Options options;
	options.function_tolerance = 0.0;
	options.gradient_tolerance = 0.0;
	options.parameter_tolerance = 0.0;
	Solver::Summary summary;
	Solve(options, &problem, &summary);

	EXPECT_EQ(summary.termination_type, CONVERGENCE);
	EXPECT_NEAR(x, 10.0, 1e-7);
	EXPECT_EQ(y, 1.0);
	}

	} // namespace ceres::internal