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

 // Ceres Solver - A fast non-linear least squares minimizer
 // Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
 // http://code.google.com/p/ceres-solver/
 //
 // 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: keir@google.com (Keir Mierle)
 //         sameeragarwal@google.com (Sameer Agarwal)
 //
 // System level tests for Ceres. The current suite of two tests. The
 // first test is a small test based on Powell's Function. It is a
 // scalar problem with 4 variables. The second problem is a bundle
 // adjustment problem with 16 cameras and two thousand cameras. The
 // first problem is to test the sanity test the factorization based
 // solvers. The second problem is used to test the various
 // combinations of solvers, orderings, preconditioners and
 // multithreading.

 #include <cmath>
 #include <cstdio>
 #include <cstdlib>
 #include <string>

 #include "ceres/autodiff_cost_function.h"
 #include "ceres/ordered_groups.h"
 #include "ceres/problem.h"
 #include "ceres/rotation.h"
 #include "ceres/solver.h"
 #include "ceres/stringprintf.h"
 #include "ceres/test_util.h"
 #include "ceres/types.h"
 #include "gflags/gflags.h"
 #include "glog/logging.h"
 #include "gtest/gtest.h"

 namespace ceres {
 namespace internal {

 const bool kAutomaticOrdering = true;
 const bool kUserOrdering = false;

 // Struct used for configuring the solver.
 struct SolverConfig {
   SolverConfig(
       LinearSolverType linear_solver_type,
       SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,
       bool use_automatic_ordering)
       : linear_solver_type(linear_solver_type),
         sparse_linear_algebra_library_type(sparse_linear_algebra_library_type),
         use_automatic_ordering(use_automatic_ordering),
         preconditioner_type(IDENTITY),
         num_threads(1) {
   }

   SolverConfig(
       LinearSolverType linear_solver_type,
       SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,
       bool use_automatic_ordering,
       PreconditionerType preconditioner_type)
       : linear_solver_type(linear_solver_type),
         sparse_linear_algebra_library_type(sparse_linear_algebra_library_type),
         use_automatic_ordering(use_automatic_ordering),
         preconditioner_type(preconditioner_type),
         num_threads(1) {
   }

   string ToString() const {
     return StringPrintf(
         "(%s, %s, %s, %s, %d)",
         LinearSolverTypeToString(linear_solver_type),
         SparseLinearAlgebraLibraryTypeToString(
             sparse_linear_algebra_library_type),
         use_automatic_ordering ? "AUTOMATIC" : "USER",
         PreconditionerTypeToString(preconditioner_type),
         num_threads);
   }

   LinearSolverType linear_solver_type;
   SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type;
   bool use_automatic_ordering;
   PreconditionerType preconditioner_type;
   int num_threads;
 };

 // Templated function that given a set of solver configurations,
 // instantiates a new copy of SystemTestProblem for each configuration
 // and solves it. The solutions are expected to have residuals with
 // coordinate-wise maximum absolute difference less than or equal to
 // max_abs_difference.
 //
 // The template parameter SystemTestProblem is expected to implement
 // the following interface.
 //
 //   class SystemTestProblem {
 //     public:
 //       SystemTestProblem();
 //       Problem* mutable_problem();
 //       Solver::Options* mutable_solver_options();
 //   };
 template <typename SystemTestProblem>
 void RunSolversAndCheckTheyMatch(const vector<SolverConfig>& configurations,
                                  const double max_abs_difference) {
   int num_configurations = configurations.size();
   vector<SystemTestProblem*> problems;
   vector<vector<double> > final_residuals(num_configurations);

   for (int i = 0; i < num_configurations; ++i) {
     SystemTestProblem* system_test_problem = new SystemTestProblem();

     const SolverConfig& config = configurations[i];

     Solver::Options& options = *(system_test_problem->mutable_solver_options());
     options.linear_solver_type = config.linear_solver_type;
     options.sparse_linear_algebra_library_type =
         config.sparse_linear_algebra_library_type;
     options.preconditioner_type = config.preconditioner_type;
     options.num_threads = config.num_threads;
     options.num_linear_solver_threads = config.num_threads;

     if (config.use_automatic_ordering) {
       delete options.linear_solver_ordering;
       options.linear_solver_ordering = NULL;
     }

     LOG(INFO) << "Running solver configuration: "
               << config.ToString();

     Solver::Summary summary;
     Solve(options,
           system_test_problem->mutable_problem(),
           &summary);

     system_test_problem
         ->mutable_problem()
         ->Evaluate(Problem::EvaluateOptions(),
                    NULL,
                    &final_residuals[i],
                    NULL,
                    NULL);

     CHECK_NE(summary.termination_type, ceres::FAILURE)
         << "Solver configuration " << i << " failed.";
     problems.push_back(system_test_problem);

     // Compare the resulting solutions to each other. Arbitrarily take
     // SPARSE_NORMAL_CHOLESKY as the golden solve. We compare
     // solutions by comparing their residual vectors. We do not
     // compare parameter vectors because it is much more brittle and
     // error prone to do so, since the same problem can have nearly
     // the same residuals at two completely different positions in
     // parameter space.
     if (i > 0) {
       const vector<double>& reference_residuals = final_residuals[0];
       const vector<double>& current_residuals = final_residuals[i];

       for (int j = 0; j < reference_residuals.size(); ++j) {
         EXPECT_NEAR(current_residuals[j],
                     reference_residuals[j],
                     max_abs_difference)
             << "Not close enough residual:" << j
             << " reference " << reference_residuals[j]
             << " current " << current_residuals[j];
       }
     }
   }

   for (int i = 0; i < num_configurations; ++i) {
     delete problems[i];
   }
 }

 // This class implements the SystemTestProblem interface and provides
 // access to an implementation of Powell's singular function.
 //
 //   F = 1/2 (f1^2 + f2^2 + f3^2 + f4^2)
 //
 //   f1 = x1 + 10*x2;
 //   f2 = sqrt(5) * (x3 - x4)
 //   f3 = (x2 - 2*x3)^2
 //   f4 = sqrt(10) * (x1 - x4)^2
 //
 // The starting values are x1 = 3, x2 = -1, x3 = 0, x4 = 1.
 // The minimum is 0 at (x1, x2, x3, x4) = 0.
 //
 // From: Testing Unconstrained Optimization Software by Jorge J. More, Burton S.
 // Garbow and Kenneth E. Hillstrom in ACM Transactions on Mathematical Software,
 // Vol 7(1), March 1981.
 class PowellsFunction {
  public:
   PowellsFunction() {
     x_[0] =  3.0;
     x_[1] = -1.0;
     x_[2] =  0.0;
     x_[3] =  1.0;

     problem_.AddResidualBlock(
         new AutoDiffCostFunction<F1, 1, 1, 1>(new F1), NULL, &x_[0], &x_[1]);
     problem_.AddResidualBlock(
         new AutoDiffCostFunction<F2, 1, 1, 1>(new F2), NULL, &x_[2], &x_[3]);
     problem_.AddResidualBlock(
         new AutoDiffCostFunction<F3, 1, 1, 1>(new F3), NULL, &x_[1], &x_[2]);
     problem_.AddResidualBlock(
         new AutoDiffCostFunction<F4, 1, 1, 1>(new F4), NULL, &x_[0], &x_[3]);

     options_.max_num_iterations = 10;
   }

   Problem* mutable_problem() { return &problem_; }
   Solver::Options* mutable_solver_options() { return &options_; }

  private:
   // Templated functions used for automatically differentiated cost
   // functions.
   class F1 {
    public:
     template <typename T> bool operator()(const T* const x1,
                                           const T* const x2,
                                           T* residual) const {
       // f1 = x1 + 10 * x2;
       *residual = *x1 + T(10.0) * *x2;
       return true;
     }
   };

   class F2 {
    public:
     template <typename T> bool operator()(const T* const x3,
                                           const T* const x4,
                                           T* residual) const {
       // f2 = sqrt(5) (x3 - x4)
       *residual = T(sqrt(5.0)) * (*x3 - *x4);
       return true;
     }
   };

   class F3 {
    public:
     template <typename T> bool operator()(const T* const x2,
                                           const T* const x4,
                                           T* residual) const {
       // f3 = (x2 - 2 x3)^2
       residual[0] = (x2[0] - T(2.0) * x4[0]) * (x2[0] - T(2.0) * x4[0]);
       return true;
     }
   };

   class F4 {
    public:
     template <typename T> bool operator()(const T* const x1,
                                           const T* const x4,
                                           T* residual) const {
       // f4 = sqrt(10) (x1 - x4)^2
       residual[0] = T(sqrt(10.0)) * (x1[0] - x4[0]) * (x1[0] - x4[0]);
       return true;
     }
   };

   double x_[4];
   Problem problem_;
   Solver::Options options_;
 };

 TEST(SystemTest, PowellsFunction) {
   vector<SolverConfig> configs;
 #define CONFIGURE(linear_solver, sparse_linear_algebra_library_type, ordering) \
   configs.push_back(SolverConfig(linear_solver,                         \
                                  sparse_linear_algebra_library_type,    \
                                  ordering))

   CONFIGURE(DENSE_QR,               SUITE_SPARSE, kAutomaticOrdering);
   CONFIGURE(DENSE_NORMAL_CHOLESKY,  SUITE_SPARSE, kAutomaticOrdering);
   CONFIGURE(DENSE_SCHUR,            SUITE_SPARSE, kAutomaticOrdering);

 #ifndef CERES_NO_SUITESPARSE
   CONFIGURE(SPARSE_NORMAL_CHOLESKY, SUITE_SPARSE, kAutomaticOrdering);
 #endif  // CERES_NO_SUITESPARSE

 #ifndef CERES_NO_CXSPARSE
   CONFIGURE(SPARSE_NORMAL_CHOLESKY, CX_SPARSE,    kAutomaticOrdering);
 #endif  // CERES_NO_CXSPARSE

   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kAutomaticOrdering);

 #undef CONFIGURE

   const double kMaxAbsoluteDifference = 1e-8;
   RunSolversAndCheckTheyMatch<PowellsFunction>(configs, kMaxAbsoluteDifference);
 }

 // This class implements the SystemTestProblem interface and provides
 // access to a bundle adjustment problem. It is based on
 // examples/bundle_adjustment_example.cc. Currently a small 16 camera
 // problem is hard coded in the constructor. Going forward we may
 // extend this to a larger number of problems.
 class BundleAdjustmentProblem {
  public:
   BundleAdjustmentProblem() {
     const string input_file = TestFileAbsolutePath("problem-16-22106-pre.txt");
     ReadData(input_file);
     BuildProblem();
   }

   ~BundleAdjustmentProblem() {
     delete []point_index_;
     delete []camera_index_;
     delete []observations_;
     delete []parameters_;
   }

   Problem* mutable_problem() { return &problem_; }
   Solver::Options* mutable_solver_options() { return &options_; }

   int num_cameras()            const { return num_cameras_;        }
   int num_points()             const { return num_points_;         }
   int num_observations()       const { return num_observations_;   }
   const int* point_index()     const { return point_index_;  }
   const int* camera_index()    const { return camera_index_; }
   const double* observations() const { return observations_; }
   double* mutable_cameras() { return parameters_; }
   double* mutable_points() { return parameters_  + 9 * num_cameras_; }

  private:
   void ReadData(const string& filename) {
     FILE * fptr = fopen(filename.c_str(), "r");

     if (!fptr) {
       LOG(FATAL) << "File Error: unable to open file " << filename;
     };

     // This will die horribly on invalid files. Them's the breaks.
     FscanfOrDie(fptr, "%d", &num_cameras_);
     FscanfOrDie(fptr, "%d", &num_points_);
     FscanfOrDie(fptr, "%d", &num_observations_);

     VLOG(1) << "Header: " << num_cameras_
             << " " << num_points_
             << " " << num_observations_;

     point_index_ = new int[num_observations_];
     camera_index_ = new int[num_observations_];
     observations_ = new double[2 * num_observations_];

     num_parameters_ = 9 * num_cameras_ + 3 * num_points_;
     parameters_ = new double[num_parameters_];

     for (int i = 0; i < num_observations_; ++i) {
       FscanfOrDie(fptr, "%d", camera_index_ + i);
       FscanfOrDie(fptr, "%d", point_index_ + i);
       for (int j = 0; j < 2; ++j) {
         FscanfOrDie(fptr, "%lf", observations_ + 2*i + j);
       }
     }

     for (int i = 0; i < num_parameters_; ++i) {
       FscanfOrDie(fptr, "%lf", parameters_ + i);
     }
   }

   void BuildProblem() {
     double* points = mutable_points();
     double* cameras = mutable_cameras();

     for (int i = 0; i < num_observations(); ++i) {
       // Each Residual block takes a point and a camera as input and
       // outputs a 2 dimensional residual.
       CostFunction* cost_function =
           new AutoDiffCostFunction<BundlerResidual, 2, 9, 3>(
               new BundlerResidual(observations_[2*i + 0],
                                   observations_[2*i + 1]));

       // Each observation correponds to a pair of a camera and a point
       // which are identified by camera_index()[i] and
       // point_index()[i] respectively.
       double* camera = cameras + 9 * camera_index_[i];
       double* point = points + 3 * point_index()[i];
       problem_.AddResidualBlock(cost_function, NULL, camera, point);
     }

     options_.linear_solver_ordering = new ParameterBlockOrdering;

     // The points come before the cameras.
     for (int i = 0; i < num_points_; ++i) {
       options_.linear_solver_ordering->AddElementToGroup(points + 3 * i, 0);
     }

     for (int i = 0; i < num_cameras_; ++i) {
       options_.linear_solver_ordering->AddElementToGroup(cameras + 9 * i, 1);
     }

     options_.max_num_iterations = 25;
     options_.function_tolerance = 1e-10;
     options_.gradient_tolerance = 1e-10;
     options_.parameter_tolerance = 1e-10;
   }

   template<typename T>
   void FscanfOrDie(FILE *fptr, const char *format, T *value) {
     int num_scanned = fscanf(fptr, format, value);
     if (num_scanned != 1) {
       LOG(FATAL) << "Invalid UW data file.";
     }
   }

   // Templated pinhole camera model.  The camera is parameterized
   // using 9 parameters. 3 for rotation, 3 for translation, 1 for
   // focal length and 2 for radial distortion. The principal point is
   // not modeled (i.e. it is assumed be located at the image center).
   struct BundlerResidual {
     // (u, v): the position of the observation with respect to the image
     // center point.
     BundlerResidual(double u, double v): u(u), v(v) {}

     template <typename T>
     bool operator()(const T* const camera,
                     const T* const point,
                     T* residuals) const {
       T p[3];
       AngleAxisRotatePoint(camera, point, p);

       // Add the translation vector
       p[0] += camera[3];
       p[1] += camera[4];
       p[2] += camera[5];

       const T& focal = camera[6];
       const T& l1 = camera[7];
       const T& l2 = camera[8];

       // Compute the center of distortion.  The sign change comes from
       // the camera model that Noah Snavely's Bundler assumes, whereby
       // the camera coordinate system has a negative z axis.
       T xp = - focal * p[0] / p[2];
       T yp = - focal * p[1] / p[2];

       // Apply second and fourth order radial distortion.
       T r2 = xp*xp + yp*yp;
       T distortion = T(1.0) + r2  * (l1 + l2  * r2);

       residuals[0] = distortion * xp - T(u);
       residuals[1] = distortion * yp - T(v);

       return true;
     }

     double u;
     double v;
   };


   Problem problem_;
   Solver::Options options_;

   int num_cameras_;
   int num_points_;
   int num_observations_;
   int num_parameters_;

   int* point_index_;
   int* camera_index_;
   double* observations_;
   // The parameter vector is laid out as follows
   // [camera_1, ..., camera_n, point_1, ..., point_m]
   double* parameters_;
 };

 TEST(SystemTest, BundleAdjustmentProblem) {
   vector<SolverConfig> configs;

 #define CONFIGURE(linear_solver, sparse_linear_algebra_library_type, ordering, preconditioner) \
   configs.push_back(SolverConfig(linear_solver,                         \
                                  sparse_linear_algebra_library_type,    \
                                  ordering,                              \
                                  preconditioner))

 #ifndef CERES_NO_SUITESPARSE
   CONFIGURE(SPARSE_NORMAL_CHOLESKY, SUITE_SPARSE, kAutomaticOrdering, IDENTITY);
   CONFIGURE(SPARSE_NORMAL_CHOLESKY, SUITE_SPARSE, kUserOrdering,      IDENTITY);

   CONFIGURE(SPARSE_SCHUR,           SUITE_SPARSE, kAutomaticOrdering, IDENTITY);
   CONFIGURE(SPARSE_SCHUR,           SUITE_SPARSE, kUserOrdering,      IDENTITY);
 #endif  // CERES_NO_SUITESPARSE

 #ifndef CERES_NO_CXSPARSE
   CONFIGURE(SPARSE_SCHUR,           CX_SPARSE,    kAutomaticOrdering, IDENTITY);
   CONFIGURE(SPARSE_SCHUR,           CX_SPARSE,    kUserOrdering,      IDENTITY);
 #endif  // CERES_NO_CXSPARSE

   CONFIGURE(DENSE_SCHUR,            SUITE_SPARSE, kAutomaticOrdering, IDENTITY);
   CONFIGURE(DENSE_SCHUR,            SUITE_SPARSE, kUserOrdering,      IDENTITY);

   CONFIGURE(CGNR,                   SUITE_SPARSE, kAutomaticOrdering, JACOBI);
   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kUserOrdering,      JACOBI);
   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kUserOrdering,      SCHUR_JACOBI);

 #ifndef CERES_NO_SUITESPARSE

   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kUserOrdering,      CLUSTER_JACOBI);
   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kUserOrdering,      CLUSTER_TRIDIAGONAL);
 #endif  // CERES_NO_SUITESPARSE

   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kAutomaticOrdering, JACOBI);
   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kAutomaticOrdering, SCHUR_JACOBI);

 #ifndef CERES_NO_SUITESPARSE

   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kAutomaticOrdering, CLUSTER_JACOBI);
   CONFIGURE(ITERATIVE_SCHUR,        SUITE_SPARSE, kAutomaticOrdering, CLUSTER_TRIDIAGONAL);
 #endif  // CERES_NO_SUITESPARSE

 #undef CONFIGURE

   // Single threaded evaluators and linear solvers.
   const double kMaxAbsoluteDifference = 1e-4;
   RunSolversAndCheckTheyMatch<BundleAdjustmentProblem>(configs,
                                                        kMaxAbsoluteDifference);

 #ifdef CERES_USE_OPENMP
   // Multithreaded evaluators and linear solvers.
   for (int i = 0; i < configs.size(); ++i) {
     configs[i].num_threads = 2;
   }
   RunSolversAndCheckTheyMatch<BundleAdjustmentProblem>(configs,
                                                        kMaxAbsoluteDifference);
 #endif  // CERES_USE_OPENMP
 }

 }  // namespace internal
 }  // namespace ceres
	// Ceres Solver - A fast non-linear least squares minimizer
	// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
	// http://code.google.com/p/ceres-solver/
	//
	// 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: keir@google.com (Keir Mierle)
	// sameeragarwal@google.com (Sameer Agarwal)
	//
	// System level tests for Ceres. The current suite of two tests. The
	// first test is a small test based on Powell's Function. It is a
	// scalar problem with 4 variables. The second problem is a bundle
	// adjustment problem with 16 cameras and two thousand cameras. The
	// first problem is to test the sanity test the factorization based
	// solvers. The second problem is used to test the various
	// combinations of solvers, orderings, preconditioners and
	// multithreading.

	#include <cmath>
	#include <cstdio>
	#include <cstdlib>
	#include <string>

	#include "ceres/autodiff_cost_function.h"
	#include "ceres/ordered_groups.h"
	#include "ceres/problem.h"
	#include "ceres/rotation.h"
	#include "ceres/solver.h"
	#include "ceres/stringprintf.h"
	#include "ceres/test_util.h"
	#include "ceres/types.h"
	#include "gflags/gflags.h"
	#include "glog/logging.h"
	#include "gtest/gtest.h"

	namespace ceres {
	namespace internal {

	const bool kAutomaticOrdering = true;
	const bool kUserOrdering = false;

	// Struct used for configuring the solver.
	struct SolverConfig {
	SolverConfig(
	LinearSolverType linear_solver_type,
	SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,
	bool use_automatic_ordering)
	: linear_solver_type(linear_solver_type),
	sparse_linear_algebra_library_type(sparse_linear_algebra_library_type),
	use_automatic_ordering(use_automatic_ordering),
	preconditioner_type(IDENTITY),
	num_threads(1) {
	}

	SolverConfig(
	LinearSolverType linear_solver_type,
	SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,
	bool use_automatic_ordering,
	PreconditionerType preconditioner_type)
	: linear_solver_type(linear_solver_type),
	sparse_linear_algebra_library_type(sparse_linear_algebra_library_type),
	use_automatic_ordering(use_automatic_ordering),
	preconditioner_type(preconditioner_type),
	num_threads(1) {
	}

	string ToString() const {
	return StringPrintf(
	"(%s, %s, %s, %s, %d)",
	LinearSolverTypeToString(linear_solver_type),
	SparseLinearAlgebraLibraryTypeToString(
	sparse_linear_algebra_library_type),
	use_automatic_ordering ? "AUTOMATIC" : "USER",
	PreconditionerTypeToString(preconditioner_type),
	num_threads);
	}

	LinearSolverType linear_solver_type;
	SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type;
	bool use_automatic_ordering;
	PreconditionerType preconditioner_type;
	int num_threads;
	};

	// Templated function that given a set of solver configurations,
	// instantiates a new copy of SystemTestProblem for each configuration
	// and solves it. The solutions are expected to have residuals with
	// coordinate-wise maximum absolute difference less than or equal to
	// max_abs_difference.
	//
	// The template parameter SystemTestProblem is expected to implement
	// the following interface.
	//
	// class SystemTestProblem {
	// public:
	// SystemTestProblem();
	// Problem* mutable_problem();
	// Solver::Options* mutable_solver_options();
	// };
	template <typename SystemTestProblem>
	void RunSolversAndCheckTheyMatch(const vector<SolverConfig>& configurations,
	const double max_abs_difference) {
	int num_configurations = configurations.size();
	vector<SystemTestProblem*> problems;
	vector<vector<double> > final_residuals(num_configurations);

	for (int i = 0; i < num_configurations; ++i) {
	SystemTestProblem* system_test_problem = new SystemTestProblem();

	const SolverConfig& config = configurations[i];

	Solver::Options& options = *(system_test_problem->mutable_solver_options());
	options.linear_solver_type = config.linear_solver_type;
	options.sparse_linear_algebra_library_type =
	config.sparse_linear_algebra_library_type;
	options.preconditioner_type = config.preconditioner_type;
	options.num_threads = config.num_threads;
	options.num_linear_solver_threads = config.num_threads;

	if (config.use_automatic_ordering) {
	delete options.linear_solver_ordering;
	options.linear_solver_ordering = NULL;
	}

	LOG(INFO) << "Running solver configuration: "
	<< config.ToString();

	Solver::Summary summary;
	Solve(options,
	system_test_problem->mutable_problem(),
	&summary);

	system_test_problem
	->mutable_problem()
	->Evaluate(Problem::EvaluateOptions(),
	NULL,
	&final_residuals[i],
	NULL,
	NULL);

	CHECK_NE(summary.termination_type, ceres::FAILURE)
	<< "Solver configuration " << i << " failed.";
	problems.push_back(system_test_problem);

	// Compare the resulting solutions to each other. Arbitrarily take
	// SPARSE_NORMAL_CHOLESKY as the golden solve. We compare
	// solutions by comparing their residual vectors. We do not
	// compare parameter vectors because it is much more brittle and
	// error prone to do so, since the same problem can have nearly
	// the same residuals at two completely different positions in
	// parameter space.
	if (i > 0) {
	const vector<double>& reference_residuals = final_residuals[0];
	const vector<double>& current_residuals = final_residuals[i];

	for (int j = 0; j < reference_residuals.size(); ++j) {
	EXPECT_NEAR(current_residuals[j],
	reference_residuals[j],
	max_abs_difference)
	<< "Not close enough residual:" << j
	<< " reference " << reference_residuals[j]
	<< " current " << current_residuals[j];
	}
	}
	}

	for (int i = 0; i < num_configurations; ++i) {
	delete problems[i];
	}
	}

	// This class implements the SystemTestProblem interface and provides
	// access to an implementation of Powell's singular function.
	//
	// F = 1/2 (f1^2 + f2^2 + f3^2 + f4^2)
	//
	// f1 = x1 + 10*x2;
	// f2 = sqrt(5) * (x3 - x4)
	// f3 = (x2 - 2*x3)^2
	// f4 = sqrt(10) * (x1 - x4)^2
	//
	// The starting values are x1 = 3, x2 = -1, x3 = 0, x4 = 1.
	// The minimum is 0 at (x1, x2, x3, x4) = 0.
	//
	// From: Testing Unconstrained Optimization Software by Jorge J. More, Burton S.
	// Garbow and Kenneth E. Hillstrom in ACM Transactions on Mathematical Software,
	// Vol 7(1), March 1981.
	class PowellsFunction {
	public:
	PowellsFunction() {
	x_[0] = 3.0;
	x_[1] = -1.0;
	x_[2] = 0.0;
	x_[3] = 1.0;

	problem_.AddResidualBlock(
	new AutoDiffCostFunction<F1, 1, 1, 1>(new F1), NULL, &x_[0], &x_[1]);
	problem_.AddResidualBlock(
	new AutoDiffCostFunction<F2, 1, 1, 1>(new F2), NULL, &x_[2], &x_[3]);
	problem_.AddResidualBlock(
	new AutoDiffCostFunction<F3, 1, 1, 1>(new F3), NULL, &x_[1], &x_[2]);
	problem_.AddResidualBlock(
	new AutoDiffCostFunction<F4, 1, 1, 1>(new F4), NULL, &x_[0], &x_[3]);

	options_.max_num_iterations = 10;
	}

	Problem* mutable_problem() { return &problem_; }
	Solver::Options* mutable_solver_options() { return &options_; }

	private:
	// Templated functions used for automatically differentiated cost
	// functions.
	class F1 {
	public:
	template <typename T> bool operator()(const T* const x1,
	const T* const x2,
	T* residual) const {
	// f1 = x1 + 10 * x2;
	residual = x1 + T(10.0) * *x2;
	return true;
	}
	};

	class F2 {
	public:
	template <typename T> bool operator()(const T* const x3,
	const T* const x4,
	T* residual) const {
	// f2 = sqrt(5) (x3 - x4)
	residual = T(sqrt(5.0)) (x3 - x4);
	return true;
	}
	};

	class F3 {
	public:
	template <typename T> bool operator()(const T* const x2,
	const T* const x4,
	T* residual) const {
	// f3 = (x2 - 2 x3)^2
	residual[0] = (x2[0] - T(2.0) * x4[0]) * (x2[0] - T(2.0) * x4[0]);
	return true;
	}
	};

	class F4 {
	public:
	template <typename T> bool operator()(const T* const x1,
	const T* const x4,
	T* residual) const {
	// f4 = sqrt(10) (x1 - x4)^2
	residual[0] = T(sqrt(10.0)) * (x1[0] - x4[0]) * (x1[0] - x4[0]);
	return true;
	}
	};

	double x_[4];
	Problem problem_;
	Solver::Options options_;
	};

	TEST(SystemTest, PowellsFunction) {
	vector<SolverConfig> configs;
	#define CONFIGURE(linear_solver, sparse_linear_algebra_library_type, ordering) \
	configs.push_back(SolverConfig(linear_solver, \
	sparse_linear_algebra_library_type, \
	ordering))

	CONFIGURE(DENSE_QR, SUITE_SPARSE, kAutomaticOrdering);
	CONFIGURE(DENSE_NORMAL_CHOLESKY, SUITE_SPARSE, kAutomaticOrdering);
	CONFIGURE(DENSE_SCHUR, SUITE_SPARSE, kAutomaticOrdering);

	#ifndef CERES_NO_SUITESPARSE
	CONFIGURE(SPARSE_NORMAL_CHOLESKY, SUITE_SPARSE, kAutomaticOrdering);
	#endif // CERES_NO_SUITESPARSE

	#ifndef CERES_NO_CXSPARSE
	CONFIGURE(SPARSE_NORMAL_CHOLESKY, CX_SPARSE, kAutomaticOrdering);
	#endif // CERES_NO_CXSPARSE

	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kAutomaticOrdering);

	#undef CONFIGURE

	const double kMaxAbsoluteDifference = 1e-8;
	RunSolversAndCheckTheyMatch<PowellsFunction>(configs, kMaxAbsoluteDifference);
	}

	// This class implements the SystemTestProblem interface and provides
	// access to a bundle adjustment problem. It is based on
	// examples/bundle_adjustment_example.cc. Currently a small 16 camera
	// problem is hard coded in the constructor. Going forward we may
	// extend this to a larger number of problems.
	class BundleAdjustmentProblem {
	public:
	BundleAdjustmentProblem() {
	const string input_file = TestFileAbsolutePath("problem-16-22106-pre.txt");
	ReadData(input_file);
	BuildProblem();
	}

	~BundleAdjustmentProblem() {
	delete []point_index_;
	delete []camera_index_;
	delete []observations_;
	delete []parameters_;
	}

	Problem* mutable_problem() { return &problem_; }
	Solver::Options* mutable_solver_options() { return &options_; }

	int num_cameras() const { return num_cameras_; }
	int num_points() const { return num_points_; }
	int num_observations() const { return num_observations_; }
	const int* point_index() const { return point_index_; }
	const int* camera_index() const { return camera_index_; }
	const double* observations() const { return observations_; }
	double* mutable_cameras() { return parameters_; }
	double* mutable_points() { return parameters_ + 9 * num_cameras_; }

	private:
	void ReadData(const string& filename) {
	FILE * fptr = fopen(filename.c_str(), "r");

	if (!fptr) {
	LOG(FATAL) << "File Error: unable to open file " << filename;
	};

	// This will die horribly on invalid files. Them's the breaks.
	FscanfOrDie(fptr, "%d", &num_cameras_);
	FscanfOrDie(fptr, "%d", &num_points_);
	FscanfOrDie(fptr, "%d", &num_observations_);

	VLOG(1) << "Header: " << num_cameras_
	<< " " << num_points_
	<< " " << num_observations_;

	point_index_ = new int[num_observations_];
	camera_index_ = new int[num_observations_];
	observations_ = new double[2 * num_observations_];

	num_parameters_ = 9 * num_cameras_ + 3 * num_points_;
	parameters_ = new double[num_parameters_];

	for (int i = 0; i < num_observations_; ++i) {
	FscanfOrDie(fptr, "%d", camera_index_ + i);
	FscanfOrDie(fptr, "%d", point_index_ + i);
	for (int j = 0; j < 2; ++j) {
	FscanfOrDie(fptr, "%lf", observations_ + 2*i + j);
	}
	}

	for (int i = 0; i < num_parameters_; ++i) {
	FscanfOrDie(fptr, "%lf", parameters_ + i);
	}
	}

	void BuildProblem() {
	double* points = mutable_points();
	double* cameras = mutable_cameras();

	for (int i = 0; i < num_observations(); ++i) {
	// Each Residual block takes a point and a camera as input and
	// outputs a 2 dimensional residual.
	CostFunction* cost_function =
	new AutoDiffCostFunction<BundlerResidual, 2, 9, 3>(
	new BundlerResidual(observations_[2*i + 0],
	observations_[2*i + 1]));

	// Each observation correponds to a pair of a camera and a point
	// which are identified by camera_index()[i] and
	// point_index()[i] respectively.
	double* camera = cameras + 9 * camera_index_[i];
	double* point = points + 3 * point_index()[i];
	problem_.AddResidualBlock(cost_function, NULL, camera, point);
	}

	options_.linear_solver_ordering = new ParameterBlockOrdering;

	// The points come before the cameras.
	for (int i = 0; i < num_points_; ++i) {
	options_.linear_solver_ordering->AddElementToGroup(points + 3 * i, 0);
	}

	for (int i = 0; i < num_cameras_; ++i) {
	options_.linear_solver_ordering->AddElementToGroup(cameras + 9 * i, 1);
	}

	options_.max_num_iterations = 25;
	options_.function_tolerance = 1e-10;
	options_.gradient_tolerance = 1e-10;
	options_.parameter_tolerance = 1e-10;
	}

	template<typename T>
	void FscanfOrDie(FILE fptr, const char format, T *value) {
	int num_scanned = fscanf(fptr, format, value);
	if (num_scanned != 1) {
	LOG(FATAL) << "Invalid UW data file.";
	}
	}

	// Templated pinhole camera model. The camera is parameterized
	// using 9 parameters. 3 for rotation, 3 for translation, 1 for
	// focal length and 2 for radial distortion. The principal point is
	// not modeled (i.e. it is assumed be located at the image center).
	struct BundlerResidual {
	// (u, v): the position of the observation with respect to the image
	// center point.
	BundlerResidual(double u, double v): u(u), v(v) {}

	template <typename T>
	bool operator()(const T* const camera,
	const T* const point,
	T* residuals) const {
	T p[3];
	AngleAxisRotatePoint(camera, point, p);

	// Add the translation vector
	p[0] += camera[3];
	p[1] += camera[4];
	p[2] += camera[5];

	const T& focal = camera[6];
	const T& l1 = camera[7];
	const T& l2 = camera[8];

	// Compute the center of distortion. The sign change comes from
	// the camera model that Noah Snavely's Bundler assumes, whereby
	// the camera coordinate system has a negative z axis.
	T xp = - focal * p[0] / p[2];
	T yp = - focal * p[1] / p[2];

	// Apply second and fourth order radial distortion.
	T r2 = xpxp + ypyp;
	T distortion = T(1.0) + r2 * (l1 + l2 * r2);

	residuals[0] = distortion * xp - T(u);
	residuals[1] = distortion * yp - T(v);

	return true;
	}

	double u;
	double v;
	};


	Problem problem_;
	Solver::Options options_;

	int num_cameras_;
	int num_points_;
	int num_observations_;
	int num_parameters_;

	int* point_index_;
	int* camera_index_;
	double* observations_;
	// The parameter vector is laid out as follows
	// [camera_1, ..., camera_n, point_1, ..., point_m]
	double* parameters_;
	};

	TEST(SystemTest, BundleAdjustmentProblem) {
	vector<SolverConfig> configs;

	#define CONFIGURE(linear_solver, sparse_linear_algebra_library_type, ordering, preconditioner) \
	configs.push_back(SolverConfig(linear_solver, \
	sparse_linear_algebra_library_type, \
	ordering, \
	preconditioner))

	#ifndef CERES_NO_SUITESPARSE
	CONFIGURE(SPARSE_NORMAL_CHOLESKY, SUITE_SPARSE, kAutomaticOrdering, IDENTITY);
	CONFIGURE(SPARSE_NORMAL_CHOLESKY, SUITE_SPARSE, kUserOrdering, IDENTITY);

	CONFIGURE(SPARSE_SCHUR, SUITE_SPARSE, kAutomaticOrdering, IDENTITY);
	CONFIGURE(SPARSE_SCHUR, SUITE_SPARSE, kUserOrdering, IDENTITY);
	#endif // CERES_NO_SUITESPARSE

	#ifndef CERES_NO_CXSPARSE
	CONFIGURE(SPARSE_SCHUR, CX_SPARSE, kAutomaticOrdering, IDENTITY);
	CONFIGURE(SPARSE_SCHUR, CX_SPARSE, kUserOrdering, IDENTITY);
	#endif // CERES_NO_CXSPARSE

	CONFIGURE(DENSE_SCHUR, SUITE_SPARSE, kAutomaticOrdering, IDENTITY);
	CONFIGURE(DENSE_SCHUR, SUITE_SPARSE, kUserOrdering, IDENTITY);

	CONFIGURE(CGNR, SUITE_SPARSE, kAutomaticOrdering, JACOBI);
	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kUserOrdering, JACOBI);
	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kUserOrdering, SCHUR_JACOBI);

	#ifndef CERES_NO_SUITESPARSE

	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kUserOrdering, CLUSTER_JACOBI);
	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kUserOrdering, CLUSTER_TRIDIAGONAL);
	#endif // CERES_NO_SUITESPARSE

	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kAutomaticOrdering, JACOBI);
	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kAutomaticOrdering, SCHUR_JACOBI);

	#ifndef CERES_NO_SUITESPARSE

	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kAutomaticOrdering, CLUSTER_JACOBI);
	CONFIGURE(ITERATIVE_SCHUR, SUITE_SPARSE, kAutomaticOrdering, CLUSTER_TRIDIAGONAL);
	#endif // CERES_NO_SUITESPARSE

	#undef CONFIGURE

	// Single threaded evaluators and linear solvers.
	const double kMaxAbsoluteDifference = 1e-4;
	RunSolversAndCheckTheyMatch<BundleAdjustmentProblem>(configs,
	kMaxAbsoluteDifference);

	#ifdef CERES_USE_OPENMP
	// Multithreaded evaluators and linear solvers.
	for (int i = 0; i < configs.size(); ++i) {
	configs[i].num_threads = 2;
	}
	RunSolversAndCheckTheyMatch<BundleAdjustmentProblem>(configs,
	kMaxAbsoluteDifference);
	#endif // CERES_USE_OPENMP
	}

	} // namespace internal
	} // namespace ceres