hello_world.cpp

#include <iostream>
#include <eigen3/Eigen/Eigen>
#include <ceres/ceres.h>
#include <glog/logging.h>
#include <sophus/so3.h>
#include <ceres/rotation.h>

using std::cout;
using std::endl;
using ceres::CostFunction;
using ceres::AutoDiffCostFunction;
using ceres::Problem;

// 求解函数f(x) = (x - 10)^2 的最小值

struct CostFunctor
{
    template <typename T>
    bool operator()(const T* const x, T* residual) const
    {
        residual[0] = x[0] - T(10);

        return true;
    }
};

int main(int argc, char* argv[])
{
    google::InitGoogleLogging(argv[0]);
    double x0 = 0.5;
    double x = x0;

    CostFunction* cost_function = new AutoDiffCostFunction<CostFunctor, 1, 1>(new CostFunctor);
    Problem problem;
    problem.AddResidualBlock(cost_function, nullptr, &x);


    Eigen::Vector3d rv = Eigen::Vector3d::Random();
    rv.normalize();
    Eigen::Matrix3d Rcw = Sophus::SO3::exp(rv).matrix();
    cout << "Rcw is\n" << Rcw << endl;
    double R[3*3];
    double fai[3];
    fai[0] = rv[0]; fai[1] = rv[1]; fai[2] = rv[2];
    ceres::AngleAxisToRotationMatrix(fai, R);
    cout << "R is " << endl;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            cout << R[3*i + j] << " ";
        }
        cout << endl;
    }

    /*
    ceres::Solver::Options options;
    options.linear_solver_type = ceres::DENSE_QR;
    options.minimizer_progress_to_stdout = true;
    ceres::Solver::Summary summary;
    ceres::Solve(options, &problem, &summary);

    std::cout << summary.BriefReport() << endl;
    cout << "x: " << x0 << " -> " << x << endl;
     */

    return 0;
}