1. eigenMatrix.cpp
#include <iostream>
#include <ctime>
#include <eigen3/Eigen/Core>
#include <eigen3/Eigen/Dense>
using namespace std;
#define MATRIX_SIZE 50
int main(int argc, char *argv[])
{
Eigen::Matrix<float, 2, 3> matrix_23;
Eigen::Vector3d v_3d;
Eigen::Matrix3d matrix_33 = Eigen::Matrix3d::Zero();
Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic> matrix_dynamic;
Eigen::MatrixXd matrix_x;
matrix_23 << 1, 2, 3, 4, 5, 6;
cout << "matrix_23:"<<endl;
cout << matrix_23 << endl;
cout << "matrix_23:" << endl;
for (int i=0;i<2;++i){
for (int j=0;j<3;++j){
cout<<matrix_23(i,j)<<endl;
}
}
v_3d << 1, 2,3;
Eigen::Matrix<double, 2,1> result=matrix_23.cast<double>() * v_3d;
cout<<"result:"<<endl;
cout<<result<<endl;
matrix_33 = Eigen::Matrix3d::Random();
cout << "matrix_33:" <<endl;
cout << matrix_33 <<endl;
cout <<"matrix_33.transpose():"<<matrix_33.transpose() <<endl;
cout <<"matrix_33.sum():"<<matrix_33.sum()<<endl;
cout <<"matrix_33.trace():"<<matrix_33.trace()<<endl;
cout <<"matrix_33 * 10"<<matrix_33 * 10<<endl;
cout <<"matrix_33.inverse():"<<matrix_33.inverse()<<endl;
cout<<"matrix_33.determinant():"<<matrix_33.determinant()<<endl;
Eigen::SelfAdjointEigenSolver<Eigen::Matrix3d> eigen_slover(matrix_33.transpose()*matrix_33);
cout<<"eigen_slover.eigenvalues():"<<eigen_slover.eigenvalues()<<endl;
cout<<"eigen_slover.eigenvectors():"<<eigen_slover.eigenvectors()<<endl;
Eigen::Matrix<double, MATRIX_SIZE, MATRIX_SIZE> matrix_NN;
matrix_NN = Eigen::MatrixXd::Random(MATRIX_SIZE, MATRIX_SIZE);
Eigen::Matrix<double, MATRIX_SIZE, 1> v_Nd;
v_Nd = Eigen::MatrixXd::Random(MATRIX_SIZE, 1);
clock_t time_stt=clock();
Eigen::Matrix<double, MATRIX_SIZE, 1> x=matrix_NN.reverse()*v_Nd;
cout<<"time use in normal invers is"<<1000*(clock()-time_stt)/(double)CLOCKS_PER_SEC<<"ms"<<endl;
time_stt=clock();
x=matrix_NN.colPivHouseholderQr().solve(v_Nd);
cout<<"time use in Qr compsition is"<<1000*(clock()-time_stt)/(double)CLOCKS_PER_SEC<<"ms"<<endl;
return 0;
}
2. CMakeLists.txt
cmake_minimum_required(VERSION 3.0)
project(useEigen)
set(CMAKE_BUILD_TYPE "Debug")
set(CMAKE_CXX_FLAGS "-O3")
include_directories("usr/include/eigen3")
add_executable(eigenMatrix eigenMatrix.cpp)
3. 查看执行结果
/home/wzl/work/slambook/ch3/eigen/build> /home/wzl/work/slambook/ch3/eigen/build/eigenMatrix
matrix_23:
1 2 3
4 5 6
matrix_23:
1
2
3
4
5
6
result:
14
32
matrix_33:
0.680375 0.59688 -0.329554
-0.211234 0.823295 0.536459
0.566198 -0.604897 -0.444451
matrix_33.transpose(): 0.680375 -0.211234 0.566198
0.59688 0.823295 -0.604897
-0.329554 0.536459 -0.444451
matrix_33.sum():1.61307
matrix_33.trace():1.05922
matrix_33 * 10 6.80375 5.9688 -3.29554
-2.11234 8.23295 5.36459
5.66198 -6.04897 -4.44451
matrix_33.inverse():-0.198521 2.22739 2.8357
1.00605 -0.555135 -1.41603
-1.62213 3.59308 3.28973
matrix_33.determinant():0.208598
eigen_slover.eigenvalues():0.0242899
0.992154
1.80558
eigen_slover.eigenvectors():-0.549013 -0.735943 0.396198
0.253452 -0.598296 -0.760134
-0.796459 0.316906 -0.514998
time use in normal invers is0.002ms
time use in Qr compsition is0.049ms
*** 已完成 ***