Eigen用法

秒速五厘米 2022-09-02 15:57 181阅读 0赞

Eigen网址：

[https://eigen.tuxfamily.org/dox/classEigen\_1\_1MatrixBase.html][https_eigen.tuxfamily.org_dox_classEigen_1_1MatrixBase.html]

可以查阅相关类的介绍以及API

**使用：**

51     //initialize
     52     std::map<int, Eigen::VectorXf> mp;
     53     mp[1].resize(400);
     54 
     55     Eigen::VectorXf x1;
     56     cout << "size:" << x1.size() << endl;
     57 
     58     Eigen::Vector2d u(-2, 3), v(4, 5);
     59 
     60     Eigen::MatrixXd m(2, 3);//2行3列
     61     m << 1, 11, 12,         //初始化
     62       2, 22, 23;
     63 
     64     //assign
     65     m(0, 0) = 2;
     66     Eigen::VectorXf x;
     67     x.resize(3);
     68     for (int i = 0; i < 2; ++i)
     69         x(i, 0) = i;
     70     cout << "size:" << x.size() << endl;
     71     cout << "data:" << *(x.data()) << " " << *(x.data()+1)  << endl;
     72     x.resize(0);
     73     cout << "size:" << x.size() << endl;    
    
    76     //arithmetic
     77     cout << "+\n" << u + v << endl;;
     78     cout << "-\n" << u - v << endl;;
     79     cout << "*\n" << u * 2 << endl;
     80     cout << "/\n" << u / 2 << endl;
     81 
     82     cout << "T\n" << u.transpose() << endl;
     83     cout << "-\n" << u.conjugate() << endl;
     84     cout << "*\n" << u.adjoint() << endl;
     85 
     86     //multiplication
     87     cout << "transpose\n" << u.transpose() * v << endl;
     88     cout << "dot\n" << u.dot(v) << endl;
     89 
     90     //math
     91     cout << "sum\n" << u.sum() << endl;
     92     cout << "mean\n" << u.mean() << endl;
     93     cout << "trace\n" << u.trace() << endl;//对角线和
     94     cout << "prod\n" << u.prod() << endl;//各元素间乘积
      95 
     96     //Similarity
     97     cout << "lpNorm---------" << endl;
     98     cout << (u - v).lpNorm<1>() << endl;
     99     cout << (u - v).lpNorm<2>() << endl;
    100     cout << (u - v).lpNorm<Eigen::Infinity>() << endl;
    101 
    102     cout << "dot---------" << endl;
    103     cout << u.dot(v) << endl;
    
    105     //pearson
    106     float mean1 = u.mean();
    107     float mean2 = v.mean();
    108     auto r1 = (u.array() - mean1);
    109     auto r2 = (v.array() - mean2);
    110     float t_dot = r1.matrix().dot(r2.matrix());
    111 
    112     Eigen::Vector2d t_v1 (r1.pow(2));
    113     Eigen::Vector2d t_v2 (r2.pow(2));
    114 
    115     cout << "pearson---------" << endl;
    116     float t_dot2 = std::sqrt(t_v1.sum() * t_v2.sum());
    119     t_dot2 = std::sqrt(t_dot2);
    120     cout << "t_dot2 " << t_dot2 << endl;
    121     float res = t_dot / t_dot2;
    122     cout << res << endl;
    
    
    124     //cos
    125     float c_v = u.dot(v);
    126     Eigen::Vector2d t_c1 (r1.pow(2));
    127     Eigen::Vector2d t_c2 (r2.pow(2));
    128     cout << "cos---------" << endl;
    129     cout << c_v / std::sqrt(t_c1.sum() * t_c2.sum()) << endl;

**类关系：**

Matrix类，继承于PlainObjectBase；

PlainObjectBase最终会使用MatrixBase/ArrayBase

MatrixBase继承于DenseBase

因此看接口的话，可以看DenseBase,MatrixBase,Matrix类

[https_eigen.tuxfamily.org_dox_classEigen_1_1MatrixBase.html]: https://eigen.tuxfamily.org/dox/classEigen_1_1MatrixBase.html