Eigen3 Cheatsheet

Cheatsheet就是你写代码时对某个库的参照表，这些接口无需记忆，只用边写边看即可：

//------------------   Eigen Cheatsheet  ---------------
//@Hanss401
//@2018/3/15

#include <iostream>
#include <Eigen/Dense>


typedef Matrix<float,Dynamic,Dynamic> MatrixfX

//define Vector
Eigen::Matrix<Dtype,n,1> vec;

//define Matrix
Eigen::Matrix<Dtype,m,n> mat;

//Matrix times const
Eigen::Matrix::Constant(3,3,1.2)*5.0;

//Martrix dot

//add/subtract  
mat3 = mat1 + mat2;           mat3 += mat1;
mat3 = mat1 - mat2;           mat3 -= mat1;

//scalar product  
mat3 = mat1 * s1;             mat3 *= s1;           mat3 = s1 * mat1;
mat3 = mat1 / s1;             mat3 /= s1;

//matrix/vector products *  
col2 = mat1 * col1;
row2 = row1 * mat1;           row1 *= mat1;
mat3 = mat1 * mat2;           mat3 *= mat1; 

//transposition adjoint * 
mat1 = mat2.transpose();      mat1.transposeInPlace();
mat1 = mat2.adjoint();        mat1.adjointInPlace();

//dot product 
//inner product * 
scalar = vec1.dot(vec2);
scalar = col1.adjoint() * col2;
scalar = (col1.adjoint() * col2).value();

//outer product * 
mat = col1 * col2.transpose();

//norm normalization * 
scalar = vec1.norm();         scalar = vec1.squaredNorm()
vec2 = vec1.normalized();     vec1.normalize(); // inplace 

//cross product * 
#include <Eigen/Geometry>
vec3 = vec1.cross(vec2);