Eigen库的简单使用

Eigen是一个C++开源线性代数库。提供有关矩阵的的线性代数运算，解方程等功能。
官方的文档在此，本文是简单的使用，以SLAM十四讲代码阅读，快速入门。
http://eigen.tuxfamily.org/dox/classEigen_1_1Transform.html

一、Ubantu安装eigen

$ sudo apt-get install libeigen3-dev

二、eigen的主要模块 Header Contents

Module	contents
#include <Eigen/Core>	Matrix and Array classes, basic linear algebra (including triangular and selfadjoint products), array manipulation
#include <Eigen/Geometry>	Transform, Translation, Scaling, Rotation2D and 3D rotations (Quaternion, AngleAxis)
#include <Eigen/LU>	Inverse, determinant, LU decompositions with solver (FullPivLU, PartialPivLU)
#include <Eigen/Cholesky>	LLT and LDLT Cholesky factorization with solver
#include <Eigen/Householder>	Householder transformations; this module is used by several linear algebra modules
#include <Eigen/SVD>	SVD decompositions with least-squares solver (JacobiSVD, BDCSVD)
#include <Eigen/QR>	QR decomposition with solver (HouseholderQR, ColPivHouseholderQR, FullPivHouseholderQR)
#include <Eigen/Eigenvalues>	Eigenvalue, eigenvector decompositions (EigenSolver, SelfAdjointEigenSolver, ComplexEigenSolver)