在Eigen官网下载任意版本均可 在install安装文件中 有两种安装方法

Method 1. Installing without using CMakeYou can use right away the headers in the Eigen/ subdirectory. In order to install, just copy this Eigen/ subdirectory to your favorite location. If you also want the unsupported features, copy the unsupported /subdirectory too.Method 2. Installing using CMakeLet s call this directory source_dir (where this INSTALL file is). Before starting, create another directory which we will call build_dir . cd build_dir cmake source_dir make installThe make install step may require administrator privileges. You can adjust the installation destination (the prefix ) by passing the -DCMAKE_INSTALL_PREFIX myprefix option to cmake, as is explained in the message that cmake prints at the end.

其中 方法一直接复制到系统目录 方法二cmke编译后指定安装目录 笔者本想用方法二更完整 但是提示错误cmake找不到系统内的目录 加了sudo也没用 笔者猜测是上层系统文件的权限问题 我给了/usr/local/include的权限 但是/usr/local/没有权限 如有错误感谢指正。使用方法一步骤如下

/*1*/解压到任意文件夹eigen3/*2*/sudo mv eign3 /usr/local/include/

CMake Error at loam_velodyne-master/CMakeLists.txt:14 (find_package): By not providing FindEigen3.cmake in CMAKE_MODULE_PATH this project has asked CMake to find a package configuration file provided by Eigen3 , but CMake did not find one. Could not find a package configuration file provided by Eigen3 with any of the following names: Eigen3Config.cmake eigen3-config.cmake Add the installation prefix of Eigen3 to CMAKE_PREFIX_PATH or set Eigen3_DIR to a directory containing one of the above files. If Eigen3  provides a separate development package or SDK, be sure it has been installed.

提示这个错误是因为CMakeLists.txt没有找到eigen3包 在CMakeLists.txt文件find_package(Eigen3 REQUIRED)前加入set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake) 同时loam_velodyne-master包内新建文件夹cmake 把eigen安装包中的FindEigen3.cmake复制到cmake内 编译通过。