Ubuntu14.04 ：By not providing “FindEigen3.cmake” in CMAKE_MODULE_PATH
今天下载了hector_slam的源码想要跑一下，结果编译不能通过，并且一直出现如下错误，烦得一逼。研究了一会儿，解决了，方法如下：
这是错误提示：
CMake Warning at hector_compressed_map_transport/CMakeLists.txt:13 (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.
解决办法：
1、找到一个FindEigen3.cmake文件，直接在电脑里面搜索就行，应该会有的，找不到的请私我。。。
2、复制到自己这个的工程下
3、在工程的CMakeLists.txt里面。添加这句话：
set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR})*******就是这句，加上就行了。这样cmake就会到你自己工程目录下去找FindEigen3.cmake了。
find_package(Eigen3)
if(NOT EIGEN3_FOUND)
# Fallback to cmake_modules
find_package(cmake_modules REQUIRED)
find_package(Eigen REQUIRED)
set(EIGEN3_INCLUDE_DIRS ${EIGEN_INCLUDE_DIRS})
set(EIGEN3_LIBRARIES ${EIGEN_LIBRARIES}) # Not strictly necessary as Eigen is head only
# Possibly map additional variables to the EIGEN3_ prefix.
else()
set(EIGEN3_INCLUDE_DIRS ${EIGEN3_INCLUDE_DIR})
endif()
