howto: Eigen Installation

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All,

This is just a brief how to on how to resolve Eigen compile time errors - which wasn't installed on my Raspberry Pi.

I kept getting the error:

CMake Error at CMakeLists.txt:12 (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.

And try as I might I couldn't find a conclusive answer. Anyway these steps should solve the issue

1) Download Eigen

hg clone https://bitbucket.org/eigen/eigen/

2) CD into the download dir

 cd eigen

3) Create a build dir

 mkdir build

4) Configure the build

cmake ..

5) Build the package

make

6) Install the package

sudo make install

And all being well that should be it!

Hope this helps

Mark