View the most recent changes for the eigen port at: eigen.darwinports.com/diff
Scroll down toward the bottom of the page to get installation instructions for eigen.
The raw portfile for eigen 2.0.0 is located here:
http://eigen.darwinports.com/dports/math/eigen/Portfile
Find related portfiles with the unique DarwinPorts.com search feature.
Check for any related Fink projects here: pdb.finkproject.org/pdb/package.php/eigen

The eigen Portfile 46400 2009-02-04 05:25:12Z illogic-al macports.org $

PortSystem 1.0
PortGroup cmake 1.0

Name: eigen
Version: 2.0.0
Category: math science
Maintainers: nomaintainer
Description: A C++ template library for linear algebra: vectors, matrices, and related algorithms.
Long Description: ${description}
Homepage: http://eigen.tuxfamily.org
Platform: darwin
Master Sites: http://download.tuxfamily.org/eigen/
use_bzip2 yes
Checksums: md5 bedfe344498b926a4b5db17d2846dbb5 sha1 ce7d035b2b27351130d8094375e54a605118233b rmd160 21781944a034792b1c939e48b1d8f54ff1c0e008

use_parallel_build yes
worksrcdir build
pre-configure { file mkdir ${worksrcpath} }

configure.args-append ../${distname} -DBUILD_SHARED_LIBS=ON

If you haven't already installed Darwin Ports, you can find easy instructions for doing so at the main Darwin Ports page.
Once Darwin Ports has been installed, in a terminal window and while online, type the following and hit return:

%  cd /opt/local/bin/portslocation/dports/eigen
%  sudo port install eigen  
Password: 

You will then be prompted for your root password, which you should enter. You may have to wait for a few minutes while the software is retrieved from the network and installed for you. Y ou should see something that looks similar to:

--->  Fetching eigen
--->  Verifying checksum for eigen
--->  Extracting eigen
--->  Configuring eigen
--->  Building eigen with target all

--->  Staging eigen into destroot

--->  Installing eigen

- Make sure that you do not close the terminal window while Darwin Ports is working. Once the software has been installed, you can find further information about using eigen with these commands:

%  man eigen
%  apropos eigen
%  which eigen
%  locate eigen

 Where to find more information: