Please add keyword ~x86 to >=dev-cpp/eigen-1.05. Thanks. Reproducible: Always Steps to Reproduce:
on x86: i've successfully installed dev-cpp/eigen-1.0.5, compiled and launched a simple test app, that basically does what you find here: http://eigen.tuxfamily.org/classEigen_1_1LinearSolver.html if you want me to do some further testing just let me know; i'm interested in the library anyways.
added ~x86, thanks Matthias, those tests are enough, closing