fix assertions, improve docs. we never assert on conditions that depend on the result of a computation!! also the assertion that rank>0 amounts to matrix!=0 which we have to leave under the responsibility of the user.
fix assertions, improve docs.
we never assert on conditions that depend on the result of a computation!!
also the assertion that rank>0 amounts to matrix!=0 which we have to leave under the responsibility of the user.

madlib/eigen,madlib/eigen,madlib/eigen,madlib/eigen