I've to perform repeated LU factor of a matrices with identical nonzero pattern.
But all the examples I'm seeing perform just one factorization.
When doing multiple factorizations, which objects would be reused?
I think I've not even seen a clear() method to clear the matrix after one factorization in order to make it ready to receive the coefficients for the next factorization.

regarding clear() there is setZero().

ok -- I found the documentation showing multiple factorizations:

http://eigen.tuxfamily.org/dox/group__T ... stems.html