Hi:
Is there a way to ask Eigen to perform sparse LLT/LDLT (over a symmetric sparse matrix ) without permutation? We have some ideas on re-ordering matrix elements and would like to test our own permutation.
Thanks for developing Eigen, it is amazing!

Sure, use NaturalOrdering<int> as the third template argument of SimplicialLDLT and apply ordering by hand. You can also implement your own ordering class to be passed to SimplicialLDLT. See https://bitbucket.org/eigen/eigen/src/c ... ew-default for some examples. If your method is effective and not too specific to a very small class of problems, you're very welcome to contribute it back to Eigen

Thank you for your reply! Let us see what we can do