Row major vs Column major orientation.

Question

Hi all,
I've a simple question concerning the Sparsity Pattern of the matrix used in Fenics.
When I do something like

dolfin::parameters["linear_algebra_backend"] = "uBLAS";
dolfin::Matrix A;
...
boost::tuples::tuple<const std::size_t*, const std::size_t*, const double*, int> t;
t  = A.data ();

How can I know if the matrix is stored with a row major or a column major orientation?

Thanks for your help

Answer 1

In the uBLAS backend we use compressed row storage, so that would be row major.