The statement “implicit none” forbids implicit typing of variables, but not
implicit procedure declaration. The new “implicit none (type, external)” syntax
forbids both, and is thus safer.
Note that the unitary test in lyapunov_solver.m that checks sparse matrix input
had to be removed. Previously, this test was passing by chance (because the
sparse test matrices had actually no zero element, hence the internal double
float storage was the same as in the dense case). Now it consistently fails
with the additional checks in disclyap_fast MEX.
Sébastien Villemot