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.
It constructs the stacked residuals and jacobian of the perfect foresight
problem.
It is an almost perfect replacement for the perfect_foresight_problem.m
routine, while being much more efficient.
Note however that the DLL never return complex numbers (it instead puts NaNs at
the place where there would have been complex). This may create problems for
some MOD files; the algorithms will need to be adapted to use a more
line-search method.