add old aggressive coarsening algorithm as option, switch default MIS ordering algorithm back to old one

Replace LINPACKcgtql1 with LAPACKstev for computing sym tri eigenvalues

Specifically, removes translated Fortran and Algol routines which had non-terminating loops if assumptions were violated with

Replace LINPACKcgtql1 with LAPACKstev for computing sym tri eigenvalues

Specifically, removes translated Fortran and Algol routines which had non-terminating loops if assumptions were violated with a standard LAPACK eigenvalue solver routine. Add new alternatives due to minor differences in eigenvalue estimates.

show more ...