The file mroutines.f contains a series of FORTRAN-77 subroutines for the solution of linear systems of equations, which is basically what you are facing in doing inverse iteration.
The file README.txt contains additional explanations and instruction on how to use the routines. See Appendix F in the class notes for more info on finite differences and inverse iteration.
-Last Revised 20 october 2008 by paulchar@astro.umontreal.ca