AztecOO: ilut: zero pivot encountered!
Created by: guoluanjing
Hi there,
I am solving a linear system using AztecOO. I'm using GMRES solver with ilut preconditioner with the defult fill-in and drop parameters. But I have encounted the error message: ilut: zero pivot encountered!
I found this old post about the error message: https://groups.google.com/forum/#!topic/trilinos/Ps9oKLYdDXA
So I've tried the following:
- double-checked that RCM ordering is on.
- I've increased the fill-in to maximum of 1,000,000, roughly the number of elements in my Jacobian matrix, and changed the drop parameter from 0 to 10. The error message still showed but the linear solve converged, but to wrong solution (negative values for chemical concentration).
- outputted the Jacobian matrix into Matlab, and checked the condition number (10^7, very large) and the singularity (it has an inverse matrix).
Please advise me for what else I could try in order to solve the problem.
Thanks a lot, Luanjing