[Trilinos-Users] NOX limitations

Heroux, Michael A maherou at sandia.gov
Thu Oct 22 11:18:49 MDT 2009

These are difficult questions to answer without some specific knowledge of the problems you are interested in solving.  Here are some thoughts:

 *   Nonlinear solvers, and the linear solvers on which they depend, do not converge in all situations.  NOX has Newton's method, and other methods that improve the convergence radius of Newton's method.  It is difficult to say a priori what NOX can and cannot solve.
 *   There is no particular limit to the number of equations NOX can handle.
 *   Initial values choices are problem-dependent.
 *   Tolerances are also problem dependent.

You can also look at the Trilinos Tutorial, which has a section on NOX.  The link is here:



On 10/22/09 4:46 AM, "Mohammad Reza Sharif" <sharif1133 at gmail.com> wrote:

It's not a long time since I have got familiar with the trilinos package. I would be glad to use it in my projects.
So, I want to use NOX package as a beginning. However, I should know its limitations as a nonlinear solver.
I would be happy if anybody helps me on the case. For example, how many equations NOX can solve simultaneously,
which equations NOX can't solve, how should be the initial values set in order to get the system of equations better solved,
what is the best tolerance that NOX can achieve,etc.


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