[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Getfem-users] Sign of model_pb - residual in Classical_Newton

From: Renard Yves
Subject: Re: [Getfem-users] Sign of model_pb - residual in Classical_Newton
Date: Thu, 26 Nov 2009 20:36:45 +0100
User-agent: Dynamic Internet Messaging Program (DIMP) H3 (1.1.2)

Dear Kostas,

Yes indeed, the sign is different between the two versions so that the sign of the residual have to be systematically changed transforming an old brick into a new one. The reason is that the new break system consider directly right hand sides (for linear bricks it is not still necessary to add to the residual the matrix times the value of the variable). So the vectors in the new brick systems have to be considered as right hand side (minus the residual for the newton algorithm). It is explained in the documentation :


Konstantinos Poulios <address@hidden> a écrit :

I have found some difficulties in nonlinear solutions in combination
with the new brick system. For a very simple nonlinear model that I
have converted from the old brick system, the classical_Newton
subroutine diverges. Trying to trace down the problem I realized that
in the first iteration step the residual of the model_pb object used
in the classical_Newton subroutine, has a different sign as the
corresponding one in the old brick system. I my test case the residual
I have checked was exclusively due to a source_term. Perhaps the
following two screenshots could be helpful to understand:

Was this sign difference to expect? Should this sign difference be
taken into consideration when migrating bricks from the old system to
the new one? Could it be a bug? My question affects version 4.0.0.


Getfem-users mailing list

reply via email to

[Prev in Thread] Current Thread [Next in Thread]