[petsc-users] ill-conditioned problems in PETSc

[w_ang_temp]

Thank you very much. And we will have a try on both MUMPS and the traditional preconditioners provided by PETSc.
 
                                                     Jim


>在 2012-06-28 23:01:44，"Hong Zhang" <hzhang at mcs.anl.gov> 写道：
>Jim,



>    In fact, I will deal with the large sparse symmetric or unsymmetric (depending on the constitutive
>model used for the soil and the formulation of equations) linear system which usually occurs in geotechnical
>problems. As you know, In most geotechnical problems, the coefficient matrix can be severely
>ill-conditioned, thus calling  for the development of robust and efficient preconditioners and iterative methods.
   
>    The iterative method and parallel solver are my choices, actually are required by my professor. As I know,
>MUMPS is just an external solver like Matlab. So is it a right way to analyse the preconditioners and iterative
>MUMPS and Superlu_dist are parallel sparse direct solvers for ill-conditioned problems.
>They can solve problems with 10k unknowns sequentially and scale up to
>10+ or 100+ processors, i.e. solve problems with 100k unknowns.
>Give them a try. Then, explore other preconditioners.


>methods provided by PETSc like CG, GMRES, Jacobi, sor, etc. for my work?
   
>    Also I do not quite understand the second part of what Barry said ('You will not be able to use the external
>solvers with those mode'). So, what does 'those mode' mean. Using quad precision?


>Yes, high precisions. Start from small problems with robust solvers, then slowly
>move to large, complex problems.


>Hong 
  





 
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