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On 15-05-11 07:19 PM, Hong wrote:<br>
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<div class="gmail_quote">Danyang:
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I recently have some time-dependent cases that have
difficulty in convergence. It needs a lot of linear
iterations during a specific time, e.g., more than 100
linear iterations for every newton iteration. In PETSc
parallel version, this number will be doubled or even
more. Our case usually needs less than 10 iterations for
every newton iteration. This is NOT caused by PETSc
relative routines as the original sequential solver (ILU)
also has the same problem.<br>
<br>
The results seems reasonable, but the large number of
iterations leads me to suspect that something is not well
implemented in a particular module. This module is
developed a long time ago by another guy and it sounds
impossible for me to check every line (thousands of lines)
and do theoretical analysis.Does PETSc or external package
provide matrix analysis to help to locate the 'suspected'
entry?<br>
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<div>We need know what solvers being used. My guess is the
default </div>
<div>gmres/bjacobi/ilu(0). Please run your code with option
'-ts_view' or '-snes_view' to find out. <br>
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Hi Hong,<br>
<br>
Sorry for the late reply. I guess there is nothing wrong in the
solver or data structure, but maybe some large entries in the linear
system that cause the problem hard to solve. I will export the
matrix to check these values.<br>
<br>
Thanks,<br>
<br>
Danyang<br>
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<div>Hong</div>
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