[petsc-users] A qustion of PETSc

[w_ang_temp]

Hello,Matt
    Thanks again.
    What you said("Use -ksp_type preonly -pc_type lu") means that I should use a direct solver.And I am puzzled.
    (1)I think this problem (single processor is ok and more than one are problematic)is typical,but I cannot
find useful infomation both in the manual and the petsc-users.So can you give me some explanation for this
phenomenon.
    (2)When I use -pc_type lu,the error message is "Matrix format mpiaij does not have a built-in PETSc LU!".
    (3)The manual says that "This approach prevents the user from the unexpected surprise of having a
corrupted matrix after a linear solve"(P72).So do you mean the problem of mine is here?
    (4)Generally I want to use the iterative approach other than the direct method.
    As a beginner,I have to learn more about the manual.And also I think an experienced senior will be a more
 useful help for me because I have gotten stuck on this problem for more than a week.
     Thanks.                                Jim




>At 2012-05-26 20:17:42,"Matthew Knepley" <knepley at gmail.com> wrote:
>Use -ksp_type preonly -pc_type lu.


 >  Matt
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