<div>Hi Barry,</div>
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<div>Thanks for your recommendation. I've managed to use mat_view to view the matrix. However, there's something which I don't understand. My linear eqns consist of 36 pts - so I see 36 rows - 0 to 35. </div>
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<div>For the uniprocessor, I saw 0-35rows. These show the coefficients of my matrix. Then there's a repeat of 0-35 rows again. But what are these values? I don't understand.</div>
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<div>For the 4 processors, I saw exactly the same 0-35rows. After that I saw 0-8 rows repeated 4 times. The values are now different, even for the same 1st 0 row. Some values are missing. I guess there's where my mistakes are.
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<div>Thank you.<br><br> </div>
<div><span class="gmail_quote">On 1/23/07, <b class="gmail_sendername">Barry Smith</b> <<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><br>Ben,<br><br> You can use -pc_type redundant -redundant_pc_type lu to solve the<br>linear system with a sequential LU to test if that improves the situation.
<br><br>Likely your generation of the matrix on 2 processes is wrong, you can run<br>with -mat_view on a small problem with both 1 and 2 processes and see if<br>they are the same in both cases.<br><br>I don't think what you propose to do below makes sense,
<br><br> Barry<br><br><br>On Tue, 23 Jan 2007, Ben Tay wrote:<br><br>> Hi,<br>><br>> In my MPI CFD code, I have to solve 2 linear eqns - momentum and poisson<br>> eqn. There's some error in the code and I don't know which one causes the
<br>> error. May I know if it is possible to solve 1 eqn in sequential mode while<br>> the other in MPI to pinpoint the error since my code works ok in a<br>> sequential mode.<br>><br>> I tried to use this for one of the eqn:
<br>><br>><br>> call<br>> MatCreateSeqAIJ(PETSC_COMM_SELF,size_x*size_y,size_x*size_y,9,PETSC_NULL_INTEGER,A_mat,ierr)<br>><br>> call VecCreateSeq(PETSC_COMM_SELF,size_x*size_y,b_rhs,ierr)<br>><br>> but there's error.
<br>><br>> Thank you.<br>><br><br></blockquote></div><br>