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<div style=""> Hi, Petsc Team,<br>
<br>
I noticed that the Petsc program often cost a lot of time to assemble a matrix, particularly when DOF is large. For example, I write a 3D structured CFD code with a linear system of 40 x 22 x 20 in dimension and DOF = 6. In a sequential computation, it takes
more than 20 minutes to finish assembling the matrix before ksp operates. This same problem should take only a few seconds for a commercial CFD software to initialize.
<br>
<br>
The processor is 2.67G Hz in speed with sufficient RAM (6GB). The largest matrix stencil is 19 points. I typically use the function: MatSetValuesStencil(A, 1, &<span style="font-style: italic;">abc</span>, 19, def, val, INSERT_VALUES). I wonder the assembling
can be faster if <span style="font-style: italic;">abc</span> is an array of multiple matrix row coordinates. But in the case of DOF >1, this seems difficult to implement.
<br>
<br>
Is this normal for Petsc or do we have any means to improve this?<br>
<br>
<br>
Thank you.<br>
<br>
<br>
Zhisong Li<br>
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