[petsc-users] How to symmetrical the pattern of an unsymmetrical matrix

[Jed Brown]

2011/1/26 Gong Ding <gdiso at ustc.edu>

> I have unsymmetrical jacobian matrix in MPIAIJ format (it is nearlly
> symmetric, I guess). I'd like to pad it to symmetrical pattern by just add 0
> to corresponding matrix entry, which is required to some matrix partition
> step.


How are you obtaining the matrix?  The best way is to preallocate those
extra zeros.

A traditional purely algebraic way is to add the transpose (zeroed in this
case), but transpose is a bad operation to perform in parallel so I would
try to avoid it.
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