[petsc-users] re. AIJ preallocation man page

[Marco Zocca]

Dear all,

I'm struggling with this statement:

"It is recommended that you call both of the above preallocation
routines [MatSeqAIJSetPreallocation and MatMPIAIJSetPreallocation] for
simplicity."

(source: https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MATAIJ.html
)

I saw that, even on a single-processor communicator,
MatMPIAIJSetPreallocation works fine (at least, it gives no errors,
but I don't know about efficiency drops).
What's the effect of the recommended double preallocation?

Thank you and KR,
Marco