Is solving a Nx * Ny system equivalent to a Nx * Ny * 1 system in PETSc?

[Wee-Beng TAY]

Hi,

I'm not sure if my question is trivial but I'm wondering if it makes any 
difference in solving a Nx * Ny system and a Nx * Ny * 1 system in 
PETSc? For e.g., 10x10 vs. 10x10x1. Will there be any problem or 
difference in answer? What about the speed?

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Thank you very much and have a nice day!

Yours sincerely,

Wee-Beng Tay