[petsc-users] Copy MPIAIJ Matrix onto MPISeq Matrices on All Processors

[Ali Berk Kahraman]

Dear All,

I have to create my Jacobian numerically using an FD function I have 
written, but the problem is that the function evaluation FormRHSFunction 
creates PETSC_COMM_WORLD objects in it, and takes 1 PETSC_COMM_WORLD 
matrix as an input.  So I cannot work it on parallel (every processor 
calculating its own portion of Jacobian), I tried but the machine gets 
confused.

My initial idea was to create the objects in PETSC_COMM_SELF type within 
the RHS function, but the input COMM_WORLD matrix standed where it was. 
So my question is, is there a way to get a complete copy of a 
distributed matrix on all the processors as seq matrices?

I cannot use the Petsc's version FD function because the FormRHSFunction 
I call to create the Jacobian is slightly different than the original 
FormRHSFunction. The original function is too expensive, so I only 
calculate the relevant parts of it in the Jacobian function.

Best Regards,

Ali Berk Kahraman
M.Sc. Student, Mechanical Engineering
Bogazici Uni. Istanbul, Turkey