[petsc-users] Blocked matrix storage

[Manav Bhatia]

Hi, 

  I am working on a problem with system of equations in complex numbers, and am splitting it up to solve it with petsc compiled for real number support:

(J_R + i J_I) (x_R + i x_I) + (r_R + i r_I) = 0

is then defined as 

[ J_R   -J_I] {x_R}  +  {r_R}  = {0}
[ J_I    J_R] {x_I}  +  {r_I}  = {0}

I have tried block-Schur solver with the Jacobian defined using the nested matrix format with a separate matrix for each quadrant of the Jacobian. This works well for diagonally dominant cases, but for high-frequency problems (J_I scales with frequency), the solver convergence is very slow. 

Now, I am attempting to create a single matrix so that I can use the other ksp+pc combinations for this system of equations. 

I am wondering if there is a natural way to create an mpiaij or an mpibaij matrix from the nested matrix defined above. 

I would appreciate any guidance on this. 

Regards,
Manav


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