function md=solversettosor(md)
%SOLVERSETTOSOR - associate solver sor to the model
%
%   Usage:
%      md=solversettosor(md)

md.mat_type='aij';
md.ksp_type='cg';
md.pc_type='sor';
md.solver_extra_option=' -pc_sor_omega 1.1 -pc_sor_its 2 ';
