 <OpenGeoSysProjectDiff base_file="square_1e2.prj">

   <add pos="after" sel="/*/linear_solvers/linear_solver">

     <linear_solver>

       <name>general_linear_solver</name>

       <eigen>

         <solver_type>IDRSTABL</solver_type>

         <precon_type>DIAGONAL</precon_type>

         <max_iteration_step>10000</max_iteration_step>

         <error_tolerance>1e-16</error_tolerance>

       </eigen>

     </linear_solver>

   </add>

   <remove sel="/*/linear_solvers/linear_solver[1]" />

 </OpenGeoSysProjectDiff>