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Hi all,
<div>I am using PETSc (dev version) to solve the Stokes + temperature equations. My DM has fields (vx, vy, p, T).</div>
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<div>I would like to use nested fieldsplits to separate the T part from the Stokes part, and apply a Schur complement approach to the Stokes block.</div>
<div>Unfortunately, I keep getting this error message:</div>
<div><span style="color: rgb(41, 249, 20); font-family: 'Andale Mono'; background-color: rgb(0, 0, 0);">[1]PETSC ERROR: DMCreateFieldDecomposition() line 1274 in /home/jolive/petsc/src/dm/interface/dm.c Decomposition defined only after DMSetUp</span></div>
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<div>Here are the command line options I tried:</div>
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<div><span style="font-family: Menlo; font-size: 11px;">-snes_type ksponly \</span></div>
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<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-ksp_type fgmres \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><span style="color: rgb(0, 132, 0);"># define 2 fields: [vx vy p] and [T] </span></div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-pc_type fieldsplit -pc_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fields <span style="color: rgb(39, 42, 216);">0</span>,<span style="color: rgb(39, 42, 216);">1</span>,<span style="color: rgb(39, 42, 216);">2</span> -pc_fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_fields <span style="color: rgb(39, 42, 216);">3</span> \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><span style="color: rgb(0, 132, 0);"># split [vx vy p] into 2 fields: [vx vy] and [p] </span></div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_pc_type fieldsplit \</div>
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<div style="margin: 0px;">-pc_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fields <span style="color: rgb(39, 42, 216);">0</span>,<span style="color: rgb(39, 42, 216);">1</span> -pc_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_fields <span style="color: rgb(39, 42, 216);">2</span> \</div>
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<div style="margin: 0px;"><span style="color: rgb(0, 132, 0);"># apply schur complement to [vx vy p]</span></div>
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<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_pc_fieldsplit_type schur \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_pc_fieldsplit_schur_factorization_type upper \</div>
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<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><span style="color: rgb(0, 132, 0);"># solve everything with lu, just for testing</span></div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_ksp_type preonly \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_pc_type lu -fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_pc_factor_mat_solver_package
superlu_dist \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_ksp_type preonly \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_pc_type lu -fieldsplit_<span style="color: rgb(39, 42, 216);">0</span>_fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_pc_factor_mat_solver_package
superlu_dist \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_ksp_type preonly \</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;">-fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_pc_type lu -fieldsplit_<span style="color: rgb(39, 42, 216);">1</span>_pc_factor_mat_solver_package superlu_dist \</div>
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<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><br>
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<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><span style="font-family: Helvetica; font-size: 12px;">Any idea what could be causing this?</span></div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><span style="font-family: Helvetica; font-size: 12px;">Thanks a lot,</span></div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"><span style="font-family: Helvetica; font-size: 12px;">Arthur</span></div>
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