<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><br></div> The snes options are not relevant since the parts of a PCFIELDSPLIT are always linear problems.<div><br></div><div> By default PCFIELDSPLIT uses a KSP type of preonly on each split (that is it applies the preconditioner exactly once inside the PCApply_FieldSplit() hence the -fieldsplit_*_ksp_ options are not relevent. You can use -fieldsplit_ksp_type gmres for example to have it use gmres on each of the splits, but note that then you should use -ksp_type fgmres since using gmres inside a preconditioner results in a nonlinear preconditioner.</div><div><br></div><div> You can always run with -ksp_view to see the solver being used and the prefixes that currently make sense.</div><div><br></div><div> Barry</div><div><br><div><br><blockquote type="cite"><div>On Dec 11, 2023, at 2:51 AM, 1807580692 <1807580692@qq.com> wrote:</div><br class="Apple-interchange-newline"><div><meta http-equiv="Content-Type" content="text/html; charset=GB18030"><div>Hello, I have encountered some problems. Here are some of my configurations.</div><div>OS Version and Type: Linux daihuanhe-Aspire-A315-55G 5.15.0-89-generic #99~20.04.1-Ubuntu SMP Thu Nov 2 15:16:47 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux</div><div>PETSc Version: #define PETSC_VERSION_RELEASE 1</div><div><span style="white-space: normal;"><span style="white-space:pre"> </span>#define PETSC_VERSION_MAJOR 3</span></div><div><span style="white-space: normal;"><span style="white-space:pre"> </span>#define PETSC_VERSION_MINOR 19</span></div><div><span style="white-space: normal;"><span style="white-space:pre"> </span>#define PETSC_VERSION_SUBMINOR 0</span></div><div><span style="white-space: normal;"><span style="white-space:pre"> </span>#define PETSC_RELEASE_DATE "Mar 30, 2023"</span></div><div><span style="white-space: normal;"><span style="white-space:pre"> </span>#define PETSC_VERSION_DATE "unknown"</span></div><div>MPI implementation: MPICH<span style="white-space:pre"> </span></div><div>Compiler and version: Gnu C</div><div>The problem is when I type </div><div>“mpiexec -n 4 ./ex19 -lidvelocity 100 -prandtl 0.72 -grashof 10000 -da_grid_x 64 -da_grid_y 64 -snes_type newtonls -ksp_type gmres -pc_type fieldsplit -pc_fieldsplit_type symmetric_multiplicative -pc_fieldsplit_block_size 4 -pc_fieldsplit_0_fields 0,1,2,3 -pc_fieldsplit_1_fields 0,1,2,3 -fieldsplit_0_pc_type asm -fieldsplit_0_pc_asm_type restrict -fieldsplit_0_pc_asm_overlap 5 -fieldsplit_0_sub_pc_type lu -fieldsplit_1_pc_type asm -fieldsplit_1_pc_asm_type restrict -fieldsplit_1_pc_asm_overlap 5 -fieldsplit_1_sub_pc_type lu -snes_monitor -snes_converged_reason -fieldsplit_0_ksp_atol 1e-10 -fieldsplit_1_ksp_atol 1e-10 -fieldsplit_0_ksp_rtol 1e-6 -fieldsplit_1_ksp_rtol 1e-6 -fieldsplit_0_snes_atol 1e-10 -fieldsplit_1_snes_atol 1e-10 -fieldsplit_0_snes_rtol 1e-6 -fieldsplit_1_snes_rtol 1e-6”</div><div>in the command line, where my path is /petsc/src/snes/tutorials.</div><div><br></div><div>It returns </div><div>“WARNING! There are options you set that were not used!</div><div>WARNING! could be spelling mistake, etc!</div><div>There are 8 unused database options. They are:</div><div>Option left: name:-fieldsplit_0_ksp_atol value: 1e-10 source: command line</div><div>Option left: name:-fieldsplit_0_ksp_rtol value: 1e-6 source: command line</div><div>Option left: name:-fieldsplit_0_snes_atol value: 1e-10 source: command line</div><div>Option left: name:-fieldsplit_0_snes_rtol value: 1e-6 source: command line</div><div>Option left: name:-fieldsplit_1_ksp_atol value: 1e-10 source: command line</div><div>Option left: name:-fieldsplit_1_ksp_rtol value: 1e-6 source: command line</div><div>Option left: name:-fieldsplit_1_snes_atol value: 1e-10 source: command line</div><div>Option left: name:-fieldsplit_1_snes_rtol value: 1e-6 source: command line”.</div><div>Please tell me what should I do?Thank you very much.</div><div><hr align="left" style="margin: 0 0 10px 0;border: 0;border-bottom:1px solid #E4E5E6;height:0;line-height:0;font-size:0;padding: 20px 0 0 0;width: 50px;"><div style="font-size: 14px; font-family: Verdana;"><a class="xm_write_card" id="in_alias" style="white-space: normal; display: inline-block; text-decoration: none !important;font-family: -apple-system,BlinkMacSystemFont,PingFang SC,Microsoft YaHei;" href="https://wx.mail.qq.com/home/index?t=readmail_businesscard_midpage&nocheck=true&name=1807580692&icon=http%3A%2F%2Fthirdqq.qlogo.cn%2Fg%3Fb%3Dsdk%26k%3DsDkxrKtOBYniaVteAHHIz5g%26s%3D100%26t%3D1647684318%3Frand%3D1648799506&mail=1807580692%40qq.com&code=" target="_blank"><table style="white-space: normal;table-layout: fixed; padding-right: 20px;" contenteditable="false" cellpadding="0" cellspacing="0"><tbody><tr valign="top"><td style="width: 40px;min-width: 40px; padding-top:10px"><div style="width: 38px; height: 38px; border: 1px #FFF solid; border-radius:50%; margin: 0;vertical-align: top;box-shadow: 0 0 10px 0 rgba(127,152,178,0.14);"><img src="http://thirdqq.qlogo.cn/g?b=sdk&k=sDkxrKtOBYniaVteAHHIz5g&s=100&t=1647684318?rand=1648799506" style="width:100%;height:100%;border-radius:50%;pointer-events: none;"></div></td><td style="padding: 10px 0 8px 10px;"><div class="businessCard_name" style="font-size: 14px;color: #33312E;line-height: 20px; padding-bottom: 2px; margin:0;font-weight: 500;">1807580692</div><div class="businessCard_mail" style="font-size: 12px;color: #999896;line-height: 18px; margin:0;">1807580692@qq.com</div></td></tr></tbody></table></a></div></div><div> </div></div></blockquote></div><br></div></body></html>