Hi Jed, I have attached the output runing under linux. It's only running with 1 processor. I am using runge kutta 3rd order to solve my problem, so there's 3 substeps per time step ie I need to solve the x/y momentum eqns 3 times per time step.
The error occurs at t=2, substep=2. It stated in the output. Btw, I am solving the x and y momentum eqns separately, since they are independent of one another. How can I solve it together? My code is: call MatSetValues(A_semi_x,1,II,1,JJ,semi_mat_x(k,kk),INSERT_VALUES,ierr) ... call MatAssemblyBegin(A_semi_x,MAT_FINAL_ASSEMBLY,ierr) call MatAssemblyEnd(A_semi_x,MAT_FINAL_ASSEMBLY,ierr) call KSPGetPC(ksp_semi_x,pc_semi_x,ierr) ksptype=KSPBCGS call KSPSetType(ksp_semi_x,ksptype,ierr) call KSPSetFromOptions(ksp_semi_x,ierr) tol=1.e-5 call KSPSetTolerances(ksp_semi_x,tol,PETSC_DEFAULT_DOUBLE_PRECISION,PETSC_DEFAULT_DOUBLE_PRECISION,PETSC_DEFAULT_INTEGER,ierr) exactly the same for y... call VecAssemblyBegin(b_rhs_semi_x,ierr) call VecAssemblyEnd(b_rhs_semi_x,ierr) call VecAssemblyBegin(xx_semi_x,ierr) call VecAssemblyEnd(xx_semi_x,ierr) call KSPSetOperators(ksp_semi_x,A_semi_x,A_semi_x,SAME_NONZERO_PATTERN,ierr) call KSPSolve(ksp_semi_x,b_rhs_semi_x,xx_semi_x,ierr) call KSPGetConvergedReason(ksp_semi_x,reason,ierr) exactly the same for y... Thanks alot! Yours sincerely, TAY wee-beng On 9/7/2011 12:26 AM, Jed Brown wrote: > On Fri, Jul 8, 2011 at 17:17, TAY wee-beng <zonexo at gmail.com > <mailto:zonexo at gmail.com>> wrote: > > Hi Jed, > > This is my output when the error happens for gmres: > > 2 KSP preconditioned resid norm 1.556688898463e+007 true resid > norm 2.58995443 > 8801e+003 ||Ae||/||Ax|| 1.232088736212e+003 > 2 KSP preconditioned resid norm 1.556688898463e+007 true resid > norm 2.58995443 > 8801e+003 ||Ae||/||Ax|| 1.232088736212e+003 > 3 KSP preconditioned resid norm 1.207952812560e+003 true resid > norm 9.05939430 > 1179e+003 ||Ae||/||Ax|| 4.309719703237e+003 > 3 KSP preconditioned resid norm 1.207952812560e+003 true resid > norm 9.05939430 > 1179e+003 ||Ae||/||Ax|| 4.309719703237e+003 3 KSP preconditioned > resid norm 1.207952812560e+003 true resid norm 9.05939430 > 1179e+003 ||Ae||/||Ax|| 4.309719703237e+003 > 3 KSP preconditioned resid norm 1.207952812560e+003 true resid > norm 9.05939430 > 1179e+003 ||Ae||/||Ax|| 4.309719703237e+003 > 3 KSP preconditioned resid norm 1.207952812560e+003 true resid > norm 9.05939430 > 1179e+003 ||Ae||/||Ax|| 4.309719703237e+003 > 4 KSP preconditioned resid norm 3.815055004710e+001 true resid > norm 1.96385966 > 1729e+002 ||Ae||/||Ax|| 9.342439899591e+001 > 4 KSP preconditioned resid norm 3.815055004710e+001 true resid > norm 1.96385966 > 1729e+002 ||Ae||/||Ax|| 9.342439899591e+001 > 4 KSP preconditioned resid norm 3.815055004710e+001 true resid > norm 1.96385966 > 1729e+002 ||Ae||/||Ax|| 9.342439899591e+001 > 4 KSP preconditioned resid norm 3.815055004710e+001 true resid > norm 1.96385966 > 1729e+002 ||Ae||/||Ax|| 9.342439899591e+001 > 4 KSP preconditioned resid norm 3.815055004710e+001 true resid > norm 1.96385966 > 1729e+002 ||Ae||/||Ax|| 9.342439899591e+001 > > > Why is the same line output multiple times? Do you have an MPI problem? > > This convergence looks funky; I suspect your preconditioner is > singular and/or nonlinear. Please send -ksp_view output as you are > running here and with -pc_type asm -sub_pc_type lu. > > > for fgmres: > > 34 KSP preconditioned resid norm 2.428114102327e-005 true resid > norm 3.35941610 > 6265e-005 ||Ae||/||Ax|| 1.598129588716e-005 > 34 KSP preconditioned resid norm 2.428114102327e-005 true resid > norm 3.35941610 > 6265e-005 ||Ae||/||Ax|| 1.598129588716e-005 > 35 KSP preconditioned resid norm 2.200715659545e-005 true resid > norm 3.88294769 > 5703e-005 ||Ae||/||Ax|| 1.847182191086e-005 > 35 KSP preconditioned resid norm 2.200715659545e-005 true resid > norm 3.88294769 > 5703e-005 ||Ae||/||Ax|| 1.847182191086e-005 > 35 KSP preconditioned resid norm 2.200715659545e-005 true resid > norm 3.88294769 > 5703e-005 ||Ae||/||Ax|| 1.847182191086e-005 > 35 KSP preconditioned resid norm 2.200715659545e-005 true resid > norm 3.88294769 > 5703e-005 ||Ae||/||Ax|| 1.847182191086e-005 > 35 KSP preconditioned resid norm 2.200715659545e-005 true resid > norm 3.88294769 > 5703e-005 ||Ae||/||Ax|| 1.847182191086e-005 > 36 KSP preconditioned resid norm 2.011575409369e-005 true resid > norm 3.89282805 > 6204e-005 ||Ae||/||Ax|| 1.851882441357e-005 > 36 KSP preconditioned resid norm 2.011575409369e-005 true resid > norm 3.89282805 > 6204e-005 ||Ae||/||Ax|| 1.851882441357e-005 > 36 KSP preconditioned resid norm 2.011575409369e-005 true resid > norm 3.89282805 > 6204e-005 ||Ae||/||Ax|| 1.851882441357e-005 > 36 KSP preconditioned resid norm 2.011575409369e-005 true resid > norm 3.89282805 > 6204e-005 ||Ae||/||Ax|| 1.851882441357e-005 > 36 KSP preconditioned resid norm 2.011575409369e-005 true resid > norm 3.89282805 > 6204e-005 ||Ae||/||Ax|| 1.851882441357e-005 > > Btw, I am solving the x and y momentum eqns so there 's 2 eqns to > solve. > > > Do you solve them separately or both at once? 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