<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><font face="tahoma, sans-serif">Dear Petsc developer: </font></div><div dir="ltr"><font face="tahoma, sans-serif">Hi, </font></div><div dir="ltr"><font face="tahoma, sans-serif"><br></font></div><div dir="ltr"><span style="font-family:arial,helvetica,sans-serif;text-align:justify">Thank you very much for your previous reply</span> .<font face="tahoma, sans-serif"><br></font></div><div dir="ltr"><p style="margin:0px;white-space:pre-wrap">I recently wrote an example of neutron diffusion, which shows that the nonlinear residuals are gradually decreasing, but the program terminates in the tenth step of the nonlinear step.The program output information is as follows.<br></p><p style="margin:0px;white-space:pre-wrap"><br></p></div></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div dir="ltr"><div dir="ltr"><p style="margin:0px"><span style="white-space:pre-wrap">-snes_fd -pc_type lu -snes_view -snes_converged_reason -snes_monitor_cancel -ksp_converged_reason -ksp_monitor_true_residual</span></p></div></div></blockquote><div dir="ltr"><div dir="ltr"><p style="margin:0px;white-space:pre-wrap"><br></p></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><p style="margin:0px"><span style="white-space:pre-wrap">iter = 0, SNES Function norm 0.999045
0 KSP preconditioned resid norm 1.143042621777e+02 true resid norm 9.990445435144e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 2.250033129078e-12 true resid norm 3.772661181818e-14 ||r(i)||/||b|| 3.776269242757e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 1, SNES Function norm 0.863398
0 KSP preconditioned resid norm 3.176569252473e+00 true resid norm 8.633978674995e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 7.360979829512e-14 true resid norm 1.835881897914e-14 ||r(i)||/||b|| 2.126345184557e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 2, SNES Function norm 0.217885
0 KSP preconditioned resid norm 5.796196387015e+01 true resid norm 2.178851605144e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 9.643306967470e-13 true resid norm 3.884638811957e-14 ||r(i)||/||b|| 1.782883608405e-13
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 3, SNES Function norm 0.217871
0 KSP preconditioned resid norm 3.792350832110e+01 true resid norm 2.178711262680e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 1.369102629758e-12 true resid norm 1.632695466260e-13 ||r(i)||/||b|| 7.493858843196e-13
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 4, SNES Function norm 0.217839
0 KSP preconditioned resid norm 2.467674567895e+01 true resid norm 2.178387732479e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 1.336018611676e-12 true resid norm 2.369440379931e-14 ||r(i)||/||b|| 1.087703692324e-13
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 5, SNES Function norm 0.217793
0 KSP preconditioned resid norm 1.325333377704e+01 true resid norm 2.177933144217e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 2.663121116220e-13 true resid norm 6.399802508715e-15 ||r(i)||/||b|| 2.938475189519e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 6, SNES Function norm 0.217546
0 KSP preconditioned resid norm 8.654271429945e+00 true resid norm 2.175456199462e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 2.103027422078e-12 true resid norm 1.896269373207e-14 ||r(i)||/||b|| 8.716651586351e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 7, SNES Function norm 0.217024
0 KSP preconditioned resid norm 5.238463146996e+00 true resid norm 2.170240974179e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 1.538914082201e-13 true resid norm 1.398699322805e-14 ||r(i)||/||b|| 6.444903305426e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 8, SNES Function norm 0.215661
0 KSP preconditioned resid norm 3.380654310210e+00 true resid norm 2.156611254980e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 5.676163043758e-14 true resid norm 2.209776803347e-15 ||r(i)||/||b|| 1.024652355979e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 9, SNES Function norm 0.213573
0 KSP preconditioned resid norm 1.833370627403e+00 true resid norm 2.135728351107e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 1.237094085371e-13 true resid norm 3.167085089319e-15 ||r(i)||/||b|| 1.482906329205e-14
Linear solve converged due to CONVERGED_RTOL iterations 1
iter = 10, SNES Function norm 0.206951
0 KSP preconditioned resid norm 1.011617991320e+00 true resid norm 2.069514796799e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP preconditioned resid norm 3.789650938118e-13 true resid norm 5.695302032970e-14 ||r(i)||/||b|| 2.751998701231e-13
Linear solve converged due to CONVERGED_RTOL iterations 1
Nonlinear solve did not converge due to DIVERGED_FUNCTION_COUNT iterations 10
SNES Object: 1 MPI processes
type: newtonls
maximum iterations=50, maximum function evaluations=10000
tolerances: relative=1e-08, absolute=1e-50, solution=1e-08
total number of linear solver iterations=11
total number of function evaluations=10623
norm schedule ALWAYS
Jacobian is built using finite differences one column at a time
SNESLineSearch Object: 1 MPI processes
type: bt
interpolation: cubic
alpha=1.000000e-04
maxstep=1.000000e+08, minlambda=1.000000e-12
tolerances: relative=1.000000e-08, absolute=1.000000e-15, lambda=1.000000e-08
maximum iterations=40
KSP Object: 1 MPI processes
type: gmres
restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement
happy breakdown tolerance 1e-30
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using PRECONDITIONED norm type for convergence test
PC Object: 1 MPI processes
type: lu
out-of-place factorization
tolerance for zero pivot 2.22045e-14
matrix ordering: nd
factor fill ratio given 5., needed 5.81047
Factored matrix follows:
Mat Object: 1 MPI processes
type: seqaij
rows=961, cols=961
package used to perform factorization: petsc
total: nonzeros=38169, allocated nonzeros=38169
total number of mallocs used during MatSetValues calls =0
not using I-node routines
linear system matrix = precond matrix:
Mat Object: 1 MPI processes
type: seqaij
rows=961, cols=961
total: nonzeros=6569, allocated nonzeros=15485
total number of mallocs used during MatSetValues calls =712
not using I-node routines
</span></p><p style="margin:0px"><span style="white-space:pre-wrap"><br></span></p><p style="margin:0px"><span style="white-space:pre-wrap"><br></span></p></div></blockquote><span style="white-space:pre-wrap">I don't know why the program was terminated. I really need your help.</span></div><div dir="ltr"><span style="white-space:pre-wrap"><br></span></div><div dir="ltr"><span style="white-space:pre-wrap">Thanks,</span></div><div dir="ltr"><span style="white-space:pre-wrap">Yingjie<br></span><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div dir="ltr"><p style="margin:0px"><span style="white-space:pre-wrap"><br></span></p></div></blockquote><span style="white-space:pre-wrap"><br></span><br></div></div></div>