<div class="gmail_quote">On Fri, Nov 11, 2011 at 05:31, Bao Kai <span dir="ltr"><<a href="mailto:paeanball@gmail.com">paeanball@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div dir="ltr">The following is the result with the options you told
me. The iteration has converged, while converged at a wrong solution,
compared to the result from LU. <br><br>tutorials]$ time ./ex78 -Ain
A_phi -rhs rhs_phi -solu solu_phi -noshift -pc_type hypre
-pc_hypre_type parasails -ksp_gmres_restart 600 -ksp_rtol 1e-7 -ksp_typ
gmres -ksp_monitor_true_residual -ksp_converged_reason<div><br>
<br> Read matrix in ascii format ...<br>m: 288399, n: 288399, nz: 4023176 <br> read A completed <br> rowNumber[0] = 13 <br> rowNumber[1] = 13 <br> rowNumber[2] = 19 <br> read A is complete ! <br><br> Read rhs in ascii format ...<br>
<br> Read exact solution in ascii format ...<br></div> 0 KSP preconditioned resid norm 1.311815748108e+00 true resid norm 3.838432566849e-03 ||r(i)||/||b|| 1.000000000000e+00<br> 1 KSP preconditioned resid norm 5.507600629359e-01 true resid norm 1.878066463331e-03 ||r(i)||/||b|| 4.892795250727e-01<br>
[...]<br>
54 KSP preconditioned resid norm 1.106994152625e-07 true resid norm 2.679208019541e-03 ||r(i)||/||b|| 6.979953334807e-01<br>Linear solve converged due to CONVERGED_RTOL iterations 54</div></blockquote></div><br><div>Look, the true residual increased. This usually means that the preconditioner is singular or nearly so. This is not a surprised, sparse approximate inverse rarely works in my experience.</div>