Thanks Jed, sorry I new using Petsc. I am runing my program with default options : mpirun -np 1 ./a.out runing the program with a few points (10) the interpolation is aceptable,
using the monitor options ie. mpirun -np 1 ./a.out -ksp_converged_reason -ksp_monitor_true_residual the output is the next 0 KSP preconditioned resid norm 7.415666989515e+05 true resid norm 1.510533668194e+04 ||r(i)||/||b|| 1.000000000000e+00 1 KSP preconditioned resid norm 4.935801698308e+02 true resid norm 1.721762948997e+01 ||r(i)||/||b|| 1.139837519183e-03 2 KSP preconditioned resid norm 1.038493428107e-01 true resid norm 9.406615966569e+00 ||r(i)||/||b|| 6.227346112594e-04 Linear solve converged due to CONVERGED_RTOL iterations 2 But if encrease the number of points to interpolate, the result is incorrect and the time of convergece encrease, the output in this case is: ..... 138 KSP preconditioned resid norm 4.897817095518e-06 true resid norm 5.455886375264e-08 ||r(i)||/||b|| 4.852601039969e-10 139 KSP preconditioned resid norm 3.535973415166e-06 true resid norm 3.717900878947e-08 ||r(i)||/||b|| 3.306793512687e-10 140 KSP preconditioned resid norm 2.450794339359e-06 true resid norm 3.009597005096e-08 ||r(i)||/||b|| 2.676810430480e-10 Linear solve converged due to CONVERGED_RTOL iterations 140 [0] time (sec) 89.940000 the code where the solution is implemented is the next: KSP ksp; KSPCreate(PETSC_COMM_WORLD,&ksp); KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN); KSPSetTolerances(ksp,1.e-5/(N+nt+1),1.e-50,PETSC_DEFAULT,PETSC_DEFAULT); KSPSetFromOptions(ksp); KSPSolve(ksp,b,x); Let me know if you need another information. Regard Alex 2013/1/31 Jed Brown <jedbrown at mcs.anl.gov> > "result is incorrect" is not helpful. Please include diagnostics. Are you > using an iterative or direct solver? Start here if you don't know what to > check: > > > http://scicomp.stackexchange.com/questions/513/why-is-my-iterative-linear-solver-not-converging > > > > On Thu, Jan 31, 2013 at 9:58 AM, Alex Salazar <alejandrocof at > gmail.com>wrote: > >> Hello, everyone >> >> I want to get the solution of algrebraic system (with a dense >> zero-diagonal simetric matrix) of a interpolation problem (using radial >> basis functions) with Petsc. >> >> For a few points (around 10 elements) using KSP I get the correct >> solution, however when I increase the number of points, the result is >> incorrect. >> >> Any Idea ? >> >> Regards Alejandro. >> >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130131/6f82da9e/attachment.html>
