ell1 norm convergence test
Ryan Yan
vyan2000 at gmail.com
Mon Sep 21 12:44:12 CDT 2009
Hi All,
The following question is only for test and comparison reason.
Is there a command line option to set up using 1-Norm(sum of absolute value
of residuals) as convergence monitor and test.
Alternatively, if I can get the residual "r" out at the end of each
iteration, then it is going to be much simpler, since I can just call
VecNorm(r, NORM_1, &r_ell1) and pass the r_ell1 into the convergence monitor
and test. Can anyone inform me if PETSc has an interface for the resuidual
r?
Or one has to call the convergence test:
MyKSPConverged(ksp,n,rnorm,flag,dummy);
and following the steps:
1. fetch the exact solution:
KSPBuildSolution(ksp,PETSC_NULL_OBJECT,x,ierr)
2. calculate the residual:
pass the Right Hand side and the Matrix in to calculate the 1-Norm. But this
step is *not* obvious, since the matrix and rhs is already distributed over
each processes.
3. set up the convergence test based on the 1_Norm residual.
Thank you very much,
Yan
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