[petsc-users] about pclu

[Barry Smith]

On Apr 5, 2011, at 9:52 PM, Ryan Yan wrote:

> Hi, 
> I am wondering is there a way of checking the residual of a direct solver. It should 
> be one shot and very small.  I tried -ksp_monitor_true_residual, but no thing shows up. I guess a piece of code 
> $Ax-b$ will do the trick?

   The reason that the monitor doesn't display anything is not the direct solver but because you are using LU with KSPType of KSPPREONLY  if you run with -ksp_type richardson or -ksp_type gmres then -ksp_monitor_true_residual will print the residual as you want.

   Barry

> 
> Thanks,
> 
> Yan