<div dir="ltr"><div><br></div>Do you have an example to reproduce it?<div><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">--Junchao Zhang</div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jan 23, 2024 at 10:49 AM <<a href="mailto:michael@paraffinalia.co.uk">michael@paraffinalia.co.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hello,<br>
<br>
I have used the GMRES solver in PETSc successfully up to now, but on <br>
installing the most recent release, 3.20.3, the solver fails by exiting <br>
early. Output from the code is:<br>
<br>
lt-nbi-solve-laplace: starting PETSc solver [23.0537]<br>
0 KSP Residual norm < 1.e-11<br>
Linear solve converged due to CONVERGED_ATOL iterations 0<br>
lt-nbi-solve-laplace: 0 iterations [23.0542] (22.9678)<br>
<br>
and tracing execution shows the norm returned by VecNorm to be 0.<br>
<br>
If I modify the function by commenting out line 217 of<br>
<br>
src/vec/vec/interface/rvector.c<br>
<br>
/* if (flg) PetscFunctionReturn(PETSC_SUCCESS); */<br>
<br>
the code executes correctly:<br>
<br>
lt-nbi-solve-laplace: starting PETSc solver [22.9392]<br>
0 KSP Residual norm 1.10836<br>
1 KSP Residual norm 0.0778301<br>
2 KSP Residual norm 0.0125121<br>
3 KSP Residual norm 0.00165836<br>
4 KSP Residual norm 0.000164066<br>
5 KSP Residual norm 2.12824e-05<br>
6 KSP Residual norm 4.50696e-06<br>
7 KSP Residual norm 5.85082e-07<br>
Linear solve converged due to CONVERGED_RTOL iterations 7<br>
<br>
My compile options are:<br>
<br>
PETSC_ARCH=linux-gnu-real ./configure --with-mpi=0 <br>
--with-scalar-type=real --with-threadsafety --with-debugging=0 <br>
--with-log=0 --with-openmp<br>
<br>
uname -a returns:<br>
<br>
5.15.80 #1 SMP PREEMPT Sun Nov 27 13:28:05 CST 2022 x86_64 Intel(R) <br>
Core(TM) i5-6200U CPU @ 2.30GHz GenuineIntel GNU/Linux<br>
<br>
</blockquote></div>