
<html><body><div style="font-family: times new roman, new york, times, serif; font-size: 12pt; color: #000000"><div>When using <a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCShellSetApply.html," target="_blank">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCShellSetApply.html,</a> do I have the guaranty that xout from "<a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscErrorCode.html#PetscErrorCode" target="_blank">PetscErrorCode</a> apply (<a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PC.html#PC" target="_blank">PC</a> pc,<a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/Vec.html#Vec" target="_blank">Vec</a> xin,<a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/Vec.html#Vec" target="_blank">Vec</a> xout)" has always been previously filled with zeros ?<br></div><div>I may have to fill xout by blocks (I would += several possibly overlapping blocks: I need to make sure xout is first filled with zero to get the correct result).<br></div><div><br></div><div>Franck<br></div></div></body></html>