<div dir="ltr"><br><br><div class="gmail_quote">On Thu, Mar 24, 2011 at 08:25, Kontsantinos Kontzialis <span dir="ltr"><<a href="mailto:ckontzialis@lycos.com">ckontzialis@lycos.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Dear all,<br>
<br>
I'm using the following function:<br>
<br>
ierr = MatMFFDGetH(sys.J, &h);<br>
CHKERRQ(ierr);<br>
<br>
to get the parameter h in the formula for the jacobian-vector product, but it returns a value of 0. But how can that be, otherwise a division by zero would result.<br></blockquote><div><br></div><div>"Gets the last value that was used as the differencing parameter."</div>
<div><br></div><div><a href="http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatMFFDGetH.html">http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatMFFDGetH.html</a></div>
<div><br></div><div>Sounds like you haven't done a multiply yet.</div></div></div>