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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif"'>Thanks
Barry and Jed. TSSetIFunction and TSSetIJacobian from petsc-dev<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif"'>are
working perfectly.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif"'>Chetan<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
petsc-users-bounces@mcs.anl.gov [mailto:petsc-users-bounces@mcs.anl.gov] <b>On
Behalf Of </b>Jed Brown<br>
<b>Sent:</b> Thursday, November 18, 2010 3:49 PM<br>
<b>To:</b> PETSc users list<br>
<b>Subject:</b> Re: [petsc-users] TS with inhomogeneous rhs<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>On Thu, Nov 18, 2010 at 23:14, Chetan Jhurani <<a
href="mailto:chetan.jhurani@gmail.com">chetan.jhurani@gmail.com</a>> wrote:<o:p></o:p></p>
<div id=":1o3">
<p class=MsoNormal> M U_t = -K U + f(t)<br>
<br>
In addition, how can the code be kept nearly identical to allow different<br>
TS types to be used (EULER, BEULER, TSRUNGE_KUTTA, TSCRANK_NICHOLSON,<br>
etc)? I'd also like to take possible advantages of M and K being<br>
constants.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>As Barry says, we are transitioning to a better API for
this. You can use TSTHETA (theta=0.5 is Crank-Nicolson, theta=1 is
Backward Euler) with TSSetIFunction and TSSetIJacobian (see the man pages or
read section 6.1.2 of the users manual). Note that an
"explicit" method for your problem above needs to solve with the mass
matrix at every time step. Unless it is very cheap (e.g. block diagonal),
then it may not be worth it. PETSc's explicit methods do not currently
support this, but support for that will be added in the next few months.
At present, you would need to do the solve in your RHSFunction.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Jed<o:p></o:p></p>
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