On Wed, Sep 26, 2012 at 7:33 PM, Jinquan Zhong <span dir="ltr"><<a href="mailto:jzhong@scsolutions.com" target="_blank">jzhong@scsolutions.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">        PetscErrorCode  KSPSetInitialGuessNonzero(KSP ksp,PetscBool  flg)<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">               
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">does not provide the option to input x0 though.</span></p></blockquote></div><br><div>It causes the vector X that you pass to KSPSolve to be used as the initial guess. Did you read the man page?</div>
<div><br></div><div><a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetInitialGuessNonzero.html">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetInitialGuessNonzero.html</a></div>