<div dir="ltr"><div><div><div>Hi Xue,<br><br></div>Extracting the symbolic Hessian
directly from AMPL may not be possible due to the fact that it is
computed only when needed using automatic differentiation included in
the AMPL library. However, you may be able to extract the Hessian at a
given point using the example 'solver' gjh freely available from the
Netlib library at <a href="http://www.netlib.org/ampl/solvers/examples/README.gjh" target="_blank">http://www.netlib.org/ampl/solvers/examples/README.gjh</a>.<br>
<br></div><div>For more info you may want to check out (both by DM Gay)<br><br>Automatic differentiation of nonlinear AMPL models:<br><a href="http://www.cs.bell-labs.com/cm/cs/what/ampl/REFS/autodiff.pdf" target="_blank">http://www.cs.bell-labs.com/cm/cs/what/ampl/REFS/autodiff.pdf</a><br>
<br>Writing NL files<br><a href="http://www.cs.sandia.gov/%7Edmgay/nlwrite.pdf" target="_blank">http://www.cs.sandia.gov/~dmgay/nlwrite.pdf</a><br></div><div><br></div>I hope this helps,<br></div> Rodrigo<div class=""><div id=":1p9" class="" tabindex="0">
<img class="" src="images/cleardot.gif"></div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jan 6, 2014 at 2:28 PM, <span dir="ltr"><<a href="mailto:xuey@andrew.cmu.edu" target="_blank">xuey@andrew.cmu.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi all,<br>
<br>
Could anyone tell me how to get the symbolic Hessian of a problem? I'm<br>
calling IPOPT from AMPL. Thanks!<br>
<br>
Best regards,<br>
<br>
Xue Yang<br>
<br>
Department of Chemical Engineering<br>
Carnegie Mellon University<br>
Pittsburgh, PA 15213<br>
<br>
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</blockquote></div><br><br clear="all"><br>-- <br><span style="font-family:Arial,Helvetica,sans-serif;font-size:14.1667px;border-collapse:collapse;color:rgb(51,51,51)"><strong><span><font color="#000000"><span style="background-color:rgb(255,255,255)">Rodrigo</span></font></span><font color="#000000"><span style="background-color:rgb(255,255,255)"> López-</span></font><span><font color="#000000"><span style="background-color:rgb(255,255,255)">Negrete</span></font></span><font color="#000000"><span style="background-color:rgb(255,255,255)"> de la Fuente</span></font></strong><br>
Email: <a href="mailto:r.lopez.negrete@gmai.com" target="_blank">r.lopez.negrete@gmail.com</a><div><span style="color:rgb(34,34,34)"><span style="background-color:rgb(255,255,255)">WWW</span></span><span style="background-color:rgb(255,255,255)">: <a href="http://rodrigo.lopez-negrete.org" target="_blank">http://rodrigo.lopez-negrete.org</a></span><br>
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