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<FONT face="Times New Roman">Dear,<BR><FONT size=2>I have had problem when I used this IPOPT option:</FONT></FONT> <BR>
<DIV align=center><FONT size=2 face=serif><B>ma57_pivot_order </B></FONT></DIV>
<FONT size=2 face=serif></FONT> <BR>
<FONT size=2 face=serif>I am solving an entire natural gas plant in AMPL and I am very interested in reducing the computational times. In the ipopt option line I introduced it in this way:</FONT> <BR>
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<DIV align=center><FONT size=2 face=serif><B>option ipopt_options " linear_solver ma57 ma57_pivot_order 4 ";</B></FONT></DIV>
<DIV align=center><FONT size=2 face=serif><B>option solver ipopt ;</B></FONT></DIV>
<FONT size=2 face=serif></FONT> <BR>
<FONT size=2 face=serif>When I run the problem, AMPL send me: </FONT><FONT size=2 face=serif><I>Unknown Keyword “ma57_pivot_order”</I></FONT><BR><FONT size=2 face=serif>Do you know what would the problem be? I should mention that I have the ipopt3.8 version.</FONT><BR><FONT size=2 face=serif></FONT><BR><FONT size=2 face=serif>Thank you very much in advance.</FONT><BR><FONT size=2 face=serif>Juan</FONT><BR><BR> </body>
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