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<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">Hi all,</FONT></SPAN>
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<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">We have been using Ipopt with good success to optimize various black-box process models, so thanks to all who have contributed to the project. However…</FONT></SPAN></P>
<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">Recently I have been running into an increasing number of crashes in IpoptCalculatedQuantities::curr_d_minus_s() on a null s pointer. When I bump up COIN_IPOPT_CHECKLEVEL to 3, I observe SmartPtr assertions starting in IpoptCalculatedQuantities::trial_slack_x_L() because ip_data_->trial()->x() is null. This occurs in AcceptTrialPoint on the max_correction = correct_bound_multiplier(…) line with the following call stack:</FONT></SPAN></P>
<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial"> ipopt.dll!_wassert(const wchar_t * expr=0x0f594ea4, const wchar_t * filename=0x0f594e40, unsigned int lineno=433) Line 384 C</FONT></SPAN></P>
<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial"> ipopt.dll!Ipopt::SmartPtr<Ipopt::Vector const >::operator*() Line 433 + 0x1c bytes C++</FONT></SPAN>
<BR><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial"> ipopt.dll!Ipopt::IpoptCalculatedQuantities::trial_slack_x_L() Line 357 + 0x8 bytes C++</FONT></SPAN>
<BR><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial"> ipopt.dll!Ipopt::IpoptCalculatedQuantities::trial_compl_x_L() Line 1823 + 0xc bytes C++</FONT></SPAN>
<BR><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">> ipopt.dll!Ipopt::IpoptAlgorithm::AcceptTrialPoint() Line 658 + 0x1d bytes C++</FONT></SPAN>
<BR><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial"> ipopt.dll!Ipopt::IpoptAlgorithm::Optimize(bool isResto=false) Line 367 C++</FONT></SPAN>
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<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">Being new to the internals of Ipopt, under what conditions will the trial x vector be null? Is there anything specific I should look for in the diagnostics that might help me identify the root cause? Any guidance would be greatly appreciated!</FONT></SPAN></P>
<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">The case in which I am currently observing this behaviour is tiny (one variable, one inequality), but I have seen it in larger ones as well. I can reproduce in both Ipopt 3.6.0 and 3.8.1.</FONT></SPAN></P>
<P><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">Thanks in advance,</FONT></SPAN>
<BR><SPAN LANG="en-ca"><FONT SIZE=2 FACE="Arial">Kelly</FONT></SPAN><SPAN LANG="en-us"></SPAN>
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