[Coin-ipopt] How is TRON used in IPOPT?

Andreas Waechter andreasw at watson.ibm.com
Fri May 20 19:36:18 EDT 2005

Hi Don,

Thanks for your interest.

> I have installed IPOPT and it is working nicely for me.  But I have a
> question about TRON.  This was included in the "OTHERS" directory as if
> it were needed software for the installation.  However, the file
> README.Windows, which describes how to build IPOPT using Compaq Visual
> Fortran, does not list any of the TRON files as needed for the
> installation.  And indeed I have build a running version without TRON.
> I am wondering if there is some kind of option to use TRON and, if this
> is true, whether this makes things work better.

TRON is most probably not necessary for your needs.  As you will have
noticed, the QUICKINSTALL instructions do not include it.

It is required for the restoration phase in case you choose the reduced
space option with filter line search.  The interface to TRON is in there
for historical reasons, but in the meantime we have implemented a
different restoration phase, which does not require TRON and usually does
a better job in our context.  If you want to force Ipopt to use TRON, you
can set the option IRESTO to 2 - this of course assumes that you built
Ipopt with TRON.  For some info see Section 2.2.3 in



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