= Welcome to the Ipopt home page =
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== Introduction ==
Ipopt ('''I'''nterior '''P'''oint '''OPT'''imizer, pronounced I-P-Opt) is a software package for large-scale [http://www-unix.mcs.anl.gov/otc/Guide/faq/nonlinear-programming-faq.html nonlinear optimization]. It is designed to find (local) solutions of mathematical optimization problems of the from
{{{
min f(x)
x in R^n
s.t. g_L <= g(x) <= g_U
x_L <= x <= x_U
}}}
where
{{{ f(x): R^n --> R }}}
is the objective function, and
{{{ g(x): R^n --> R^m }}}
are the constraint functions. The vectors {{{ g_L }}} and {{{ g_U }}} denote the lower and upper bounds on the constraints, and the vectors {{{x_L}}} and {{{x_U}}} are the bounds on the variables {{{x}}}. The functions {{{f(x)}}} and {{{g(x)}}} can be nonlinear and nonconvex, but should be twice continuously differentiable. Note that equality constraints can be formulated in the above formulation by setting the corresponding components of {{{g_L}}} and {{{g_U}}} to the same value.
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== Background/Download ==
Ipopt is written in C++ and is released as open source code under the [http://www.opensource.org/licenses/cpl.php Common Public License (CPL)]. It is available from the [http://www.coin-or.org/ COIN-OR initiative]. The code has been written by [http://www.andrew.cmu.edu/user/claird/ Carl Laird] (Carnegie Mellon University) and [http://www.research.ibm.com/people/a/andreasw/ Andreas Wächter], who is the COIN project leader for Ipopt.
You can obtain the Ipopt code either via subversion or in form of nightly generated tarballs. If you want to use subversion (recommended, because it makes it easier for you to obtain updates), please refer to the [http://www.coin-or.org/Ipopt/documentation/ documentation] and the [https://projects.coin-or.org/CoinHelp/ General Configuration and Installation Instructions for COIN projects]. To get the tarball, go to the COIN [http://www.coin-or.org/Tarballs/Ipopt Ipopt tarball directory], and look for a file like Ipopt_''x.y.z''.tgz, where ''x.y.z'' is the version number.
The '''latest release is''': [[Image(https://projects.coin-or.org/Ipopt/chrome/site/Ipopt-latest.png)]]
'''Please make sure you read the [https://projects.coin-or.org/CoinHelp/wiki/current-issues current issues page] before you try to install Ipopt.'''
Individual files can also be obtained from the svn web interface (see the "Browse Source" button above). The Ipopt distribution can be used to generate a library that can be linked to one's own C++, C, or Fortran code, as well as a solver executable for the [http://www.ampl.com AMPL] modeling environment. The package includes interfaces to [http://cuter.rl.ac.uk/cuter-www/ CUTEr] optimization testing environment, and the [http://www.mathworks.com/products/matlab MATLAB] programming environment. IPOPT can be used on Linux/UNIX, Mac OS X and Windows platforms.
As open source software, the source code for Ipopt is provided without charge. You are free to use it, also for commercial purposes. You are also free to modify the source code (with the restriction that you need to make your changes public if you decide to distribute your version in any way, e.g. as an executable); for details see the CPL license. And we are certainly very keen on feedback from users, including contributions!
In order to compile Ipopt, certain third party code is required (such as some linear algebra routines, or the AMPL Solver Library). Those are available under different conditions/licenses.
We provide this program in the hope that it may be useful to others, and we would very much like to hear about your experience with it. If you found it helpful and are using it within our software, we encourage you to add your feedback to these wiki-based webpages, [wiki:SuccessStories Success Stories].
Since a lot of time and effort has gone into Ipopt's development, '''please cite the following publication if you are using Ipopt for your own research''':
A. Wächter and L. T. Biegler, '''On the Implementation of a Primal-Dual Interior Point Filter Line Search Algorithm for Large-Scale Nonlinear Programming''', ''Mathematical Programming'' 106(1), pp. 25-57, 2006
If you want to learn more about Ipopt, you can find references in the "Papers about Ipopt" section [wiki:IpoptPapers here].
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== Documentation ==
This is a new version of code that has been previously released as Fortran code (see
[http://www.coin-or.org/Ipopt/ipopt-fortran.html Home Page for pre-3.0 version of Ipopt (Fortran Version)]). The new C++ version has first been released on Aug 26, 2005 as version 3.0.0.
Online documentation, including '''instructions for downloading and installing Ipopt''', is available at [http://www.coin-or.org/Ipopt/documentation/ http://www.coin-or.org/Ipopt/documentation/]. A PDF version of this documentation can be downloaded [https://projects.coin-or.org/Ipopt/browser/stable/3.2/Ipopt/doc/documentation.pdf?format=raw here].
It might also be helpful to consult the [https://projects.coin-or.org/CoinHelp/ General Configuration and Installation Instructions for COIN projects]. Instructions specific to the MATLAB interface can be found at the [wiki:MatlabInterface Matlab interface] webpage.
We have also a [http://list.coin-or.org/mailman/listinfo/coin-ipopt mailing list] where you can subscribe to get notifications about updates and to post questions and comments regarding Ipopt. If you believe you found a '''bug''' in the code, please use the bug report system (see the [http://projects.coin-or.org/Ipopt/report "View Tickets"] and [http://projects.coin-or.org/Ipopt/newticket "New Ticket"] tabs on put of this page); please include as much information as possible, and if possible some (ideally simple) example code so that we can reproduce the error. Note that you will have to log in first, as described [wiki:EditingWikiPages here].
Make sure you visit the [wiki:FAQ FAQ (Frequently Asked Questions)] if you want to know more.
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== Project Links ==
[http://www.coin-or.org/ COIN-OR Initiative]
[wiki:FAQ FAQ (Frequently Asked Questions)]
[http://www.coin-or.org/Ipopt/documentation/ Online Ipopt documentation]
[http://www.coin-or.org/Ipopt/documentation/node9.html (with installation instructions)]
[https://projects.coin-or.org/CoinHelp/ General configuration and installation instructions for COIN projects]
[https://projects.coin-or.org/CoinHelp/wiki/current-issues Current configuration and installation issues page for COIN projects]
[http://www.coin-or.org/Tarballs/Ipopt/ Ipopt tarball download directory]
[http://list.coin-or.org/mailman/listinfo/coin-ipopt mailing list]
[http://projects.coin-or.org/Ipopt/newticket Report a bug] (this requires that you [wiki:EditingWikiPages login] first)
[wiki:SuccessStories Success Stories]
[wiki:HintsAndTricks Hints and tricks]
[wiki:IpoptAddFeatures Additional Features]
[wiki:MatlabInterface Matlab interface]
[wiki:IpoptPapers Papers related to Ipopt]
[http://www.coin-or.org/GAMSlinks/benchmarks Several benchmarks in GAMS, including Ipopt]
[http://www.coin-or.org/Ipopt/ipopt-fortran.html Home Page for pre-3.0 version of Ipopt (Fortran Version)]