.. _ipopt:

IPOPT
=====
IPOPT (Interior Point OPTimizer) is an open source interior point optimizer, designed for large-scale nonlinear optimization.
The source code can be found `here <https://www.coin-or.org/download/source/Ipopt/>`_.
The latest version we support is 3.13.2.

Installation
------------
IPOPT must be installed separately, then linked to pyOptSparse when building.
For the full installation instructions, please see `their documentation <https://coin-or.github.io/Ipopt/INSTALL.html>`_.
OpenMDAO also has a very helpful `script <https://github.com/OpenMDAO/build_pyoptsparse/>`_ which can be used to install IPOPT with other linear solvers.
Here we explain a basic setup using MUMPS as the linear solver, together with METIS adapted from the OpenMDAO script.

#. Download the tarball and extract it to ``$IPOPT_DIR`` which could be set to for example ``$HOME/packages/Ipopt``.

#. Install METIS, which can be used to improve the performance of the MUMPS linear solver.

   .. code-block:: bash

      # build METIS
      cd $IPOPT_DIR
      git clone https://github.com/coin-or-tools/ThirdParty-Metis.git
      cd ThirdParty-Metis
      ./get.Metis
      ./configure --prefix=$IPOPT_DIR
      make
      make install

#. Install MUMPS

   .. code-block:: bash

      # build MUMPS
      cd $IPOPT_DIR
      git clone https://github.com/coin-or-tools/ThirdParty-Mumps.git
      cd ThirdParty-Mumps
      ./get.Mumps
      ./configure --with-metis --with-metis-lflags="-L${IPOPT_DIR}/lib -lcoinmetis" \
           --with-metis-cflags="-I${IPOPT_DIR}/include -I${IPOPT_DIR}/include/coin-or -I${IPOPT_DIR}/include/coin-or/metis" \
           --prefix=$IPOPT_DIR CFLAGS="-I${IPOPT_DIR}/include -I${IPOPT_DIR}/include/coin-or -I${IPOPT_DIR}/include/coin-or/metis" \
           FCFLAGS="-I${IPOPT_DIR}/include -I${IPOPT_DIR}/include/coin-or -I${IPOPT_DIR}/include/coin-or/metis"
      make
      make install

#. Build IPOPT

   .. code-block:: bash

      # build IPOPT
      cd $IPOPT_DIR
      mkdir build
      cd build
      ../configure --prefix=${IPOPT_DIR} --disable-java --with-mumps --with-mumps-lflags="-L${IPOPT_DIR}/lib -lcoinmumps" \
           --with-mumps-cflags="-I${IPOPT_DIR}/include/coin-or/mumps"
      make
      make install     

#. You must add the IPOPT library path to the ``LD_LIBRARY_PATH`` variable for things to work right.
   This could be done for example by adding the following to your ``.bashrc``:

   .. code-block:: bash

     export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$IPOPT_DIR/lib

   Furthermore, the environment variable ``$IPOPT_DIR`` must be set correctly in order to link to pyOptSparse.
   Alternatively, you can manually define the variables ``$IPOPT_LIB`` and ``$IPOPT_INC`` for the lib and include paths separately.


#. Now clean build pyOptSparse. Verify that IPOPT works by running the relevant tests.

Options
-------
Please refer to the `IPOPT website <https://coin-or.github.io/Ipopt/OPTIONS.html>`__ for complete listing of options.
The following are the options which are set by default within pyOptSparse.
All other options take the default value with IPOPT unless specified by the user.

.. optionstable:: pyoptsparse.pyIPOPT.pyIPOPT.IPOPT
   :filename: IPOPT_options.yaml


Informs
-------
.. optionstable:: pyoptsparse.pyIPOPT.pyIPOPT.IPOPT
   :type: informs

API
---
.. currentmodule:: pyoptsparse.pyIPOPT.pyIPOPT

.. autoclass:: IPOPT
   :members: __call__