[Coin-ipopt] Re: IPOPT

Andreas Waechter andreasw at watson.ibm.com
Thu Feb 3 17:36:58 EST 2005

Hi Sid,

[I'm copying my reply to the Ipopt mailing list]

The current official release of Ipopt (which is mainly written in Fortran)
has a C interface.  If you download the code, you seen an example in


(unfortunately, we didn't write proper documentation specificly for the C
interface, but most things should be clear from the regular documentation
in README.IPOPT and the example - if there are questions, I might be able
to help).

Ipopt can solve QPs, but it hasn't really been tuned to that task, and
might perform rather poorly with the default options.  For example, QP
solvers usually compute good starting points themselfs, whereas Ipopt just
takes what the user provides (since for general nonlinear problems finding
a good starting point is not easy).  However, if you decide you want to
use the current release of Ipopt to solve QPs, I might be able to give you
some hints on which options to choose to make it work better for this
special case.

We are currently working on a C++ version of the code, which at some point
will replace the Fortran version.  In there we want to include starting
point heuristics for LPs and QPs, and also improve the code from other
points of view.  You are welcome to try the beta C++ version, but it is
still subject to change, and there is not yet much documentation.



On Thu, 3 Feb 2005, Siddhartha Goel wrote:

> Hi Andreas,
> I have a basic question on IPOPT. Can I invoke the solver from C code? I
> am working on a network simulator, and I am basically looking for an open
> source QP solver, I was looking on the COIN-OR page and I thought maybe
> IPOPT will do the job?
> Thanks,
> Sid
> HRL Laboratories LLC - Information Systems & Sciences Laboratory

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