# [Ipopt] unexpected inequality constraints

Stefan Vigerske stefan at math.hu-berlin.de
Fri May 29 04:44:49 EDT 2015

```Hi,

maybe you could raise this issue with the pyipopt project:
https://github.com/xuy/pyipopt/issues

Giving them some code to reproduce this should be helpful, too.

Stefan

On 05/28/2015 05:02 PM, Knut Heidemann wrote:
> Hi,
>
> I am currently using pyipopt for solving a quadratic problem with linear
> equality constraints.
> However, I am puzzled by IPOPTS's statement:
>
> "Number of nonzeros in inequality constraint Jacobian: 1"
>
> There should not be any entry in whatever inequality Jacobian if I am
> not having any inequality constraints (g_U = g_L), right?
>
> Maybe that is the reason why I am running into a SEGFAULT when
> evaluating the constraint Jacobian? [1]
>
> Does anybody know how to find out what is going on?
>
> Best,
> Knut.
>
>
> [1]:
>
> (gdb)******************************************************************************
> This program contains Ipopt, a library for large-scale nonlinear
> optimization.
>   Ipopt is released as open source code under the Eclipse Public License
> (EPL).
> ******************************************************************************
>
> This is Ipopt version 3.11, running with linear solver ma27.
>
> [Callback:E] eval_jac_g
> [Callback:R] eval_jac_g(1)
> [Callback:R] eval_jac_g
> Number of nonzeros in equality constraint Jacobian...:        6
> Number of nonzeros in inequality constraint Jacobian.:        1
> Number of nonzeros in Lagrangian Hessian.............:        0
>
> [Callback:E] eval_jac_g
> [Callback:R] eval_jac_g(2)
> [Callback:R] eval_jac_g
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007fffed3b4151 in
> Ipopt::GenTMatrix::ComputeRowAMaxImpl(Ipopt::Vector&, bool) const ()