  The open-source nonlinear solver Ipopt (https://projects.coin-or.org/Ipopt)
is a widely-used software package for the solution of large-scale non-linear
optimization problems. At its heart, it employs a third-party linear solver to
solve a series of sparse symmetric indefinite systems. The speed, accuracy and
robustness of the chosen linear solver is critical to the overall performance
of Ipopt. In some instances, it can be beneficial to scale the linear system
before it is solved.
  In this paper, different scaling algorithms are employed within Ipopt with a
new linear solver HSL_MA97 from the HSL mathematical software library
(http://www.hsl.rl.ac.uk). An extensive collection of problems from the CUTEr
test set (http://www.cuter.rl.ac.uk) is used to illustrate the effects of
scaling.
