[Ipopt] AMPL options problem

[Andreas Waechter]

Hi Juan,

Not all Ipopt options can be set from the AMPL command line.  You can see 
the list of options available through AMPL by typing

ipopt -=

in a shell, where "ipopt" is your AMPL Ipopt solver executable.

I added this particular option to the list of recognized options in AMPL, 
and committed it to Ipopt/trunk.  It will be available in the next release 
(or now in trunk, if you use the develpment version via svn).

But you can always set all Ipopt option using the ipopt.opt file.  So, 
even with your current Ipopt version, you can just create a file called 
'ipopt.opt' in the directory where you run AMPL, and include the line

ma57_pivot_order 4

See also the Ipopt documentation about the use of the ipopt.opt options 
file.

Hope this helps,

Andreas

On Thu, 12 May 2011, Juan Ignacio Laiglecia wrote:

>
> Dear,
> I have had problem when I used this IPOPT option:
> ma57_pivot_order
>
> I am solving an entire natural gas plant in AMPL and I am very interested in reducing the computational times. In the ipopt option line I introduced it in this way:
>
> option ipopt_options " linear_solver ma57 ma57_pivot_order 4 ";
> option solver ipopt ;
>
> When I run the problem, AMPL send me: Unknown Keyword “ma57_pivot_order”
> Do you know what would the problem be? I should mention that I have the ipopt3.8 version.
>
> Thank you very much in advance.
> Juan
>