# \[AMPL 24514\] Handling solver options with $

**URL:** <https://discuss.ampl.com/t/ampl-24514-handling-solver-options-with/362>\
**Category:** Google Group Mirror\
**Created:** [February 6, 2023, 6:03pm UTC](https://discuss.ampl.com/t/ampl-24514-handling-solver-options-with/362 "2023-02-06T18:03:35Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Julkin](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/julkin/32/195_2.png) [@Julkin](https://discuss.ampl.com/u/Julkin)\
**Post date:** [February 6, 2023, 6:03pm UTC](https://discuss.ampl.com/t/ampl-24514-handling-solver-options-with/362/1 "2023-02-06T18:03:35Z")

</div>

Hello,

I had some code that was running smoothly with past academic bundles of AMPL. However, when running it with the latest bundles I downloaded last week, I got an unexpected error handling the options. The following is a minimal working example illustrating it:

---

<div class="post-metadata">

**Author:** ![AMPL\_Google\_Group](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@AMPL\_Google\_Group](https://discuss.ampl.com/u/AMPL_Google_Group)\
**Post date:** [February 7, 2023, 5:42pm UTC](https://discuss.ampl.com/t/ampl-24514-handling-solver-options-with/362/2 "2023-02-07T17:42:28Z")

</div>

Dear Julio,

The ability to list solver options without spaces between them, as in

`option gurobi_options 'outlev 0';`  
`option gurobi_options $gurobi_options 'presolve 0';`

is an undocumented feature of the original AMPL-solver library (ASL). Our Gurobi 10.0 distribution comes with a solver binary named “gurobiasl” that is built with ASL, and that includes this feature. (Try “option solver gurobiasl;”.) However, the same distribution includes a “gurobi” binary that is built on our new [MP interface](https://amplmp.readthedocs.io/en/latest/). As you have seen, MP does require spaces between solver options.

We are in the process of switching all linear/quadratic MIP solvers to the MP interface, which has been enhanced in a number of ways. Most importantly, from a modeler’s view, MP recognizes a significantly broader variety of convenient [constraint expressions](https://amplmp.readthedocs.io/en/latest/rst/model-guide.html), and has a more consistent system for naming solver options (though old names are still recognized).

---

<div class="post-metadata">

**Author:** ![Julkin](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/julkin/32/195_2.png) [@Julkin](https://discuss.ampl.com/u/Julkin)\
**Post date:** [February 8, 2023, 9:14am UTC](https://discuss.ampl.com/t/ampl-24514-handling-solver-options-with/362/3 "2023-02-08T09:14:03Z")

</div>

Thanks a lot Bob for your, once again, crystal clear explanation.

Best regards,  
Julio.