Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

Options

- RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page

🔒 This topic is **solved** and **locked**.
Need further help from the community? Please
sign in and ask a **new** question.

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

Posted 05-28-2020 06:04 PM
(1545 views)

I want to get the constraints causing infeasibility and store it in a table for printing. SAS doesn't allow me to use IIS=on when using milp solver.

1 ACCEPTED SOLUTION

Accepted Solutions

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

You can use the Output Delivery System to write the EXPAND / IIS output to a data set:

```
ods output expand=myexpand;
```

You can then use PROC PRINT if you want, but it will look very similar. Both ways display only the IIS (and not all the other variables and constraints) in the Results Viewer.

7 REPLIES 7

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

MILP IIS is available in SAS Optimization 8.5 (SAS Viya 3.5), released in November 2019:

For other releases, you might try using the RELAXINT option, in case the LP relaxation is infeasible:

`solve with lp relaxint / iis=on;`

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

I have base sas 9.4 and SAS EG 7.1. Looks like I don't have that yet.

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

OK, that result is a *good* thing when you want to figure out why a problem is infeasible. It means that even the linear programming relaxation is infeasible. The following statement will then show you the resulting IIS found by the solver to help you diagnose the infeasibility:

`expand / iis;`

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

Is there a way I can just proc print the infeasibility causing constraints than going through the entire log.

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

You can use the Output Delivery System to write the EXPAND / IIS output to a data set:

```
ods output expand=myexpand;
```

You can then use PROC PRINT if you want, but it will look very similar. Both ways display only the IIS (and not all the other variables and constraints) in the Results Viewer.

**SAS Innovate 2025** is scheduled for May 6-9 in Orlando, FL. Sign up to be **first to learn** about the agenda and registration!

Multiple Linear Regression in SAS

Learn how to run multiple linear regression models with and without interactions, presented by SAS user Alex Chaplin.

Find more tutorials on the SAS Users YouTube channel.