Hi I have a MIP problem and I coded it in GAMS. But When I used conditional terms (IF rule), The games showed error: "Endogenous relational operations require model type "dnlp"" This error occurs when I add constraint: con8(i,j,n,k)..x(i,j,k)$((U-T(k)-(D(j,n)/V))>0)=l=x(j,n,k) ; In this constraint T(k) is the variable which has been calculated from other constraints. I find out that if I remove T(k), the GAMS works truly. Could anybody help me?

asked 05 Jan '15, 10:32

majid's gravatar image

majid
112
accept rate: 0%


Using a variable after the dollar is in most cases a recipe for disaster for NLP solvers (you introduce a discontinuity here). You should reformulate things or if you know what you are doing, explicitly solve as a DNLP model (probably after rewriting the constraint with an ifthen function) .

link

answered 05 Jan '15, 13:39

erwin's gravatar image

erwin
40113
accept rate: 10%

edited 06 Jan '15, 01:23

Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here

By RSS:

Answers

Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "Title")
  • image?![alt text](/path/img.jpg "Title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Tags:

×51
×6

Asked: 05 Jan '15, 10:32

Seen: 2,862 times

Last updated: 06 Jan '15, 01:23

OR-Exchange! Your site for questions, answers, and announcements about operations research.