# Defining an if condition in a constraint

**URL:** <https://discourse.julialang.org/t/defining-an-if-condition-in-a-constraint/76228>\
**Category:** Optimization (Mathematical)\
**Tags:** question, package, jump, optimization\
**Created:** [February 11, 2022, 9:58am UTC](https://discourse.julialang.org/t/defining-an-if-condition-in-a-constraint/76228 "2022-02-11T09:58:39Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![jacobusmmsmit](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jacobusmmsmit/32/217669_2.png) [@jacobusmmsmit](https://discourse.julialang.org/u/jacobusmmsmit)\
**Post date:** [February 11, 2022, 11:03am UTC](https://discourse.julialang.org/t/defining-an-if-condition-in-a-constraint/76228/2 "2022-02-11T11:03:44Z")

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I’m not an experienced JuMP user, but I think you are looking for `@NLconstraint`.

Here is an example:

> [@Conditional constraint if else in JuMP](https://discourse.julialang.org/t/conditional-constraint-if-else-in-jump/6795/12):
>
> This is not a constraint. Do you mean @NLconstraint(model, eq[i in I; x0[i] \>= 0], 2y[i]^3 - 1 == x0[i]) which is equivalent to for i in I if x0[i] \>= 0 @NLconstraint(model, 2y[i]^3 - 1 == x0[i]) end end

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