# using "max" in nonlinear constraints

**URL:** <https://discourse.julialang.org/t/using-max-in-nonlinear-constraints/21606>\
**Category:** Optimization (Mathematical)\
**Tags:** question\
**Created:** [March 7, 2019, 9:45pm UTC](https://discourse.julialang.org/t/using-max-in-nonlinear-constraints/21606 "2019-03-07T21:45:24Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![odow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/odow/32/28685_2.png) [@odow](https://discourse.julialang.org/u/odow)\
**Post date:** [March 7, 2019, 10:34pm UTC](https://discourse.julialang.org/t/using-max-in-nonlinear-constraints/21606/4 "2019-03-07T22:34:02Z")

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@zhangxz1123, you’re looking for the [splatting syntax](http://www.juliaopt.org/JuMP.jl/latest/nlp/#Syntax-notes-1) (note: I’m not sure if this works on JuMP v0.18, which it looks like you’re using. It does on the latest JuMP v0.19.):

```julia
using JuMP, Ipopt
m = Model(with_optimizer(Ipopt.Optimizer))
N = 4
@variable(m, x[i=1:N] >= i)
f(y...) = max(y...)
JuMP.register(m, :f, N, f, autodiff=true)
@NLobjective(m, Min, f(x...))
optimize!(m)
```

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