# \[JuMP\] Sum function with additional constraints on indexes

**URL:** <https://discourse.julialang.org/t/jump-sum-function-with-additional-constraints-on-indexes/4001>\
**Category:** Optimization (Mathematical)\
**Created:** [May 31, 2017, 12:59am UTC](https://discourse.julialang.org/t/jump-sum-function-with-additional-constraints-on-indexes/4001 "2017-05-31T00:59:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Joao\_Saran](https://avatars.discourse-cdn.com/v4/letter/j/e5b9ba/32.png) [@Joao\_Saran](https://discourse.julialang.org/u/Joao_Saran)\
**Post date:** [May 31, 2017, 12:59am UTC](https://discourse.julialang.org/t/jump-sum-function-with-additional-constraints-on-indexes/4001/1 "2017-05-31T00:59:58Z")

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My Objective Function is the following:

@setObjective(m,Min, sum{costs[i,j]\*x[i,j,k,t],i= nodes, j = nodes, k = vehicles, t = periods})

AND I would like to make “i \< j” in the sum expression above! It is like adding a constraint on the indexes only for this expression. Is this possible? How is the syntax?

Thank you very much.

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**Author:** ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)\
**Post date:** [May 31, 2017, 1:27am UTC](https://discourse.julialang.org/t/jump-sum-function-with-additional-constraints-on-indexes/4001/2 "2017-05-31T01:27:06Z")

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That is ancient syntax.  
Read the docs:  
[http://www.juliaopt.org/JuMP.jl/0.17/quickstart.html](http://www.juliaopt.org/JuMP.jl/0.17/quickstart.html)

You can (now) use an `if` clause inside `sum`.

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**Author:** ![Joao\_Saran](https://avatars.discourse-cdn.com/v4/letter/j/e5b9ba/32.png) [@Joao\_Saran](https://discourse.julialang.org/u/Joao_Saran)\
**Post date:** [May 31, 2017, 11:03pm UTC](https://discourse.julialang.org/t/jump-sum-function-with-additional-constraints-on-indexes/4001/3 "2017-05-31T23:03:11Z")

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I worked with Julia only once for a college project. It’s been a long time. I had no idea the syntax had changed. Thank you very much. You helped a lot.