# Default subsidiary algorithm in NLopt AUGLAG

**URL:** https://discourse.julialang.org/t/default-subsidiary-algorithm-in-nlopt-auglag/12654
**Category:** Optimization (Mathematical)
**Tags:** jump
**Created:** [July 25, 2018, 2:37pm UTC](https://discourse.julialang.org/t/default-subsidiary-algorithm-in-nlopt-auglag/12654 "2018-07-25T14:37:18Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![mrapo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mrapo/32/3911_2.png) [@mrapo](https://discourse.julialang.org/u/mrapo)
#### Post date: [July 25, 2018, 2:37pm UTC](https://discourse.julialang.org/t/default-subsidiary-algorithm-in-nlopt-auglag/12654/1 "2018-07-25T14:37:18Z")

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I wan to use the NLopt’s **Augmented Lagrangian algorithm** in JuMP environment. In the [documentation](http://nlopt.readthedocs.io/en/latest/NLopt_Reference/#Local/subsidiary_optimization_algorithm.md) it is mentioned that the AUGLAG algorithm uses a subsidary algorithm for the optimization and that this local search algorithm can be changed by user. However I could not find any information about what the default subsidary algorithm might be. Is there possibly a way to check in JuMP environment which algorithm AUGLAG is currently using?

Thanks beforehand.

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### Author: ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [July 25, 2018, 8:57pm UTC](https://discourse.julialang.org/t/default-subsidiary-algorithm-in-nlopt-auglag/12654/2 "2018-07-25T20:57:34Z")

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> [@mrapo](#):
>
> However I could not find any information about what the default subsidary algorithm might be.

There isn’t one. It [defaults to NULL](https://github.com/stevengj/nlopt/blob/1226c1276dacf3687464c65eb165932281493a35/src/api/options.c#L94) and AUGLAG will [throw an error if you didn’t specify one](https://github.com/stevengj/nlopt/blob/1226c1276dacf3687464c65eb165932281493a35/src/api/optimize.c#L742-L745). Documentation PRs are welcome.

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### Author: ![mrapo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mrapo/32/3911_2.png) [@mrapo](https://discourse.julialang.org/u/mrapo)
#### Post date: [July 26, 2018, 6:51am UTC](https://discourse.julialang.org/t/default-subsidiary-algorithm-in-nlopt-auglag/12654/3 "2018-07-26T06:51:54Z")

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Thanks for the answer @stevengj. I want to specify that I’m using :LD\_AUGLAG and I’m not getting an error. The optimization works as it should. I still wonder which subsidiary algorithm this one is using.