# JuMP GLPK method solver

**URL:** https://discourse.julialang.org/t/jump-glpk-method-solver/69048
**Category:** Optimization (Mathematical)
**Tags:** jump
**Created:** [October 1, 2021, 2:37pm UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048 "2021-10-01T14:37:29Z")
**Posts on this page:** 8
**Page:** 1

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### Author: ![shce](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@shce](https://discourse.julialang.org/u/shce)
#### Post date: [October 1, 2021, 2:37pm UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/1 "2021-10-01T14:37:29Z")

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Hello,

I am trying to solve a linear problem using GLPK. I have already found a solution but I would like to know which method is being used by GLPK to solve the LP problem.

My call is:

```julia
model = Model(GLPK.Optimizer)
# Set variables and constraints
JuMP.optimize!(model)

```

Does JuMP tell GLPK to solve the problem using Simplex method by default? Does GLPK decide which method it will use?

Thanks in advance,

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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: [October 2, 2021, 6:23am UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/2 "2021-10-02T06:23:20Z")

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It uses the simplex method by default:

[https://github.com/jump-dev/GLPK.jl/blob/d11ae27aaa3666217786850c564aeffa138a6dac/src/MOI\_wrapper/MOI\_wrapper.jl#L130-L151](https://github.com/jump-dev/GLPK.jl/blob/d11ae27aaa3666217786850c564aeffa138a6dac/src/MOI_wrapper/MOI_wrapper.jl#L130-L151)

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<div class="post-metadata">

### Author: ![shce](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@shce](https://discourse.julialang.org/u/shce)
#### Post date: [October 4, 2021, 8:01am UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/3 "2021-10-04T08:01:29Z")

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Thank you very much! So if I would like to use another method, I would have to specify it manually, right?

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<div class="post-metadata">

### 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: [October 4, 2021, 8:14am UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/4 "2021-10-04T08:14:03Z")

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Yes

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<div class="post-metadata">

### Author: ![shce](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@shce](https://discourse.julialang.org/u/shce)
#### Post date: [October 4, 2021, 9:46am UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/5 "2021-10-04T09:46:50Z")

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Thanks again 🙂

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### Author: ![nico](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nico/32/211667_2.png) [@nico](https://discourse.julialang.org/u/nico)
#### Post date: [December 28, 2022, 2:29pm UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/6 "2022-12-28T14:29:34Z")

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how do you specify it?

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<div class="post-metadata">

### Author: ![shce](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@shce](https://discourse.julialang.org/u/shce)
#### Post date: [December 29, 2022, 11:00am UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/7 "2022-12-29T11:00:25Z")

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Hello nico,

As far as I know, there are only three possible methods: [GLPK.jl/MOI\_wrapper.jl at dee196eabbc87da2a3bfcf210e3ebe17b302a178 · jump-dev/GLPK.jl · GitHub](https://github.com/jump-dev/GLPK.jl/blob/dee196eabbc87da2a3bfcf210e3ebe17b302a178/src/MOI_wrapper/MOI_wrapper.jl#L94)

I haven’t used them myself but I guess you can specify them as:

```julia
model = GLPK.Optimizer(method = GLPK.XXX)

```

See the following function:

> <https://github.com/jump-dev/GLPK.jl/blob/dee196eabbc87da2a3bfcf210e3ebe17b302a178/test/MOI_wrapper.jl#L142>

Regards,

shce

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<div class="post-metadata">

### Author: ![nico](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nico/32/211667_2.png) [@nico](https://discourse.julialang.org/u/nico)
#### Post date: [December 29, 2022, 11:43am UTC](https://discourse.julialang.org/t/jump-glpk-method-solver/69048/8 "2022-12-29T11:43:01Z")

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Thanks a lot!