# First alpha release of JuMP 0.19 (JuMP/MathOptInterface)

**URL:** <https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099>\
**Category:** Optimization (Mathematical)\
**Created:** [October 10, 2018, 3:40am UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099 "2018-10-10T03:40:50Z")\
**Posts on this page:** 14\
**Page:** 1

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**Author:** ![miles.lubin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/miles.lubin/32/279_2.png) [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Post date:** [October 10, 2018, 3:40am UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/1 "2018-10-10T03:40:50Z")

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To help out early adopters in the big [transition](https://discourse.julialang.org/t/mathoptinterface-and-upcoming-breaking-changes-in-jump-0-19/4874) to JuMP/MathOptInterface, we’ll be making development tags of JuMP `master` up to the JuMP 0.19 release. The first development release, `v0.19-alpha` is now tagged. This is the first tag of JuMP/MathOptInterface branch that we’ve been working on for the past year.

See [NEWS.md](https://github.com/JuliaOpt/JuMP.jl/blob/master/NEWS.md) for a list of breaking changes and new features that will turn into the release notes for 0.19. We also list the major known issues that we intend to fix before the final release.

See the [docs](http://www.juliaopt.org/JuMP.jl/latest/installation.html) for a list of solvers that are compatible and not yet compatible with JuMP/MathOptInterface.

To install on Julia 1.0:

`] add JuMP#v0.19-alpha`

The tag is also compatible with Julia 0.6, but this compatibility may be dropped before the 0.19 release.

**Note** : `alpha` means that breaking changes are still underway. We’re asking for interested early adopters to test out the development release and provide feedback. Expect important things to occasionally be broken or not yet implemented. Expect to look at the ([now much tidier](http://www.juliaopt.org/JuMP.jl/latest/style.html)) source code to understand how something works. Expect that your existing JuMP models will not work without some changes. We’ve put a lot of effort into testing, and there are no known correctness bugs, but we still recommend caution since the code is new. Please don’t use the alpha release to run critical services. 🙂

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**Author:** ![chkwon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chkwon/32/3632_2.png) [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Post date:** [October 10, 2018, 12:35pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/2 "2018-10-10T12:35:13Z")

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Great! I’m learning the new grammar.

```julia
using JuMP, GLPK
m = Model(with_optimizer(GLPK.Optimizer))
@variable(m, x, Bin)
@variable(m, y[1:10] >= 0)
@objective(m, Min, -x + sum(y[i] for i in 1:10) )
JuMP.optimize!(m)
@show JuMP.result_value(x)
@show JuMP.result_value(y[1])
@show JuMP.result_value(y)

```

The last line produces an error.

```julia
julia> @show JuMP.result_value(y)
ERROR: MethodError: no method matching result_value(::Array{VariableRef,1})
Closest candidates are:
  result_value(::VariableRef) at /Users/chkwon/.julia/packages/JuMP/LjMor/src/variables.jl:557
  result_value(::JuMP.GenericAffExpr) at /Users/chkwon/.julia/packages/JuMP/LjMor/src/aff_expr.jl:244
Stacktrace:
 [1] top-level scope at show.jl:555

```

Is this a bug?

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<div class="post-metadata">

**Author:** ![miles.lubin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/miles.lubin/32/279_2.png) [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Post date:** [October 10, 2018, 12:47pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/3 "2018-10-10T12:47:13Z")

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No, not a bug. We’re following the Julia convention of using broadcast syntax for operations that map every element of an array. Use `JuMP.result_value.(y)` instead. ([Mention broadcasting syntax by mlubin · Pull Request #1537 · jump-dev/JuMP.jl · GitHub](https://github.com/JuliaOpt/JuMP.jl/pull/1537))

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**Author:** ![chkwon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chkwon/32/3632_2.png) [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Post date:** [October 10, 2018, 1:23pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/4 "2018-10-10T13:23:51Z")

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Thanks!

I have another question. What will be the equivalent way of doing `status == :Optimal`?

I tried

```julia
JuMP.termination_status(m) == MathOptInterface.Success

```

which works, if I install `MathOptInterface` manually. But it seems that JuMP works without manually installing MOI. Is there a way without MOI?

Anyway, to do `status=:Optimal`, it seems

```julia
JuMP.termination_status(m) == MathOptInterface.Success && JuMP.primal_status(m) == MathOptInterface.FeasiblePoint

```

Is this a correct and recommended way?

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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 10, 2018, 1:26pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/5 "2018-10-10T13:26:44Z")

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Yes, your second way is correct.

I usually add a const MOI like so:

```julia
const MOI = JuMP.MathOptInterface

JuMP.termination_status(model) == MOI.Success

```

Maybe JuMP should export the `MOI` symbol.

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<div class="post-metadata">

**Author:** ![chkwon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chkwon/32/3632_2.png) [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Post date:** [October 10, 2018, 1:28pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/6 "2018-10-10T13:28:52Z")

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Thanks! I think it is a wonderful idea to export `MOI`.

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<div class="post-metadata">

**Author:** ![chkwon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chkwon/32/3632_2.png) [@chkwon](https://discourse.julialang.org/u/chkwon)\
**Post date:** [October 11, 2018, 1:32pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/7 "2018-10-11T13:32:23Z")

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When Clp finds a problem infeasible, it returns `Success`. I guess it needs to be `InfeasibleNoResult`.

```julia
using JuMP, Clp

solvers = Clp.Optimizer

m = Model(with_optimizer(solver))

@variable(m, x >= 0)
@objective(m, Min, x)
@constraint(m, x <= -1)

JuMP.optimize!(m)

term_status = JuMP.termination_status(m)
primal_status = JuMP.primal_status(m)
dual_status = JuMP.dual_status(m)

@show solver
@show term_status
@show primal_status
@show dual_status

```

```julia
Coin0507I Presolve determined that the problem was infeasible with tolerance of 1e-08
Clp3003W Analysis indicates model infeasible or unbounded
Clp0006I 0 Obj 0 Primal inf 0.9999999 (1)
Clp0006I 0 Obj 0 Primal inf 0.9999999 (1)
Clp0001I Primal infeasible - objective value 0
Clp0032I PrimalInfeasible objective 0 - 0 iterations time 0.002
solver = Clp.Optimizer
term_status = Success::TerminationStatusCode = 0
primal_status = UnknownResultStatus::ResultStatusCode = 8
dual_status = InfeasibilityCertificate::ResultStatusCode = 4

```

Shouldn’t `term_status` be `InfeasibleNoResult`?

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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 11, 2018, 2:06pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/8 "2018-10-11T14:06:15Z")

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The `dual_status` shows `InfeasibilityCertificate`, thus Clp has found a Farkas proof of primal infeasibility.

If Clp was unable to find a certificate of primal infeasibility, it should return `InfeasibleNoResult`.

Some solvers (e.g. nonlinear ones) may return a termination status `Success` and a primal status `InfeasiblePoint`.

This is a good example of how the MOI status reporting system allows a much richer description of why the solver terminated.

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**Author:** ![bbrunaud](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bbrunaud/32/1737_2.png) [@bbrunaud](https://discourse.julialang.org/u/bbrunaud)\
**Post date:** [October 15, 2018, 10:16pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/9 "2018-10-15T22:16:29Z")

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Question: What is the way to access not implemented API functions?.. before I would do a `ccall` to `m.internalModel.inner.ptr`.

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<div class="post-metadata">

**Author:** ![miles.lubin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/miles.lubin/32/279_2.png) [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Post date:** [October 27, 2018, 9:24pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/10 "2018-10-27T21:24:42Z")

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See the [RawSolver](http://www.juliaopt.org/MathOptInterface.jl/stable/apireference.html#MathOptInterface.RawSolver) attribute, e.g., `MOI.get(model, MOI.RawSolver())`. The plumbing might not be connected for your favorite solver though.

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**Author:** ![hdavid16](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hdavid16/32/11531_2.png) [@hdavid16](https://discourse.julialang.org/u/hdavid16)\
**Post date:** [November 26, 2019, 3:34am UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/11 "2019-11-26T03:34:30Z")

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`MOI.get(model, MOI.RawSolver())` gives me an error:

ERROR: OptimizeNotCalled()

Is there a way to access the internal model before optimizing?

Solution Found: (disregard previous message)  
I used `MOI.get(model.moi_backend.optimizer, MOI.RawSolver())` and it worked

Edit: The returned internal model is empty both for Gurobi and CPLEX before the model is solved. Something off with the plumbing?

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<div class="post-metadata">

**Author:** ![hdavid16](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hdavid16/32/11531_2.png) [@hdavid16](https://discourse.julialang.org/u/hdavid16)\
**Post date:** [November 27, 2019, 6:01am UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/12 "2019-11-27T06:01:23Z")

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Edit to above post: Found how to get the CPLEX.Model to be synchronized with the JuMP model:

```julia
MOI.Utilities.attach_optimizer(model) 

```

With this, you can now access the model variables, constraints, etc in the internal model.

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<div class="post-metadata">

**Author:** ![miles.lubin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/miles.lubin/32/279_2.png) [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Post date:** [November 27, 2019, 1:40pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/13 "2019-11-27T13:40:58Z")

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That’s correct. I would also recommend using [direct mode](http://www.juliaopt.org/JuMP.jl/v0.20.0/solvers/#Direct-mode-1) if you intend to map variables between the underlying solver and the JuMP model.

I’m closing this thread because the discussion has veered away from the 0.19 alpha release. Please open a new topic if you have additional questions on accessing the internal model.

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<div class="post-metadata">

**Author:** ![miles.lubin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/miles.lubin/32/279_2.png) [@miles.lubin](https://discourse.julialang.org/u/miles.lubin)\
**Post date:** [November 27, 2019, 1:41pm UTC](https://discourse.julialang.org/t/first-alpha-release-of-jump-0-19-jump-mathoptinterface/16099/14 "2019-11-27T13:41:03Z")

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