# Question about LP format file generation

**URL:** <https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460>\
**Category:** Optimization (Mathematical)\
**Tags:** jump\
**Created:** [November 18, 2022, 3:54pm UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460 "2022-11-18T15:54:36Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![kevinqiao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kevinqiao/32/44492_2.png) [@kevinqiao](https://discourse.julialang.org/u/kevinqiao)\
**Post date:** [November 18, 2022, 3:54pm UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460/1 "2022-11-18T15:54:36Z")

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I’m using JuMP v1.4.0 and I want to generate an LP format file of the following model, but it doesn’t work, the file is not generated, and I don’t know why. Thanks in advance.

using JuMP  
using Gurobi

model = Model(Gurobi.Optimizer)  
@variable(model, x \>= 0)  
@variable(model, 0 \<= y \<= 3)  
@objective(model, Min, 12x + 20y)  
@constraint(model, c1, 6x + 8y \>= 100)  
@constraint(model, c2, 7x + 12y \>= 120)  
optimize!(model)  
write\_to\_file(model, “modelplus.lp”)  
@show termination\_status(model)

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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:** [November 20, 2022, 6:09pm UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460/2 "2022-11-20T18:09:10Z")

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> the file is not generated

The file is generated, it just writes to the directory returned by `pwd()`. This is likely not where you expected it to be?

You can always give the full path, for example, on my machine it would be `write_to_file(model, "/Users/Oscar/Desktop/modelplus.lp")`.

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<div class="post-metadata">

**Author:** ![kevinqiao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kevinqiao/32/44492_2.png) [@kevinqiao](https://discourse.julialang.org/u/kevinqiao)\
**Post date:** [November 21, 2022, 1:19am UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460/3 "2022-11-21T01:19:10Z")

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It works, thank you so much. BTW, the NLP is not supported by write\_to\_file(), is there any way to generate files like this to be used in other platforms?

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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:** [November 21, 2022, 1:19am UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460/4 "2022-11-21T01:19:51Z")

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> the NLP is not supported by write\_to\_file

You can use the `.nl` file format: `write_to_file("model.nl")`

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<div class="post-metadata">

**Author:** ![kevinqiao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kevinqiao/32/44492_2.png) [@kevinqiao](https://discourse.julialang.org/u/kevinqiao)\
**Post date:** [November 21, 2022, 7:03am UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460/5 "2022-11-21T07:03:04Z")

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It generates a file by using the method, but I’ve no idea what the model in the .nl file means. It looks like the following:

g3 1 1 0  
564 695 1 0 500 0  
426 1  
0 0  
484 0 0  
0 0 0 1  
0 0 0 0 0  
5632 22  
0 0  
0 0 0 0 0  
C0  
o1  
o1  
v36  
o2  
n1.5  
o0  
n1  
o2  
n0.15  
o5  
o3  
v0  
…

I don’t know if the file could be used in my work, but thank you anyway.

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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:** [November 21, 2022, 7:14am UTC](https://discourse.julialang.org/t/question-about-lp-format-file-generation/90460/6 "2022-11-21T07:14:32Z")

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Its a standard file format [nl (format) - Wikipedia](https://wikipedia.org/wiki/Nl_(format)), albeit not very user friendly one.

What do you want to do with the file? You can read it using `read_from_file`.