# JuMP.write\_to\_file small change to model

**URL:** <https://discourse.julialang.org/t/jump-write-to-file-small-change-to-model/83543>\
**Category:** Optimization (Mathematical)\
**Tags:** jump\
**Created:** [June 30, 2022, 1:20am UTC](https://discourse.julialang.org/t/jump-write-to-file-small-change-to-model/83543 "2022-06-30T01:20:57Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Stuart\_Rogers](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stuart_rogers/32/10694_2.png) [@Stuart\_Rogers](https://discourse.julialang.org/u/Stuart_Rogers)\
**Post date:** [June 30, 2022, 1:20am UTC](https://discourse.julialang.org/t/jump-write-to-file-small-change-to-model/83543/1 "2022-06-30T01:20:57Z")

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I have created a large LP in a JuMP model. I want to write a small variation, e.g. fixing a variable or changing the RHS of a scalar constraint, of the LP to a MPS file using JuMP. write\_to\_file. Once the original LP has been written to a MPS file, is there a quick way to write the small variation of the original LP to a different MPS file? JuMP.write\_to\_file takes the same amount of time to write the original and very slightly modified JuMP model LPs to MPS files. I need the MPS files, because I am using a LP solver that is not a currently supported JuMP solver.

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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:** [June 30, 2022, 1:58am UTC](https://discourse.julialang.org/t/jump-write-to-file-small-change-to-model/83543/2 "2022-06-30T01:58:58Z")

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> is there a quick way to write the small variation of the original LP to a different MPS file

No, nor is there an easy way to do this at the JuMP or MOI level. if it’s just changing the right-hand side, the easiest thing is probably to write a function which modifies the actual file, rather than going through JuMP.

> I need the MPS files, because I am using a LP solver that is not a currently supported JuMP solver.

Which solver?

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<div class="post-metadata">

**Author:** ![Stuart\_Rogers](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stuart_rogers/32/10694_2.png) [@Stuart\_Rogers](https://discourse.julialang.org/u/Stuart_Rogers)\
**Post date:** [June 30, 2022, 2:34am UTC](https://discourse.julialang.org/t/jump-write-to-file-small-change-to-model/83543/3 "2022-06-30T02:34:26Z")

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I am using PDLP in OR-Tools v9.3. [Advanced LP Solving &nbsp;|&nbsp; OR-Tools &nbsp;|&nbsp; Google Developers](https://developers.google.com/optimization/lp/lp_advanced)