# Update optimization model by changing variables to coefficients

**URL:** <https://discourse.julialang.org/t/update-optimization-model-by-changing-variables-to-coefficients/124642>\
**Category:** Optimization (Mathematical)\
**Tags:** jump\
**Created:** [January 10, 2025, 1:48pm UTC](https://discourse.julialang.org/t/update-optimization-model-by-changing-variables-to-coefficients/124642 "2025-01-10T13:48:54Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![WalterMadelim](https://avatars.discourse-cdn.com/v4/letter/w/3e96dc/32.png) [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Post date:** [January 11, 2025, 2:25am UTC](https://discourse.julialang.org/t/update-optimization-model-by-changing-variables-to-coefficients/124642/5 "2025-01-11T02:25:39Z")

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I don’t think in a realistic operations research problem we will make use of the dual variable of a general QP (or QCQP).

We tend to write dual programs for convex conic programs (including convex SOCP). (Do we also write dual programs for QP? seems exists but I don’t encounter it often).

The Gurobi solver is usable but some times may have problems like [Gurobi Error 10005: Unable to retrieve attribute 'Pi' - #7 by WalterMadelim](https://discourse.julialang.org/t/gurobi-error-10005-unable-to-retrieve-attribute-pi/53691/7)

I have a bit of experience about the Gurobi solver. Sometimes I encounter strange behaviors. Perhaps tuning those parameters could help make it more stable, like `Presolve`, `DualReductions`

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