# Modifying coefficient of quadratic term in objective function

**URL:** <https://discourse.julialang.org/t/modifying-coefficient-of-quadratic-term-in-objective-function/51622>\
**Category:** Optimization (Mathematical)\
**Created:** [December 10, 2020, 5:46pm UTC](https://discourse.julialang.org/t/modifying-coefficient-of-quadratic-term-in-objective-function/51622 "2020-12-10T17:46:46Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![guilhermebodin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/guilhermebodin/32/6982_2.png) [@guilhermebodin](https://discourse.julialang.org/u/guilhermebodin)\
**Post date:** [December 10, 2020, 5:46pm UTC](https://discourse.julialang.org/t/modifying-coefficient-of-quadratic-term-in-objective-function/51622/1 "2020-12-10T17:46:46Z")

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Suppose I have this problem:

```julia
using JuMP, OSQP
m = Model(OSQP.Optimizer)
@variable(m, x[1:3] >= 0)
@constraint(m, sum(x) .>= 1)
@objective(m, Min, x[1] + 2x[2] + 3x[3]^2 + 2x[1]^2)
optimize!(m)
objective_value(m)

```

I can modify the objective coefficient term of `x[1]` without reinstantiating the all problem with

```julia
set_objective_coefficient(m, x[1], -5.0)
optimize!(m)
objective_value(m)

```

But can I modify the objective coefficient of `x[1]^2` without reinstantiating the problem?

---

<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:** [December 10, 2020, 5:59pm UTC](https://discourse.julialang.org/t/modifying-coefficient-of-quadratic-term-in-objective-function/51622/2 "2020-12-10T17:59:17Z")

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No. But you can just set a new objective with `@objective`.