# Searching for a simple polynomial curve fitting example

**URL:** <https://discourse.julialang.org/t/searching-for-a-simple-polynomial-curve-fitting-example/5302>\
**Category:** Optimization (Mathematical)\
**Tags:** question\
**Created:** [August 9, 2017, 12:50pm UTC](https://discourse.julialang.org/t/searching-for-a-simple-polynomial-curve-fitting-example/5302 "2017-08-09T12:50:08Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![J\_T](https://avatars.discourse-cdn.com/v4/letter/j/57b2e6/32.png) [@J\_T](https://discourse.julialang.org/u/J_T)\
**Post date:** [March 19, 2021, 5:10am UTC](https://discourse.julialang.org/t/searching-for-a-simple-polynomial-curve-fitting-example/5302/7 "2021-03-19T05:10:51Z")

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Thank you!

Can I ask for learning purposes what is the practical difference between fixing coefficients (or setting bounds) and defining constraints ?

Edit: I found the answer in another thread: [fixing-vs-constraining-a-variable-in-jump](https://discourse.julialang.org/t/fixing-vs-constraining-a-variable-in-jump/27609/6)

P.S. For others reference, I ended up adding

```julia
set_optimizer_attribute(m, "tol_bnd", 1e-11 )

```

before the results stabilised and the absolute errors looked suitably like Chebychev equi-oscillation (with obvious root at `x=1`).

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