# Linear Quadratic Integrator
**URL:** https://discourse.julialang.org/t/linear-quadratic-integrator/113245
**Category:** Modelling & Simulations
**Tags:** control, controlsystems
**Created:** [April 19, 2024, 3:34pm UTC](https://discourse.julialang.org/t/linear-quadratic-integrator/113245 "2024-04-19T15:34:33Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@iabraham](https://discourse.julialang.org/u/iabraham)
#### Post date: [April 19, 2024, 3:34pm UTC](https://discourse.julialang.org/t/linear-quadratic-integrator/113245/1 "2024-04-19T15:34:34Z")
The [ControlSystems](https://github.com/JuliaControl/ControlSystems.jl) package seems to provide a lqr function for the LQR problem. I was wondering whether there was any plans to provide the lqi function for the Linear Quadratic Integrator problem. - e.g. [Scilab](https://help.scilab.org/docs/2024.0.0/en_US/lqi.html) or [MATLAB](https://www.mathworks.com/help/control/ref/ss.lqi.html)
---
### Author:  [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)
#### Post date: [April 19, 2024, 3:41pm UTC](https://discourse.julialang.org/t/linear-quadratic-integrator/113245/2 "2024-04-19T15:41:36Z")
See [Integral action · JuliaSimControl](https://help.juliahub.com/juliasimcontrol/dev/integral_action/)
and the tutorials linked from within.
---
### Author:  [@iabraham](https://discourse.julialang.org/u/iabraham)
#### Post date: [April 19, 2024, 10:01pm UTC](https://discourse.julialang.org/t/linear-quadratic-integrator/113245/3 "2024-04-19T22:01:51Z")
Thanks! It would be great if there was an equivalent/similar function. Can it be considered a feature request?
---
### Author:  [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)
#### Post date: [April 20, 2024, 8:52am UTC](https://discourse.julialang.org/t/linear-quadratic-integrator/113245/4 "2024-04-20T08:52:14Z")
Matlab has a lot of `lqXXX` functions that are all similar but subtly different and are generally quite confusing, e.g., what is the difference between `lqrd` and `dlqr`? I have opted to provide the building blocks for users to put together what they need, rather than introducing the same large number of confusing functions. You can use the functions listed under [model augmentation](https://juliacontrol.github.io/RobustAndOptimalControl.jl/dev/#Model-augmentation) to form the augmented statespace system required. If the exact formulation you need is not there, I prefer to add features to the model augmentation rather than adding a special-purpose lqr method.