# Sub plus (₊) instead of dot in the dot notation in equations displayed by ModelingToolkit

**URL:** <https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113>\
**Category:** Modelling & Simulations\
**Tags:** question, modelingtoolkit\
**Created:** [May 13, 2021, 11:13pm UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113 "2021-05-13T23:13:10Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![zdenek\_hurak](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zdenek_hurak/32/53118_2.png) [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Post date:** [May 13, 2021, 11:13pm UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113/1 "2021-05-13T23:13:10Z")

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I was just wondering what was the reason for displaying the MTK equations using (for example) `capacitor₊n₊v` instead of `capacitor.n.v` (as in the [RC Circuit example](https://mtk.sciml.ai/stable/tutorials/acausal_components/)). Couldn’t dots be used for displaying as well (when they are used for inputs anyway)? I confess that reading the displayed equations is not particularly convenient as I occasionally have troubles to distinguish `₊` and `+`.

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [May 14, 2021, 3:37am UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113/2 "2021-05-14T03:37:41Z")

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Yeah it could. I think there is an issue on this.

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**Author:** ![baggepinnen](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/baggepinnen/32/693_2.png) [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)\
**Post date:** [May 14, 2021, 1:58pm UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113/3 "2021-05-14T13:58:29Z")

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It was closed  
[https://github.com/SciML/ModelingToolkit.jl/issues/907](https://github.com/SciML/ModelingToolkit.jl/issues/907)

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**Author:** ![zdenek\_hurak](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zdenek_hurak/32/53118_2.png) [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Post date:** [June 29, 2021, 5:36pm UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113/4 "2021-06-29T17:36:45Z")

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I am hesitating as for where to place it, perhaps it could be more appropriate in the Issues, but I will give it a try here.

Looking at one recent problem [[Update parameters in ModelingToolkit using callbacks](https://discourse.julialang.org/t/update-parameters-in-modelingtoolkit-using-callbacks/63770)] here at Discourse, I noticed that the old issue that we discussed here still persist:

```julia
julia> states(sys)
3-element Vector{Any}:
 model₊y(t)
 myController₊integralError(t)
 myController₊manipulatedVariable(t)

```

So, was it finally decided to keep the `₊` as the separation character after the issue was closed?

Note also that in the legend in the figure [https://global.discourse-cdn.com/julialang/original/3X/3/e/3e3d1d70af56d0610bd595aa51e64cd0e8eae60a.png](https://global.discourse-cdn.com/julialang/original/3X/3/e/3e3d1d70af56d0610bd595aa51e64cd0e8eae60a.png) in that post, some entries use `.` and some `₊`.

May I kindly attract @YingboMa 's attention to this? Many thanks.

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [June 29, 2021, 6:45pm UTC](https://discourse.julialang.org/t/sub-plus-instead-of-dot-in-the-dot-notation-in-equations-displayed-by-modelingtoolkit/61113/5 "2021-06-29T18:45:49Z")

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There’s going to be some major changes to the namespacing, and they will be happening ASAP because they are being put into the same release as the symbolic array changes (which already merged).