# Large number of @variables in ModelingToolkit

**URL:** <https://discourse.julialang.org/t/large-number-of-variables-in-modelingtoolkit/82399>\
**Category:** Modelling & Simulations\
**Tags:** modelingtoolkit\
**Created:** [June 8, 2022, 1:53am UTC](https://discourse.julialang.org/t/large-number-of-variables-in-modelingtoolkit/82399 "2022-06-08T01:53:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![QuantumWorm](https://avatars.discourse-cdn.com/v4/letter/q/c37758/32.png) [@QuantumWorm](https://discourse.julialang.org/u/QuantumWorm)\
**Post date:** [June 8, 2022, 1:53am UTC](https://discourse.julialang.org/t/large-number-of-variables-in-modelingtoolkit/82399/1 "2022-06-08T01:53:17Z")

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[https://neuralpde.sciml.ai/stable/pinn/system/](https://neuralpde.sciml.ai/stable/pinn/system/)

When I need several variables I can write  
@parameters t, x  
@variables u1(…), u2(…), u3(…)

and in solver use  
@named pde\_system = PDESystem(eqs,bcs,domains,[t,x],[u1(t, x),u2(t, x),u3(t, x)])

What is the right way to generalize this for a large number of variables? I would like to do something like  
@variables u[1:n] (…)  
@named pde\_system = PDESystem(eqs,bcs,domains,[t,x],u(t, x))

and then I could use u[1] instead of u1 etc, but that doesn’t work.

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<div class="post-metadata">

**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 8, 2022, 10:01am UTC](https://discourse.julialang.org/t/large-number-of-variables-in-modelingtoolkit/82399/2 "2022-06-08T10:01:38Z")

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That sems like a parsing issue. Open an issue in Symbolics. It looks like just the direct call form `@variables t x u[1:5](t,x)` is handled.