# DiffEqOperators symbolic tutorial throwing error
**URL:** https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468
**Category:** Numerics
**Tags:** diffeq
**Created:** [June 6, 2021, 3:21pm UTC](https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468 "2021-06-06T15:21:56Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@gbrunkhorst](https://discourse.julialang.org/u/gbrunkhorst)
#### Post date: [June 6, 2021, 3:21pm UTC](https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468/1 "2021-06-06T15:21:56Z")
Hi Everyone: the SciML ecosystem looks amazing. I’m just getting started with both Julia and these packages. The tutorial [DiffEqOperators](https://github.com/SciML/DiffEqOperators.jl/blob/master/docs/src/symbolic_tutorials/mol_heat.md) gives the following error:
Lines
```julia
# Method of lines discretization
dx = 0.1
order = 2
discretization = MOLFiniteDifference([x=>dx],t)
# Convert the PDE problem into an ODE problem
prob = discretize(pdesys,discretization)
```
Error
TypeError: in isa, expected Type, got a value of type typeof(IntervalDomain)
Stacktrace:
[1] symbolic\_discretize(pdesys::PDESystem, discretization::MOLFiniteDifference{Vector{Pair{Num, Float64}}, Num})
@ DiffEqOperators C:\Users\greg.julia\packages\DiffEqOperators\6CWxd\src\MOLFiniteDifference\MOL\_discretization.jl:48
[2] discretize(pdesys::PDESystem, discretization::MOLFiniteDifference{Vector{Pair{Num, Float64}}, Num})
@ DiffEqOperators C:\Users\greg.julia\packages\DiffEqOperators\6CWxd\src\MOLFiniteDifference\MOL\_discretization.jl:350
[3] top-level scope
@ In[13]:2
[4] eval
@ .\boot.jl:360 [inlined]
[5] include\_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base .\loading.jl:1094
Hopefully it is helpful for me to post this here. Let me know if there is a fix.
Thanks!
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [June 6, 2021, 3:27pm UTC](https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468/2 "2021-06-06T15:27:48Z")
That needs to be updated for [Add domains by tinosulzer · Pull Request #245 · JuliaSymbolics/Symbolics.jl · GitHub](https://github.com/JuliaSymbolics/Symbolics.jl/pull/245)
---
### Author:  [@gbrunkhorst](https://discourse.julialang.org/u/gbrunkhorst)
#### Post date: [June 6, 2021, 3:41pm UTC](https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468/3 "2021-06-06T15:41:30Z")
Thanks! Let me know if there are next steps for me (or wait for an update). I’m unclear if “That needs to be updated” means the tutorial, the source code, the package, or something else needs to be updated. Thanks.
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [June 6, 2021, 5:45pm UTC](https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468/4 "2021-06-06T17:45:07Z")
See that pull request. It needs to update to using Interval, in the docs and maybe some in the package. This is to be expected though since the tutorial has a big bold “this is pre-alpha” on the top! But this is rather easy to fix, so if you want to dive in feel free to open a PR. It’s mostly just a find/replace.
---
### Author:  [@gbrunkhorst](https://discourse.julialang.org/u/gbrunkhorst)
#### Post date: [June 6, 2021, 6:09pm UTC](https://discourse.julialang.org/t/diffeqoperators-symbolic-tutorial-throwing-error/62468/5 "2021-06-06T18:09:30Z")
Thanks for the clarification, I saw the pre-alpha flag. I’ll see if I can understand the find/replace sufficiently to help out.