# Symbolics not simplifying fully

**URL:** <https://discourse.julialang.org/t/symbolics-not-simplifying-fully/89842>\
**Category:** New to Julia\
**Created:** [November 6, 2022, 4:19pm UTC](https://discourse.julialang.org/t/symbolics-not-simplifying-fully/89842 "2022-11-06T16:19:06Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![AwesomeQuest](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/awesomequest/32/38910_2.png) [@AwesomeQuest](https://discourse.julialang.org/u/AwesomeQuest)\
**Post date:** [November 6, 2022, 4:19pm UTC](https://discourse.julialang.org/t/symbolics-not-simplifying-fully/89842/1 "2022-11-06T16:19:06Z")

</div>

When multiplying `expr * expr^-1 ` . `Symbolics.simplify `/ `Symbolics.simplify_fractions` don’t return 1

```julia
julia> using Symbolics

julia> @variables m mol
2-element Vector{Num}:
   m
 mol

julia> simplify(eval(Meta.parse("m^3*mol^-1")) * eval(Meta.parse("m^-3*mol")))
(m^3)*((1 / m)^3)
julia> simplify_fractions(eval(Meta.parse("m^3*mol^-1")) * eval(Meta.parse("m^-3*mol")))
(m^3)*((1 / m)^3)

```

What am I missing?

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<div class="post-metadata">

**Author:** ![jmair](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jmair/32/35117_2.png) [@jmair](https://discourse.julialang.org/u/jmair)\
**Post date:** [November 6, 2022, 4:52pm UTC](https://discourse.julialang.org/t/symbolics-not-simplifying-fully/89842/2 "2022-11-06T16:52:28Z")

</div>

The cancellation is not well defined for `m=0`, could that be why?

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<div class="post-metadata">

**Author:** ![Benny](https://avatars.discourse-cdn.com/v4/letter/b/49beb7/32.png) [@Benny](https://discourse.julialang.org/u/Benny)\
**Post date:** [November 7, 2022, 5:33am UTC](https://discourse.julialang.org/t/symbolics-not-simplifying-fully/89842/3 "2022-11-07T05:33:25Z")

</div>

If that were the case, I would expect the `mol` variables to not cancel either because of `mol=0`

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<div class="post-metadata">

**Author:** ![Syx\_Pek](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/syx_pek/32/6364_2.png) [@Syx\_Pek](https://discourse.julialang.org/u/Syx_Pek)\
**Post date:** [November 7, 2022, 6:27am UTC](https://discourse.julialang.org/t/symbolics-not-simplifying-fully/89842/4 "2022-11-07T06:27:51Z")

</div>

Naively, (added `Symbolics`)

```julia
julia> @variables x
1-element Vector{Num}:
 x

julia> x*inv(x)
1

julia> x^2*inv(x)^2
(x^2)*((1 / x)^2)

julia> x^2*inv(x)*inv(x)
1

```