# Flux.jl - Best way to do efficient division by a parameter.

**URL:** <https://discourse.julialang.org/t/flux-jl-best-way-to-do-efficient-division-by-a-parameter/19773>\
**Category:** Machine Learning\
**Tags:** question\
**Created:** [January 18, 2019, 8:16am UTC](https://discourse.julialang.org/t/flux-jl-best-way-to-do-efficient-division-by-a-parameter/19773 "2019-01-18T08:16:22Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![JJB](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jjb/32/6773_2.png) [@JJB](https://discourse.julialang.org/u/JJB)\
**Post date:** [January 18, 2019, 8:16am UTC](https://discourse.julialang.org/t/flux-jl-best-way-to-do-efficient-division-by-a-parameter/19773/1 "2019-01-18T08:16:22Z")

</div>

The following function evaluation:

```julia
function OneDiv(x)
    return 1.0 ./ x
end
@code_warntype OneDiv(Flux.param([0.1]))

```

Compiles to:

```julia
Body::Any
1 ─ %1 = (Core.tuple)(1.0, x)::Tuple{Float64,TrackedArray{…,Array{Float64,1}}}
│ %2 = %new(Base.Broadcast.Broadcasted{Flux.Tracker.TrackedStyle,Nothing,typeof(/),Tuple{Float64,TrackedArray{…,Array{Float64,1}}}}, /, %1, nothing)::Base.Broadcast.Broadcasted{Flux.Tracker.TrackedStyle,Nothing,typeof(/),Tuple{Float64,TrackedArray{…,Array{Float64,1}}}}
│ %3 = invoke Base.materialize(%2::Base.Broadcast.Broadcasted{Flux.Tracker.TrackedStyle,Nothing,typeof(/),Tuple{Float64,TrackedArray{…,Array{Float64,1}}}})::Any
└── return %3

```

Note the `Any` there. I was wondering how to make this compile to a concrete type and remove the `Any` here? If I change `./` to `/`, it fails with: `MethodError: no method matching Float64(::Flux.Tracker.TrackedReal{Float64})`.

My param in question is actually a scalar, an in that case the code works fine with `/`, but I changed it to a single-element array because it didn’t seem like `train!` worked with scalar params. If there is a way for `train!` to work with scalar params, however, then that’s another option.