# Method not found error

**URL:** <https://discourse.julialang.org/t/method-not-found-error/108760>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [January 13, 2024, 5:29am UTC](https://discourse.julialang.org/t/method-not-found-error/108760 "2024-01-13T05:29:34Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![temp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/temp/32/202801_2.png) [@temp](https://discourse.julialang.org/u/temp)\
**Post date:** [January 13, 2024, 5:29am UTC](https://discourse.julialang.org/t/method-not-found-error/108760/1 "2024-01-13T05:29:34Z")

</div>

Hi, I’m new to Julia. I can’t follow what’s going wrong here.  
When I run the following code in REPL, it is able to run and create a chain of convolution layers:

```julia
A = Chain([Flux.Conv((3,3), 1=>3, stride=1, pad=2, bias=false) for _ in 1:3])

```

However, when I include it in a function in a file called net.jl, in the following way:

```julia
using LinearAlgebra, Flux 

function init_filters(K = 3, #num unrollings
                    M = 64, #num filters in each filter bank 
                    P = 7, #square filter size, 
                    s = 1, #stride of convolutions
                    C = 1, #num input channels
                    t₀ = 0 #threshold
                    )

        A = Chain([Flux.Conv((P,P), C=>M, stride=s, pad=(P-1)//2, bias=false) for _ in 1:K])
        B = Chain([Flux.ConvTranspose((P,P), M=>C, stride=s, pad=(P-1)//2, bias=false) for _ in 1:K])

        W = randn(M,C, P, P) 
        τ = t₀ * ones(K, 2, M, 1, 1)

        for k in 1:K
            A[k].weight = W
            B[k].weight = W
        end

        return A, B, τ
end
init_filters()

```

gives the following error:

```julia
ERROR: MethodError: no method matching expand(::Val{4}, ::Rational{Int64})

Closest candidates are:
  expand(::Any, ::Tuple)
   @ Flux ~/.julia/packages/Flux/UsEXa/src/layers/conv.jl:6
  expand(::Any, ::Integer)
   @ Flux ~/.julia/packages/Flux/UsEXa/src/layers/conv.jl:7

Stacktrace:
 [1] calc_padding(lt::Type, pad::Rational{Int64}, k::Tuple{Int64, Int64}, dilation::Tuple{Int64, Int64}, stride::Tuple{Int64, Int64})
   @ Flux ~/.julia/packages/Flux/UsEXa/src/layers/conv.jl:48
 [2] Conv(w::Array{Float32, 4}, b::Bool, σ::Function; stride::Int64, pad::Rational{Int64}, dilation::Int64, groups::Int64)
   @ Flux ~/.julia/packages/Flux/UsEXa/src/layers/conv.jl:158
 [3] Conv(k::Tuple{Int64, Int64}, ch::Pair{Int64, Int64}, σ::typeof(identity); init::Function, stride::Int64, pad::Rational{Int64}, dilation::Int64, groups::Int64, bias::Bool)
   @ Flux ~/.julia/packages/Flux/UsEXa/src/layers/conv.jl:168
 [4] (::var"#22#24"{Int64, Int64, Int64, Int64})(#unused#::Int64)
   @ Main ./none:0
 [5] iterate
   @ ./generator.jl:47 [inlined]
 [6] collect
   @ ./array.jl:782 [inlined]
 [7] init_filters(K::Int64, M::Int64, P::Int64, s::Int64, C::Int64, t₀::Int64)
   @ Main ~/Documents/Untitled Folder/CDLNet/net.jl:24
 [8] init_filters()
   @ Main ~/Documents/Untitled Folder/CDLNet/net.jl:23
 [9] top-level scope
   @ ~/Documents/Untitled Folder/CDLNet/net.jl:68

```

PS: Updating Flux did not help.

---

<div class="post-metadata">

**Author:** ![gdalle](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gdalle/32/27854_2.png) [@gdalle](https://discourse.julialang.org/u/gdalle)\
**Post date:** [January 13, 2024, 8:42am UTC](https://discourse.julialang.org/t/method-not-found-error/108760/2 "2024-01-13T08:42:44Z")

</div>

Hi!  
Could you provide a complete MWE (minimum working example) with all the variables and package imports necessary? This will be helpful for debugging

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**Author:** ![bertschi](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bertschi/32/33462_2.png) [@bertschi](https://discourse.julialang.org/u/bertschi)\
**Post date:** [January 13, 2024, 9:26am UTC](https://discourse.julialang.org/t/method-not-found-error/108760/3 "2024-01-13T09:26:49Z")

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The problem is that your padding in not an Integer:

```julia
A = Chain([Flux.Conv((3,3), 1=>3, stride=1, pad=(7-1)//2, bias=false) for _ in 1:3])

```

fails with the same error. Instead of constructing a rational – as `//` does (check the docs via `?//` in the REPL) – you probably want to use integer division, i.e., `div(7 - 1, 2)` or `(7 - 1) ÷ 2` [`÷` can be entered as `\div<tab>`].

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<div class="post-metadata">

**Author:** ![temp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/temp/32/202801_2.png) [@temp](https://discourse.julialang.org/u/temp)\
**Post date:** [January 14, 2024, 8:37pm UTC](https://discourse.julialang.org/t/method-not-found-error/108760/4 "2024-01-14T20:37:04Z")

</div>

Thanks a lot this solved the problem!