I’d like to preserve the custom type after it has been broadcasted. Currently I have the following:

```
struct SigmaPoints{T} <: AbstractMatrix{T}
x0::Array{T, 1}
xi::Array{T, 2}
end
Base.size(S::SigmaPoints) = (size(S.xi, 1), size(S.xi, 2) + 1)
Base.getindex(S::SigmaPoints{T}, inds::Vararg{Int,2}) where {T} = if inds[2] == 1 S.x0[inds[1]] else S.xi[inds[1], inds[2] - 1] end
Base.setindex!(S::SigmaPoints{T}, val, inds::Vararg{Int,2}) where {T} = if inds[2] == 1 S.x0[inds[1]] = val else S.xi[inds[1], inds[2] - 1] = val end
```

`SigmaPoints`

is essentially a matrix where the first column is saved in `x0`

instead of `xi`

```
julia> S = SigmaPoints(ones(2), zeros(2,4))
4×5 SigmaPoints{Float64}:
1.0 0.0 0.0 0.0 0.0
1.0 0.0 0.0 0.0 0.0
julia> S .+ ones(2)
4×5 Array{Float64,2}:
2.0 1.0 1.0 1.0 1.0
2.0 1.0 1.0 1.0 1.0
```

Mathematically that’s correct. However, I’d like to preserve the `SigmaPoints`

type for basic operations (e.g. multiplications, additions, etc) with scalars and vectors.

I have read the manual, but I am struggling to map the example to this case.