Multi Dimension Interpolation with Unitful

General Usage
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1

I am trying to interpolate f : \mathbb{R_{units}} \to \mathbb{R_{units}}^3 where there are unitful units on both the grid and the data.

I found this example that showed me how to get f : \mathbb{R} \to \mathbb{R}^3 interpolation working without units, but when I add units it errors out.

This works fine:

f(a) = 2*a * u"A"
agrid = (0:0.5:5) * u"A"
vals = [f(a) for a in agrid]
itp = interpolate((agrid,), vals, Gridded(Linear()))

And so does this:

f(a) = [1*a, 2*a, 3*a]
agrid = (0:0.5:5) 
vals = [f(a) for a in agrid]
itp = interpolate((agrid,), vals, Gridded(Linear()))

But when I combine multi-dim and Units it doesn’t work:

f(a) = [2*a, 1*a, 3*a] * u"A"
agrid = (0:0.5:5) * u"A"
vals = [f(a) for a in agrid]
itp = interpolate((agrid,), vals, Gridded(Linear()))

It throws:

MethodError: no method matching Interpolations.GriddedInterpolation(::Type{Unitful.Quantity{Float64, 𝐈^2, Unitful.FreeUnits{(A^2,), 𝐈^2, nothing}}}, ::Tuple{StepRangeLen{Unitful.Quantity{Float64, 𝐈, Unitful.FreeUnits{(A,), 𝐈, nothing}}, Base.TwicePrecision{Unitful.Quantity{Float64, 𝐈, Unitful.FreeUnits{(A,), 𝐈, nothing}}}, Base.TwicePrecision{Unitful.Quantity{Float64, 𝐈, Unitful.FreeUnits{(A,), 𝐈, nothing}}}, Int64}}, ::Vector{Vector{Unitful.Quantity{Float64, 𝐈^2, Unitful.FreeUnits{(A^2,), 𝐈^2, nothing}}}}, ::Interpolations.Gridded{Interpolations.Linear{Interpolations.Throw{Interpolations.OnGrid}}})

The type `Interpolations.GriddedInterpolation` exists, but no method is defined for this combination of argument types when trying to construct it.

Is there something I am doing wrong or is Unitful not yet fully supported in Interpolations? (I have run into that with other packages, most work surprisingly well with units but not always)

2

See if this solution helps, basically collecting the ranges to arrays.

3

Thanks, no I still get the same error when they are vectors.

But maybe I will just use a similar wrapper like they were using to strip and re-attatch units :frowning: