Julia 0.6 breaks scaling with LinSpace grid?

[gabrielgggg]

Hello, all! I upgraded to the latest version and now some code is complaining about my use of LinSpace. Am I doing something wrong? The error I get is:

ERROR: MethodError: no method matching coordlookup(::LinSpace{Float64}, ::Float64)
Closest candidates are:
  coordlookup(::UnitRange, ::Any) at /home/gmihalache/.julia/v0.6/Interpolations/src/scaling/scaling.jl:71
  coordlookup(::StepRange, ::Any) at /home/gmihalache/.julia/v0.6/Interpolations/src/scaling/scaling.jl:73
  coordlookup(::StepRangeLen, ::Any) at /home/gmihalache/.julia/v0.6/Interpolations/src/scaling/scaling.jl:76
Stacktrace:

Thank you!

[sglyon]

Hi @gabrielgggg could you please post a code snippet you used to construct your interpolation object?

Thank you!

[gabrielgggg]

Sure, one of the calls is:

iV = Interpolations.scale(interpolate(V0, ( BSpline(Cubic(Line())), BSpline(Cubic(Line())) ), OnCell()), gg.y, gg.b)

where the type of V0 is Array{Float64, 2} and gg.y and gg.b are LinSpace{Float64}.

BUT!!! This self-contained example works:

using Interpolations
V0 = Array{Float64, 2}(5, 6)
yGrid = linspace(-1.0, 1.0, 5)
bGrid = linspace(2.0, 3.0, 6)
iV = Interpolations.scale(interpolate(V0, ( BSpline(Cubic(Line())), BSpline(Cubic(Line())) ), OnCell()), yGrid, bGrid)

This seems to be because linspace now returns something with type

julia> typeof(yGrid)
StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}

whereas in my code I was using LinSpace{Float64} variables for my grids. I never know what's the idiomatic way to do stuff like this, so any advice is greatly appreciated!

[gabrielgggg]

The old code works if I don't explicitly type my grid variables. Alternatively, I could type them using the new StepRangeLen type. It's not clear to me what's best practice. I'm sorry if this is not Interpolations-specific!

[sglyon]

Hey @gabrielgggg you've identified this as not Interpolations.jl specific

This section of the release notes explains the change and what the new StepRangeLen type does.

Given that this is the default behavior going forward, I would recommend that once you are ready to move to Julia 0.6 full time that you use that type instead of LinSpace when typing your variables. Then, like you noted above, Interpolations.jl will just work.

[timholy]

The implementation for StepRange is effectively the same as the implementation for StepRangeLen which could also be used for LinSpace. No reason we can't support a general Range object.