roots cannot handle functions that return intervals

[dpsanders]

Also seems to be true of newton1d.

cc @eeshan9815

[Kolaru]

Do you mean something like that ?

julia> g(x::Interval) = x^2 - 2
g (generic function with 1 method)

julia> roots(g, -2..2)
ERROR: MethodError: no method matching g(::ForwardDiff.Dual{ForwardDiff.Tag{#g,IntervalArithmetic.Interval{Float64}},IntervalArithmetic.Interval{Float64},1})

[dpsanders]

I meant something like

julia> g(x) = x..x
g (generic function with 1 method)

julia> roots(g, -2..2)
ERROR: MethodError: no method matching atomic(::Type{IntervalArithmetic.Interval{IntervalArithmetic.Interval{Float64}}}, ::IntervalArithmetic.Interval{Float64})
Closest candidates are:

[Kolaru]

Is there an use case where this makes sense ? If the return value of g is an interval I don't know how g(x) = 0 should be interpreted.

[lbenet]

I've read somewhere that such cases occur and are of interest. Yet, in my opinion, we should perhaps document the current limitations and eventually add that functionality.