You sure about that? -0 is the Int 0.
Note that this has nothing to do with find*, it’s simply because that’s what you asked for from isequal.
julia> isequal(0.0, -0.0)
false
julia> isequal(0.0, 0.0)
true
If you don’t want this behavior, you simply need to provide the condition that you expect. == should compare -0.0 and 0.0 equal so you can just do
julia> findall(==(0), a)
4-element Array{Int64,1}:
1
2
3
6