element-wise max(a,b,c,d) does not work: "ordering is not well-defined for arrays"

[micklat]

I think that if max(a,b,c) is OK, then so should max(a,b,c,d) be. And yet:

julia> xs = [randn(3,4) for _ in 1:4];

julia> max(xs[1],xs[2],xs[3])
3x4 Array{Float64,2}:
 -0.134074   0.426187  0.493014  -0.122643
  1.22624    1.35207   0.879993   0.785643
  0.246837  -0.20105   1.417      0.091331

julia> max(xs[1],xs[2],xs[3],xs[4])
ERROR: ArgumentError: ordering is not well-defined for arrays
 in afoldl at operators.jl:83
 in max at operators.jl:97

[micklat]

would it help the project if I make a PR for some tests under julia/test/reduce.jl?

[JeffBezanson]

Ah, it's those f***ing functors again.

[pao]

would it help the project if I make a PR for some tests under julia/test/reduce.jl?

Absolutely.

[tkelman]

backported in #13107

[micklat]

great! thanks