its neat that default arguments values in #julialang can be computed from other argument values.

you can have a whole bunch of code to define the default argument in the function signature itself.

you can also speed up your broadcasted code with DontMaterialize.jl , this gives identical perfor

if you want more sugary syntax you can use pipes ,

also a small correction in the above code is the output of diff is 1 element a Vector of Vectors and abs. will fail on it .

There's two kinds of maths wizardry that you come across, one you see and know is beyond your skill ingenuity and the other is simple and obvious and yet leaves you wondering why you never thought of it before .