hypot errors when both units are zero

[platawiec]

On Julia 0.6.2:

import Unitful: m

hypot(0.0m, 0.0m)

gives the error:

ERROR: DimensionError: m and NaN are not dimensionally compatible.
Stacktrace:
 [1] hypot(::Unitful.Quantity{Float64,Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)},Unitful.FreeUnits{(Unitful.Unit{:Meter,Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}}(0, 1//1),),Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}}}, ::Unitful.Quantity{Float64,Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)},Unitful.FreeUnits{(Unitful.Unit{:Meter,Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}}(0, 1//1),),Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}}}) at ./math.jl:475

The same issue occurs for @fastmath hypot, but does not occur when more arguments are passed: hypot(0m, 0m, 0m) evaluates to 0m.

Currently I get around this with:

function Base.hypot(x::Unitful.Quantity, y::Unitful.Quantity)
    if iszero(x) && iszero(y)
        return zero(x)
    else
        return hypot(x, y)
   end
end

but this is a band-aid, so I wanted to open this issue in case there is a better way.

[ajkeller34]

This is resolved when using the very latest Julia build and the master branch of Unitful. The next Unitful release will be for Julia 0.7 only.