Hmm, that's surprising. Looks like we're using generic broadcasting machinery for that operation (check out what @which P.*P returns). Might be good to add .* to this line: https://github.com/JuliaLang/julia/blob/b7f1aa7554c71d3759702b9c2e14904ebdc94199/base/arraymath.jl#L69. Want to make a pull request?
Best, --Tim
