Shortcut multiply and divide for PtEtaPhiMassArrayMethods

[nsmith-]

Not just for speed, but also because earlier it was doing the wrong thing and multplying eta and phi:

a = uproot_methods.TLorentzVectorArray.from_ptetaphim(
    np.full(10, 20.),
    np.linspace(-5, 5, 10),
    np.linspace(-np.pi, np.pi, 10),
    np.full(10, 20.),
)
a * 500

produced phi values in the thousands!

Also, make the __repr__ a bit more clear.

[jpivarski]

I see—you added a specialization to prevent the wrong thing. (Literal multiplication of all elements? Which would be correct for cartesian but wrong for cylindrical coordinates?)

There isn't a test here, but do I have your word that you've tested it? :)

[nsmith-]

I'll add some tests

[jpivarski]

Thank you!

[jpivarski]

And ping me when you're done so that I don't forget to merge it.

[nsmith-]

@jpivarski all good