[RogerL]

I was just about to say the same thing. This is bad code/documentation. Single letter variable names is almost always wrong if it isn't i for an index or such (and even then, would typing 'idx' kill you?). And as parameters, so much worse. Don't make me guess how to call your function please.

[vegabook]

or maybe terseness helps put your brain into pure algorithmic mode? After all that's how mathematical notation works and SDFs are pretty mathematical.