trinary mathematical operator: [derivative of a with respect to b of degree c].

- salpo
- x
_{1}is sloped/inclined/slanted/aslant with angle x_{2}to horizon/frame x_{3}.

- cneparbi
- x
_{1}is the derivative of x_{2}with respect to x_{3}. - sau'au
- mekso binary operator: del, nabla, quabla, partial-derivative vector/tensor operator; outputs the functional-valued formal-covector (or analog thereof) of partial derivatives with respect to X
_{1}(tensor in the same format and order), each degree X_{2}(default: 1).