Multivariable calculus - Wikipedia
https://en.wikipedia.org/wiki/Multivariable_calculusA study of limits and continuity in multivariable calculus yields many counterintuitive results not demonstrated by single-variable functions. For example, there are scalar functions of two variables with points in their domain which give different limits when approached along different paths. E.g., the function. approaches zero whenever the point is approached along lines through the origi…