The definition of differential in mathematics: from the function B=f(A), two groups of numbers A and B are obtained. In A, when dx approaches itself, the limit of the function at dx is called the differential of the function at dx, and the central idea of the differential is infinite division.

Precautions:

Generally speaking, differential and integral are a function transformation-through a certain process, from a known function to a new function, which is a mapping (correspondence) in which "domain" and "range" are function sets.

If the difference is not considered as a constant, then differentiation and integration are inverse transformations: first, differentiate a function, and then integrate it, which is equal to itself; Integrate and then differentiate a function equal to itself. Division is the inverse of multiplication, and integration is the inverse of differentiation.

Just as multiplication must be feasible in the integer range, division may not be feasible (for example, if 5 is divided by 3, the result is out of the integer range. ), in the range of elementary function, differentiation must be feasible, and integration may not be feasible (for example, the result of integrating elementary function e (-x 2) is beyond the range of elementary function).