which implies that the concept of DTM is derived from Taylor series expansion, but the
method does not evaluate the derivative symbolically? However, relative derivatives are
calculated by an iterative procedure which is described by the transformed equations of the
original functions. In this paper, we use the lower case letters to represent the original
functions and an upper case letter to represent the transformed functions. In actual
applications, the function y (x) is expressed by a finite series equation (3) can be written as