ABSTRACT
This chapter discusses different types of interpolation methods and discovers interpolation of interval data especially. Considering the many applications of mathematical functions in different methods, it is important to have a function rule. Sometimes, we may only have some data from a function, and if we want to know the behavior of the function, we must have a graph of the function. This can be done using a very powerful interpolation function such as spline. Sometimes, as we consider the approximate location of points or coordinates, the drawn curve may not pass through some points, in which case, we will have another form of approximation called the curve fitting. In both cases, for better approximation, we select an interpolation function that behaves similar to the approximate behavior of the points and their distribution.
