CALCULLA - Least squares method calculator: polynomial ...
https://calculla.com/polynomial_regressionFor polynomial degrees greater than one (n>1), polynomial regression becomes an example of nonlinear regression i.e. by function other than linear function. Using the least squares method, we can adjust polynomial coefficients { a 0 , a 1 , … , a n } \{a_0, a_1, \dots, a_n\} { a 0 , a 1 , … , a n } so that the resulting polynomial fits best to the measured data.
Polynomial interpolation - Wikipedia
https://en.wikipedia.org/wiki/Polynomial_interpolationPolynomials can be used to approximate complicated curves, for example, the shapes of letters in typography, given a few points. A relevant application is the evaluation of the natural logarithm and trigonometric functions: pick a few known data points, create a lookup table, and interpolate between those data points. This results in significantly faster computations. Polynomial interpolation also forms the basis for algorithms in numerical quadrature and numerical ordinary differential equat…