Introduction - If you have any usage issues, please Google them yourself
Simply speaking, the so-called fitting refers to a function known to a number of discrete function values (f1, f2, ..., fn), by adjusting the number of undetermined coefficient function f (λ1, λ2, ..., λ3), makes the function and known points of difference (least squares significance) the smallest. To be determined if the function is linear, is called linear regression or linear regression (mainly in the statistics), otherwise known as non-linear fitting, or nonlinear regression. Expressions can also be a sub-function, this case is called spline fitting.