Regression Data Analysis, Overfitting, Loocv, Crossvalidation, Calibration.
ϕ_1​(x) + c_2 ​ϕ_2​(x) + … + c_i​ ϕ_i​(x) where c_1​, c_2​, …, c_i​ are the coefficients that determine how much of each basis function contributes to the overall function f(x). The choice of basis functions depends on the characteristics of the functions you want to approximate and the specific