NewFit creates a new polynomial fitting context, with points and the degree of the polynomial.

NewFitIntRange is similar to NewFit, except it only accept integer value for x, and the value of x must be in range [0, 1024).

PowCache caches x^i in PowCache[x][i].

XTXCache3 is the cache of XᵀX of degree 2 with integer matrix X = [[1,0,0], [1,1,1], [1,2,4]...].

Fit models a polynomial y from sample points xs and ys, to minimizes the squared residuals.