For the function $f\left(x\right)=\underset{n\to \infty }{\lim }\frac{\ln \left([1+9x^2]\right)-9^n{x}^{2n}\cos \left(9x^2\right)}{1+9^n{x}^{2n}}$ ,  number of points of discontinuity in $(-3,3)$  is (where [.] denotes G.I.F)