x*(1-\frac{x^2}{2}+\frac{x^4}{8}-\frac{x^6}{48}+\frac{x^8}{384})=sqrt(2*pi)-(\frac{x}{1\cdot 1}-\frac{x^3}{2\cdot 3}+\frac{x^5}{8\cdot 5}-\frac{x^7}{48\cdot 7}+\frac{x^9}{384\cdot 9}+0.5*sqrt(2*pi))