\(f(x)=f(0)+\frac{f'(0)}{1!}x+\frac{f''(0)}{2!}x^2+\frac{f^{(3)}(0)}{3!}x^3\cdots\)
\(\cos x =1-\frac{1}{2!}x^2+\frac{1}{4!}x^5-\frac{1}{6!}x^6+\cdots\)
k:
スケール