The function \(f\) has derivatives of all orders for all real numbers, and \(f^{(4)}(x)=e^{\sin{x}}\). If the third-degree Taylor polynomial for
\(f\) about \(x=0\) is used to approximate \(f\) on the interval \([0,1]\), what is the Lagrange error bound for the maximum error on the interval \([0,1]\) ?
The error is given by:
$$ R_n(x)= \frac{f^{n+1}(z)}{(n+1)!}(x-c)^{n+1} $$
The value of \(z\) that will maximize the error on the interval \([0,1]\) is \(z=1\) since sine increases until \(\pi/2\).
Therefore, the maximum error when \(n=3\) (3rd degree polynomial), \(c=0\) (centered around \(x=0\)) and \(z=1\) is:
$$ R_3(x)= \frac{f^{3+1}(1)}{(3+1)!}(1-0)^{3+1} $$
$$ = \frac{f^4(1)}{4!} $$
$$ = \frac{e^{\sin1}}{4!} $$
$$ \approx \boxed{0.097} $$