Fermi's Golden Rule
From Lumipedia
\begin{Bmatrix}
B_{0}(z)=1\\
B_{1}(z)=z-1\\
B_{2}(z)=2z^2-3z+1\\
etc.\\
\end{Bmatrix} and generally [math]B_{k}(z)=\sum_{h=0}^{k}b_{k, h}z^{k}[/math]
[math] f(x) = \begin{cases} 1 & -1 \le x \lt 0 \\ \frac{1}{2} & x = 0 \\ 1 - x^2 & \text{otherwise} \end{cases} [/math]
