The astute observer will notice from Figure 1.2.4(a) that while the $\mathrm{\δ}$-band is symmetric around $x\=a$, the $\mathrm{\ϵ}$-band that is prescribed by Definition 1.2.1 is not uniformly filled by the corresponding horizontal blue band. If the horizontal blue band is to be symmetric with respect to $L$, then the corresponding edges of the vertical blue band will not be symmetric with respect to $x\=a$. Hence, the beginnings of a computational strategy should start evolving. For an increasing function like $f\left(x\right)\=\ln \left(x\right)$, rather than try manipulating absolute values and inequalities, instead solve the equations $f\left(a-{\mathrm{\δ}}_L\right)\=L-\mathrm{\ϵ}$ and $f\left(a\+{\mathrm{\δ}}_R\right)\=L\+\mathrm{\ϵ}$ for ${\mathrm{\δ}}_L$ and ${\mathrm{\δ}}_R$, then set $\mathrm{\δ}\=\min \left({\mathrm{\δ}}_L\,{\mathrm{\δ}}_R\right)$. This process is formalized in Examples 1.2.5-8.