m=fefo(1+feD)\mathrm{m}=\frac{f_{e}}{f_{o}}\left(1+\frac{f_{e}}{D}\right)m=fofe(1+Dfe)
fefa(1+feD)\frac{f_{e}}{f_{a}}\left(1+\frac{f_{e}}{D}\right)fafe(1+Dfe)
m=fefo\mathrm{m}=\frac{f_{e}}{f_{o}}m=fofe