The equation should be
ϕ = tan − 1 ( Im ( G ( i ω ) ) Re ( G ( i ω ) ) ) . {\displaystyle \phi =\tan ^{-1}\left({\frac {\operatorname {Im} \left(G(i\omega )\right)}{\operatorname {Re} \left(G(i\omega )\right)}}\right).}
Return to errata.
ϕ = cos x 2 {\displaystyle \phi =\cos {\frac {x}{2}}}
