10.6.20 Analytic functions
(3) Condition: Using the Cauchy-Riemann conditions, find out whether this function is analytic or not at least at one point: \[ z \cos \bar{z} \]
Differentiation of analytic functions, finding their real and imaginary parts, finding the number of roots of complex equations using the argument principle, Roucher's theorem and much more in this section.