shz=[e^z-e^(-z)]/2
shz=0,即=[e^z-e^(-z)]/2=0
即:[e^z-e^(-z)]=0
即:e^(2z)-1=0,
e^(2z)=1
2z=Ln1,
z=(1/2)Ln1=(1/2)*[ln1+i(2kpi)]
=(1/2)*[i(2kpi)]
=k(pi)i
(k为任意整数)
注意到:Lnz=ln|z|+iArgz.