@Carl Love 
Thanks for your useful suggestions

@Kitonum 
Thanks for your comments and your  attached worksheet. Really, assuming x be complex, I want to plot Real and imaginary parts of x as a function of y for several values of z and r.

@Thomas Richard 
Thanks for your comments. 

Thanks again for your help.

Following my previous question, I tried to plot a new equation, but I couldn't. May you help me to do this?

(k and omega are real)

2.mw

@Rouben Rostamian  

Thank you very much!
I'll double check the parameters.

@Carl Love 

Thanks Sir! I'll check the parameters again.