I plotted these functions in the extended complex plane and some experts in this community helped me to analyze these figures and we got these explanations (Thanks to all the experts who helped me a lot):
1-In the yellow area the cos(phase(f(z))) =1 that means the phase(f(z)) =0.
2-In the blue area the cos(phase(f(z))) =-1 that means the ![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1490537/image.png)
What I learned before that
this happens at the points when
on the positive real axis and
this happen at the points when
on the negative real axis. My question
why as time passes these colors (yellow for ( the phase(f(z)) =0) ) and blue when
change their position as seen in the following figure? Does that mean the real and imaginary axes rotated with time and changed their positions?
I appreciate any help