The position of default angle 0

Please, I want to know the position of default angle 0 on the circle , And the direction of angular rotation is Clock-wise or Counter Clock-wise ?

[John D'Errico]

This is about MATLAB? Pretty sure that wikipedia would tell you that. Ok, I know that for a fact. Maybe search for "polar coordinates". Why wait for an answer?

[Walter Roberson]

Which circle? And which direction are you looking at it from?