Hi,

I do not fully understand what you want to achieve, but "to tell if the enemy is on the left or right" you can do the following:
(I did not use the code-Tags here, as the code was strangely messed up)

vev_diff(temp,you.x, my.x);
vec_to_angle(zombang,temp);

var angleDifference[2];
angleDifference.pan = ang(zombang.pan - my.pan);

// this code is inelegent as it is just an example
if (angleDifference.pan > 0) { my.pan -= 4.5*time_step; }
if (angleDifference.pan < 0) { my.pan += 4.5*time_step; }