MATLAB: Arcus tangent function error

Question

Hi, I have created a function for calculating arc of tangent. I have occured error saying "Output argument 'teta' is not assigned on some execution paths"

    function teta = myatan(x, z)
    z = -z;
    if nargin==1
    x_o=1;    
    end
    if x>0
      teta=atan(z/x);
    elseif z>=0 & x<0
      teta=pi+atan(z/x);
   elseif z<0 & x<0
      teta=-pi+atan(z/x);
   elseif z>0 & x==0
      teta=pi/2;
   elseif z<0 & x==0
      teta=-pi/2;
   end

Answer 1

You don't cover the case where x==0 and z==0.