complex=cluster is create, add,  get_x, get_y, get_rho, get_theta,
                   equal,similar,copy

  rep=struct[x,y:real]

  create=proc(x,y:real) returns (cvt) signals (overflow,underflow)
         return (rep${x:x,y:y})
         end create

  add=proc(a,b:cvt) returns (cvt) signals (overflow,underflow)
      return (rep${x:a.x+b.x, y:a.y+b.y})
        resignal overflow,underflow
      end add

  get_x=proc(c:cvt) returns (real) signals (overflow,underflow)
        return (c.x)
        end get_x

  get_y=proc(c:cvt) returns (real) signals (overflow,underflow)
        return (c.y)
        end get_y

  get_rho=proc(c:cvt) returns (real) signals (overflow,underflow)
          return (square_root(c.x*c.x+c.y*c.y))
            resignal overflow,underflow
          end get_rho

  get_theta=proc(c:cvt) returns (real) signals (overflow,underflow)
            return (arctangent2(c.x,c.y))
              resignal overflow,underflow
          end get_theta

  equal=proc(c1,c2:cvt) returns (bool)
        return (c1=c2)
        end equal

  similar=proc(c1,c2:cvt) returns (bool)
        return (c1=c2)
        end similar

  copy=proc(c:complex) returns (complex)
       return(c)
       end copy

end complex