def u1transform(self, z):
zeta = (<NUM_LIT:1>/self.rot_matrix)*(z - self.center)  <EOL>x, y = real(zeta), imag(zeta)<EOL>return x/self.radius.real + <NUM_LIT>*y/self.radius.imag<EOL>
This is an affine transformation (same as used in
        self._parameterize()) that sends self to the unit circle.