def geometric_conj_ab(a, b):
 (a, b) = map(sympify, (a, b))
 if ((abs(a) == oo) or (abs(b) == oo)):
  return (a if (abs(b) == oo) else b)
 else:
  return ((a * b) / (a + b))

def geometric_conj_ab ( a , b ) : ( a , b ) = map ( sympify , ( a , b ) ) if ( ( abs ( a ) == oo ) or ( abs ( b ) == oo ) ) : return ( a if ( abs ( b ) == oo ) else b ) else : return ( ( a * b ) / ( a + b ) )
conjugation relation for geometrical beams under paraxial conditions .