def waist2rayleigh(w, wavelen):
 (w, wavelen) = map(sympify, (w, wavelen))
 return (((w ** 2) * pi) / wavelen)

def waist2rayleigh ( w , wavelen ) : ( w , wavelen ) = map ( sympify , ( w , wavelen ) ) return ( ( ( w ** 2 ) * pi ) / wavelen )
calculate the rayleigh range from the waist of a gaussian beam .