def rayleigh2waist(z_r, wavelen):
 (z_r, wavelen) = map(sympify, (z_r, wavelen))
 return sqrt(((z_r / pi) * wavelen))

def rayleigh2waist ( z_r , wavelen ) : ( z_r , wavelen ) = map ( sympify , ( z_r , wavelen ) ) return sqrt ( ( ( z_r / pi ) * wavelen ) )
calculate the waist from the rayleigh range of a gaussian beam .