def period(A,M1,M2):
    """ 
    calculate binary period from separation. 

    Parameters
    ----------
    A : float
        separation A Rsun.
    M1, M2 : float
        M in Msun.

    Returns
    -------
    p
        period in days.

    """

    A *= rsun_cm
    print(A)
    velocity = np.sqrt(grav_const*msun_g*(M1+M2)/A)
    print(old_div(velocity,1.e5))
    
    p = 2.*np.pi * A / velocity

    p  /= (60*60*24.)
    return p
def period ( A , M1 , M2 ) : A *= rsun_cm print ( A ) velocity = np . sqrt ( grav_const * msun_g * ( M1 + M2 ) / A ) print ( old_div ( velocity , 1.e5 ) ) p = 2. * np . pi * A / velocity p /= ( 60 * 60 * 24. ) return p
calculate binary period from separation. 

    Parameters
    ----------
    A : float
        separation A Rsun.
    M1, M2 : float
        M in Msun.

    Returns
    -------
    p
        period in days.