Calculates the entropy of your system at each point in time 
    for your given phase space density evolution in time.
    
    Parameters
    ----------
    phase_space_density_array : array
        array which represents the phase space density at every point in time

    Returns:
    -------
    entropy : array
        The entropy of the particle at every point in time via the phase space density method.

def calc_entropy(phase_space_density_array):
    """
    Calculates the entropy of your system at each point in time 
    for your given phase space density evolution in time.
    
    Parameters
    ----------
    phase_space_density_array : array
        array which represents the phase space density at every point in time

    Returns:
    -------
    entropy : array
        The entropy of the particle at every point in time via the phase space density method.
    
    """
    entropy = -_scipy.constants.Boltzmann*_np.log(phase_space_density_array)
    return entropy