def sensitivity(Ntp, Nfn, eps=numpy.spacing(1)):
    """Sensitivity

    Wikipedia entry https://en.wikipedia.org/wiki/Sensitivity_and_specificity

    Parameters
    ----------
    Ntp : int >=0
        Number of true positives.

    Nfn : int >=0
        Number of false negatives.

    eps : float
        eps.
        Default value numpy.spacing(1)

    Returns
    -------
    sensitivity: float
        Sensitivity

    """

    return float(Ntp / (Ntp + Nfn + eps))