def cat(x, y, alpha, eta=1, purity=1):
    cos = numpy.cos
    exp = numpy.exp
    return (1 + eta * (exp(-x ** 2 - (y - alpha) ** 2) + exp(-x ** 2 -
    (y + alpha) ** 2) + 2 * purity * exp(-x ** 2 - y ** 2) * cos(2 * \
    alpha * x)) / (2 * (1 + exp(- alpha ** 2)))) / 2
Multiphoton shrodinger cat. eta is the fidelity, alpha the number
dataset/ETHPy150Open enthought/mayavi/docs/source/mayavi/auto/wigner.py/cat