Frequencyswept cosine generator, with a timedependent frequency specified as a polynomial.
This function generates a sinusoidal function whose instantaneous frequency varies with time. The frequency at time t is given by the polynomial poly.
Parameters :  t : ndarray
poly : 1D ndarray (or arraylike), or instance of numpy.poly1d
phi : float, optional


Returns :  A numpy array containing the signal evaluated at ‘t’ with the requested : timevarying frequency. More precisely, the function returns :
where `phase` is the integral (from 0 to t) of ``2 * pi * f(t)``; : ``f(t)`` is defined above. : 
See also
scipy.signal.waveforms.chirp
Notes
New in version 0.8.0.