Frequency-swept cosine generator, with a time-dependent 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.
t : ndarray
poly : 1D ndarray (or array-like), or instance of numpy.poly1d
phi : float, optional
A numpy array containing the signal evaluated at ‘t’ with the requested :
time-varying 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. :
New in version 0.8.0.