def chirp(t, f0, t1, f1, method='linear', phi=0, vertex_zero=True):
    # 'phase' is computed in _chirp_phase, to make testing easier.
    phase = _chirp_phase(t, f0, t1, f1, method, vertex_zero)
    # Convert  phi to radians.
    phi *= pi / 180
    return cos(phase + phi)
Frequency-swept cosine generator.
dataset/ETHPy150Open scipy/scipy/scipy/signal/waveforms.py/chirp