Fs = 44100; % Sampling frequency in Hz
T = 1; % Total duration of the signal in seconds
f = 120; % Frequency of the oscillator
t = 0:(1./Fs):(T - (1./Fs)); % Time vector
p = 2.0 .* pi .* t; %Phase vector
y = sin(f.*p);

Fs = 44100; % Sampling frequency in Hz
T = 1; % Total duration of the signal in seconds
f0 = 1; % Start chirp at
f1 = 120; % end chirp at (Better keep f1>f0)
t = 0:(1./Fs):(T - (1./Fs)); % Time vector
p = 2.0 .* pi .* t; %Phase vector
y = sin(f0.*p + 2.*pi.*(((f1-f0)/(2.*T)).*t.^2));

s = diff(f0.*p + 2.*pi.*(((f1-f0)/(2.*T)).*t.^2)); % Get the first derivative of phase to find the **rate of change**.

r = f0.*p + 2.*pi.*(((f1-f0)/(2.*T)).*t.^2);  % The phase as above.
z = r(end) + cumsum(ones(1,T.*Fs).*0.017097); % A running sum of duration T.*Fs (samples).