Hi,
Here is one of the possible ways to generate your signals:
N = 1e3; % Number of data points
T0 = pi; % Can be any number
t = linspace(0, T0, N); % time space with N data points
f0=1000; f1=2000; f2=2000;
x1 = sin(2*pi*f0*t)+sin(2*pi*f1*t)+sin(2*pi*f2*t);
T1 =2*pi; % Can be any number
t1 = linspace(0, T1-pi/N, N); % time space with N data points
x11 = sin(2*pi*f0*t1);
T2 = 3*pi; % Can be any number
t2 = linspace(T1, T2-pi/N, N); % time space with N data points
x22 = sin(2*pi*f1*t2);
T3 = inf;
t2 = linspace(T2, T3, N);
x33 = sin(2*pi*f2*t2);
Good luck
