I am not certain what you are asking.
Try this —
L = 30; % Signal Length (s)
Fs = 200; % Sampling Frequency (Hz)
t = linspace(0, Fs*L, Fs*L+1)/Fs; % Time Vector
f = sin(2*t).^3;
figure
plot(t, f)
grid
xlabel('Time (s)')
ylabel('Amplitude')
title('$f(t) = sin(2\cdot t)^3$', 'Interpreter','latex')
.
