Matlab: Generate a pure tone with *.m file

To play a pure tone (sine wave) in Matlab, type the following code in a new file and save it as genTone.m:

function genTone(Fs, F, time)
t = 0:1/Fs:time;
y = sin(2*pi*F*t);
sound(y,Fs);
end

Now play sound in command

>> genTone(16000,100,0.5);
>> genTone(16000,1000,0.5);

The 3000Hz sound below will be wrong since it is greater than the 4000/2 = 2000 Hz Nyquist frequency.

>> genTone(4000,3000,0.5);

References:

how do i generate sound using MATLAB?
Chapter 2: Practical Audio Processing / tonegen.m (http://mcloughlin.eu/)