In this activity, it is recommended that you use the Editor window to create a script. $($Editor $$ New $$ Script$).$ Run MATLAB or Octave. In the command window $($or in a new script$)$ try to input the following:

$\%$ Generation of a square wave

$t=0$:$0\mathrm{.}1$:$10$

$y1=sin(t)$

$y3=sin\frac{3^{***}t}{3}$

$y5=sin\frac{5^{***}t}{5}$

$y7=sin\frac{7^{***}t}{7}$

$y9=sin\frac{9^{***}t}{9}$

$y=y1+y3+y5+y7+y9$

plot$(t,y)$

What do the codes $y3,y5,y7$ and $y9$ represent when it comes to generation of square wave?