Meaning of a sentence in a code

M=3;n=0:30*M-1;
m=0:29;
x=sin(2*pi*0.04*n);
% y=x([1:M:length(x)]);

[Raj Arora]

meaning of commented line?

Answer 1

[KSSV]

You can know it by your self. Just take a print of the values.

M=3;
n=0:30*M-1;
m=0:29;
x=sin(2*pi*0.04*n);
idx = 1:M:length(x)    % generate indices picking every third element of array 

idx = 1×30

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88

y=x(idx)   % extract the elements 

y = 1×30

0 0.6845 0.9980 0.7705 0.1253 -0.5878 -0.9823 -0.8443 -0.2487 0.4818 0.9511 0.9048 0.3681 -0.3681 -0.9048 -0.9511 -0.4818 0.2487 0.8443 0.9823 0.5878 -0.1253 -0.7705 -0.9980 -0.6845 -0.0000 0.6845 0.9980 0.7705 0.1253