how to interpret this expression?

Could you please put the braces for this expression. I mean does this expression mean

a) a( N - winLength * 2 : N )=0; this

1) a( N - ( winLength * 2 ) : N ) = 0; or

2) a( ( N - winLength ) * 2 : N ) = 0;

n the same with this expression also

b) a ( 1 : winLength * 2 ) = 0;

1) a ( 1 : ( winLength * 2 ) ) = 0; or

2) a ( (1 : winLength ) * 2 ) = 0;

Answer 1

[David Sanchez]

Let us suppose

a = [1 2 3 4 5 6 7 8]; winLength = 3; N = 7;

- a( N - winLength * 2 : N )=0 -> elements from N-winLength*2 till element N is zero: N-winLength*2 = 7-3*2=1 -> a(1:7)=0 a = [0 0 0 0 0 0 0 8]

- a( N - ( winLength * 2 ) : N ) = 0 -> same than above

- a( ( N - winLength ) * 2 : N ) = 0 -> (N-winLength)*2=(7-3)*2 =4*2=8 -> a(8:7) -> this produces an empty matrix for the example presented, but I'm sure you can think about any other example.

- a(1:winLength*2) = 0 is the same than a(1:(winLength*2)) = 0 -> a(1:3*2) = a(1:6) = [1 2 3 4 5 6]

- a((1:winLength)*2) = a((1:3)*2) = a(1:3)*2 = [2 4 6]

[KJDS SRINIVASA RAO]

Thanks for your help