Need help for these two commands

These are two lines

dif = length(sig) - length(ADSR);

x = cat(2, ADSR, zeros(1,dif));

What is purpose of zeros(1,dif) Plz explain

Answer 1

[Wayne King]

It is appending (padding) zeros on the end of ADSR so that the total length of x is the length of the signal, sig:

length(ADSR)+ (length(sig)-length(ADSR))

Answer 2

[Fangjun Jiang]

It creates a 1 by dif matrix and all its value is zero.

cat(2, ADSR, zeros(1,dif)) is the same as [ADSR, zeros(1,dif)]

I want to give a caution on using function length().

    LENGTH(X) returns the length of vector X.  It is equivalent
    to MAX(SIZE(X)) for non-empty arrays and 0 for empty ones.

Answer 3

[Walter Roberson]

The code is constructing a vector that pads ADSR with 0s to be the same length as sig is.

Another way of doing this would be:

x = zeros(size(sig));
x(1:length(ADSR)) = ADSR;