[Help]+Matrix Operation

I found a program from internet, the following is the part code:

t=0:1/1e3:0.999;
a=randint(1,10);
b=ceil(10*t+0.01);
s=a(b);　　　

% I do not know what a(b) means. a is 1*10 matrix，b is 1*1000 matrix.

Who can tell me, thank u!

Answer 1

[Nirmal]

b is being used as an index.

t is an array with elements incrementing my 0.999, which means b is also an array. Now elements of b is used as an index to construct s.

Answer 2

[Sweety]

<<a=[1 2 3;1 2 3]