Complex Vectors in Matlab d

Question

I am lost on how to make the vector x j = sin(pi(j-1)/10), j = 1,...,21 in matlab.

Also I am trying to make the vector x j = 2 -j , j=0,1,...,20.

For the last one I tried which I am trying to get the cumulative sum without a for loop.

 x = 0:20
 s = cumsum(2^-x)

I know that the should both have relatively similiar answers but I only understand how to make simple vectors and not these complex ones.

Answer 1

To make the vector x _j = sin(pi(j-1)/10), j = 1,...,21 you do exactly that:

j = 1:21;
xj = sin(pi*(j-1)/10);

Similarly, to make the vector x _j = 2 ^-j , j=0,1,...,20:

j = 0:20
xj = 2.^-j

Do note the .^ operator. You usually want to apply element-wise operators in these cases.