Summation with a vector

Hi guys I'm new here and I'm just learning Matlab for signal processing.

I'm trying to solve this summation:

I've tried using sum:

    >> n=[-10:10];
    >> x=zeros(1,length(n));
    >> sum(x(n==i),i=1..10);

but I'm getting a not a valid target assignment error..

I also saw symsum but I don't know how to implement that on computing a vector.

Please help me, and thanks in advance. P.S. I'm using MATLAB 7.12.

Answer 1

[Azzi Abdelmalek]

n=-10:10
x=[zeros(1,11) ones(1,10)]
stem(n,x)

[Brent]

I'm sorry but can you explain 2nd line of the code? I don't get how you did the summation from that. And to make sure, is the output zeros from -10:0 and ones from 1:10?

[Azzi Abdelmalek]

By definition, Kronecker delta function is defined as:

delta(k)=1 if k=0
delta(k)=0 elsewhere

you have the sum of delayed Kronecker delta function,

delta(k-1)=1 if k=1
delta(k-1)=0 elsewhere

delta(k-2)=1 if k=2
delta(k-2)=0 elsewhere
...

delta(k-10)=1 if k=10
delta(k-10)=0 elsewhere

Make the sum of these delayed signals, you will find what I posted above