how to write this range in Matlab?

how do we write the following type of range in matlab:

∑_jϵN=m_nj

i.e. j lies in N.

Thanks.

[Azzi Abdelmalek]

This is not clear

[Walter Roberson]

It looks to me as if it might be the sum over those j that are elements of (N = m) to (N = n), with the term to be summed being j ?

Answer 1

[Walter Roberson]

I am going to guess that this is

sum(N(N >= m & N <= n))

Answer 2

[Steven Lord]

Use linear indexing.

% Generate sample data
x = (1:20).^2;

% Generate a set N over which to sum
N = randperm(20, 5)

% Compute the sum over the set N
sumXN = sum(x(N))

% Since the kth element of x is just k^2, check by summing N^2
% Use .^ to perform element-wise squaring
sumN2 = sum(N.^2)

sumXN and sumN2 should be the same.