Using symsum for arrays

Question

Astrid Schiulaz 2020-6-25

评论： Astrid Schiulaz 2020-6-26

Hello everybody, I have two arrays of data and I want to write a code for this

I tried

s=symsum( (a(:)-mean(a)).*(b(r+1:n-r)-mean(b)), k, 1, n-r);

but it's not working, I tried using solutions with sum but I get an array as an output and I'm not sure how to do this.

Answer 1

Gaurav Aggarwal 2020-6-25

Hi Astrid,

I am not sure how did you do it using the sum function, I tried it and I am getting a single value as an output and not an array.

I am assuming a and b are meant to be the means of their respective arrays, and that limit of summations go from 1 to n-r

%% (a{i} - a)
first = a(1:n-r) - mean(a);
%% (b{i+r} - b)
second = b(r+1:n) - mean(b);
%% 
answer = sum(first .* second);

Let me know if this helps you. Thanks.

Astrid Schiulaz 2020-6-26

It worked, I made a mistake with the indexes. Thanks!