i dont know whats the problem with this fails with variable test

function [summa index]=max_sum(v,n)
m=zeros(1,length(v));
x=zeros(1,length(v));
j=1;
if n>length(v)
    summa=0;
    index=-1;
    
elseif n<length(v)
    for ii=1:length(v)
        if ii<=length(v)-n+1
           x=v(:,ii:n+ii-1);
           m(ii)=sum(x); 
        else   
            x=v(:,ii:length(v));
            z=v(:,1:j);
            m(ii)=sum(x)+sum(z);
            j=j+1;
        end
    end
    [y i]=max(m);
    summa=max(y);
    index=max(i);
else
    summa=sum(v);
    index=1;
end

[Mario Malic]

We also don't know what's the problem. Could you tell us?

What is this?[summa index]

[Shekhda Dhrumil]

here v is an array,n is a number.

we have to make continuous group of n element from v.

then we need to find whose sum is highest and then we need to provide that highest sum as output in summa and the index of first element of that group in output argument index.

Answer 1

[Image Analyst]

When you do

m(ii)=sum(x); 

x is a 2-D array. So sum(x) is a 1-D array, because it's summing each column, and you're trying to put a whole array into a single element, the ii'th element of m. What do you intend to sum? The whole array? If so, do this:

m(ii)=sum(x(:)); 

[Shekhda Dhrumil]

no its not working

[Image Analyst]

length() is the max size in either direction. You need to get the rows and columns explicitly:

[rows, columns] = size(v);

Then use rows or columns in your loop(s).

Is v a vector or a 2-d matrix? How is the "continuous group of n element from v" to be made from v? Have you considered conv() or conv2() to sum of values in a sliding window? Or movmean()?

[Shekhda Dhrumil]

v is just a vector not 2-d array so i think length() is ok to use.

[Image Analyst]

If it's a vector, with one index, then why are you doing things like

x = v(:, ii:n+ii-1) 

which means "take all rows, and the ii'th column through the (n+ii+1)'th row? It should have only one index, not 2.

[Shekhda Dhrumil]

so that i can copy that particular part of that vector in other vector and then add its all element to find sum of that part.

is there any simple alternative to that problem?

[Image Analyst]

I don't think you need the if and for loop. You can simply use movmean().