How do I write a loop which creates a random number and adds the previous values

This is how i try it

for i=1:23;
    a(i) = randn(1);
    a = a + a(i);
end

Answer 1

[Adam Danz]

"How do I write a loop which creates a random number and adds the previous values?"

To add to the previous value, the loop must start at index #2. See inline comments for details.

% number of iterations
n = 23;    

% Always pre-allocate your loop arrays.
% Define the first random value and use NaNs to fill the rest of the array. 
a = [randn(1), nan(1,n-1)];  

% Create random numbers in loop, start with 2
for i = 2:n;
    a(i) = a(i-1) + randn(1); 
end

However, you don't need a loop. This line does the same thing as the loop above.

a = cumsum(randn(1,n)); 

[Jehona]

Thanks a lot Adam!!

Answer 2

[Ajay Kumar]

res_sum = 0;
for i=1:23;
    a(i) = randn(1);
    res_sum = res_sum + a(i);
end

[Jehona]

thanks Ajay!

Do you know how to write it so that I create each time a random number and add it to the previous so that sum is also 1x23?

[Ajay Kumar]

res_sum = 0;
for i=1:23;
    a(i) = randn(1);
    res_sum(i+1) = res_sum(i) + a(i);
end

the sum will be 1x24 because the first value of sum is 0. You can however delete the first element

res_sum = res_sum(2:end);

[Adam Danz]

FYI, you don't need a loop to do this. See the last line of my answer for a non-loop method.

[Ajay Kumar]

Thanks Adam.