How do I get a loop that takes a sum to store each value in a vector?

Hey Matlab community, y'all have been very helpful. I got another one for ya. I have a potential formula that takes the sum of series I made. What I want is each sum to be stored in a vector after each iteration, so that I can plot it. heres my code. Also I think it requires an empty vector of correct dimensions such as zeros(blah,blah) but I must have done it wrong because it returns empty

    sumv=0;
n=0;
an=0;
for k=1:120

    an=.68+sumv-(.68+sumv).*.0693;
    sumv=an;

end

Your help and suggestions are greatly appreciated

Answer 1

[Star Strider]

If you want the value of sumv stored at each iteration of your k loop, index it to create a vector from it:

sumv(1)=0;
n=0;
an=0;
for k=1:120
    an=.68+sumv(k)-(.68+sumv(k)).*.0693;
    sumv(k+1)=an;
end

figure(1)
plot(sumv)
grid

You could preallocate by putting:

sumv = zeros(1,121);

in place of:

sumv(1)=0;

That’s good programming practice, but here it likely doesn’t make much of a difference in terms of speeding up your loop. I decided to keep with your original construction rather than preallocate.

[Adam Palmer]

Alright, I gotcha. Thanks Star Strider!

[Star Strider]

My pleasure!

(Your ‘y’all’ got my attention. W&L and UVA here...)