Saving data in a loop as a vector

I have a binomial expansion which requests the user to input an x value between (-1,1). I am trying to save the term by term output of the above code into a vector but everything i try gives me an error. I think its perhaps because my n sequence starts at zero? If i try to put binx(n) = .... it throws an error.

I basically just want to save all the passes through the loop in a single vector, currently it only saves the last one. All other examples I've found online don't seem to work in this case.

Answer 1

[dpb]

Indeed, Matlab arrays are immutably 1-based...just compute an index...

N=12;                % generalize number terms...
binx=zeros(N+1,1);   % preallocate for output
term=binx;
idx=0;               % index variable initialize...
for n=0:N
  idx=idx+1;         % and increment first...
  term(idx) = ...
  binx(idx) = binx(idx-1) + term;
  ...

Of course, w/ Matlab, you could compute term() then bin becomes

bin=cumsum(term);

after the loop. This then would cause rearrangement of your output displays, so not necessarily the thing to do here; simply pointing out Matlab vectorized syntax in general...

[sourestdeeds]

Aye, i tried a method like this before, and just tried the method shown and still get this error "Subscript indices must either be real positive integers or logicals."

[sourestdeeds]

Your answer has clarified why this approach isn't ideal though!

I will try a different method for plotting!

[dpb]

Woops...forgot to special-case the first instance of idx-1; better route would be to compute the first value prior to entering the loop, the run the loop from 1:N, and initializing idx=1 instead of 0.