Standard Deviation from a certain point

I have written a program where i am running a program to reach an equilibrium but i not want to find the std from the first point were it reaches N/2 till the end of the program i know i need to set up an index but i am not getting much luck on how to go about it can anyone help

N=34 %total number of particles
n=N % amount on left hand side
  TIME = 200; % setting up array for time
  NUMBER = zeros (200, 1); % setting up array for number
NUMBER (1) = n; % causing the plot to start at n  or 4

for i = 2:TIME;

if  n/N > rand(1) ; % if n/N is less than the random number generated take one from the left 
    n = n-1;
else  n = n+1;  % otherwise add one to the left

end

     NUMBER(i) = n;

end

[Image Analyst]

time is a built in function. You do not assign anything to it. Also, you never even initialized the badly-named time or n.

[confused]

sorry i left out two first line in the program! i just edited it also i have taken out the time in my program it was left there from previous workings on the program.

Answer 1

[Thorsten]

Your program is fine. After the loop, you just have to compute

i1 = find(NUMBER == floor(N/2), 1, 'first');
std(NUMBER(i1:end))

This is easier than trying to find i1 within the loop. If you like to do it in the loop, use

i1 = NaN;
for ...

     if ~isnan(i1) && n == floor(N/2)
         i1 = i;
     end