Averaging a Random Walk with Numbers Spanning [-1,1]

Hello,

I need a random number generator whose values span [-1,1] (was using 2*rand-1) and I'm going to count the number of sign changes, then run that a whooole bunch of times and then average the sign changes.

I feel like I'm getting good results when I don't incorporate the '-1' part of the 2*rand-1... can anyone help me clear this issue up?

% Begin Loop for averaging sign changes
for j=1:10 % Number of iterations: better statistics the larger this is
clear count T starty e i
% Preallocate and such
steps=10; % Number of steps to be taken! should be large.. was testing 
% small values
y_init=0;  
y=y_init*ones(1,steps); 
e=2*randn(1,steps)-1; % Numbers span [-1,1]
count=0;
%
% Begin loop to (repetitively) count sign changes in random walk
    for i=1:(steps-1); 
        y(i+1)=y(i)+e(i+1)  
    end 
%    
% From MATLAB 'help rand'
% Example 1: Generate values from the uniform distribution on the
%       interval [a, b].
%          r = a + (b-a).*rand(100,1);
%          newstep= -1 + 2.*rand(100,1)
%
zeros(j)=length(find(abs(diff(sign(y)))==2));
    if j==1
        time=[1:1:steps]; 
        plotrandom=plot(time,y);
    end
end

AVGnoBounces=mean(zeros)

Thanks for any help!!! -Mike

[Walter Roberson]

Naming a variable "zeros" is going to interfere with use of the zeros() function, and is going to confuse readers.

[Michael]

Sorry...

Answer 1

[Matt Fig]

Wouldn't this be easier?

T = 2*rand(1,10)-1;
Num_change = sum(logical(diff(sign(T))))

[Michael]

So Sorry I haven't seen your result or thanked you!