Vector y seems to change without my modifying it

In this short script I'm trying to simulate three coin flips in a row. The code and output are below.

Notice that in this particular run of the script, vector y comes out to be [1 1 1]. I display each element after each iteration, but after the for loop is completed, when I display vector y, it comes out as [0 0 1].

I've run this script numerous times and the final display statement always comes out different from what is indicated in the element-by-element display.

Have no idea why this is happening.

Thanks, Patrick

%*****************

clear disp('start')

M=3

for i= 1:M

    disp(i)
    a=rand(1,1)
    if a<0.1
       y(1,M)=0;
    else
       y(1,M)=1;
    end
    disp(y(1,M));
end;
disp(y)
%**************

OUTPUT OF ABOVE SCRIPT

start

M =

     3

     1

a =

    0.7635

     1

     2

a =

    0.6279

     1

     3

a =

    0.7720

     1

     0     0     1

Answer 1

[Star Strider]

The problem is in your y assignments:

y(1,M)=0;

and:

y(1,M)=1;

Change the reference to:

y(1,i)=0;

and:

y(1,i)=1;

to see if that produces the result you want.

Answer 2

[Sean de Wolski]

Use the debugger!

Put a break point on the first line of the loop. Run the file and then step through. This will help you see where y changes (or displays) and more importantly help you learn to debug.