Ending an infinite loop

What I want to do is start with some term I (at time x = 0). Then after a random time (using the command exprnd), this number I will either move up one or move down one. This then becomes the new I and the process starts again untill I = 0. How would I do this?

I was thinking of writing something like this:

"I = 100

x = exprnd(2)

y = 2*(randi([0,1]))- 1

while I = 100

x

I + y

I = I + y

end"

However I don't know how to end this, and therefore I can't graph it or anything to check if it works because it keeps on working out the values for ever. How do I do this?

[Azzi Abdelmalek]

 I = 100 x I + y I = I + y  ? what does that  mean

[Dipesh]

Fixed it

[Azzi Abdelmalek]

for which value of I do you want to stop it? and what means

 x
 I+y

[Dipesh]

I want it to stop when I = 0. I is going to be on 'y' axis. x is a exponential random variable with mean 2. y is a random 1 or -1 so I thought by doing I + y, I will add 1 or take 1 away from the graph. It makes sense as a stairstep plot. As x "time" goes accross, the graph either randomley goes up 1 or down 1. This keeps happening until I = 0.

[Azzi Abdelmalek]

I+y and what? I+y will be affected to which variable? the same question for x

[Azzi Abdelmalek]

and if you add randomly 1 & -1 you will never close the loop

Answer 1

[Matt Fig]

With I initially at 100, you may never get out of the loop. This will go until I gets to the origin (or ctrl+c).

I = 5; % Start at 5 
while I
   I = I + (-1)^round(rand);
   plot(I,0,'o')
   xlim([-20 20])
   pause(1);
end