How to Terminate a Loop After Reaching the Desired Value?

Right now I need to write a loop of code that repeats the function

r(n+1)=L*r(n)

(Such that the 'r' value on the left = the matrix 'L' times the value of 'r' that came before the value on the left.)

Until r converges/stops changing (or until r(n+1)=r(n)).

All I have so far is

while r(n+1) ~= r(n)
    r(n+1)=L*r(n)
end

Does anybody know how to stop a loop when a series converges? I'm so lost.

Answer 1

[KSSV]

tol = 10^-5 ;     % fix your tolerance value 
while abs(r(n+1)-r(n))>tol
    r(n+1)=L*r(n)
end