Why aren't my if statements working

This program is a 1d random walk. The random walk works. The walker is supposed to reflect or bounce inside a range (-10 to 10). I used an if statement for this. But my if statements dont work at all. Its as if the statements didnt exist at all. The program behaves the same whether I have it or not. There has to be a mistake in my code. Please help.

iterations= 1;
Num_steps = 1000;                                
Random_steps_r = NaN(Num_steps,iterations);      
for i = 1:iterations
    Random_steps_r(:,i) = cumsum(-1 + 2 * round(rand(Num_steps,1)),1); 
end
x=Random_steps_r; 
deltax=diff(x);
xMax=10;
xMin=-10;
if all(x(1:999)+deltax>xMax)
    x=xMax-(x+deltax-xMax);
elseif all(x(1:999)+deltax<xMin)
    x=xMin-(x+deltax-xMin);
end
comet(x)

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/431095-random-walk-problem#answer_348451

I explained all() about it already .