I have a differential equation:

$frac{dx}{dt}=sech(x-1)$

I want to add noise to it and try to solve it numerically, but it seems that I am programming something wrong, because there is no noise. I am trying to do this by adding a random number.

```
ClearAll("Global`*")
pars = {(Alpha) = 1, (Beta) = 1/20, (Gamma) = 1,
h = 1, (Omega) = 2 Pi 1/2, (Mu) = 1, xs = -1, xe = 1}
f = Sech(x(t) - xe)
sys = NDSolve({x'(t) ==
ArcTan(1 D(f, x(t))) + RandomReal({-1/10, 1/10}),
x(0) == xs}, {x}, {t, 0, 500})
Plot({Evaluate(x(t) /. sys), xe}, {t, 0, 10}, PlotRange -> All,
PlotPoints -> 40)
```