Hello,

The idea: parameter "a" will have a new random value each 10 days.

The way I did it is working but it can get very long especially if I do it for a system of equations and for long time more than a year (365 days).

The code:

with(DEtools); with(plots);

n := 5;

for i to n do Ra[i] := RandomTools:-Generate(distribution(Uniform(0.1e-1, .5))); a[[i]] := Ra[i] end do;

b := 0.1e-2;

T := 10;

eq := diff(L(t), t) = a*L(t)-b;

init[1] := L(0) = 100;

sol[1] := dsolve({init[1], subs(a = a[[1]], eq)}, L(t), range = 0 .. T, numeric);

init[2] := L(T) = rhs(sol[1](T)[2]);

sol[2] := dsolve({init[2], subs(a = a[[2]], eq)}, L(t), range = T .. 2*T, numeric);

init[3] := L(2*T) = rhs(sol[2](2*T)[2]);

sol[3] := dsolve({init[3], subs(a = a[[3]], eq)}, L(t), range = 2*T .. 3*T, numeric);

p[1] := odeplot(sol[1], [t, L(t)], t = 0 .. T);

p[2] := odeplot(sol[2], [t, L(t)], t = T .. 2*T);

p[3] := odeplot(sol[3], [t, L(t)], t = 2*T .. 3*T);

p := display([p[1], p[2], p[3]]);

display(p);

Thank you