The ODEs I’m solving typically takes an hour and I would like it to print the current time step for every, e.g. 10 time steps. I have tried the method shown on this page about progress bar, but it doesn’t work (i.e. nothing is displayed) on both VS Code and jupyter notebook. Then I tried using a discrete callback with the following codes:
function lorenz!(du, u, p, t)
du[1] = 10.0 * (u[2] - u[1])
du[2] = u[1] * (28.0 - u[3]) - u[2]
du[3] = u[1] * u[2] - (8 / 3) * u[3]
end
u0 = [1.0; 0.0; 0.0]
tspan = (0.0, 100.0)
prob = ODEProblem(lorenz!, u0, tspan);
function do_nth!(integrator)
println(@sprintf("no. of time steps : %4d, t = %.3e", length(integrator.sol.t), integrator.t))
return nothing
end
condition1(u, t, integrator) = (mod(length(integrator.sol.t), 50) == 0) # triggered every 50 time steps
cb1 = DiscreteCallback(condition1, do_nth!; save_positions=(false,false));
sol1 = solve(prob, FBDF(autodiff=true))
sol2 = solve(prob, FBDF(autodiff=true), callback=cb1)
I use FBDF(autodiff=true)
in the above code because that’s the specific solver I will be using for my actual ODE. Now the problem is that sol1
and sol2
give different solution, and by comparing the second component of the solution to the example in the documentation, it looks like sol2
(the one with the callback) is wrong. So what else did I do wrong? What’s the best way to show the progress every X time steps?