DifferentialEquations.jl default options for a solver


#1

In DifferentialEquations.jl, how can I find out the default options for a specific solver? In particular, I’d like to know the default options for the ODE solver DP5. I see a description of options in the docs, but I don’t see what are the defaults.

I’m asking because I’m trying to recapitulate results that I’ve previously calculated in Matlab with the ode45 function, which I believe is the same solver as DP5. The default options in Matlab are documented here.

I find the results in DifferentialEquations.jl do not exactly match Matlab’s ode45 because different time steps are chosen. I’ve attempted to make the time steps the same by setting the same abstol and reltol parameters as in Matlab, but this does not seem sufficient as DifferentialEquation.jl still tends to use less time steps. In some problem instances, I have to set abstol and reltol to be much more sensitive at 1e-8 to more closely match the final solutions generated using only 1e-4 in Matlab, but then the running time becomes slower. I suspect that changing other options like the maximum time step (qmax) in DifferentialEquations.jl may help in equalizing the results.