Issue
Question is as above. After reading the documentation, I can change the integrator itself (RK45,RK23, DOP853, etc), however I cannot find information on the order of these integrators, or on ways to limit the integrator to 1st order.
How can this be done? Do I have to use a particular ODE solver method that is by default 1st order, or can I edit any method to be 1st order?
Solution
For many integrators, the order is a fixed property. There are some methods – let’s call them meta integrators – that switch between different integrators, but they are still limited to the order of these integrators. Thus, you cannot simply control the order of the integrator and leave everything else the same.
If you really want a first-order method, it’s easy to implement the Euler method – unless you want step-size adaption.
Mind that the order of an integrator denotes how its error behaves for small step sizes. In this respect, a higher order is nothing that should cause a problem per se. I would therefore find it remarkable if using a first-order method solves a problem. Sometimes, individual methods can have problems or the problem is stiff, but here the solution is to use another solver (for stiff problems), not a first-order solver. If you consistently observe a result for all solvers, it is by far more likely that this your true result or you made a mistake defining your derivative or similar.
Answered By - Wrzlprmft
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