inetgrate_n_steps does not affect the internal state of a stepper

[vhartman]

Hey
In the controlled Adams-Bashforth-Moulton stepper I am implementing, I am working with an internal state which keeps track of the previous steps and derivatives. Since this is a controlled stepper, using integrate_n_steps results in a call to integrate_adaptive. However, since the stepper is passed by value, the internal state of the stepper in integrate_n_steps does not change. I think a similar problem occurs in the rosenbrock4 stepper, and every step is treated like a first step.

I am not sure if this is intended.

Best regards,
Valentin

[mariomulansky]

You can pass explicit references to the stepper (ie std::ref(stepper)). For steppers with internal state this is required.