Tips & Suggestions¶
SOFT gives a ‘Step-size underflow in Runge-Kutta integrator’ error.
This error is usually due to one of two reasons: (i) something is wrong with the
magnetic field you are running with, or (ii) the integrator tolerance
@Equation tolerance
is too strict.
The former reason is possible only when using a numerical magnetic field and is indicative of a problem in one or several of the magnetic field components. You should check to make sure that the magnetic field actually looks fine before proceeding.
The latter reason occurs if @Equation tolerance
is set to a too small
value. Very few applications require an accuracy in the computed quantities to
machine epsilon, and for both performance and stability reasons,
@Equation tolerance
should therefore be set to a value significantly
larger than machine epsilon. On most systems, machine epsilon is around
\(2\cdot 10^{-16}\).