Hi!
I i have a 2nd order ODE where i want to chance the derivatives of x(t) and y(t) exactly at sqrt(x(t)^2+y(t)^2)=1 ,or before, as close to 1 as possible.
I found "event=" in/dsolve/numeric/events, where i can define the trigger and the action.
What is the difference between: "event=[[sqrt(...)-1,diff(x(t),t)=...],[sqrt(...)-1,diff(y(t),t)=...]]" and "event=[[sqrt(...)-1,[diff(x(t),t)=...,diff(y(t),t)=...]]]", because i get different results, which one is the correct form?