Return 2nd derivative (der of state2der1)
function state2der2 extends Modelica.Icons.Function; input Real u[3] "Required values for state and der(s)"; input Real dummy "Just to have one input signal that should be differentiated to avoid possible problems in the Modelica tool (is not used)"; input Real dummy_der; input Real dummy_der2; output Real sder2; end state2der2;