function [ sol1 ] = resolnl(npt,qq,xi,k,ydot,dt)
%UNTITLED Summary of this function goes here
%   Detailed explanation goes here
sol1(1)=qq(1);sol1(2)=qq(1)+dt*qq(2);
%
for lijl=3:npt
    sol1(lijl)=2*sol1(lijl-1)-sol1(lijl-2)+(xi-dg(ydot(lijl-1)))*(sol1(lijl-1)-sol1(lijl-2))*dt-sol1(lijl-1)*(k+d2g((ydot(lijl)-ydot(lijl-1))/dt))*dt^2;
    %
end