Beispiel - SAM - ETH Zürich

1 y = y_expl;
2
3 E_kin = 0.5*(y(2,:).^2);
4 E_pot = -g/l*cos(y(1,:));
5 E_pot = E_pot - min(E_pot) + min(E_kin);
6 E_tot = E_kin + E_pot;
7
8 % Plot of evolution of energies
9 f i g u r e(’name’,’Pendulum: energy’);
0 p l o t(tg,E_kin,’b-’,...
1 tg,E_pot,’c-’,...
2 tg,E_tot,’r-’);
3 x l a b e l(’{\bf time t}’,’fontsize’,14);
4 y l a b e l(’{\bf energy}’,’fontsize’,14);
5 legend(’kinetic energy’,’potential energy’,’total energy’);
6 t i t l e(’Energies for {\bf explicit} Euler discrete evolution’);
7
8 i f (nargin > 3),
p r i n t(’-depsc2’, s p r i n t f(’%s_EnExpl.eps’,filename)); end
9
0 % Tracking energies for implicit Euler
1 y = y_imp;
2 E_kin = 0.5*(y(2,:).^2);
Numerische
Mathemtik
R. Hiptmair
rev 35327,
25. April
2011
1.4
p. 93