
How to get second derivatives using ode45
Posted:
Apr 30, 2013 9:49 AM


Hello!
I am stuck in solving a problem with ode45. I would like to get the second derivatives in order to plot the acceleration and to calculate some other values.
However I only get the velocity and position.
It looks like this:
options= odeset('RelTol',1e3,'AbsTol',1e6); [t_vec,Y]=ode45(@(t,y) vib_equ(t,y,c_s_f,c_s_r,v_val,F_d_val,m_c,I_g_c,l,l_f,l_r,u_f,u_f_dot,v,L,i_d),[0 t_max], zeros(1,4), options);
z_cf= Y(:,1); z_cf_dot= Y(:,2); z_cr= Y(:,3); z_cr_dot= Y(:,2);
I would like to use the function vib_equ to get both z_cf_ddot and z_cr_ddot but I cannot figure it out, maybe there is another way, much easier but I really don't know.

