Student Support Forum: 'system of ODE's in matrix form?' topicStudent Support Forum > General > Archives > "system of ODE's in matrix form?"

 Next Comment > Help | Reply To Topic
 Author Comment/Response Mike Antonakakis 07/16/09 10:45pm I'm doing some homework where I am trying to solve for two variables. I have an equation written in matrix form (if my math grammar isn't correct, I apologize). I have a few matrices: q={{vy[t]},{r[t]} <-- these are the two variable I need to end up plotting vs time q'={{vy'},{r'}} A={{a,b},{c,d}} u={{e},{f}} where a,b,c,d,e,f are constants. Now the equation given is q'=A.q+u. This gives me two differential equations: vy'=a*vy+b*r+e and r'=c*vy+d*r+f I don't have any issue using NDSolve to solve those two equations, I type this: q = NDSolve [{vy'[t] == a*vy[t] + b*r[t] + e*dt, r'[t] == c*vy[t] + d*r[t] + f*dt, r[0] == 0, vy[0] == 0}, {vy, r}, {t, 3}] and I get what I'm looking for. So my question is, is there any way to skip the part where I find the two differential equations myself? In other words, is there a way I can input the equation in matrix form and solve for vy[t] and r[t] in one step? I just started using Mathematica a few days ago, and have never used anything more complicated than a TI-83+ before this, so please excuse my lack of knowledge. I've attached the file that works for me when I input the two equations myself. Attachment: ch10-12hopefullyfinal.nb, URL: ,

 Subject (listing for 'system of ODE's in matrix form?') Author Date Posted system of ODE's in matrix form? Mike Antonak... 07/16/09 10:45pm Re: system of ODE's in matrix form? yehuda ben-s... 07/21/09 01:38am Re: Re: system of ODE's in matrix form? Mike Antonak... 07/25/09 08:16am
 Next Comment > Help | Reply To Topic