Error in ode45 (line 115)
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I'm trying to solve a second-order ODE and am receiving the following errors:
Error in ode45 (line 115)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0,
options, varargin);
Error in code (line 17)
[out1,out2] = ode45(ode,[0 100],cond);
Here's my code:
syms phi(t) theta(t)
phid(t) = diff(phi,t);
thetad(t) = diff(theta,t);
q(t) = [phi(t);theta(t)];
qd(t) = diff(q,t);
qdd(t)= diff(qd,t);
a = 10;
b = 3;
y = 2;
d = 5;
M = [a+b*(sin(theta))^2 y*cos(theta);y*cos(theta) b];
C = [b*thetad*sin(theta)*cos(theta) -y*thetad*sin(theta)+b*phid*sin(theta);-b*phid*sin(theta) 0];
G = [0;-d*sin(theta)];
ode = 0 == M*qdd+C*qd+G;
cond = [q(0)==[1;-1], qd(0)==[0;0]];
[out1,out2] = ode45(ode,[0 100],cond);
I'm not very experienced with Matlab, so I apologize if this is an obvious mistake I'm making.
Thank you in advance!
0 Comments
Answers (1)
Walter Roberson
on 21 Jan 2021
ode45 can never be used for symbolic expressions. See dsolve() instead, or see the first example for odeFunction
3 Comments
Walter Roberson
on 21 Jan 2021
That is not an error, that is a warning that dsolve does not know how to solve that system. Either dsolve does not have the algorithm for that system, or else there is no closed form solution for the system, or else the system is inconsistent for closed form.
You should follow the guidance in odeFunction first example.
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