I am trying to write a system of coupled ODEs to eventually pass through ode45(). The equations are:
When I try the following code in an attempt to produce those equations and solve then for n = 3, I get the following error:
options = odeset('RelTol',3e-14,'AbsTol',1e-15,'Stats','on');
[t,y]=ode45(@hmmPD,[0 5000],[0.1 0.2 0.3],options);
figure
plot(t,y(:,1),'b')
hold on
plot(t,y(:,2),'r')
hold on
plot(t,y(:,3),'g')
title('Compare')
hold off
function dydt = hmmPD(t,y)
k=1/5;
a=1.25;
r=1/4;
n=3;
m=4;
for i = 1:n
for j = 1:n
dydt = [(k/m)*(sin(-y(i)+a)-r*sin(-2*y(i)) + sin(y(j)-y(i)+a)-r*sin(2*(y(j)-y(i))));];
end
end
end
Error using odearguments (line 95)
HMMPD returns a vector of length 1, but the length of initial conditions vector is 3. The vector
returned by HMMPD and the initial conditions vector must have the same number of elements.
Error in ode45 (line 106)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);
Error in LargeSystem (line 4)
[t,y]=ode45(@hmmPD,[0 5000],[0.1 0.2 0.3],options);
This appears, to me at least, to be a dimensionality issue. The for loops are likely not doing what I expect and either not constructing the equation I was attempting to or the size of the dydt vector is not right. Either way, I have tried quite a few things but haven't been able to fix it. Any suggestions?
