I need to plot several trajectories of a solutions of ODE like here:
http://www.wam.umd.edu/~petersd/246/matlabauton.html
hold on
for a1=-7:2:5
for a2=-7:2:1
[ts,ys] = ode45(g,[0,4],[a1;a2]);
plot(ys(:,1),ys(:,2))
[ts,ys] = ode45(g,[0,-4],[a1;a2]); % Doesn't work in octave
plot(ys(:,1),ys(:,2))
end
end
hold off
But ode45 doesn't work for decreasing time
[ts,ys] = ode45(g,[0,4],[a1;a2]); - works fine
[ts,ys] = ode45(g,[-4,0],[a1;a2]); - gives the same result as above
[ts,ys] = ode45(g,[0,-4],[a1;a2]); - doesn't work as it works in matlab
So I can plot only half of solution and trajectory is incomplete.
Also if a result grows too fast I couldn't plot the trajectory for specific
initial conditioins at all, because of error:
Solving has not been successful. The iterative integration loop exited at time
t = 1.523467 before endpoint at tend = 4.000000 was reached. This may happen
if the stepsize grows smaller than defined in vminstepsize. Try to reduce the
value of "InitialStep" and/or "MaxStep" with the command "odeset".
Could you fix solvers to make their behaviour more close to matlab one? Matlab
1) solves ODE for decreasing time and 2) shows only warning if a solution
becomes too big.
Thanks )
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