Dear All,

I am working on ODEs and have obtained the plot for "variable vs time". I would like to know if it is possible and how to analyze those data in the frequency domain.ODEs.mw

Thank you.

Very kind wishes,

Wang Zhe

Dear All, 

I work on the period doubling phenomenon by integrating the dynamical system at some particular parameter values. My main commands are as follows

restart:
with(DEtools): with(plots): with(plottools):
a:=-1: b:=-3: c:=3: d:=1: omega:=1: v1:=1: f:=-4: epsilon:=0.01: 
sys:=diff(u1(t),t)=v1*u1(t)-(omega+u2(t)^2)*u2(t)+u1(t)*(a*(u1(t)^2+u2(t)^2)+b*z(t)^2),
     diff(u2(t),t)=(omega+u1(t)^2)*u1(t)+v1*u2(t)+u2(t)*(a*(u1(t)^2+u2(t)^2)+b*z(t)^2),
     diff(z(t),t)=z(t)*(-v1+c*(u1(t)^2+u2(t)^2)+z(t)^2)+epsilon*z(t)*(v2+f*z(t)^4):

solC:=dsolve({eval(sys, v2=2.0500014987),
              u1(0)=0.6,u2(0)=0.6,z(0)=0.1},
              type=numeric, method=rkf45, maxfun=10^7,
              range=350..750):
p1:=odeplot(solC, [sqrt(u1(t)^2+u2(t)^2),z(t)],
               refine=2,
               color=burgundy,
               thickness=1);
 

The resulting curves are quite blurring and furry. I have tried to increase the "refine" or the "numpoints" values, but with minimal improvement. I would like to know if there a way to obtain clean and sharp integral curves?  

I would be very grateful if someone could help me! 

Thank you in advance.

With kind wishes,

Wang Zhe

Hello,

I would like to study the period doubling bifurcation behaviors of autonomous ODEs.

Although I know how to plot the Poincare section and bifurcation diagram for non-autonomous ODEs, such as Duffing oscillator, I totally stuck at the autonomous ones. Could you please help me.

It could be greatly helpful if you could share me the code of bifurcation diagram for, say, Rossler or Lorenz systems? 

Thank you in advance.

Very kind wishes,

Wang Zhe