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2 votes
2 answers
160 views

Reduce System of 3 ODEs to 2 ODEs

I'm currently self-studying the book "Nonlinear Dynamics and Chaos". I got the following system $$ \dot{x} = -kxy \\ \dot{y} = kxy - ly \\ \dot{z} = ly $$ According to a comment on one of ...
syncedChaos's user avatar
3 votes
2 answers
83 views

Solving and plotting the 2-D Lorenz Equation

We are asked to first solve and then plot the phase plane of \begin{align} \begin{cases} \dot{x}=\sigma x - \sigma y\\ \dot{y} = \rho x-y \end{cases}, \ \sigma, \ \rho >0. \end{align} Now the ...
algevristis's user avatar
6 votes
0 answers
155 views

Nature of ODE $\dot x=x^2-\frac{t^2}{1+t^2}$

Discuss the equation $\dot{x}=x^2-\frac{t^2}{1+t^2}$. Make a numerical analysis. Show that there is a unique solution which asymptotically approaches the line $x=1$. Show that all solutions below ...
Ri-Li's user avatar
  • 9,098
2 votes
0 answers
43 views

Prove that there exists $\delta \in(0, \infty)$ such that when $y(0)=\delta$, the solution to the ODE for $y$ loses uniqueness in finite positive time

Consider $\dot{x}=f(x)$ where differentiation is with respect to $t$. Suppose there exist $x_0>0$, such that $f\left(x_0\right)=0$, and $\epsilon>0$ such that $$ \left|\int_{x_0}^{x_0+\epsilon} \...
Ri-Li's user avatar
  • 9,098
1 vote
1 answer
190 views

Prove the $k$-th power of the logistic map with parameter $\mu = 4$ has $2^k$ fixed points

I'm trying to solve an exercise in which I need to prove that the logistic map with parameter $\mu = 4$, $F_4:[0,1]\to[0,1]$, $F_4(x) = 4x(1-x)$, satisfies that for every positive integer $k$, $F_4^k$ ...
Marc's user avatar
  • 195
0 votes
0 answers
85 views

Is there an analytic solution for the following non-linear equation $x'(t) = a(t) + b\, x(t) + c\,x^3(t)$?

Here $b, c$ are constants. Of course there exists locally a solution by the Picard-Lindelöf theorem but I'm looking for an explicit expression. In fact, this question comes from here but I changed the ...
Noix07's user avatar
  • 3,679
2 votes
0 answers
93 views

A first order non-linear differential equation?

I'm trying to solve this non-linear differential equation : $$ \frac{dy}{dx}= \frac{y^3}{(y+1)^2(y+2)^2} $$ with the boundary condition $y(x_0)=x_0$, $x>0$, and $y(x)$ being a positive function. ...
Giuseppe's user avatar