I have to solve the equation in range from 0 to 7pi:


with boundary conditions

x(0)=1.5, x'[0]=0.

This is what I can do, but then I have a problem.

How to draw it with Evaluate in phase space? I also have to substitute the solution to the left side of differential equation and draw this formula in range of 0 < t < 7pi, on the y axis from -2 to 2. I have to use ParametricPlot and Evaluate, but don't know how. I mean, I tried to do so but it didn't work :/

  • 1
    Could you include your attempts with ParametricPlot in your question? – Chris K Nov 10 at 19:27
eqn = x''[t] - (1/2) (1 - x[t]^2) x'[t] + x[t];
sol = NDSolveValue[{eqn == 0, x[0] == 3/2, x'[0] == 0}, x, {t, 0, 7 Pi}];

ParametricPlot[Evaluate[{t, sol[t]}], {t, 0, 7 Pi}, AspectRatio -> 1 / GoldenRatio]

enter image description here


Plot[Evaluate @ sol[t], {t, 0, 7 Pi}]

same picture

enter image description here

Eq = X''[t] - (1/2) (1 - X[t]^2) X'[t] + X[t] == 0;
sol = NDSolve[{Eq, X'[0] == 0, X[0] == 3/2}, X, {t, 0, 7 Pi}];
Plot[X[t] /. sol, {t, 0, 7 Pi}]
New contributor
Naeem Jan is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.

Your Answer


By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.