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[SOLVED] NDSolve and ParametricPlot


Well-known member
Feb 1, 2012
s = NDSolve[{x'[t] == y[t], 
   y'[t] == -x[t] - .2*2*y[t] - .2*x[t]^3 + 3*.2*Cos[t], x[0] == 1, 
   y[0] == 2}, {x, y}, {t, 100}]

ParametricPlot[Evaluate[{x[t], y[t] /. s}], {t, 0, 100}]
So I have a plane autonomous system but there is a $\cos t$ in the ODEs. I would use this code to construct a limit cycle but I think having a $\cos t$ in the ODE is messing it up. How can I proceed?