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I'm trying to solve and plot the following in Mathematica:

eqns = {x'[t] == 
    x[t] - y[t] - 
     x[t] (x[t]^2 + y[t]^2) + (x[t] y[t])/Sqrt[x[t]^2 + y[t]^2], 
   y'[t] == 
    x[t] + y[t] - y[t] (x[t]^2 + y[t]^2) - 
     x[t]^2/Sqrt[x[t]^2 + y[t]^2]};
DSolve[eqns, {x, y}, t]

This is supposed to be an example of unstable attractor ODE. However, execution never ends and I don't manage to see the solution of the equation.

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    $\begingroup$ Try using NDSolve instead $\endgroup$
    – b3m2a1
    Commented May 26, 2019 at 20:55

2 Answers 2

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To visualize a 2D system, I would start with StreamPlot:

vf = {x', y'} /. First@Solve[eqns /. f_[t] :> f, {x', y'}]; (* strip the args *)
StreamPlot[vf, {x, -2, 2}, {y, -2, 2}]

Mathematica graphics

You can use StreamPoints to highlight the structure and Epilog to mark the attractor at $(1,0)$:

ics = {{{Cos[1/5], Sin[1/5]}, Red},
       {{0.5, 0}, Magenta}, {{1.5, 0.}, Magenta}};
StreamPlot[vf, {x, -2, 2}, {y, -2, 2},
 StreamPoints -> {Append[ics, Automatic]},
 Epilog -> {White, EdgeForm[Black], Disk[{1, 0}, 0.03]}]

Mathematica graphics

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eqns = {x'[t] == 
    x[t] - y[t] - 
     x[t] (x[t]^2 + y[t]^2) + (x[t] y[t])/Sqrt[x[t]^2 + y[t]^2], 
   y'[t] == 
    x[t] + y[t] - y[t] (x[t]^2 + y[t]^2) - 
     x[t]^2/Sqrt[x[t]^2 + y[t]^2]};
sol = NDSolve[Join[{x[0]==1.5, y[0]==1.5}, eqns], {x, y}, {t, 0, 50}];
ParametricPlot[{x[t], y[t]}/.sol//Evaluate, {t, 0, 50}, PlotRange->All]

enter image description here

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