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I used the following commands:

s = NDSolve[{X'[t] == 10 (X[t] - Y[t]), 
   Y'[t] == X[t] (28 - Z[t]) - Y[t], Z'[t] == X[t] Y[t] - (8/3) Z[t], 
   X[0] == Y[0] == Z[0] == 0.001}, {X, Y, Z}, {t, 100}]

ParametricPlot3D[Evaluate[{X[t], Y[t], Z[t]} /. s], {t, 0, 100}]

but I am not sure if I am right, the results are strange. Am I right? How can I plot $X,Y,Z?$

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  • $\begingroup$ Try restricting the PlotRange: ParametricPlot3D[Evaluate[{X[t], Y[t], Z[t]} /. s], {t, 0, 100}, PlotRange -> 40] -- looks like it then goes off to infinity instead of getting orbiting another critical point. $\endgroup$
    – Michael E2
    Commented Nov 23, 2019 at 16:27
  • $\begingroup$ nice, is the command "s=..." right? How can i plot $X,Y,Z$? $\endgroup$
    – George
    Commented Nov 23, 2019 at 16:29
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    $\begingroup$ Do you mean separately? Use Plot, look in the documentation for NDSolve, or look at these examples: mathematica.stackexchange.com/questions/134222/… $\endgroup$
    – Michael E2
    Commented Nov 23, 2019 at 16:34
  • $\begingroup$ the link doesn't help me. I am trying to understand, I am a beginner. I used reference.wolfram.com/language/ref/NDSolve.html, but I need to plot them in one graph $\endgroup$
    – George
    Commented Nov 23, 2019 at 16:43
  • $\begingroup$ Did you try replacing ParametricPlot3D with Plot? -- Also, if you want the Lorenz system, I think the first equation has X and Y switched. $\endgroup$
    – Michael E2
    Commented Nov 23, 2019 at 17:03

1 Answer 1

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As long as this system is the Lorenz attractor, you have a changed sign in the first equation, so it blows up. Now it is fixed.

s = Quiet @ NDSolve[{X'[t] == -10 (X[t] - Y[t]), Y'[t] == X[t] (28 - Z[t]) - Y[t], Z'[t] == X[t] Y[t] - (8/3) Z[t], X[0] == Y[0] == Z[0] == 1/100}, {X[t], Y[t], Z[t]}, {t, 0, 10}]

ParametricPlot3D[Evaluate[{X[t], Y[t], Z[t]} /. s], {t, 0, 10}]
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