Hello,
I can obtain ?[t] as a solution of an ODE and plot it thanks to the following code
s = NDSolve[{eqL?, ?[0] == .79, ?'[0] == 0}, ?, {t, 0, 2}]
Plot[Evaluate[?[t] /. s], {t, 0, 2}, PlotRange -> All]
I would like to obtain the plot of x[t] which is a coordinate depending of ?[t]
x[t] = 1/2 (2 r Cos[?[t]] + Sqrt[2] Sqrt[2 l^2 - r^2 + r^2 Cos[2 ?[t]]])
May you help me to define the appropriated code so as to plot x[t] ?
Thanks a lot for your help.
Hi there,
it would have helped to have the actual ODE, but I will for this illustration just make one up:
eqL\[Gamma] = \[Gamma]''[t] - \[Gamma]'[t] - \[Gamma][t] == Sin[t];
You can then run your NDSolve
s = NDSolve[{eqL\[Gamma], \[Gamma][0] == .79, \[Gamma]'[0] == 0}, \[Gamma][t], {t, 0, 2}]
Then you can define the x[t]; note that you need to add values for l and r unless you want to use Manipulate or Animate.
x = 1/2 (2 r Cos[\[Gamma][t]] + Sqrt[2] Sqrt[2 l^2 - r^2 + r^2 Cos[2 \[Gamma][t]]]) /. {s[[1, 1]], r -> 1, l -> 1}
and plot
Plot[x, {t, 0, 3}]
Cheers,
M.
Thank you
You perfectly answer to my question.
