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MathGroup Archive 2002

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Getting Coordinates from plot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32953] Getting Coordinates from plot
  • From: Winston Garira <uceswga at ucl.ac.uk>
  • Date: Thu, 21 Feb 2002 02:07:08 -0500 (EST)
  • Reply-to: Winston Garira <uceswga at ucl.ac.uk>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

Can someone help me on this one. 
I would like a list of coordinates so that I can analyze them further
and possibly import into a "prettier" graphing package. What should
I do when using the NDSolve function?

I have tried the menu command: Input -> Get Graphics Coordinates.
This requires me to use Mod1 key which I don't have on my keyboard.

How can I get coordinates of the plot from the following:


Pends[init1_, init2_, time_, k_, {c_, w_, p_}] := 
      Module[{}, 
        pend = NDSolve[{
	  x1''[t] + c x1'[t] + ((1 + p Cos[w t])) Sin[x1[t]] == k (x2[t] - x1[t]), 
          x2''[t] + c x2'[t] + ((1 + p Cos[w t])) Sin[x2[t]] == k (x1[t] - x2[t]), 
              x1[0] == init1[[1]], x1'[0] == init1[[2]], 
              x2[0] == init2[[1]], x2'[0] == init2[[2]]}, 
	      {x1, x2}, {t, 0, time}, 
	      MaxSteps -> 200000]; 
	      xd[t_] := x1[t] /. pend[[1]]; 
	      xdd[t_] :=x1'[t] /.pend[[1]]; 
	      xr[t_] := x2[t] /. pend[[1]]; 
	      xrd[t_] :=x2'[t] /.pend[[1]];
	      ];
   c = 0.1;  w = 2.0;  p = 2.0;
   Pends[{1.37, 0}, {-1.17, 0}, 5000, 0.0, {c, w, p}];
   ParametricPlot[{ {xd[t], xdd[t]}, {xr[t], xrd[t]}}, {t, 1000, 1500}];
   
   
   
 Winston 



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