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Re: Plotting after integrating the solution of system of differential equations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124018] Re: Plotting after integrating the solution of system of differential equations
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Thu, 5 Jan 2012 06:00:56 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

You seem to have a non-numeric paramater p in your initial-value 
problem, so that NDSolve is not even providing a solution.

On 1/4/12 5:02 AM, Itzhak Shechtman wrote:
> I would be grateful for any help in overcoming this:
>
> In the system
>
> 1.
> q[x_,y_]=1+2 x+x^2+y^2;
> k[x_,y_]=(4 x/(1+2 x+x^2+y^2))^0.5;
> B=5.5 10^7;
> sol=NDSolve
> [{x''[t]==B*(2(1-k[x[t],y[t]])^2*EllipticK[k[x[t],y[t]]]-(2-k[x[t],y[t]]^2*(1+x[t]))*EllipticE[k[x[t],y[t]]])/(q[x[t],y[t]]^1.5*k[x[t],y[t]]^2*(1-k[x[t],y[t]]^2)),
> y''[t]==B*2 y[t]*EllipticE[k[x[t],y[t]]]/(q[x[t],y[t]]^1.5*(1-k[x[t],y[t]]^2)),x[0]==p,x'[0]==0,y[0]==-10^5,y'[0]==v},{x,y},{t,0,20}];
>
> 2.
> sol1=NIntegrate[y'[20]/.sol,{p,0.01,1}];
>
> 3.
> Plot[y'[20]/.sol1,{v,10^3,10^5}]
>
> I don't know how to combine the 3 parts of the problem.
> Thank you for taking the trouble.   Itzhak Shechtman
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305



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