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