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Re: NDsolve problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg110745] Re: NDsolve problem
  • From: Narasimham <mathma18 at hotmail.com>
  • Date: Sun, 4 Jul 2010 03:10:24 -0400 (EDT)
  • References: <i0kif0$183$1@smc.vnet.net>

On Jul 2, 4:27 pm, "ntina... at libero.it" <ntina... at libero.it> wrote:
> Hello,
> I haven't been using Mathematica for some years and now I need to ask you=
 for
> help with NDSolve. I'm using version 6.0.
---
> Thank you in advance.
> Regards,
> Valentina

Boundary Conditions for y and y' need to be given at x = 0 exactly. If
nearby points are taken for defining BC, different constants would
result in. In the following, the constant looks wavy, but  note y axis
plot values are  in a narrow range, are reasonably constant.

s=NDSolve[{y''[x]+(2/x) y'[x]+(1+(2*a/x)*E^(-b*x))
(y[x])==0,y[0.1]==1,y'[0.1]==-a},y,{x,0.1,60}]
Plot[Evaluate[(x*y[x])^2+(((x-0.5 Pi)*y[x-0.5 Pi]))^2/.s[[1]]],{x,
10,60},PlotRange->All]

Narasimham



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