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MathGroup Archive 2007

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Re: Ndsolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84053] Re: Ndsolve
  • From: "Kevin J. McCann" <kjm at KevinMcCann.com>
  • Date: Fri, 7 Dec 2007 06:55:10 -0500 (EST)
  • References: <fjauk0$raa$1@smc.vnet.net>

NDSolve actually does generate an internal (x,y) table of numerical 
values; however, it then continues on and calculates an 
InterpolationFunction. The advantage of the latter is that you can take 
derivatives, etc.

You might check the documentation on NDSolve.


Clear[y, Y]
Y = y /. First[NDSolve[{y'[x] == y[x], y[0] == 1}, y, {x, 0, 1}]]

You can check the BC:

Y[0]
1

Also
Plot[Y[x]-Y'[x],{x,0,1}]

Cheers,

Kevin




DrunkenButterfly wrote:
> I'm confused about the "interpolation" thing. Why if I have some diff eq with boundary conditions NdSolve doesn't give me a numerical solution? And suppose I have 
> 
> y'[x]== f[x] 
> with y[a]== b as a condition (a,b any numbers) 
> 
> How can I find f[0], for example? (Generalizing, how can I find f[c], where c is a number?)
> 
> Thanks to everyone! And please, help me :(
> 


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