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Re: Re: O.D.E in Power Series

• To: mathgroup at smc.vnet.net
• Subject: [mg18410] Re: [mg18271] Re: O.D.E in Power Series
• From: Attico Nicola <nicola at Linuz.sns.it>
• Date: Wed, 7 Jul 1999 00:11:07 -0400
• Sender: owner-wri-mathgroup at wolfram.com

On Fri, 25 Jun 1999, Kevin J. McCann wrote:

> Define z = x+3, the DE becomes:
> 
> -3y[z] - 2 z y'[z] + y''[z] == 0
> 
> Which is solvable by DSolve in terms of hypergeometric functions. Careful,
> these functions can get large for some arguments.

>>>> I am not sure why Mathematica 
>>>> can't see this simple transformation.

I want to underline this question!
Why sometimes the package NDSolve seems
the best thing around the word and permits to
solve very difficult differential equation
so easly, and sometimes it seems so stupid
that also a liner sobstitution is too difficult?
Someone is able to reply to this question?

Bye

Nicola