Re: Differential equation with several variables in the function

• To: mathgroup at smc.vnet.net
• Subject: [mg97160] Re: Differential equation with several variables in the function
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Fri, 6 Mar 2009 05:38:58 -0500 (EST)
• Organization: Uni Leipzig
• References: <goqpau\$lqg\$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de

```Hi,

if you wish to solve a differential equation you can't say
that the function should have the form f[x+y], because
the *differential equation* determines how the solution look
like and not *you*. If you know how the solution look like,
you don't need to solve the equation any more.

Regards
Jens

petterbe at gmail.com wrote:
> Hi,
> I have a differential equation were the function F[.] depends on
> several varibles,x,y,z. I would like to solve the differential
> equation for the entire function. However, I only manage to get
> solutions from Mathematica if I have one variable in the function. For
> example DSolve[egn==0, F[x],x]. If i try to solve for my entire
> function F[x+y+z] using DSolve[egn==0, F[x+y+z],x] or even just add 1
> to the function (F[x+1]) I get the error message "DSolve::litarg: To
> avoid possible ambiguity, the arguments of the dependent variable in
> XXX should literally match the independent variables."
>
> Does anybody have some good suggestions?
> Thanks
>

```

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