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Re: Differential equation with several variables in the function

• To: mathgroup at smc.vnet.net
• Subject: [mg97273] Re: Differential equation with several variables in the function
• From: dh <dh at metrohm.com>
• Date: Mon, 9 Mar 2009 05:18:46 -0500 (EST)
• References: <goqpau$lqg$1@smc.vnet.net>

Hi,

you must try to formulate your problem as simply a s possible. If your 

consider f[x+y] then you should introduce a new variable z=x+y and 

formulate your problem in terms of the one variable function f[z].

If you would give a simple example of your problem, you may get more 

specific answers.

hope this helps, Daniel





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

>