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Re: ODE in mathematica. what is wrong?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91324] Re: ODE in mathematica. what is wrong?
  • From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
  • Date: Fri, 15 Aug 2008 06:55:25 -0400 (EDT)
  • Organization: University System of Maryland
  • References: <g813bb$4r$1@smc.vnet.net>

Several things are wrong. First, you didn't put spaces between things 
like rho and y, where I assume you meant to multiply. Second, for a 
numerical integration everything must be a number (except y and its 
derivatives); so, you need to specify hbar, rho, epsilon,k, ...

Those are just the syntax issues. BTW, if you are going to use 
subscripted things like y_sub_o you need to use the Notation package and 
Symbolize them.

Now, your differential equation set has multiple equations for y'[x]. Is 
that what you really meant? I am not sure what problem you are solving 
here. Perhaps one second order differential equation with different sets 
of initial conditions? I am not sure.

Kevin

hoi-su jung wrote:
> Hi,
> I am a freshman of Mathematica, I need help here...
> 
> I met such problem as:
> 
> NDSolve[{ y'[x] == -\[Rho]y[x], y[0] == Subscript[y, 0], 
>   I\[HBar] y'[x] == \[Epsilon]y[x], y[0] == Subscript[y, 0], 
>   y''[x] + 2 \[Rho]y'[x] + k^2 == 0, y'[0] == Subscript[g, 0]}, y, x]
> NDSolve::dvnoarg: The function y appears with no arguments.
> 
> How to Handle???
> 


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