[Date Index]
[Thread Index]
[Author Index]
Re: ODE in mathematica. what is wrong?
*To*: mathgroup at smc.vnet.net
*Subject*: [mg91320] Re: [mg91307] ODE in mathematica. what is wrong?
*From*: Murray Eisenberg <murray at math.umass.edu>
*Date*: Fri, 15 Aug 2008 06:54:12 -0400 (EDT)
*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst
*References*: <200808141101.HAA00111@smc.vnet.net>
*Reply-to*: murray at math.umass.edu
First, insert the missing spaces between other names and y (and avoid
the Subscript expressions):
NDSolve[{y'[x]==-\[Rho] y[x],y[0]==y0,I \[HBar] y'[x]==\[Epsilon]
y[x],y[0]==y0,y''[x]+2 \[Rho] y'[x]+k^2==0,y'[0]==g0},y,x]
Second,it doesn't make sense to ask for a NUMERICAL solution, with
NDSolve, unless you specify an interval: the last argument should not be
x but rather something like {x,0,2}.
Third, I'm suspicious of your system of differential equations, because
if I ask for an exact, symbolic expression by using DSolve instead of
NDSolve...
DSolve[{y'[x]==-\[Rho] y[x],y[0]==y0,I \[HBar] y'[x]==\[Epsilon]
y[x],y[0]==y0,y''[x]+2 \[Rho] y'[x]+k^2==0,y'[0]==g0},y[x],x]
... then I get an error DSolve::overdet "There are fewer dependent
variables than equations, so the system is overdetermined."
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???
>
--
Murray Eisenberg murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 413 549-1020 (H)
University of Massachusetts 413 545-2859 (W)
710 North Pleasant Street fax 413 545-1801
Amherst, MA 01003-9305
Prev by Date:
**Re: Another Out of Memory Problem**
Next by Date:
**Re: ODE in mathematica. what is wrong?**
Previous by thread:
**Re: ODE in mathematica. what is wrong?**
Next by thread:
**Re: ODE in mathematica. what is wrong?**
| |