Re: NDSolve and vector functions
- To: mathgroup at smc.vnet.net
- Subject: [mg87953] Re: NDSolve and vector functions
- From: dh <dh at metrohm.ch>
- Date: Mon, 21 Apr 2008 03:25:17 -0400 (EDT)
- References: <fu9vl0$ie2$1@smc.vnet.net>
HI,
thank's a lot for the replies. I think the most practicable way is the
solution due to Carl. He packs all vector valued constants into
functions that only evaluate if the argument is numeric. I will play
around with this to check if there are no surprises.
thank's again, Daniel
dh wrote:
> Hello all,
>
> does anybody know a way to compute a vector valued function using
>
> NDSolve without explicitely specifying all vector components. Here is a
>
> simple example: Although NDSolve[{p'[t]==p[t],p[0]=={1,0}},p,{t,0,1}] works,
>
> NDSolve[{p'[t]==p[t]+{1,1},p[0]=={1,0}},p,{t,0,1}]
>
> does not work because p[t] in "p[t]+{1,1}" is treated as a scalar and
>
> the expression is evaluated to {1+p[t],1+p[t]} what is clearly not
>
> intended. Even in "IdentityMatrix[2].p[t]+{1,1}"
>
> "IdentityMatrix[2].p[t]" is treated like a scalar and added to the
>
> components of {1,1}.
>
> do I miss something???
>
> Daniel
>
>
>