Re: Kernel Crashing with NDSolve Command
- To: mathgroup at smc.vnet.net
- Subject: [mg73761] Re: Kernel Crashing with NDSolve Command
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Wed, 28 Feb 2007 04:23:43 -0500 (EST)
- Organization: Uni Leipzig
- References: <erop18$94d$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
Hi,
have you ever taken a look onto the conditions,
that a numerical solution of an initial value
problem exists ??
There is a propery of the right hand side
called Lipshitz continuous and Min[] will
violate this condition.
Second, you don't need assigment statements
because
NDSolve[
{y'[x]==Min[s[x]+Sin[x],Cos[x]-s[x]],y[0]==0}/.
s[x]->x^2,
y,{x,0,3}]
will work
and instead of s[x]->x^2
you may use the output of Solve[]
Regards
Jens
pradeep wrote:
> Hi all
> i have this rather innocuous looking NDSolve command thats crashing the
> mathematica kernel,
> NDSolve[{y'[x]==Min[s[x]+Sin[x],Cos[x]-s[x]],y[0]==0,s[x]==x^2},{y,s},{x,0,3}]
>
> If i were to substitute s[x] in this equation with x^2 and then try
> solving, i get an answer, if i assign s[x] in advance and try solving
> it, i still get an answer but the nature of the algorithm followed by
> NDSolve doesnt allow it to take s[x] as a dependent variable and still
> have it occur inside the Min function! i find that weird!
> Someone have an explanation??
> thanks in advance!
> Pradeep
> p.s. also note the that the nature of my application is such that i'd
> like to solve this bunch of equations in a single shot without
> assignment statements hence i dont have use for the two approaches that
> i mentioned worked.
>