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>

```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
you may use the output of Solve[]

Regards
Jens

> 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??
> 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.
>

```

• Prev by Date: Questions ...
• Next by Date: Re: Roman Numerals -- Thanks
• Previous by thread: Questions ...
• Next by thread: monomials in Graded Lexicographic Order and associated factorials - correction