Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: NDSolve - Nice function but stiffness-problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg96471] Re: NDSolve - Nice function but stiffness-problem
  • From: "slawek" <human at site.pl>
  • Date: Sat, 14 Feb 2009 03:09:59 -0500 (EST)
  • References: <gh8hih$qv5$1@smc.vnet.net> <ghavmr$o6o$1@smc.vnet.net>

U¿ytkownik "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de> napisa³ w 
wiadomo¶ci news:ghavmr$o6o$1 at smc.vnet.net...
> for larger A, f[x] change the sign and than no solution
> for the boundary value problem exist any more.
> Mathematica report the x position where f[x] become
> negative.


False, D[f[x],x]==Exp[A f[x]] is an evolution equation, i.e.

Loop with stepsize going to null
  fnew = fold + stepsize * Exp[A fold]
end loop

If an start value exist for the first fold there is no reason to 
"nonexistence" of another fnew. A one step more is always possible.

slawek




  • Prev by Date: Re: Laplace Transform Exponential Shift
  • Next by Date: newbie here,, need help with parametrics
  • Previous by thread: Re: NDSolve - Nice function but stiffness-problem
  • Next by thread: Re: NDSolve - Nice function but stiffness-problem