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