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. >