Re: System of differential equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg128990] Re: System of differential equations*From*: stephen.p.luttrell at gmail.com*Date*: Fri, 7 Dec 2012 01:38:53 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <k9pq4e$hnp$1@smc.vnet.net>

I found that converting your input cell to TraditionalForm and then back again to StandardForm - thus causing the terms in the differential equations to be reorganised - made NDSolve work though you now get a "NDSolve::mxst: Maximum number of 10000 steps reached ..." warning message. Stephen Luttrell West Malvern, UK On Thursday, 6 December 2012 09:56:30 UTC, hazem.ab... at gmail.com wrote: > Dear all, > > I want to solve this system of equations but I always get an error > > > > NDSolve::ndnum:Encountered non-numerical value for a derivative at t==0 > > > > can any one help me on this > > > > s=NDSolve[{ > > ph1''[t]+ph1'[t]+sin[ph1[t]]-mu[t]-mu'[t]==0.005, > > ph2''[t]+ph2'[t]+sin[ph2[t]]+mu[t]+mu'[t]==0.005, > > 0.2mu'[t]+mu[t]==ph1'[t]-ph2'[t], > > ph2[0]==0, > > ph1[0]==0, > > ph2'[0]==0, > > ph1'[0]==0, > > mu[0]==0 > > }, > > {ph1[t],ph2[t],mu[t]}, > > {t,0,5000} > > ] > > > > thanks in advance,