Re: 2nd order differential equation help

*To*: mathgroup at smc.vnet.net*Subject*: [mg31481] Re: 2nd order differential equation help*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Thu, 8 Nov 2001 04:54:15 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <9sb4rb$h1n$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hmm, a second order equation needs two initial conditions ? What is your eqn1[t_] doing ? DSolve[{g''[t] + 0.1g'[t] + g[t] == 0, g'[0]==1, g[0]==0}, g[t] ] Regards Jens Peter Dimitriou wrote: > > Exactly how do I get this into a form Mathamatica will accept? It has > been a number of years since enrolling in diffeq, however I think I am > close to correct but would appreciate help. > > the problem; > > Solve the differential equation: > > g''(t) + 0.1 g'(t) + g(t) = 0 > > where the previous equation uses conventional mathematical notation. > You must transfrom the equation and initial conditions into > Mathematica syntax. > > for t between 0 and 10 Pi > > subject to the initial conditions > g(0) = 0, > g'(0) = 1 > > Plot your results. > > My attempt is as follows: > > Clear[g] > > Clear[eqn] > > eqn[t_] = g''[t] + 0.1g'[t] + g[t] == 0 > > Clear[eqn1] > > eqn1[t_] = g'[t] + 0.1g[t] + ?g[t] == 0 > > solution = DSolve[{eqn[t], eqn1[t]}, g'[0] == 1, > g[0] == 0, g[t], {t, 0, 10\[Pi]}] > > DSolve::dsvar: g[0]==0 cannot be used as a variable. > > what am I dont doing right? any suggestions helpful