Re: Solving a nasty rational differential equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg74625] Re: Solving a nasty rational differential equation*From*: dh <dh at metrohm.ch>*Date*: Thu, 29 Mar 2007 02:25:57 -0500 (EST)*References*: <eud32p$k50$1@smc.vnet.net>

$Version=5.1 for Microsoft Windows (October 25, 2004) Ho Roger, if you want a clear cut answer, then do not give details that are irrelevant and can not be understood without context , but concentrate on the question. I can only guess what your problem is. Do you want to integrate g[x] twice, like Integrate[Integrate[g[x],x],x]? What does x20, x15 e.t.c. mean, are these constants or should it read x^20 ...? Anyway in both cases Mathematica will integrate without problems. Daniel Roger Bagula wrote: > I have this nasty differential equation: ( Lorentz invariant elliptical > invariant Klein-Gordon) > -(hbar2/(2*m))*Sum[D[Phi[x[i]],{x(i),2}],{i,1,4}]+2*m*c2*J{Sqrt[m/m0]]=0 > The substition I'm working with is the Kerr mass one of: > m/m0->(r/r0)^2 > and J as an elliptical invariant like: > J[x_]=(-x20+228*x15-494*x10-228*x5-1)3/(1728*x5*(x10+11*x5-1)5) > I isolate the radial part of the second differential ( in a polar four > sopace the angular part isn't importyant mostly to mass radial solutions) > The Phi part is straight forfowd so I'm left with a double interagation > of a nasty rational function: ( m^2->r^4) > f[x_]=(-x20+228*x15-494*x10-228*x5-1)3/(1728*x*(x10+11*x5-1)5) > or if > hbar^2/(m^2*c^2)-->r^2 > g[x_]=(-x20+228*x15-494*x10-228*x5-1)3/(1728*x^7 *(x10+11*x5-1)5) > What I tried after the Integration wouldn't stop in my Mathematica > was doing a term wise integration ( 64 terms, every 5th one non-zero). > >