Re: NDSolve of partial differentiel equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg18696] Re: NDSolve of partial differentiel equation*From*: Don Paddleford <don-paddleford at worldnet.att.net>*Date*: Thu, 15 Jul 1999 01:46:11 -0400*Organization*: AT&T WorldNet Services*References*: <7lul3m$lar@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Christian Damgaard wrote: > > Dear All, > > I am trying to solve a set of partial differential equation with three > variables nummerically. However, as far as I see Mathematica only allows two > variables in NDSolve. Is that correct ? > > The equations look like: px[x,y,t]==expr, py[x,y,t]==expr > > with boundary conditions: px[a,y,t]==0, px[b,y,t]==0,py[x,c,t]==0, > py[x,d,t]==0 > > and initial conditions: px[x,y,0]==expr,py[x,y,0]==expr > > If have tried something like: > > NDSolve[ {px[x,y,t]==expr, py[x,y,t]==expr, px[a,y,t]==0, > px[b,y,t]==0,py[x,c,t]==0, py[x,d,t]==0, > px[x,y,0]==expr,py[x,y,0]==expr},{px[x,y,t],py[x,y,t]},{x,x0,x1},{y,y0,y1},{ > t,t0,t1}] > > but it replyes that there are to many variables. > replacing {x,x0,x1},{y,y0,y1},{t,t0,t1} with {{x,x0,x1},{y,y0,y1},{t,t0,t1}} > does not work either. > > Christian Damgaard > cfd at dmu.dk Christian, I raised this question to Wolfram a while back and was told NDSolve would handle two variable PDE's at most.