NDSolve of partial differentiel equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg18442] NDSolve of partial differentiel equation*From*: "Christian Damgaard" <cfd at dmu.dk>*Date*: Wed, 7 Jul 1999 00:11:29 -0400*Organization*: UNI2 Internet Kunde*Sender*: owner-wri-mathgroup at wolfram.com

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