Re: Help me : Solve a simple PDE in Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg110519] Re: Help me : Solve a simple PDE in Mathematica*From*: thaihang le <thaihang.le at gmail.com>*Date*: Tue, 22 Jun 2010 07:01:40 -0400 (EDT)*References*: <hvmvoo$pp1$1@smc.vnet.net> <hvn9ms$7iv$1@smc.vnet.net>

Dear Steve, Thank you for your great help. With your answer, no i understand. Solving PDE is not as simple although we know the equation and boundary. The most important is how to imply it in Mathematica. Mathematica uses Method of lines and solve very well simple PDE. But as my problem, the boundary condition is split in two domains : At z= 0 : When r < 1 : The dirichlet boundary is used : u[r,z] =0 When r > 1 : the Neumann is used : D[u[r,z],{r,1}] = 0 That's why i dont know how to imply this in Mathematica. For example, if the boundary is the same like this : r < 1 : u[r,z]=0 r> 1 : u[r,z] =1 I can imply in Mathematica as : z=0 : u[r,0] == If[r > 1, 1, 0]. Thanks again Steve. I try to go by another approach.