Re: How can I do this?

*To*: mathgroup at smc.vnet.net*Subject*: [mg19155] Re: How can I do this?*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Thu, 5 Aug 1999 23:58:58 -0400*Organization*: Universitaet Leipzig*References*: <7obbiv$3rm@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Bill, it depend on the problem. Ifthe 2d problem can be transformed to a rectangular domain f[t,x]=Sum[ c[i,j] p[j,t] g[j,x], {i,0,n1},{j,0,n2}] (notice the product form of the basis function) thats the way how partial differential equations solved by Fourier expansion. If you can't get a rectangular domain f[t,x]=Sum[c[i,j] b[i,j,t,x],{i,0,n1},{j,0,n2}] will be more general. How ever you will have problems to find an orthogonal basis b[i,j,t,x]. Hope that helps Jens > My question is, How do I go about constructing a function similar to the one > above but now of two variables so that in the expansion > > f[t, x] = c[1] p[1, x]+c[2]p[2, x] + ... > > the c's are functions of t so that formal differentiations and integrations > with respect to t can be carried out on it. > > Thanks, > > Bill Bertram