Re: Re: Placeholders in matrix notation

*To*: mathgroup at smc.vnet.net*Subject*: [mg29930] Re: [mg29899] Re: Placeholders in matrix notation*From*: "Hugh Philipp" <hph at com.dtu.dk>*Date*: Thu, 19 Jul 2001 03:56:56 -0400 (EDT)*Organization*: Reserach Center COM - DTU*References*: <9j0hhl$fjn$1@smc.vnet.net> <200107180608.CAA18930@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Can anybody think of a way to define a non-commutative differential operator that you can just plug into matrix equations? Perhaps the problem might be that the matrix routines assume that things commute... There is always a work around, but it would be nice to just say - 'Here is my operator. Here are my hairy matrix expressions. Go tell me how everything comes out.' and - do this making it look as close to the stuff I scratch on a back of an envelope as possible. -Hugh. ----- Original Message ----- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de> To: mathgroup at smc.vnet.net Subject: [mg29930] [mg29899] Re: Placeholders in matrix notation > Hmm, > > perhaps because {D[#,x],0} is an operator ? > and it has nothing to do with an dot product but > > Inner[#1[#2] &, {D[#, x] &, 0*# &}, {f[x], g[x]}] > > will work. > > Regards > Jens > > "Douglas F." wrote: > > > > I want to use the partial differential operator in matrix algebra. The function > > it operates on would be in another matrix. > > > > Here, I am using "d" to represent the partial operator > > {esc}pd{esc}{ctrl-_}x{ctrl-space} > > > > [d 0] . Transpose[ f[x]| g[x] ] > > > > But Mathematica won't let me do the matrix multiplication. How do you do that? > > > > -D

**References**:**Re: Placeholders in matrix notation***From:*Jens-Peer Kuska <kuska@informatik.uni-leipzig.de>