Differential operators

*To*: mathgroup at smc.vnet.net*Subject*: [mg2166] Differential operators*From*: sherod at boussinesq.Colorado.EDU (Scott Herod)*Date*: Wed, 11 Oct 1995 01:58:52 -0400*Organization*: University of Colorado at Boulder

I was trying to write a small piece of code to play with computing commutators of vector fields. I wanted something like vector = x D[#, x] + y D[#, y] &; etc. Unfortunately I noticed the following annoying behavior. ---------------------------------------------- Mathematica 2.2 for Solaris Copyright 1988-93 Wolfram Research, Inc. License valid through 28 Nov 1995. -- Open Look graphics initialized -- In[1]:= vector = D[#, x] & Out[1]= D[#1, x] & In[2]:= Simplify[vector] Out[2]= 0 & In[3]:= vector = Dt[#, x] & Out[3]= Dt[#1, x] & In[4]:= Simplify[vector] Out[4]= 0 & ----------------------------------------------- I know that I could write my own derivative operator but it would be nice to use the built in version. Suggestions? Notice that vector does work correctly. ----------------------------------------------- In[5]:= vector Out[5]= Dt[#1, x] & In[6]:= vector[f] Out[6]= Dt[f, x] ---------------------------------------------- Scott A. Herod Applied Mathematics Unversity of Colorado, Boulder (sherod at newton.colorado.edu)