A web search turned up this citation as well:
http://portal.acm.org/citation.cfm?id=32488
Allan Adler wrote:
> Let f(x1,...,xn) and g(x1,...,xn) be polynomials in n variables.
> I'd like to define the operation f # g as follows: replace each xi
> in f be the corresponding partial derivative operator d/dxi and then
> apply the resulting differential operator f(d/dx1,...,d/dxn) to g.
>
> How does one do that? I don't know if it is directly possible in Maxima.
> At any rate, it might be possible to speed it up by writing it directly
> in Lisp. I don't know how to do that and last time I tried to figure out
> how to do so, which was some time ago, I think I ran into a problem about
> the number of variables that a user defined function using lisp can have,
> which I vaguely recall being 1. (Possibly I'm getting confused with REDUCE,
> which I also tried to use.)
>
> Another complication is that Maxima might get confused if some of the
> coefficients are subject to let rules, such as some algebraic numbers,
> and maybe not properly treated as constants by the differentiations.
> --
> Ignorantly,
> Allan Adler
> * Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
> * comments do not reflect in any way on MIT. Also, I am nowhere near Boston.
>
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