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From: edp@vmsdev.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.))
Newsgroups: comp.sys.handhelds
Subject: Re: Building an Algebraic
Message-ID: <12965@shlump.nac.dec.com>
Date: 29 Jun 90 11:57:33 GMT
References: <QaWnlIy00WBKM0gUw-@andrew.cmu.edu>
Sender: newsdaemon@shlump.nac.dec.com
Reply-To: edp@vmsdev.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.))
Organization: Digital Equipment Corporation
Lines: 21


> I would like to build an algebraic expression from within a program.
> What I want to do is something like:
> Pull 2 from the stack, then pull 3 from the stack and make '2*S^3' ,
> so then I could take the derivative of it.

If two algebraic objects (including simple numbers and names) are on the
stack (call them a and b), you can form the algebraic a*S^b with the following:

	<< "*S^" SWAP + + "'" SWAP + OBJ-> >>

or with:

	<< 'S' SWAP ^ * >>

The former is longer, but does not do some of the evaluations you get in
the latter case.  E.g., if a is 0, the latter program will return 0, but
the former will return 0*S^b.


				-- edp