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From: d0mo@dtek.chalmers.se (Mats Olsson)
Newsgroups: comp.sys.handhelds
Subject: Abstract data types in HP48
Message-ID: <1991Mar14.141613.28288@mathrt0.math.chalmers.se>
Date: 14 Mar 91 14:16:13 GMT
Sender: news@mathrt0.math.chalmers.se (Evald Nyhetsson)
Organization: Dep of Mathematics, Chalmers, Gothenburg
Lines: 32

Hi folks!

I have a little thought.

As you know, the HP48 has some abstract data types built-in,
called "Long Real", "External", etc (I bet it IS an "Internal" as well!).
(They all have hidden structures and are therefore represented as
their names on the stack (=> abstract))

Now the idea:
How about to create an *own* one, for example a "Symbolic Matrix" data
type. It should then be shown on the stack as just the string 
"Symbolic Matrix", but when you pushed the down-arryw key, 
you would be able to look at, and edit, the symbolic matrix in a 
matrix editor. (This implies of course that one has redifined the down-
arrow key, to check for that kind of data type, and also that you've 
written a symolic-matrix editor)

I think it really *is* need for a symbolic matrix data 
type, and wouldn't it be nice if it could be made in that "professional" way?

Then one could add operators, such as *,+,1/x,det etc, and also some
selectors (to get an object at a specific position of the matrix, etc),
to work on that data type...

How about it? Is it possible? I welcome any comments!!

Regards,

Mats Olsson,
Chalmers Univerity of Technology,
Sweden