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From: edp@jareth.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.))
Newsgroups: comp.sys.handhelds
Subject: Re: 48sx ROOT question
Message-ID: <23823@shlump.lkg.dec.com>
Date: 25 Jun 91 15:09:38 GMT
References: <1991Jun24.203727.3043@nntp-server.caltech.edu>
Sender: newsdaemon@shlump.lkg.dec.com
Reply-To: edp@jareth.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.))
Organization: Digital Equipment Corporation
Lines: 41

In article <1991Jun24.203727.3043@nntp-server.caltech.edu>,
tim@nijinsky.ipac.caltech.edu (Tim Conrow) writes:

>1) Does ROOT always need an algebraic to solve? Does this slow it down?
>   I assume programs are faster, n`est pas?

Valid arguments for ROOT are either a program or symbolic in level 3,
the global name to solve for in level 2, and a guess or list of guesses
in level 1.  So, yes, you can give ROOT a program.  The program should
take no arguments from the stack and return exactly one result to the
stack.

I would not expect this to be faster, unless algebraic syntax is forcing
you to use some work-arounds to get at non-algebraic commands (like
UTPN).  Barring that, programs are not any faster, because algebraics
and programs are stored and evaluated very much the same way.

>2) Another speed issue: Can ROOT be made to work for less than 12 digit
>   precision? Full precision takes too long and is unnecessary for my
>   purposes. I tried putting a RND(equation,6) call in my algebraic, but
>   it got no faster.

No.  Hewlett-Packard probably decided this was not necessary because the
ROOT algorithm is very good for many functions and usually converges
quickly.  You might be able to play with the function to help ROOT
converge more quickly -- perhaps by exaggerating return values or by
transforming the domain in the region of asymptotic behavior (e.g., if
the function is nearly flat over a long region, transform the domain to
make that region smaller).

> Does the HP Programmer's Manual deal with this?]

The Programmer's Reference Manual shows that programs are acceptable as
input, but it does not answer your other questions directly.  (It does
show only a global name acceptable as the level 2 input.)



				-- edp (Eric Postpischil)
				"Always mount a scratch monkey."
				edp@jareth.enet.dec.com