From: brianc@iastate.edu (Brian J Cerveny)
Newsgroups: comp.sys.hp48
Subject: Re: Hp48 and TI85 compared
Date: 11 Sep 92 01:21:05 GMT
Organization: Iowa State University, Ames IA

In <1992Aug20.215637.9692@utagraph.uta.edu> b645zjo@utarlg.uta.edu (Rick Homard) writes:

>>In article <1992Aug20.023308.6024@unixg.ubc.ca>, ochealth@unixg.ubc.ca (ochealth) writes...

>>>Unit Management
>>>
>>>Not supported on the TI85.
>> 
>>I assume this means you can't define your own? Can you perform arithmetic
>>with units?
>>>
>TI doesn't call them units. Rather it is just simple conversion between
>units.  
>And yes you can define your own unit conversions.

Then what do you mean by Unit Management?

>I compared the TI85's root finder with the HP48 (using the root finding
>program supplied by Bill Wickes on the net).  The results are incredible.
>The same 30th order polynomial was input to each machine.  The HP48 found
>all of the roots in 80 seconds.  I stopped the TI85 after 15 minutes.
>It is obvious that the TI85 gets heavily labored when required to perform
>at its limits.


>>>The TI85 performs some fudging (rounding, et al) on calculations.
>>>
>>>Examples:
>>>
>>>0.333333333333 * 3 = 1

Funny, with Float set in the MODE menu, I get .999999999999.  If you round to
any finite number, you will get 1.(n-1), where n=fixed point.  Make sure you 
have FLOAT set.

>>>and
>>>sin (3.14159265359) = 0
>
Same here, I get -2.000000000000E-13 when I enter that in my machine.

>>If I remember TI, they don't really round the answer, they just display
>>part of the answer (ie the first 12 digits, and the 13 and 14 are kept
>>internally). Sort of like the HP with 10 FIX on all the time, but trailing

As mentioned above, it's not really like 10 FIX (the equivalent on TI would be
11 fixed) unless there are more than 12 digits in the result, AND the
thirteenth digit is >=5 after any internal rounding is done.
For example:

    .44444444444444 displays as-is.
    .44444444444445 displays as-is (since the 5 is in the fourteenth place,
                    not affecting the 12th)
    .44444444444454 displays as .444444444445.  The fourteenth digit is OK,
                    but the five in the 13th place rounds the 12th displayed
                    digit.
  

>This is still "fudging" notheless.  Regardless of how many decimal places
>you take .33333333 , when you multiply it by 3 you get .999999999 to the
>same number of decimal places.
>Also sin(3.14159265359) is a small number but not zero.  The sin(pi)
>is zero but 3.14159265359 is not pi.

Right, and my TI-85 agrees.  Check your setup.

>>How fast is it? Does it return an error estimate? I had a TI56 that did
>>Simpson's rule, and it was SLOW. When it finished you had NO CLUE whether
>>the answer is meaningful. The HP uses an adaptive algorithm which will
>>usually return usefull results to an integral, and give you a good idea
>>whether the numerical result is close, or way off.

>It is fast and it returns an error estimate in a variable, just like
>the HP48.  As what method it uses I do not know.

My TI-68 uses Simpson's Rule, and since the 68 is much like the 85 in non-
graphical or programming function, the TI-85 probably does to.

>>Is there any way to "get inside" the TI85? I mean software wise. A lot
>>of power in the HP48 comes from being able to add low level machine language
>>programs that blow away any user level program. For example, the recent ML
>>FFT is blindingly fast, and it can't be done quickly in user code.
>> 
>I do not know.  I have only had it for about a week now.

I'm curious about this too.  There is no mention whatsoever about this in the
manual, so I doubt it.  But you never know.  :)  

I tried calling the technical help line but they were closed.  (The tech line
is open from 8a - 4:20p, and is a long distance call... :(  What's the HP
tech support like?)  I wanted to ask about low-level programming, and the
absence of I/O port programmability.  Since port I/O isn't a part of the
high-level language, it would have to be available from machine-level,
which is at this time a questionable prospect.

-- 
   // Brian J. Cerveny (brianc@iastate.edu)
 \X/  Disclaimer:  The views expressed above are my own.  So there.
From: akcs.joehorn@hpcvbbs.cv.hp.com (Joseph K. Horn)
Date: Sun, 6 Sep 1992 06:40:02 GMT
Subject: Re: deleting libdat_v1.0 :<
Message-ID: <2aa9a144.1660.1comp.sys.hp48.1@hpcvbbs.cv.hp.com>