From: george@unixg.ubc.ca (George chow)
Subject: Re: Hp48 and TI85 compared
Organization: University of British Columbia, Vancouver, B.C., Canada
Date: Thu, 20 Aug 1992 15:54:13 GMT

In article <1992Aug20.023308.6024@unixg.ubc.ca> ochealth@unixg.ubc.ca (ochealth) writes:
>In article <1992Aug14.210022.15328@utagraph.uta.edu> b645zjo@utarlg.uta.edu (Rick Homard) writes:
>>Hello to all interested in knowing how the TI85 compares with the
>>HP48.
>>
>>This is a (non comprehensive) comparison of the HP48S and the TI85
>>available features and commands.
>>
>>==========================================================================
>>Plotting and Graphing
>>
>>The TI85 plots a bit faster than the HP48.
>
>!!!!

I've always wondered why the HP48 is so slow at plotting. My Casio fx-8000G
also beats my 48sx at plotting. The only calculator that's slower than my
HP is the Sharp Super-Scientific.

>>The TI85 has better and more zooming features.
>
>hmm, this needs explaining? How is one zoom better? How many ways can you
>zoom and pan anyway?

Maybe it's easier? My friend's Sharp has a nice pan feature where you just
cursor over in the direction you want. The calculator scrolls over and 
plots extra pieces of the function as required.

>>The TI85 can solve simultaneous equations (30 unknown maximum).  Indeed
>>the HP48 can do this also but it does not have a user interface to do it
>>from.  A nice feature but slow when solving anything larger than 15 unknowns.
>
>Simultaneous Linear equations? The HP48 can solve these, and more that 30 too.
>(assuming memory permits)

If you mean that you can formulate the system as Ax = b where A is a matrix
and x and b are vectors and just invert A, then no, that's not a feature.
Matrix inversion isn't a stable operation (just crack open your linear algebra
text). 

>>The TI85 performs some fudging (rounding, et al) on calculations.
>>
>>Examples:
>>
>>0.333333333333 * 3 = 1
>>and
>>sin (3.14159265359) = 0
>
>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
>zeros aren't displayed.

That sounds just like my TI-66.

>>The TI85 also performs numerical integration and differentiation in the
>>graphical environment.
>
>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.

Hmmm... I must have missed something from reading my HP's manual. How do you
get an error bound from the HP on your integral? (What do you mean by 'and 
gives you a good idea whether the numerical result is close'?)

>Well, I won't be trading in my 48SX, but it bugs me that the TI85 has built
>in matrix stuff the HP doesn't (eigenvalues, LU etc). That stuff is nasty
>to write, and I'd rather have it built in (even though I can add that easily
>from the NET). I think the HP48 has some White Elephant code that was put
>in for marketing: like the equation writer. It sure looks cool on the box,
>but I rarely use it. I'd rather have some extra functions, or Matrix things
>or Polynomial things built in instead. (AT least I can add them!)

Almost the same feeling here. I was rather surprised when I first got my 48sx
that HP didn't include anything substantial for matrices. Well, I suppose we
have to be thankful that at least there's enough primitive function for us
to cobble together our own. (BTW, I tried converting some of the stuff from
_Numerical Recipes_ but I never had the patience to complete finish it...)

>>Rick Homard
>>
>
>
>-- 
>______________________________________________________________________________
>jpm: ochealth@unixg.ubc.ca         
>                            Happily using OS/2 2.0 because MS Windows isNT ___
>                                                      Insert VapourFeature ^^^

George