Some 49G+ Limitations



#13

Being a new 49G+ owner I have been trying some of the functions to see how well it handle "extremes". Needless to say, I am disappointed with what I have found thus far:


o 1000! = 1e500 with no overflow warning.

o 1.5! = 1.329 but in my opinion should give an improper (non-integer) input warning.

o Comb(2000,1000) = 1e500 with no overflow warning.

o asin(acos(atan(tan(cos(sin(7) = 7.000003185 which is no better than the 32sii and not up to TI 89 accuracy.


Is anyone aware of a list of other 49G+ limitations, bugs, etc.?


Regards,

John


#14

Hi, John;

let's see:

Quote:
o 1000! = 1e500 with no overflow warning.
Please, try:
[MODE][FLAGS][down-arrow] 6 times and [|/CHK]
You'll see that, now, overflow returns an error message. BTW, flag 20, underflow, may be checked for error as well. To maintain this setting, confirm with [OK] twice.
Quote:
o 1.5! = 1.329 but in my opinion should give an improper (non-integer) input warning.
This is because the [!] function (and also FACT) computes GAMMA(x-1) when the argument is not an integer.

Quote:
o Comb(2000,1000) = 1e500 with no overflow warning.
Same as first quote.

Quote:
o asin(acos(atan(tan(cos(sin(7) = 7.000003185 which is no better than the 32sii and not up to TI 89 accuracy.
The actual value is 7.00000318497 (STD mode set). What is the value obtained with the TI89?

Hope this gives you some new info.

Best regards.

Luiz (Brazil)

Edited: 9 Feb 2005, 1:23 a.m.


#15

TI89 ROM Version 2.05 results 7 + 2.83714e-8 (at least in it's emulation).

BTW, if you need an exact result for 1000! and COMB(2000;1000), the HP-49 has a CAS.

Ciao.....Mike


#16

HI, Mike;

Yeap! I actualy found a "many digits" result for 1000!... They were so too many I gave up reading.

Thanks!

Luiz (Brazil)


#17

Many complain about their appearance but no one about his brain. IMHO, talking about limitations of a HP49G+ is like blaming the sharp knife when you bleed. But its good habit to know the limits.

I "grew up" (mathematically) with an HP-41 which has not too much math by factory default. What I needed I had to program on my own or buy a plug-in module (if I only had the $ as student back in those days). Thoday an HP-49 comes packed with nearly all math you may dream of. So it demands a high knowledge in math from the user about all ifs and buts. That leads me to an idea: how about a bare calculator (with a screen as big as an HP200LX or a Sharp Zaurus) with an simple programming language (or two) to do your own solutions and enough storage to download ready to use application packs. That way this calculator will grow with your demands/tasks. In the end you'll have a very personal tool that fits _exactly_ *your* needs.

Ciao.....Mike
(sorry for the subject drift)


#18

Hi, Mike;

I agree with you. You see, I take the HP49G as the closest scheme for this "custom" calculator. As you say, the HP49G already has all math tools you can dream of. If adding any particular procedure to the existing OS is an easy matter, then it is already one possible, not too expensive solution. The upgradable OS has been the major reason I bought two of them.

Cheers.

Luiz (Brazil)(somehow driffting the subject as well)

#19

No calcualtor will ever be perfect and every machine has its quirks.

"That leads me to an idea: how about a bare calculator (with a screen as big as an HP200LX or a Sharp Zaurus) with an simple programming language (or two) to do your own solutions and enough storage to download ready to use application packs. That way this calculator will grow with your demands/tasks. In the end you'll have a very personal tool that fits _exactly_ *your* needs."

That is why I love programming. Making the calculator (and Excel, Word, the VCR) fit the user's needs. Having memory is more important that too many extras.

#20

Thanks Luiz and Mike for teaching me about some of the 49G+ features.

A happier and less frustrated user,

John


#21

After reading all these discursions about how calculators handle 'extremes' these are the results for the following functions on a HP65, HP41CX and HP48G:

a)1000!

HP65(9.999999999E99) wich is interpreted as an overflow

HP41CX(OUT OF RANGE)

HP48G the same as stated for the HP49G+

b)1.5!

HP65 -display blinks

HP41CX (DATA ERROR)

HP48G the same as stated for the HP49G+

c)asin(acos(atan(tan(cos(sin(7))))))

HP65(7.003719916) worse than HP49G+, HP48G and HP41CX

HP41CX(6.999519575) worse than HP49G+, HP48G

HP48G the same as stated for the HP49G+

Certainly the results improve with the newer models, but a strange thing for case c), HP41CX gives a result that aproaches from under the correct value, instead of all others.


#22

Hi Ralph. You can find the results of more comparisons at:

http://www.voidware.com/calcs/torturetest.htm


Regards,

John


#23

Thanks John, great site!

Ralph

#24

Nice to see my append was helpful. But I am a bit frustrated: An HP-49 or TI-89 has more math built in than I am ever able to understand. That's not a problem of those calculators, it's just an issue of capabilities: I will not in my lifetime understand such papers (alas PostScript only). No calculator may help me to see all coherencies that make up our world.

But what I miss on machines like the HP-49 is a system that calculates with errors, internal errors too. So the answer of asin(acos(atan(tan(cos(sin(7)))))) would be 7 +/- 0.00xy% or an interval [7-e; 7+e]. There is (was?) a FORTRAN lib for that (cant remember neither its name nor source). I once had a system on the HP-41 to calculate with errors (no-no, not with internal errors of cause, and not with intervals). It was for estimating errors when calculating with measured values. I just had to program the formula, the derivation for each variable was done with the PPC-ROM.

Ciao.....Mike (not having a full imagination of this world does not stop me dreaming...)


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