wp 34s exponent limits?



#28

was playing around with large numbers on my wp 34s. noticed something interesting. i seem not to be able to directly enter exp larger than 299. but it seems the calculator will handle up to exp 384. Kinda unexpected given that 42s went up to exp 499..

did i miss something?

Edited: 26 Aug 2012, 11:16 a.m.


#29

Even the lowly 10bII+ will do E499. ;-)


#30

Try to compute 449! on the HP 10bII+. On the WP 34S (DBLON) I get 3.851930518028072576321584769129658e997

or try 2123!: 1.479907299403249333203306687282144e6143 :-)

Edited: 26 Aug 2012, 12:43 p.m.

#31

Please read page 38f of TFM for the limits and p. 156f for the reasons. By turning to double precision real numbers you can go up to 10^6145 (see p. 177). Sufficient for your needs?


#32

i see. thanks ;)

#33

Hello all,

I take the opportunity of this thread to ask you this humble question: does such a large (and the word is weak) number (10^6145) make sense ?


I mean: is there anything we could measure or count that would require such a number? I guess that even the number of elementary particles in the whole universe (at least as we currently know it) is far below this number.

I would be very glad if someone could enlighten me on this topic!

Many thanks advanced.

Cheers.


Jean-Michel


#34

I thought I read that the current estimate of elementary particles in the Universe is something like 10^80.

#35

Numbers with huge exponents are useful even if they are not useful for counting things (note that floating point is a poor scheme for counting things.) Mostly they're useful for doing computations without worrying about exponent overflow/underflow problems. Not there are not of other pitfalls in doing floating point computations.Details of FP computation woes ....

#36

Bonjour Jean-Michel,

Our double precision format follows a standard format (voir p. 177 svp.). The maximum exponent is a mere consequence. Of course we could have reduced it by two bits so we'd have got something like 10^(+/-1500), so anybody may safely enter 10^999 at least ;-) By deviating from "decimal128" (voir Wikipedia svp.) there may have arisen SW problems - but ask Pauli about this :-)


#37

We could have used a different format reals, the SW implications there aren't great.

I did think about a fifteen digit real format which would have allowed us to distinguish strings from reals (but not integers from either).

I'd prefer to be able to claim to be IEEE-854 compatible however.


- Pauli


#38

Quote:
I'd prefer to be able to claim to be IEEE-854 compatible however.

IEEE-754 sounds better ;-)

#39

IEEE 754-2008 :-)


- Pauli


#40

Quote:
IEEE 754-2008 :-)

Would you ever refer to anything other than the valid edition of a standard? I won't even think of it ;-)
#41

The exponent range support is a function of the floating point format used. You can enter exponents larger than 299 -- all the way to 384 in fact.

In double precision mode, a different format is used which increases the exponent range.


- Pauli


#42

so you really can enter up to exp 384 in SP mode? It wont let me do it. I can only enter 299 directly. But when i multiply that by say 1e50 i do get exp 349.

What am i doing wrong? ;(


#43

What firmware version?

On version 3225, I press EEX 3 8 4 and it works fine.


- Pauli


#44

firmware 3.13233

Hmm. now it does let me enter it directly... maybe i was in some wierd mode earlier? maybe because I reseted it?

well, if it happens again i will try to replicate and post my findings. I couldve sworn that i couldn't enter exp 384 directly earlier and that it only let me entered up to 299....


Edited: 26 Aug 2012, 8:44 p.m.


#45

Oiiiek wildpig,

Just watch the exponent during digit entry :-)

#46

not related directly to exp. I tried to do inverse tan on infinity. it crashed on me. ;( should i ve set some flag so that it might give pi/2 approximation as the answer? Also interestingly, tan (pi/2) give something to the exp of 15....


#47

Quote:
not related directly to exp. I tried to do inverse tan on infinity. it crashed on me. ;( should i ve set some flag so that it might give pi/2 approximation as the answer? Also interestingly, tan (pi/2) give something to the exp of 15....

I guess you're confusing the WP34s with a CAS calculator. ;-)

#48

no, i am not expecting it to give me pi/2 as the answer to inv tan (inf). but i was expecting something like an approximation of pi/2. Also when i do tan (pi/2), was expecting inf and not some wierd something to exp 15 as an answer.

Also it shouldn't crash when i do inv tan (inf)....


#49

tan(pi/2) isn't infinity in limited precision.

The value for pi/2 is rounded appropriately.

pi/2 is roughly    1.5707963267948966192313216916397514420985...
when rounded it is 1.5707963267948970000000000000000000000000...

The tan of this latter value isn't infinite....


- Pauli


#50

I guess that would be the case why tan of approximated pi/2 is not inf.

maybe i should stop taking inv tan of inf since it will crash ;)


#51

Oiiiik wildpig,

Pauli repaired it. Try TAN^(-1) of -infinity now and you'll get -90 degrees on the WP 34S :-)


#52

It was meant to do this all along but a typo got in the way....


- Pauli

#53

Yes this is a bug :-(
Fixed in the sources. A new build will happen eventually.

- Pauli


#54

I've updated the release package. Pascal has recompiled the multi-platform emulators, too.


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