| Author | Comment |
AlephMobius
Marine
Posted: 1 Mar 2003
11:35 GMT
Total Posts: 18 | On my TI-89 2^3^4 is evaluated as 2^(3^4). On Casio and HP calculators it is evaluated as (2^3)^4. Regardless of what calculators do which is mathematically correct? |
Barrett
Administrator
Posted: 1 Mar 2003
11:50 GMT
Total Posts: 1676 | i'd have to say the TI is correct.. although this is a good question. you'd have to consult an order of operations professional. but when you write:
--4
-3
2
(disregard those -'s)
you usually think of that as 2^(3^4)
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-Barrett A |
Digital
Guardian
Posted: 1 Mar 2003
12:01 GMT
Total Posts: 1051 | I don't know about the HW2 manuals but in the HW1 manual the process of evaluating eqations is clearly defined on pages 538-539 and it tells why it does that. If you have a resource cd go open the manual and look up EOS (Equation Operating System). |
AlephMobius
Marine
Posted: 1 Mar 2003
15:00 GMT
Total Posts: 18 | I know what the manual says but is that always correct in the mathematical scheme of things? Technically all the manual is telling us is what the TI-89 returns, not what would be considered right or wrong elsewhere. If + - * and / are evaluated left to right why arent exponents? |
ShockTroop
Goliath
Posted: 2 Mar 2003
04:51 GMT
Total Posts: 170 | I just did it out, and if you calculate 2^3^4 it's 4096, and the same with (2^3)^4 because the parentheses are just about ignored. Using 2^(3^4), it ends up being 2^81, which is 2,417,851,639,229,258,349,412,352 (I was using the comp calc hehe). I also did it out on my TI-83+, and 2^3^4 comes out to be 4096, which can be evaluated as either 2^3^4 or (2^3)^4. Maybe there's an Associative of Exponents where the parentheses don't matter, but you'd have to be using the same order. Evaluating 2^4^3, 4^2^3, and 4^3^2 also comes out to be 4096, but 3^4^2 and 3^2^4 comes out to be 6561, so it could be a Property and not an Axiom. I don't know if that has to do with anything, but maybe there's no associative anyway... |
AlephMobius
Marine
Posted: 2 Mar 2003
09:02 GMT
Total Posts: 18 | What im saying is that the TI89 returns 2^81, why isnt it 8^4? |
zkostik
Carrier
Posted: 2 Mar 2003
10:31 GMT
Total Posts: 2486 | Maybe it just didn't simplify the number or something?
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AlephMobius
Marine
Posted: 2 Mar 2003
14:55 GMT
Total Posts: 18 | No, my TI-89 always gives me 2,417,851,639,229,258,349,412,352. |
AlephMobius
Marine
Posted: 3 Mar 2003
08:37 GMT
Total Posts: 18 | The TI-81, TI-83+,HP-48GX, and Casio AFX 2 return 4096. The TI-89 is the only one I can find that puts the parenthesis around 3^4 instead of 2^3. How about if we email ti-cares? |
Digital
Guardian
Posted: 3 Mar 2003
12:07 GMT
Total Posts: 1051 | wise idea and good question. |
AlephMobius
Marine
Posted: 3 Mar 2003
13:15 GMT
Total Posts: 18 | I will email them shortly. Not that it makes any difference but the Casio fx-7400g+ gives 4096 too. My math teacher told me that the correct evaluation of 2^3^4 is 2^(3*4) which gives 2^12 which is 4096. |
AlephMobius
Marine
Posted: 5 Mar 2003
12:42 GMT
Total Posts: 18 | Here is what I got from ti-cares:
Entering 2^3^4 leaves the unit to interpret what the expression really
means, and there are three schools of thought regarding this:
1. Associate left to right. The TI-8X series graphing handhelds, with the
exception of the TI-89, follow this strategy. This convention relies on the
user to clear up questionable areas with parentheses.
2. Associate right to left. The TI-89, TI-92, TI-92 Plus, and Voyage 200
and DERIVE do this.
3. Have the device or software return a syntax error until parentheses are
given.
It is recommended to always use parentheses where the rules of algebra may
not be clear.
Regards,
Yowanda Andersen |
zkostik
Carrier
Posted: 5 Mar 2003
21:10 GMT
Total Posts: 2486 | Sounds cool. Kinda like a a deep mathematicians though. Haha,I'd like to see what TI would say in responce. Hopefully a real person and not a bot will respond on that issue.
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Barrett
Administrator
Posted: 5 Mar 2003
21:40 GMT
Total Posts: 1676 | Z, read his comment again, that IS what TI had to say about it, and they did a good job explaining it.
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-Barrett A |
The Hobo King
Probe
Posted: 6 Mar 2003
14:41 GMT
Total Posts: 4 | Holy s*** people!! were do you get all this crap? |
