- number ^ power issue? HP Prime

[CR Haeger]

Hi,

I did not notice following with prior HP Prime firmware:

-3^2 yields -9 but
(-3)^2 yields +9

I hope I am missing something here, otherwise this is a problem.

[Jonathan Cameron]

(05-28-2014 04:58 PM)CR Haeger Wrote:  -3^2 yields -9 but ...

I think this must due to precedence of operators. The Prime (now) thinks that unary negation is lower precedence than exponentiation.

By the way, when I do this in python I get the same thing:


>>> -3**2
-9
>>>

[Thomas Radtke]

Both results appear to be correct.

1. how would you evaluate 0-3^2?

2. the square of a negative number is positive

I hope *I* have not missed anything here.

[Thomas Radtke]

(05-28-2014 05:09 PM)Jonathan Cameron Wrote:  I think this must due to precedence of operators. The Prime (now) thinks that unary negation is lower precedence than exponentiation.

Please have a look here:

http://en.wikipedia.org/wiki/Order_of_operations

In written or printed mathematics, the expression −3^2 is interpreted to mean −(3^2) = −9,[3] [...]

[3] Allen R. Angel, Elementary Algebra for College Students 8/E; Chapter 1, Section 9, Objective 3

[Tim Wessman]

48 and 50 do the same in an algebraic obj...

[DrD]

http://www.wolframalpha.com/input/?i=-3^2

-ditto-

[Tugdual]

(05-28-2014 05:29 PM)DrD Wrote:  http://www.wolframalpha.com/input/?i=-3^2

-ditto-

Same on Google, same on Bing.

[CR Haeger]

Thanks all - yes the Prime (and other calculators) are doing this correctly.

My error.

[Tim Wessman]

(05-28-2014 06:11 PM)CR Haeger Wrote:  Thanks all - yes the Prime (and other calculators) are doing this correctly.

Woohoo! I get to win for once!

[Steve Simpkin]

(05-28-2014 07:05 PM)Tim Wessman Wrote:  

(05-28-2014 06:11 PM)CR Haeger Wrote:  Thanks all - yes the Prime (and other calculators) are doing this correctly.

Woohoo! I get to win for once!

Well don't let it go to your head

Seriously, Tim. Thank you for all you do and for communicating information with us. Without you and Cyrille I suspect there would be no new RPN calculators from HP and certainly no RPN mode in the Prime.

Steve Simpkin

[Tugdual]

(05-28-2014 07:05 PM)Tim Wessman Wrote:  

(05-28-2014 06:11 PM)CR Haeger Wrote:  Thanks all - yes the Prime (and other calculators) are doing this correctly.

Woohoo! I get to win for once!

Ha ha ha thumbs up Tim

[CR Haeger]

(05-28-2014 07:05 PM)Tim Wessman Wrote:  

(05-28-2014 06:11 PM)CR Haeger Wrote:  Thanks all - yes the Prime (and other calculators) are doing this correctly.

Woohoo! I get to win for once!

Don't worry, there are a lot more things the Prime can do correctly that I still wouldn't recognize as being correct. Blame my out of date firmware...