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HP Forum Archive 07

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HP calcs with X^Y function
Message #1 Posted by mapet on 17 Jan 2002, 2:59 a.m.

Most of calcs have Y^X function. How many calcs can you find with X^Y function?

      
Re: HP calcs with X^Y function
Message #2 Posted by thibaut.be on 17 Jan 2002, 3:20 a.m.,
in response to message #1 by mapet

As far as I know, only : - HP 9810A - HP 35

have the x^y function. Is that right ?

            
Re: HP calcs with X^Y function
Message #3 Posted by mapet on 17 Jan 2002, 3:24 a.m.,
in response to message #2 by thibaut.be

I think there are more...

                  
Re: HP calcs with X^Y function
Message #4 Posted by Ernie Malaga on 17 Jan 2002, 7:06 p.m.,
in response to message #3 by mapet

Yes, there are more. The HP-38G is one of them. The HP-39G is another. There may be more.

What's funny is that neither has an X- or Y-register per se (as far as I know), so the label is meaningless anyway.

-Ernie

                        
Re: HP calcs with X^Y function
Message #5 Posted by mapet on 18 Jan 2002, 3:26 a.m.,
in response to message #4 by Ernie Malaga

Some of the newest algebraic calcs have X^Y function. Others have Y^X. Both seems to act in the same way. So why the labels are different?

PS Compare HP 39G/40G, HP 30S, HP 6S

                              
There is a difference betwwen x^y function and x^y label
Message #6 Posted by Thibaut.be on 18 Jan 2002, 4:47 p.m.,
in response to message #5 by mapet

I mean that the calcs I mentioned really calculate x^y accoding to the position of the numbers in the stack; this is not the case for the later models you mentioned...

However keep on posting some more quizzes, I really enjoy it

                              
Re: HP calcs with X^Y function
Message #7 Posted by Vieira, Luiz C. (Brazil) on 21 Jan 2002, 12:09 a.m.,
in response to message #5 by mapet

Hi;

This is something I did not notice so far. Yes, I agree with Thibaut: the HP35 was the first - and the only - pocket RPN with x^y. All others offered [y^x] function (and label) to agree with other non-commutative math operations, i.e.: /, -, %. (Please, if the term commutative is not used this way, forgive-me and help me placing the correct one.) Say, 4-7 is not equal to 7-4, while 4+7 is equal to 7+4 (mathematical results). Raising to a power is non-commutative. Let's take this: at the moment we need 4-3, the sequence 4 ENTER 3 [-] will give the expected result; what about 4^3? We would place 4 ENTER 3 [y^x]; if there is a [x^y] function, the sequence should be 3 ENTER 4 [x^y] (remember, x and y reffer to stack-registers X and Y).

The algebraics differ for the math sequence: 4 [x^y] 3 [=] works fine, as 4 [y^x] 3 [=] is confusing for those already familiar with algebraic notation.

With RPN models, the input sequence will really dictate who will be raised to who, but [y^x] will always mean [y-contents ^ x-contents]. In the new ones, y- meaning level 2 argument, and x- meaning level 1 argument. With the 49G, the [y^x} key adds a single [^] character, algebraic or RPN mode.

Cheers.

                                    
Re: HP calcs with X^Y function
Message #8 Posted by Andrés C. Rodríguez (Argentina) on 23 Jan 2002, 4:59 p.m.,
in response to message #7 by Vieira, Luiz C. (Brazil)

If I recall correctly, the HP35 does not have an "antilog" key, so the reason to have x^y instead of y^x is to make it easy to do 10 x^y as an antilog shortcut.

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