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POWERS OF NUMBERS
04-30-2021, 08:04 PM (This post was last modified: 04-30-2021 08:04 PM by aurelio.)
Post: #1
POWERS OF NUMBERS
Excuse me for my trivial question, but how happened that the function (calculated by an internal routine) y^x changed starting from the HP45 after to has been, on the HP35, x^y ?
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04-30-2021, 08:20 PM (This post was last modified: 04-30-2021 08:31 PM by trojdor.)
Post: #2
RE: POWERS OF NUMBERS
I don't know about the 'official' reason, but at the time...when I was actively using both...I remember thinking the newer/45 way felt more logical within the RPN 'postfix' philosophy.
(You first enter a number, then you apply an operation to it. You don't enter the operation first, ala algebraic.)

It also seems easier (to me) when using the 1/x in conjunction with the y^x in order to do various roots of numbers, particularly if they're already on the stack as the result of a previous operation.
For instance, if I've already got a 729 on the x register, and I want to do a cube root, it's as simple as 3, 1/x, y^x, and I've got 9.

mike

ENTER > =
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04-30-2021, 08:39 PM
Post: #3
RE: POWERS OF NUMBERS
(04-30-2021 08:20 PM)trojdor Wrote:  I don't know about the 'official' reason, but at the time...when I was actively using both...I remember thinking the newer/45 way felt more logical within the RPN 'postfix' philosophy.
(You first enter a number, then you apply an operation to it. You don't enter the operation first, ala algebraic.)

mike
Thank-you for your reply, Mike, I'm agree, it's more logical (personally I've not a great experience/feeling with algebraic calculators), but usually, having to choose the first answer I give to myself is not the good one Smile, maybe there is another reason more "official", as you wrote
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04-30-2021, 08:49 PM (This post was last modified: 05-01-2021 07:01 PM by Guenter Schink.)
Post: #4
RE: POWERS OF NUMBERS
(04-30-2021 08:04 PM)aurelio Wrote:  Excuse me for my trivial question, but how happened that the function (calculated by an internal routine) y^x changed starting from the HP45 after to has been, on the HP35, x^y ?
There is a Museum somewhere Big Grin they have an explanation.
Quote:The 35 is well-known for having an x^y key instead of y^x. This makes a lot of sense on the 35 since it didn't have a 10x key. If you wanted the anti-log of a number in x, you entered 10 x^y.

Günter
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04-30-2021, 09:01 PM (This post was last modified: 04-30-2021 09:06 PM by aurelio.)
Post: #5
RE: POWERS OF NUMBERS
[quote='Guenter Schink' pid='147130' dateline='1619815752']
There is a Museum somewhere Big Grin they have an explanation.
Quote:

Shame on me Sad , I missed it completely, my first calculator was the 25c Smile thank-you Günter
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04-30-2021, 10:48 PM (This post was last modified: 04-30-2021 10:50 PM by Dave Britten.)
Post: #6
RE: POWERS OF NUMBERS
Interestingly, x^y makes it easier to calculate a sequence of powers, since you go from the "top" downward.

e.g.: 2^2^2^2 = 2^(2^(2^2))

On a 35: 2 ENTER 2 x^y 2 x^y 2 x^y

On a 45: 2 ENTER 2 y^x 2 x><y y^x 2 x><y y^x

Yes, I know there are other ways to do this specific example (fill the stack with 2, etc.), but you get the idea. Smile
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05-01-2021, 01:37 PM (This post was last modified: 05-01-2021 01:39 PM by aurelio.)
Post: #7
RE: POWERS OF NUMBERS
Shame twice on me, I wrote "starting from the HP45", forgetting that the second pocket calculator, made by HP has been the HP80, not scientific, but anyway equipped with the y"x key Sad
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05-03-2021, 07:09 AM
Post: #8
RE: POWERS OF NUMBERS
I've found here another previous old discussion very interesting about that key....
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05-03-2021, 07:57 AM
Post: #9
RE: POWERS OF NUMBERS
Oh - that is interesting - a negative zero value!
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