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+--- Thread: POWERS OF NUMBERS (/thread-16844.html)
POWERS OF NUMBERS - aurelio - 04-30-2021 08:04 PM
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 ?
RE: POWERS OF NUMBERS - trojdor - 04-30-2021 08:20 PM
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
RE: POWERS OF NUMBERS - aurelio - 04-30-2021 08:39 PM
(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.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
(You first enter a number, then you apply an operation to it. You don't enter the operation first, ala algebraic.)
mike
, maybe there is another reason more "official", as you wrote
RE: POWERS OF NUMBERS - Guenter Schink - 04-30-2021 08:49 PM
(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
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
RE: POWERS OF NUMBERS - aurelio - 04-30-2021 09:01 PM
[quote='Guenter Schink' pid='147130' dateline='1619815752']
There is a Museum somewhere
they have an explanation.Quote:
Shame on me
, I missed it completely, my first calculator was the 25c thank-you Günter
RE: POWERS OF NUMBERS - Dave Britten - 04-30-2021 10:48 PM
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.
RE: POWERS OF NUMBERS - aurelio - 05-01-2021 01:37 PM
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
RE: POWERS OF NUMBERS - aurelio - 05-03-2021 07:09 AM
I've found here another previous old discussion very interesting about that key....
RE: POWERS OF NUMBERS - EdS2 - 05-03-2021 07:57 AM
Oh - that is interesting - a negative zero value!