Casio fx-29 - how to enter "y"

[tcab]

Today I noticed my partner pull out an old Casio fx-29 calculator that I didn't know she had!

Here is a photo I found on a website of this calculator.


Needless to say I immediately had a play.

I liked the keyboard feel and the glowing blue display. The time it took to calculate SIN was longer than I thought - about a second. I'm sure HP was never that slow!?

Then I hit the main stumbling block - how to do x^y. I can't find a manual online and not sure how to enter a second number before pressing the x^y key. Can anyone please give me a hint on how to drive this thing?

P.S. Relatedly, found this interesting article about operator precedence in Casio's calculator design history.

[Massimo Gnerucci]

(12-05-2018 07:29 AM)tcab Wrote:  Today I noticed my partner pull out an old Casio fx-29 calculator that I didn't know she had!

Here is a photo I found on a website of this calculator.


Needless to say I immediately had a play.

I liked the keyboard feel and the glowing blue display. The time it took to calculate SIN was longer than I thought - about a second. I'm sure HP was never that slow!?

Then I hit the main stumbling block - how to do x^y. I can't find a manual online and not sure how to enter a second number before pressing the x^y key. Can anyone please give me a hint on how to drive this thing?

P.S. Relatedly, found this interesting article about operator precedence in Casio's calculator design history.

Isn't it [x] x^y [y] = ?
I have one at home, could check this evening...

[tcab]

Yes that seems to work - thanks. What confused me was when I enter a number then hit the x^y key the calculator does something to the number and changes it. E.g. "2 x^y" gives me 0.6931 (confusing!) and when I keep going and hit "4 =" then finally I get the answer 16.

What is 0.6931 supposed to mean? Seems you have to ignore the intermediate number and just press on with the key sequence. Entering different x values followed by x^y give different "intermediate" numbers. Very confusing.

[Massimo Gnerucci]

0.6931 is approximately ln 2

[tcab]

Fascinating. I just crunched a series of numbers on the Casio fx-29, and indeed, pressing NUM x^y is the same as pressing NUM ln.

I wonder what the relationship between ln and x^y is, such that the calculator feels the need to do this...

[Didier Lachieze]

(12-05-2018 08:53 AM)tcab Wrote:  I wonder what the relationship between ln and x^y is, such that the calculator feels the need to do this...

Once you have implemented the algorithms for ln(x) and e^x, you can easily get x^y as x^y = e^(ln(x)*y)

[ijabbott]

I never had a fx-29, but I'm pretty sure I had a fx-39 at some point during my school years. I don't remember seeing any strange behaviour for the x^y key so I guess they changed it between the fx-29 and fx-39, although I no longer have the calculator to check.

[Albert Chan]

(12-05-2018 01:00 PM)ijabbott Wrote:  I never had a fx-29, but I'm pretty sure I had a fx-39 at some point during my school years.
I don't remember seeing any strange behaviour for the x^y key so I guess they changed it between the fx-29 and fx-39,
although I no longer have the calculator to check.

Any AOS calculator that had [X<>Y] key cannot assume x^y = exp(y * ln(x)).
It had to wait until [=] key is pressed (or other operators, say + - x /)

So, based on googled fx-39 pictures, you will not see ln(x) intermediates.

[edryer]

Quote:The time it took to calculate SIN was longer than I thought - about a second. I'm sure HP was never that slow!?

Interesting no factorial function, probably as this was an entry level Scientific, however I believe this was on the FX-501P (likely +1 years, 1979) but not the later fx-29 equivalent (likely the FX-80 +1-2 years).

69! was very slow on the early TI's that had the function, likely the Casio and HP's as well.

[ijabbott]

(12-05-2018 02:31 PM)Albert Chan Wrote:  

(12-05-2018 01:00 PM)ijabbott Wrote:  I never had a fx-29, but I'm pretty sure I had a fx-39 at some point during my school years.
I don't remember seeing any strange behaviour for the x^y key so I guess they changed it between the fx-29 and fx-39,
although I no longer have the calculator to check.

Any AOS calculator that had [X<>Y] key cannot assume x^y = exp(y * ln(x)).
It had to wait until [=] key is pressed (or other operators, say + - x /)

So, based on googled fx-39 pictures, you will not see ln(x) intermediates.

Actually, it might have been an fx-110 I had, which was similar to the fx-39, but with extra digits on the display, and the angle/sd mode switch in a different place. EDIT: Probably not though, because I don't remember mine having a dB conversion function. I've not seen a dedicated dB conversion function on a calculator before!