Faulty example (Corrected now)

Please report errors, omissions, corrections and suggestions for the DM32 User Manual and the built-in Quick Reference Guide.
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PierreMengisen
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Faulty example (Corrected now)

Post by PierreMengisen »

your example of RPN processing is not correct.
3.3.3 ( 2/7 × ( 27 ÷ 2.5 ) - ( 2 + 4 ) ) × π
is not equal to 27 2.5 × 2 4 + - 2/7 × π ×
but 27 2.5 ÷ .2.7 × 2 4 + - π ×
Last edited by PierreMengisen on Wed May 31, 2023 3:01 pm, edited 1 time in total.
Pierre
[TI59 with PC100C; TI-84 Plus CE-T; HP41CV with HP IL loop & 2*82161A DCD & 82162 TP; HP15C; HP28S; DM41; DM41L; DM42; DM41X]
HPMike
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Re: Faulty example

Post by HPMike »

PierreMengisen wrote:
Wed May 24, 2023 5:35 pm
your example of RPN processing is not correct.
3.3.3 ( 2/7 × ( 27 ÷ 2.5 ) - ( 2 + 4 ) ) × π
is not equal to 27 2.5 × 2 4 + - 2/7 × π ×
but 27 2.5 ÷ .2.7 × 2 4 + - π ×
Although your expression is certainly correct for a calculator such as the DM32 with fractions, in general for RPN the expression would be 27 ↑ 2.5 ÷ 2 ↑ 7 ÷ x 2 ↑ 4 + - π x

Also, both the manual and your RPN expressions lack the Enter keystroke ↑ which is confusing, especially to someone not familiar with RPN data entry.
Last edited by HPMike on Sun May 28, 2023 2:03 am, edited 1 time in total.
DM15L, S/N 00548. DM42, SN: 00159. DM41X, SN: 00973. DM32, SN 00054.
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Emy
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Re: Faulty example

Post by Emy »

Thanks. Fixed.

Also removed the fraction from the example expression; it showcases the feature but it's indeed not a good place in the manual for that.
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PierreMengisen
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Re: Faulty example

Post by PierreMengisen »

Please don't let your resolution of Example 3.3.3 be a mathematical horror! :oops:

It's all about respecting the hierarchy of operations
1) Parentheses
2) Exponents
3) Multiplication and division (from left to right)
4) Addition and Subtraction (from left to right)

( 2/7 × ( 27 ÷ 2.5 ) - ( 2 + 4 ) ) × π

so first do the brackets => 10.8 for the first and 6 for the second
but now you have to multiply 10.8 by 2/7 but not 6 which is not involved at the moment
so we have (21.6/7-6) × π which gives us -102/35 × π = -2.9142857
result -9.155498590461683152091132145557409...

in summary: 27 ↑ 2.5 ÷ .2.7 × 2 ↑ 4 + - π × ≈ -9.1555
Pierre
[TI59 with PC100C; TI-84 Plus CE-T; HP41CV with HP IL loop & 2*82161A DCD & 82162 TP; HP15C; HP28S; DM41; DM41L; DM42; DM41X]
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Emy
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Re: Faulty example

Post by Emy »

PierreMengisen wrote:
Sat May 27, 2023 7:29 pm
a mathematical horror! :oops:
Horror? Are you suggesting the result should not be 34 digit-long?
Peet
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Re: Faulty example

Post by Peet »

Emy wrote:
Sat May 27, 2023 9:38 pm
Horror? Are you suggesting the result should not be 34 digit-long?
The RPN input example and the sample calculation are different/wrong and both doesn't fit to the algebraic expression.

i would type in: 2 7 / 27 2.5 / * 2 4 + - pi *
My programmable calculators - former: CBM PR100, HP41CV, HP28S, HP11C - current: HP48G(256kB), HP35S, Prime, DM41X, DM42
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PierreMengisen
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Re: Faulty example

Post by PierreMengisen »

Emy wrote:
Sat May 27, 2023 9:38 pm
PierreMengisen wrote:
Sat May 27, 2023 7:29 pm
a mathematical horror! :oops:
Horror? Are you suggesting the result should not be 34 digit-long?
No. the mathematical horror is not to respect the hierarchy of operations !!! please wake up.
Pierre
[TI59 with PC100C; TI-84 Plus CE-T; HP41CV with HP IL loop & 2*82161A DCD & 82162 TP; HP15C; HP28S; DM41; DM41L; DM42; DM41X]
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Emy
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Re: Faulty example

Post by Emy »

Emy wrote:
Thu May 25, 2023 10:20 am
Thanks. Fixed.
PierreMengisen wrote:
Sun May 28, 2023 8:45 am
please wake up.
I'm fully awake thank you very much, even though I'm not a mathematician by trade. Besides, I've already addressed this. Just wait for the next revision of the manual to be published.
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PierreMengisen
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Re: Faulty example

Post by PierreMengisen »

The correction is OK. The example is more judicious and above all correctly treated.
Thank you.
Pierre
[TI59 with PC100C; TI-84 Plus CE-T; HP41CV with HP IL loop & 2*82161A DCD & 82162 TP; HP15C; HP28S; DM41; DM41L; DM42; DM41X]
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