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HP300s smartcalc error


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Post: #2
01-05-2010, 12:31 AM
Scott Smith Offline
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Hi,

When I do the following calc on my smartcalc I get the wrong ansswer. Any ideas anyone?

The calc is 78724*pi*.075^2*.5

I get an answer of 800 instead of around 695.

Thanks

Scott

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Post: #3
01-05-2010, 12:42 AM
Scott Smith Offline
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further to this if I multiply by .500000001 instead of 0.5 I get the correct answer.

Looks like I am back to my 48 or 30s

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Post: #4
01-05-2010, 11:31 AM
Hubert Weikert Offline
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Hi,

With my 300s I get 221*(329/800)*PI, which converts with S<=>D to 695.5839564

Hubert

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Post: #5
01-05-2010, 01:49 PM
Norman Dziedzic Offline
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Funny,

For 221*(329/800)*PI I get 285.527...

Did you copy something down wrong?

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Post: #6
01-05-2010, 04:36 PM
Scott Smith Offline
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Hi Guys,

I too get 285.382 from the above formula.

I have done this eqn over and over again on my 300s and always get 800. I have even saved intermediate values in registers and still get the wrong answer.

My 38G gives me the correct answers, so too does my 35s and 48.

Looks like I got a dud.

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Post: #7
01-05-2010, 07:26 PM
Tim Wessman Offline
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I repeated it on my emulator. I'm not sure if it is the actual code used in the unit though, or a reimplementation. . .

I suspect it is a setting of some kind causing the problems. Not sure which one though.

TW

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Post: #8
01-06-2010, 03:58 PM
Hubert Weikert Offline
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Sorry, I had not checked what I wrote!

The correct term is (221+329/800)*PI, which results in 695.58...

The error depends on the setting of the fraction mode (SET UP/down).
My calc is in MATH (MthIO) format mode.

setting ab/c (Mixed) gives 695.58...

setting d/c (improper) gives 800, thats the erroneus display.

Hubert


Edited: 7 Jan 2010, 11:27 a.m.

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Post: #9
01-06-2010, 12:56 PM
Bart (UK) Offline
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Hi,

I have tried this by doing = between each multiplication (and S<=>D where necessary) and in the second last step have 1391.167193. Multiply this by 0.5 (i.e. display is "Ans x 0.5") and it returns 800 as well.

However, the correct answer is displayed if the equation is done in reverse.


edit: taking the last step as "Ans / 2" also gives 800


Edited: 6 Jan 2010, 1:00 p.m.

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Post: #10
01-06-2010, 01:13 PM
Walter B Offline
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Quote:
in the second last step have 1391.167193. Multiply this by 0.5 (i.e. display is "Ans x 0.5") and it returns 800 as well. ... taking the last step as "Ans / 2" also gives 800
Does this mean this device is unable to calculate 1391.167193 / 2 ? That's elementary math! :( Hard to believe.
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