When I change into engineering/scientific mode with a precision of e.g. 1 digit, '70E-9 *cos(0)' gets simplified into 1/e^16 (cas is set to exact). What is going on here?

I am unable to reproduce your error. I get 7.0E-8

A couple of questions:

-In the answer, is that e the normal (2.71828...) e?

-Do you have E defined to be a variable with a value?

-Can you explain *exactly* what you're doing?

Example, I am in RPN mode, enter 70E-9 *cos(0) in single quotes, and hit EVAL (or simplify, whatever) and get 7.0E-8

Set mode to engineering with precision 1, cas mode exact. Open equation editor, enter cos(0) * 0.01 (another example). Select whole expression and simplify it, or close the equation editor and invoke SIMPLIFY (EVAL does not exhibit this behaviour). It gets simplified to 1/e^5 (yes, that's e, the exponential function).

I have made a recording of this in the emulator:

http://www.mediafire.com/?9cnml3z1c3yvhw8

Hi Juraj,

I confirm I get the same strange result when using SIMPLIFY and low display digits in Exact Mode. This seems to be a problem with version 2.15 of the calculator firmware. In version 2.09 it will request Approx. mode and display the correct answer.


To others,

Just entering the equation with EVAL it seems it always gets the right answer, irrespective of display digits setting.

To reproduce the error:
Have version 2.15 and set display to either FIX 1, SCI 1 or ENG 1
Enter the equation in Equation Writer, select it completely and use SIMP
or
enter the equation on the command line '70E-9·COS(0)' go to CONVERT -> REWRITE -> SIMPLIFY


EDIT:

Further to the above: it seems also to be a problem with the 50g association of integers and exact mode, and floating numbers and approx. mode.
Enter the equation as:
(70/1000000000)*COS(0)
and it will simplify it correctly.


Thus the v. 2.09 response is correct to request Approx. Mode because of the 70E-9. It does not request it when 70/1000000000 is entered. The 50g is wrong by just giving an answer that is incorrect. Something broke here between 2.09 & 2.15.

Edited: 7 Nov 2012, 6:48 a.m.

In approx mode, 1•0.01 gets simplified right into 6.7E-3. This is really dangerous! How the hell did not anyone discover this earlier? That was on my 3rd or 4th day of owning a 50g....

Edited: 7 Nov 2012, 10:59 a.m.

How do you do ?

In RPN mode I get the right answer

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How do you do ?

In RPN mode I get the right answer

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Edited: 7 Nov 2012, 11:52 a.m.

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How the hell did not anyone discover this earlier? That was on my 3rd or 4th day of owning a 50g....

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In approx mode, 1•0.01 gets simplified right into 6.7E-3.

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Edited: 7 Nov 2012, 12:06 p.m.

Interesting. I tested this on a emulator, though, which would have been an older version. I left my physical HP50g at home, so I'll have to check this on that later.

I can also confirm this behavior on the HP50G ROM 2.15

Han

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Interesting. I tested this on a emulator, though, which would have been an older version. I left my physical HP50g at home, so I'll have to check this on that later.

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It looks like my physical calculator does have this issue. Maybe I should try to install an older version?