Re: [libreoffice-users] Awkward behaviour of LO Calc

On 29/03/16 09:38, lorieul wrote:
> Hello to all,
>
> I have found a fancy behavior of Calc but I cannot decide whether it is
> a bug or a "feature". Hence I was looking for your advice before posting
> a bug report (if required).
>
>    1. Open LO Calc
>    2. In A1 enter formula "=1-2^2" and press enter key
>       The result shown is -3 which is ok since
>       1-2² = 1-(2²) = 1-4 = -3
>    3. In A2 enter formula "=-2^2" and press enter key
>       I would expect this to be treated as -2² = -(2²) = -4
>       But Calc considers it as (-2)² = +4
>       Quite obviously, a work around is to define the formula as
>       "=-(2^2)" which indeed returns -4
>
> I've checked the wiki page dedicated to operators [1] but it does not
> give much information on operator precedence.
>
> > From my standpoint, both examples show an inconsistent behavior of Calc.
> For me, either we should have both 1-2^2 = 1+4 = 5 and -2^2 = +4
> Or we should have both 1-2^2 = 1-4 = -3 and -2^2 = -4
>
> However, perhaps some of you have a different view point on the matter ?
> In other words, is that a bug or is it perfectly normal ?

It looks as though someone has been following a bad example.

A quick search brings up
https://en.wikipedia.org/wiki/Order_of_operations

which says

"There exist differing conventions concerning the unary operator − 
(usually read "minus"). In written or printed mathematics, the 
expression −3^2 is interpreted to mean 0 − (3^2) = −9 .... but in .... 
Microsoft Office Excel (and other spreadsheet applications) and the 
programming language bc, unary operators have a higher priority than 
binary operators"

Contrary to, eg, perl.

Ouch! Quite contrary to expectation. Here lie monsters :-)


--
Mike Scott
Harlow, Essex, England

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