Re: Calc: `*' binds more strongly than `/'

[Daniel Brockman <daniel@brockman.se>]

Christian Schlauer <cs-muelleimer-rubbish.bin@arcor.de> writes:

> I don't have to think about such things /at all/ in /all
> other programs/ I use, because they use the common syntax,
> and I don't see the benefit of Emacs having its own rules.

Well, Emacs is better than all other programs in _many_ ways. :-)

> What do you win with that convenient behaviour compared to that it
> confuses people that also use other, more common spreadsheets [...]?

Apart from saving keystrokes, we'll provide good notation
that lets users type mathematical expressions involving
fractions more like the way they normally think about them.

There is a reason why mathematicians write

                            A B
                            ---
                            C D

instead of

                         A B / (C D).

Stefan's suggestion that `A / B C' and `A / B * C' mean
different things is interesting, however.

>> (You could make the same argument for `+' and `-' --- i.e.,
>> that `A-B+C' should mean `A-(B+C)'.  However, this is not as
>> natural because one usually does not think of sums as units.
>> Writing `A-B-C' is completely natural, but `A/B/C' is not
>> completely natural --- in fact, it is a little confusing.)
>
> Here I don't follow you -- except for that you can write `A/B/C' in
> Calc or any other software, and you will get the same result
> *everywhere*, even in Calc. (But I wouldn't write it that way either.)

I was just pointing out that `/' and `-' are different beasts
(anticipating an argument that they should work analoguously).

>> I think this is good notation, but I also think that it
>> would be a good idea to warn the user and make sure that
>> they know what they are doing when entering such things.
>
> I fully agree with Stefan:
>
> | In any case, I still haven't heard any concrete reason
> | why the non-standard behavior of calc is preferred to
> | the more common behavior.

I have presented at least one concrete reason.  (See above.)

> | Neither is perfect because there is no such thing,

There is such a thing as `better', though.

> | but one of them is sufficiently surprising to deserve
> | big warnings in the Calc doc and the Org doc, whereas
> | the other would be "business as usual".

Granted.

I think the feature is worth the warnings.

-- 
Daniel Brockman <daniel@brockman.se>