bug#47302: 27.1; calc math-format-number formatting for floats without decimals is unusual

[Dave Gillespie]

Wow, it has been a long time since I got any correspondence on Calc!

Yes, I used the notation "123." versus "123.0" with the goal to keep the output 
concise for casual interactive users.  I agree with Mattias that it is best to 
leave the default as it is.

Calc has a C language mode ('d C' keystroke, controlled by calc-language).  It 
is a good point that C mode (and probably others like it) should format 
integer-valued floats as "123.0" even if the default mode does not.  If we 
apply Jelle's patch, I suggest making it conditional on calc-language so that 
it applies only in modes such as C mode.  Or perhaps rework it as a text 
transformation using calc-language-filter.

You could even create a JSON language mode, but most likely the basic C mode is 
close enough to serve that purpose.

Thanks!

                                                                -- Dave



-----Original Message-----
From: Jelle Licht <jlicht@fsfe.org> 
Sent: Thursday, April 22, 2021 8:04 AM
To: Mattias Engdegård <mattiase@acm.org>; Stefan Kangas <stefan@marxist.se>
Cc: 47302@debbugs.gnu.org; Dave Gillespie <Daveg@synaptics.com>
Subject: Re: bug#47302: 27.1; calc math-format-number formatting for floats 
without decimals is unusual

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Mattias Engdegård <mattiase@acm.org> writes:

> 21 apr. 2021 kl. 17.16 skrev Stefan Kangas <stefan@marxist.se>:
>>
>> Jelle Licht <jlicht@fsfe.org> writes:
>
>>> (calc-eval "123.0") ; => "123."
>>> (calc-eval "0.0") ; => "0."
>>>
>>> I would expect this output to be either "123.0" or "123" and "0.0" or
>>> "0" respectively.
>
> Jelle, thanks for the report!
>
> Calc distinguishes integers from floating-point numbers by the presence of a 
> decimal point, so removing it is probably not a good idea. The lack of a 
> trailing 0 after the decimal point is clearly intended but mainly a cosmetic 
> issue; it's uncommon in hand-writing but not in computerese.
>
> We could put a 0 after the decimal point but not doing so saves some space in 
> the often narrow Calc windows. I'd suggest leaving it as it is. The notation 
> is distinctive enough that there is no serious risk of misunderstanding.
>
> If you disagree, do say.
Hi Mattias,

It would be nice to have a (formatting) option to print 'full'
floating-point numbers. There are a lot of other knobs to tweak
w.r.t. printing numbers, so in that sense it does not seem totally
inconceivable for such a thing to exist.

The context in which I would use this is one where the output of calc is
being used by other programs and data formats (e.g. JSON). For now, I'll
just have to have emacs read and then subsequently print the result of
my calc-adventures, which works fine.

Thanks for the consideration,
 - Jelle