Re: [O] getting calc-units working in table formulas

[Eric Abrahamsen]

Michael Brand <address@hidden> writes:

> Hi Eric
>
> This answers only one of your questions:
>
> On Tue, Dec 16, 2014 at 5:21 AM, Eric Abrahamsen
> <address@hidden> wrote:
>> #+BEGIN_SRC emacs-lisp
>>   (defmath uconvert (expr target-units)
>>     (math-convert-units expr target-units))
>> #+END_SRC
>
> I would prefer
>
> #+BEGIN_SRC emacs-lisp
>   (defmath uconv (expr target-units &optional pure)
>     (math-convert-units expr target-units pure))
> #+END_SRC
>
>
>> | km    | ft                  |
>> |-------+---------------------|
>> | 2.5km | uconvert(2.5 km ft) |
>> #+TBLFM: $2=uconvert($1 ft)
>
> Calc syntax uses comma to separate the function arguments, see
> examples in e. g.
> http://orgmode.org/manual/Formula-syntax-for-Calc.html

I was hoping I'd made a more interesting mistake than that! Thanks for
clearing that up.


> | km     | ft           |
> |--------+--------------|
> | 2.5 km | 8202.0997 ft |
>
> #+TBLFM: $2 = uconv($1, ft)
>
> Btw, to have the units only in the column header:
>
> |  km |        ft |
> |-----+-----------|
> | 2.5 | 8202.0997 |
>
> #+TBLFM: $2 = uconv($1 * @<$1, @<$2, t)
>
> The same without a user's defmath:
>
> |  km |        ft |
> |-----+-----------|
> | 2.5 | 8202.0997 |
>
> #+TBLFM: $2 = usimplify($1 * @<$1 / @<$2)

Wow, interesting stuff. I had no idea...

I'd still like to provide a small patch to the documentation, alerting
users to the fact that units work out of the box. Does anyone have any
opinions on including a defmath for `math-convert-units'? (The 'pure
variant seems like a fine choice.)

Lastly, is there a way to both use output formatting, and retain the
unit name (if desired)? Right now I get this:

| km    | units | conversion |
|-------+-------+------------|
| 2.5km | ft    |    8202.10 |
#+TBLFM: $3=uconvert($1, $2); %.2f


Ie, the "ft" falls off the results when I add the "%.2f". Is it possible
to retain that and have formatting?

Eric