From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Abrahamsen <eric@ericabrahamsen.net>
Subject: Re: getting calc-units working in table formulas
Date: Tue, 16 Dec 2014 14:33:44 +0800
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Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> I've been playing with calc-units, and it's pretty amazing. See all the
> units with `calc-view-units-table'.
>
> Some calc-units stuff works out the box (maybe have to require
> calc-units?), I think this should be mentioned in the manual:
>
> | distance | time   | speed       |
> |----------+--------+-------------|
> | 3 km     | 2.5 hr | 1.2 km / hr |
>
> #+TBLFM: @2$3=$1/$2
>
> Who knew it could do that?! Probably everyone but me... It doesn't need
> the constants.el package, and looks nicer in the input, to boot.
>
> calc-units makes a few of its functions available via defmath:
>
> | speed        | simplified speed |
> |--------------+------------------|
> | 40km / 2.5hr | 16. km / hr      |
> |              |                  |
>
> #+TBLFM: @2$2=usimplify($1)
>
> But it's got a lot more tricks. I think unit conversion would be very
> handy to have, but there's something I'm not getting about using
> defmath. For instance, this works:
>
> | km    |      ft |
> |-------+---------|
> | 2.5km | 8202.10 |
>
> #+TBLFM: $2='(calc-eval (math-convert-units (calc-eval $1 'raw) (calc-eval "ft" 'raw))); %.2f

I wonder if the problem is the 'raw in here. To the best of my
knowledge, calc-eval needs that 'raw flag to work properly with this.
But it doesn't look like `org-table-eval-formula' will ever send that
flag. I hope someone who knows this code better than me can comment...