Hi, On Mon, Oct 12 2020, Eric S Fraga <e.fr...@ucl.ac.uk> wrote:
> On Monday, 12 Oct 2020 at 10:22, Christian Moe wrote: >> I think I was thinking about adding mode flags for unit computations, >> like in the imagined example above (`$3=$2+$1;u'), similar to what has >> been done for duration computations. > > This would be very useful, actually. I use embedded calc all the time > with units; being able to use some of the same expressions in a table > would be highly welcome. The functions that one can use in calc formulas can be extended using the 'defmath' lisp command. I paste here from my notes (not about monetary units, but easily adapted): +++++++++++++++++++++++++++++++ Defining a new calc function for unit conversion with defmath #+BEGIN_SRC emacs-lisp (defmath uconv (expr target-units &optional pure) (math-convert-units expr target-units pure)) #+END_SRC #+RESULTS: : calcFunc-uconv | km | ft | |--------+--------------| | 2.5 km | 8202.0997 ft | #+TBLFM: $2=uconv($1, ft) Using the units from the table header (if the 3rd arg is given to uconv, the output is stripped of the unit): | km | ft | |-----+-----------| | 2.5 | 8202.0997 | #+TBLFM: $2 = uconv($1 * @<$1, @<$2, t) The standard calc function usimplify also works for this use case: | km | ft | |-----+-----------| | 2.5 | 8202.0997 | #+TBLFM: $2 = usimplify($1 * @<$1 / @<$2) A lisp equivalent of the above #+begin_src elisp (calc-eval "usimplify(2.5 km / ft)") #+end_src #+RESULTS: : 8202.09973753 Let's define a function that converts to base units #+begin_src elisp (defmath ustd (expr) (math-simplify-units (math-to-standard-units expr nil))) #+end_src #+RESULTS: : calcFunc-ustd | distance | time | speed | std unit speed | speed in ft/s | |----------+--------+-------------+------------------+------------------| | 3 km | 2.5 hr | 1.2 km / hr | 0.33333333 m / s | 1.0936133 ft / s | #+TBLFM: @2$3=$1/$2::@2$4=ustd($3)::@2$5=uconv($-1, ft/s) ++++++++++++++++++++++++++++++++++++ -- Paul Scherrer Institut Dr. Derek Feichtinger Phone: +41 56 310 47 33 Group Head HPC and Emerging Technologies Email: derek.feichtin...@psi.ch Building/Room No. OHSA/D17 Forschungsstrasse 111 CH-5232 Villigen PSI
