Hello! In qalc I can do calculations using measuring units like this:
> 5 W * 3 s
(5 watts) × (3 seconds) = 15 J
I’d like to be able to do something similar also in GNU Octave. I think the symbolic library could be a place to look at, but I found nothing “already done”. Do any of you know of a way to achieve this functionality?
I don’t think symbolic will solve your problem at all
With symbolic variables
J, s
andW
, theWs
won’t be converted toJ
automatically.automatically no, but perhaps there’s a way to replace it. If there’s a way to check if a variable is “divisible by another symbolic one” then it would be not so hard to implement this behavior
The Octave miscellaneous package has embedded GNU units which should be helpful.
It looks interesting, but more focused on conversions than actual operations it seems:
octave:37> a.value = 100 a = scalar structure containing the fields: value = 100 unit = W octave:38> a.unit = 'W' a = scalar structure containing the fields: value = 100 unit = W octave:39> b.value = 3 b = scalar structure containing the fields: value = 3 unit = s octave:40> b.unit = 's' b = scalar structure containing the fields: value = 3 unit = s octave:41> a*b error: binary operator '*' not implemented for 'scalar struct' by 'scalar struct' operations
I think I’ve found a solution. Matlab has implemented
symunits
in the symbolic toolbox and I’ve found the original? on Github. Hopefully it is compatible to GNU Octave.This looks very VERY promising! I’ll try to install it tomorrow and Post here the results! Thanks?
I downloaded it and tried to run it, but it gets stuck in a loop and I don’t know how it could be fixed:
error: max_recursion_depth exceeded error: called from baseUnitSystem <unknown>
it seems the problem is in the line
coreUnits = buildCoreUnits(u.baseUnitSystem);
in the file
u.m
, I think becauseu.baseUnitSystem
tries to “call itself”. I don’t know what this should be supposed to do, and have no idea on how to possibly fix it :(It seems that the implementation of
classdev
in Octave is unfortunately not complete enough yet.😒