Is it possible to do calculations with GNU Octave using measuring units? (lemmy.kde.social)

submitted 6 months ago by tubbadu@lemmy.kde.social to c/opensource@lemmy.ml

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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?

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[-] Successful_Try543@feddit.de 6 points 6 months ago* (last edited 6 months ago)

The Octave miscellaneous package has embedded GNU units as a function which should be helpful.

[-] tubbadu@lemmy.kde.social 3 points 6 months ago

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

[-] Successful_Try543@feddit.de 4 points 6 months ago

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.

[-] tubbadu@lemmy.kde.social 4 points 6 months ago

This looks very VERY promising! I'll try to install it tomorrow and Post here the results! Thanks?

[-] tubbadu@lemmy.kde.social 2 points 6 months ago

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 because u.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 :(