https://bugs.kde.org/show_bug.cgi?id=473669
Bug ID: 473669
Summary: KRunner can give erroneous output when evaluating
equations involving implicit mutiplication
Classification: Plasma
Product: krunner
Version: 5.27.7
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: calculator
Assignee: plasma-b...@kde.org
Reporter: arraybo...@gmail.com
CC: alexander.loh...@gmx.de, natalie_clar...@yahoo.de
Target Milestone: ---
SUMMARY
KRunner's calculator fails to apply the order of operations properly when
dealing with implicit multiplication. It appears to use libqalculate's default
Adaptive parsing mode, which is able to apply implicit multiplication before
applying any other operation (even if this violates PEMDAS). This probably
comes in handy for expressions involving variables, like "5/2x" (where 2x is
meant to be taken as it's own thing), but for expressions consisting solely of
known values (like what KRunner's calculator probably usually handles), it can
result in extremely odd output. For instance, 6/2(2+1) = 9 according to PEMDAS,
but KRunner outputs a 1 as the implicit multiply of 2(2+1) gets done before the
division.
STEPS TO REPRODUCE
1. Open KRunner by pressing Alt+F2.
2. Type "=6/2(2+1)"
OBSERVED RESULT
1
EXPECTED RESULT
9
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 22.04 LTS
(available in About System)
KDE Plasma Version: 5.27.7
KDE Frameworks Version: 5.104.0
Qt Version: 5.15.3
ADDITIONAL INFORMATION
I believe this can be fixed by using libqalculate's "conventional" parsing mode
on all calculations. This should be as easy as adding one line of code into
https://invent.kde.org/plasma/plasma-workspace/-/blob/master/runners/calculator/qalculate_engine.cpp
in the QalculateEngine::evaluate function.
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