
\begin{DoxyItemize}
\item infos = Information about the mathcheck plugin is in keys below
\item infos/author = Thomas Waser \href{mailto:thomas.waser@libelektra.org}{\tt thomas.\+waser@libelektra.\+org}
\item infos/licence = B\+S\+D
\item infos/provides = check
\item infos/needs =
\item infos/placements = presetstorage
\item infos/status = maintained unittest discouraged nodep
\item infos/metadata = check/math
\item infos/description =
\end{DoxyItemize}

Compares a key value to a mathematical expression using polish prefix notation defined in the {\ttfamily check/math} metakey. Operations are {\ttfamily + -\/ / $\ast$} . Operants are keys with names relative to the parent key. How the values are compared is specified at the beginning of the metakey using the conditions {\ttfamily $<$, $<$=, ==, !=, =$>$, $>$, \+:=} {\ttfamily \+:=} is used to set key values. All values are interpreted as {\ttfamily double} floating point values.

\subsubsection*{Keynames}

Keynames are all either relative to to-\/be-\/tested key (starting with {\ttfamily ./} or {\ttfamily ../}), relative to the parentkey (starting with {\ttfamily @/}) or absolute (e.\+g. {\ttfamily system/key}).

\subsection*{Examples}

{\ttfamily check/math = \char`\"{}== + ../testval1 + ../testval2 ../testval3\char`\"{}} compares the keyvalue to the sum of testval1-\/3 and yields an error if the values are not equal. {\ttfamily check/math = \char`\"{}\textbackslash{}$<$= -\/ \textbackslash{}@/testval1 $\ast$ \textbackslash{}@/testval2 \textbackslash{}@/testval3\char`\"{}} tests if the keyvalue is less than or equal to testval1 -\/ (testval2 $\ast$ testval3) and yields an error if not.

Full example\+: \begin{DoxyVerb}    kdb mount mathcheck.dump /example/mathcheck dump mathcheck
    kdb set user/example/mathcheck/a 3.1
    kdb set user/example/mathcheck/b 4.5
    kdb set user/example/mathcheck/k 7.6
    kdb setmeta user/example/mathcheck/k check/math "== + ../a ../b"
    kdb set user/example/mathcheck/k 7.7   # fails
\end{DoxyVerb}


To calculate values on-\/demand you can use\+: \begin{DoxyVerb}    kdb setmeta user/example/mathcheck/k check/math ":= + @/a @/b"
    kdb get user/example/mathcheck/k       # 12.5
    kdb set user/example/mathcheck/a 5.5
    kdb get user/example/mathcheck/k       # 10
\end{DoxyVerb}


It also works with constants\+: \begin{DoxyVerb}    kdb setmeta user/example/mathcheck/k check/math ":= + ../a '5'"
    kdb get user/example/mathcheck/k       # 10.5
    kdb set user/example/mathcheck/a 8.0
    kdb get user/example/mathcheck/k       # 13
\end{DoxyVerb}


\subsection*{Status}

mathcheck does not work with icc 14.\+0.\+2 20140120, and some gcc versions when using debug. Additionally, it fails to run on Open\+B\+S\+D. Until these problems are fixed it is discouraged to use. 