'mathml'-option does not produce correct output for $\implies$ and $\impliedby$

[yalguzaq]

Compiling a file containing the commands $\implies$ ($\implies$) and $\impliedby$ ($\impliedby$) via normal command make4ht markup.tex produces the desired result, whereas make4ht markup.tex 'mathml,mathjax' shows the weird output.

Note: minimal latex file only contains $\implies$ and $\impliedby$.

[michal-h21]

Thanks for the report. It seems that wrong Unicode character is used for \Longrightarrow, and \Lonfleftarrow is not handled at all. I will fix that in TeX4ht sources, in the meantime, you can use this configuration file:

\Preamble{xhtml}
\MathSymbol\mathrel{Longleftarrow}
\Configure{Longrightarrow}        {\expandafter\csname x:unicode\endcsname{27F9}}
\Configure{Longleftarrow}         {\expandafter\csname x:unicode\endcsname{27F8}}
\begin{document}
\EndPreamble

[yalguzaq]

One more thing, could you also redefine \iff? Thank you very much!

[michal-h21]

Sure. I've found that there is more issues for long arrows, so I fixed them too.