[luatex] A problem with LuaLatex and tikz that might be related to the LuaTeX engine.

[Emmanuel Charpentier]

Dear list,

I have met a case where the same file (which includes a tikz picture)
compiles fine with pdflatex but gives an incorrect result with
LuaLaTeX. Shortly : whereas pdflatex generates the "right" result,
lualatex generates, in one case, a figure terribly shifted to the top
of the page.

I asked the author of the knitr package (which turns out to be also the
author of the tiksDriver package for R) about this problem, and he
answers :

> Thanks for the report! Unfortunately I'm not familiar with LuaTeX, 
> and I don't know what happened in this case after I tried your 
> example.

I examined the differences between the tikz files generated with
pdflatex and lualatex, and saw that the numerical coordinates seem
quite different. I think that this might be bound to the measurement
systems used by those two compilers.

Since those two compilers use the same  tikz package, I think that this
problem might be related to the compilers themselves.

A tarball containing a longer description and the two compilationtrees
demonstrating the problem (including sources, logs and resulting files)
is available at https://drive.google.com/open?id=0B1gfn4_V_wm3c1RodzZ1U
0JMNGM

I'd appreciate to be CC'd of any thoughts this might inspire you : I'm
not on the list...

Sincerely,

--
Emmanuel Charpentier