[luatex] rounding errors with node.dimensions?

[Frank Mittelbach]

Am 13.04.16 um 10:17 schrieb Hans Hagen:
>> which should give me the internal width of all nodes inside with the
>> glue setting applied (at least that's the way I understand the manual).
>
> such calculations are in floats
>
> you can try tex.sp(result) to do rounding

point is if it only work "most of the time" then it is not possible to 
use it to do manipulations in lua and turn back a result to TeX for 
further processing as on the TeX level 1sp difference may throw you off 
badly. And then then the function is fairly pointless.

And I really don't see how to use tex.sp here the result of 
node.dimensions appears to be already in sp (whole numbers) the only 
issue is that it is off by a few ...

frank