Minor differences in generated DVI files about rstex HOT 7 CLOSED

Didn't see your comment until now. It's certainly worth investigating the difference. My knowledge of dvi format is very limited right now so it will take some time to determine if it does something wrong. Also interesting is that both MiKTeX (which I belive is the same as TeX Live in this respect but I haven't confirmed this) and rsTeX produce the same dvi files on trip test but differ on gentle.dvi. Seems the trip test does not test all that much when it comes to dvi output.

from rstex.

After the recent commits (specifically c780e16), the diff of DVI files generated from the above example went away! This is hope that maybe the outputs can be reconciled…

Here's a different input with which there's a difference:

\input plain

This manual would not have come into being without the aid of others.
In particular the proofreading and

\bye

The difference is quite minor:

% diff test-TeX.dvi.txt test-rsTeX.dvi.txt
86,90c86,90
< 194: right3 223728 h:=16739338+223728=16963066, hh:=1074 
< 198: setchar116 h:=16963066+254863=17217929, hh:=1090 
< 199: setchar104 h:=17217929+364090=17582019, hh:=1113 
< 200: setchar101 h:=17582019+291271=17873290, hh:=1131 
< 201: w0 223727 h:=17873290+223727=18097017, hh:=1146 
---
> 194: w0 223727 h:=16739338+223727=16963065, hh:=1074 
> 195: setchar116 h:=16963065+254863=17217928, hh:=1090 
> 196: setchar104 h:=17217928+364090=17582018, hh:=1113 
> 197: setchar101 h:=17582018+291271=17873289, hh:=1131 
> 198: right3 223728 h:=17873289+223728=18097017, hh:=1146 

or side-by-side:

% diff -y --suppress-common-lines test-TeX.dvi.txt test-rsTeX.dvi.txt
194: right3 223728 h:=16739338+223728=16963066, hh:=1074      |	194: w0 223727 h:=16739338+223727=16963065, hh:=1074 
198: setchar116 h:=16963066+254863=17217929, hh:=1090 	      |	195: setchar116 h:=16963065+254863=17217928, hh:=1090 
199: setchar104 h:=17217929+364090=17582019, hh:=1113 	      |	196: setchar104 h:=17217928+364090=17582018, hh:=1113 
200: setchar101 h:=17582019+291271=17873290, hh:=1131 	      |	197: setchar101 h:=17582018+291271=17873289, hh:=1131 
201: w0 223727 h:=17873290+223727=18097017, hh:=1146 	      |	198: right3 223728 h:=17873289+223728=18097017, hh:=1146 

As I understand it, this is 1 scaled point (I think) in the word aid, that resolves itself at the end of the word… probably a difference in the details of how rounding is done in the two programs. This difference would matter only at absurdly high (nonexistent in reality) resolutions, so it doesn't affect the visual appearance in any material way. (And again, the whole point of a lot of decisions in TeX is so that such rounding differences should not affect things…) Still, might be something interesting to look into.

from rstex.

Yes, I agree, looks like different rounding. I still have a few places where I use double, I'm gonna change those to floats and see if it makes a difference.

from rstex.

Based on some output I somewhat suspect it's the other way around (TeX Live tex uses double in some place where rsTeX uses float), but I haven't looked into the details. (This just based on seeing more digits printed in some places in the output from tex.)

from rstex.

Please take a look at the latest upload, also try increasing dvi_buf_size to some larger value. On my machine miktex and rstex agree almost completely on gentle now.

from rstex.

Wow great, I installed MikTeX on macOS, and with

const int dvi_buf_size = 800;

changed to

const int dvi_buf_size = 4000;

(or greater) the two DVI files for gentle.tex agree 100%, with no diffs!

There are actually differences when TeX Live tex is used, but I think it would be a separate project to look into why TeX Live and MikTeX differ :-)

from rstex.

Closing this “issue”, as the output is identical between rsTeX and MiKTeX!

Also, I just learned that the DVI files are not strictly required to be identical: https://tex.stackexchange.com/questions/416376/should-different-tex-implementations-e-g-miktexs-and-tex-lives-produce-iden

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