[ho-tex] vertical spacing with amsmath+fleqn+hyperref

[Reinhard Kotucha]

On 2016-05-15 at 09:30:09 +0100, David Carlisle wrote:

 > On 14 May 2016 at 23:38, Reinhard Kotucha <reinhard.kotucha at web.de> wrote:

 >> BTW, even without hyperref, vertical spacing doesn't look correct.
 >> When amsmath is used *and* the fleqn option is set, there is more
 >> vertical space between the first and second equation than between
 >> others.  But this is certainly an amsmath issue and unrelated here.

 > Note however that it is always wrong to have a display math at the
 > start of a paragraph or immediately after another you get spurious
 > "white" paragraphs in that case,

But even without hyperref, spacing is correct unless the fleqn option
is set.

I just noticed that spacing is also incorrect when I omit the fleqn
option and set \textwidth=3cm.  Maybe amsmath doesn't take \hsize into
account properly.  What I don't understand is why the extra vertical
space is only added between the first and second equation and spacing
is as expected anywhere else.

 > but it would be good if hyperref didn't change spacing anyway.

It doesn't deliberately, as far as I understand.  It adds hyperlinks
to equation numbers.  hyperlinks are whatsits and whatsits have an
impact on line breaks.  So hyperref has to fix all these undesired
line breaks and amsmath's fleqn option is simply not supported yet.

 > Unlikely to get to this before the for first TL2016 cutoff (code
 > too risky to attempt to change in that timeframe!)

David, I never expected a solution in the near future.  But I'm very
glad that you are investigating at all.  Since only macro packages are
involved, everything can be updated easily when TL-2016 is released.

Regards,
  Reinhard

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