Libertinus: Minus sign not aligned with fraction bar

[Matzeee]

At first: Thank you very much for your great work!

I think the minus sign is not correctly aligned with the fraction bar.
It is already visible in the supplied libertinus-testmath.pdf, but I created an example to make it clearer.

This also causes a problem with \xrightarrow etc.
On some zoom steps, every single minus sign is visible.

In XITS Math, they are almost perfectly aligned.
(The fraction bar is a tiny little bit lower, but \xrightarrow is perfect)

[fred-wang]

I noticed that bug too while running my MathFonts script on Libertine Math. This is a problem with the AxisHeight value.

[khaledhosny]

I’ll try to fix this, but abusing minus for extensible arrows is just a XeTeX limitation (inherited from TeX), the font already supports proper extensible arrows.

[jmaibaum]

This not only affects the minus sign, but also plus and equality, and probably other operators, see for example:

[Matzeee]

I really do not want to be impolite, but could you have a look at this again?

For me it is the only issue that stops me from using Libertinus and I did not find any combination of regular, sans, mono and mathfont that looks comparably well.

Or is it worth a try to report this as a TeX bug or enhancement?

[fred-wang]

@khaledhosny So isn't the issue that the AxisHeight value from the MATH table does not match the middle of the + and - signs?

[khaledhosny]

I’m wondering about this as well, and also wondering how it never occured to me before. Let me try and see.

[khaledhosny]

I remember now. There are two issues here, the first one is axis height not aligned with +-=, and the other is arrow glyphs not aligned with the minus sign. The first is simple to fix, the second needs some work.

[khaledhosny]

The minus should be aligned with the fraction bar now, but still not aligned with the arrows.

[khaledhosny]

[khaledhosny]

All should be fixed now: