U+2044 FRACTION SLASH does not create vulgar fractions

[dscorbett]

Font

NotoSansMath-Regular.otf

Where the font came from, and when

Site: https://github.com/notofonts/math/releases/tag/NotoSansMath-v2.539
Date: 2023-03-18

Font version

Version 2.539

Issue

U+2044 FRACTION SLASH overlaps adjacent digits. The font should support 'numr' and 'dnom'.

Character data

2⁄3
U+0032 DIGIT TWO
U+2044 FRACTION SLASH
U+0033 DIGIT THREE

Screenshot

[khaledhosny]

This also depends on the intended use of the font. In math layout, vulgar fractions are created by the layout engine (just like regular fractions), and the font provides data to control the positioning of the numerators and demonstrators as well as alternate fraction slash glyphs growing in size to be used for larger numerators and denominator as needed.

Supporting vulgar fractions in regular text layout would require additional numerator and denominator glyphs.

[khaledhosny]

FWIW, math layout engines can make arbitrary fractions as they do the scaling of the numerators and denominators themselves:

The issue here is only for text mode, and supporting this requires adding pre-scaled versions of the digits once for numerators and once for denominators, and probably better done by the text font.