On Monday, 2 March 2026 15:45:03 GMT onf wrote: > [forgot to Cc the list] > > Forwarded message from onf on Mon Mar 2, 2026 at 1:36 PM: > > On Mon Mar 2, 2026 at 11:36 AM CET, G. Branden Robinson wrote: > > At 2026-03-02T10:21:50+0100, onf wrote: > > > the problem with square roots in groff's eqn is that groff only knows > > > a single type of square root (the small one). Therefore if an equation > > > requires a higher square root, the only thing groff can do is set the > > > small one in a larger size, and you get an overly thick, overly wide > > > symbol as a result. > > > > It's so old that Kernighan and Cherry noted it in the eqn users' guide. > > > > https://github.com/g-branden-robinson/retypesetting-mathematics/releases/d > > ownload/v1/eqnuser.pdf > > > > See ยง10. > > I am aware of that, but Sigfrid might not be. > > It's also worth remembering the context in which they were writing it, > though. The printers of the time were fairly limited in all sorts of > ways including the number of glyphs they could work with. In today's > conditions, however, their advice would be fairly stupid. The proper > -- and technologically absolutely feasible -- solution is to make eqn > capable of setting typographically correct large square roots, not > insisting users change their equations. The logic is hardly different > from adding support for longer identifiers rather than insisting that > users find a way to name their macros and registers using only two > characters. > > Cheers, > onf
Hi onf, As far as I know unicode allocates a single code for SQUARE ROOT (U+221A) and another for RADICAL SYMBOL BOTTOM (U+23B7). Fonts such as "DejaVuMathTeXGyre" go much further offering different pre-composed sizes of the square root sign and also a glyph for the tip and one for the extension line. So yes it possible to "build" a square root of an arbitrary height using the 3 glyphs. The problem is that the extender and the tip are not in unicode, their postscript names are not "official" (in the AGL), so the only way for groff to access them is via \N'nnn', which is only guaranteed to work for that particular version of that particular font. If someone were to create a font with the 3 glyphs and we gave them groff names, sqbt, sqex and sqtp, then the changes to eqn would be doable. The alternative is to lobby unicode to allocate codes for the extender and the tip, i.e. the same as U+239B/C/D which are the top/middle/bottom of a left parenthesis. Cheers Deri
sqrt.pdf
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