Script r

[kauesena]

For the math script r, perhaps it would be nice to create a variant like this:

[tiroj]

Is this style more/less common in certain countries or conventions of math typesetting?

[davidmjones]

You can blame David Griffiths and/or Cambridge University Press. See, e.g., https://tex.stackexchange.com/questions/21274/script-r-symbol

I'm skeptical about adding it as a variant of U+1D4FB.

[kauesena]

In many countries this is the kind of cursive r, we are taught at schools. The reason for my suggesting this is that it is very distinct to the typical serif italic r, whereas the current one is not. The proprietary font MathTime Pro, designed by Michael Spivak, has this glyph as a variant as is showcased on this page. I did not manage to find an example, but I have seen this variant used in some Springer books. As David Griffiths mentioned, @davidmjones uses this r in his widely adopted electromagnetism textbook.

Adding the descending lowercase script z would also be nice. A version of this character also exists in MathTime Pro.

[tiroj]

Part of the issue here may be the decision to move to a chancery style of lowercase script in the most recent STIX release, to match the chancery capitals that were made default in STIX Two. We now have two complete sets of upper and lowercase script styles in regular and bold weights: chancery (default) and roundhand (ss01). In the upcoming 2.20 release, we will also be implementing the new Unicode variation selector sequences for the roundhand capitals.

The styles of r and z suggested here are common in 19th Century derivatives of the roundhand writing, so are easier to accommodate in that style; they are not the normal ductus for these letters in the chancery style. So one approach would be to add these only as variants within the roundhand style. Another approach would be to actually replace the existing roundhand r and z with these forms if they are considered preferred in a math context.

[Atreyu-94]

I was just coming to make this suggestion. In the teaching of electrodynamics for undergraduates, David Griffiths' book is essential. And with this script r substitutes a more advanced and complicated notation. I had already thought to make a font with just that glyph so I could use it. If they add that variation it would be very useful for teaching physics.