Full Math Symbols?

[tecosaur]

Hello,

Out of impatience, I see that in 2017 @mjabbink said "Extended Math symbols will come in 2019" and then in 2018 "We will design a version of Plex with full mathematical glyphs next year". Now that it's 2019 I was wondering how much longer we'll have to wait?

Also I'm curious as to how extensive addition will be; specificly, which of the following blocks are planning on being included?

• Mathematical Operators block (U+2200 – U+22FF)
• Supplemental Mathematical Operators block (U+2A00 – U+2AFF)
• Mathematical Alphanumeric Symbols block (U+1D400 – U+1D7FF)
• Letterlike Symbols block (U+2100 – U+214F) has a math subset
• Miscellaneous Mathematical Symbols-A block (U+27C0 – U+27EF)
• Miscellaneous Mathematical Symbols-B block (U+2980 – U+29FF)
• Miscellaneous Technical block (U+2300 – U+23FF) has a math subset
• Geometric Shapes block (U+25A0 – U+25FF) has a math subset
• Miscellaneous Symbols and Arrows block (U+2B00–U+2BFF Arrows) has a math subset (U+2B30 – 2B44 and U+2B47 – 2B4C)
• Arrows block (U+2190–U+21FF)
• Supplemental Arrows-B block (U+2900–U+297F)
• The various math symbols in other blocks that haven't yet been added (Such as U+2034 triple prime)

thanks!

tecosaur.

[BoldMonday]

Math support for IBM Plex is still on the roadmap. But how many glyphs – out of the thousands of glyphs that are in those blocks – are sufficient for a first release is still being determined. A full Math character set comparable to the likes of STIX easily surpasses 5,000 glyphs.

For what kind of purpose would you use a font like this?

[tecosaur]

Most of the documents I produce are made in LaTeX. I have found the design choices made in plex to match quite well and so have adopted it as part of my default template. However, a significant irritation comes from the difficulty in finding a good math font to match.

What I am hoping to see is sufficient Maths support for a LaTeX package to be produced, and for it to be able to satisfy the range of symbols I use day to day. Of the top of my head, these are the character sets I use most frequently, i.e. the 99% from most used to least.

1. Letters a-z, true italic — 52 characters
2. Greek letters, italic - 48 characters
3. Common operations (+-×±∓ etc.) — ~20? characters
4. Deliminators, large deliminators ([{⟨ etc. — ~10 characters + mirrored
5. Sum / Product (∑ ∏) — 2 characters
6. Arrows — ~30 characters
7. Relation symbols (∩∪⊂⊇≠≫ etc.) — ~40 characters
8. Special sets, i.e. blackboard letters (ℤ ℚ ℝ ℂ etc.) - 26 characters (uppercase only)
9. Special operators, using Caligraphic Variants (𝓛 𝓟 etc.) - 26 to 52 characters (have yet to use lower case)
10. A few miscellaneous others, let's say ~50

Total: ~300 characters, but you already have the italic letters and (I think) greek, so
Total New: ~200 characters

200 ≪ 5,000 so that's good.

This is what I'd consider a bare minimum to be potentially viable.

In order to actualy be an clear choice though, I'd imagine one would really need all the symbols listed here https://www.caam.rice.edu/~heinken/latex/symbols.pdf which is around 500 symbols.

I'm afraid that maths people such as myself seem to really like their symbols, but at least there's a fair bit or re-use that goes on, e.g. with equals sign combined with: dot, dash, strike, two dots in middle, two dots on ends, circle above, triangle above etc.

This goes a bit beyond your question "For what kind of purpose would you use a font like this?" but hopefuly it may be of help in working out what glyphs to include.

[mjabbink]

Behind schedule on this due to budget constraints and focus on CJK (Chinese, Japanese, Korean). It will certainly be moving into 2020.

[tecosaur]

@mjabbink thanks for the update. If you don't mind I have two more questions

• How far into the planning stage are you?
• What's the chance of more update as you get closer to starting? (i.e. have decided we'll be doing these glyphs, have now started, halfway through etc.)

[mjabbink]

@tecosaur I would not look for this until end of 2020. We are in the middle of CJK and I hope to get this going now in the beginning of Q1 2020. There is a slight chance for sooner but it’s looking slim.

[Arcitec]

Ping @inferno986return (#122).

[Arcitec]

By the way @mjabbink, with the math symbol set, it would be possible to create a IBM Plex Mono Code variant which is literally just Mono but with certain mappings from character sequences to single math characters. Such as <= into ⩽ and >> into ≫. A fan could create that after the math set exists. Just throwing the idea out there.

For an example of such a sequence transformation, see https://github.com/tonsky/FiraCode.

PS: IBM Plex is gorgeous. Great job, everyone involved!

[abrudz]

As mentioned here, APL symbols are now part of this project. It can be tricky to get the various APL symbols to look good together, especially as many are shared with the general mathematical symbols. The below table and samples from IBM's existing APL fonts, Courier APL2 Unicode and APL2 Unicode may be helpful here.

Table of related symbols

          stars: *⍣⍟⋆
        circles: ⍥○⍟⌽⍉⊖⍜⊙⌾⌼
        slashes: /⌿⍁≠≢
    backslashes: \⍀⍂
        uptacks: ⍊⍎⊥
      downtacks: ⍡⍑⍕⊤
       epsilons: ∊⍷
           jots: ∘⍤⍛⍎⍕⍝⌻⌾
         commas: ,⍪;⍮
       diamonds: ⋄⌺⍚
           dels: ⍫∇⍢⍒
         stiles: ⍒⍋∥⍭|⍦⍧⍅⍆
         deltas: ∆⍙⍋
      up arrows: ↑⍐⍏
    down arrows: ↓⍗⍖
   right arrows: →⍈⍆
    left arrows: ←⍇⍅
          shoes: ⊂⊆⊇⊃∪∩⍝⍦⋔⍧
      diaeresis: ¨⍡⍢⍨⍣⍤⍩
    comparisons: <≤>≥⍩⍃⍄
         wedges: ∧⍲∨⍱⍓⍌
     equalities: =⌸≠≡≢
          tacks: ⊢⊣⊥⌶⊤⍎⍕
          quads: ⍠⌹⌸⍯⌺⎕⍁⍂⌼⌻⍃⍄⍓⍌⍔⍍⍞⍰⍐⍗⍇⍈
      underbars: ⊆⊇⍊⍘⍙⍚⍛⍜⍮⍶⍷⍸⍹
         alphas: ⍺⍶
         omegas: ⍵⍹
         dashes: -⌿⍀⍪⊖÷
       overbars: ¯⍑
         tildes: ~⍲⍱⍬⍫⍭⍨
         colons: ⍠:⌹÷
       brackets: ⌷[]

Courier APL2 Unicode

APL2 Unicode

[mjabbink]

When we get to finally do the math font We can cover APL2. Might be able to phase out project and cover APL2 first, box glyphs (since we’re developing those for Korean release in February 2020), then tackle the rest of the beast.

[JimEBlevins]

I informed the StackExchange:TeX community about the announced 2020 mathematics extension of IBM Plex.
Which OpenType math-fonts are available?.

The Tex.StackExchange page's focused discussion of existing mathematical fonts may interest developers.

Two asides:

• Using the most recent distribution, I found that the Mono font had problems with punctuation (in urls), which disappeared when I used the Mono Text font.
• I am delighted by the IBM Plex family of fonts, which I find to be more readable on my laptop than the excellent Libertinus family of fonts with its excellent Mathematics extension of its Serif font (which may have advantages for printed documents).

[JimEBlevins]

For what kind of purpose would you use a font like this?

The mathematics extension of IBM Plex should aspire to be a free, open-source (SIL OTF) competitor to the mathematics extension of Microsoft's Cambria, which has already been adopted as the font for ISO manuals. Cambria aspires to replace Times New Roman as the workhorse for printed text, while being more legible for on-screen use. Both Cambria and IBM Plex Serif have distinct and independent designs, so a friendly rivalry should drive improvements in both fonts.

Plex's free and open attributes simplify the sharing of documents and code with others, especially for the joint editing of documents when a collaborator may use Macs or UNIX / GNU Linux.

For on-screen use, the Plex family is more legible than Cambria, e.g., because of its higher x-height (while Cambria has an x-height that is greater than Times New Roman's but that is less than Microsoft's fonts for on-screen documents (Verdana, Tahoma, and Trebuchet). The Plex family is more coherent than Microsoft's ClearType C-fonts, which were quickly designed.

With an excellent Math extension, IBM Plex could become the leading font for on-line scientific and technical documents and for drafting and proof-reading such printed documents. It should also appeal to businesses, schools, universities, and governments for producing documents for on-screen reading.

Users of LaTeX may try this invocation of Plex:
`
\usepackage{luatexbase}
\usepackage{microtype}
\usepackage{luatextra}
\usepackage{luaotfload}
\usepackage{fontspec}

\setmainfont[
Extension=.otf,
UprightFont={IBM Plex Serif-Text},
BoldFont={IBM Plex Serif-Bold},
ItalicFont={IBM Plex Serif-Italic},
BoldItalicFont={IBM Plex Serif-BoldItalic}
]{IBM Plex Serif}[Ligatures=TeX,Scale=MatchUppercase]
% Scales Plex to default size, e.g., to Helvetica´s size.

\setmonofont{IBM Plex Mono Text}[Scale=MatchLowercase,
Ligatures=TeX]
\setsansfont{IBM Plex Sans Text}[Scale=MatchUppercase,
Ligatures=TeX]
`

[abrudz]

With an excellent Math extension, IBM Plex could become the leading font for on-line scientific and technical documents and for drafting and proof-reading such printed documents. It should also appeal to businesses, schools, universities, and governments for producing documents for on-screen reading.

I really like Plex, but actually, my biggest problem with it, is that it is just too successful in achieving its goal of being "distinctly IBM"; it is too IBM. I don't feel like I can use it for my own generic things because I'll give the false impression of my project being endorsed by IBM!

[mjabbink]

Looks like 2021. Need funding.

[abrudz]

@mjabbink I read through the entire ibm.com/plex and noticed:

The unexpected and expressive tone of the Selectric typeface, Italic 12 was a major influence in Plex Mono Italic.

The accompanying Italic 12 type sample looked remarkably familiar. Turns out I recently created a modern clone of its derivative which includes all APL symbol and (thus) many mathematical symbols. Feel free to use for inspiration/guidance.

[abrudz]

Need funding.

How much?

[mjabbink]

@abrudz Cool project and yes it looks like Italic 12. The funding is not small. Doing the entire Math character set we’re looking to achieve is a lot of work and I think we’re doing with the Serif but need to make a decision there (sans or serif?). I lean on serif as use case is typically within white papers and heavy documentation.

[inferno986return]

@abrudz Cool project and yes it looks like Italic 12. The funding is not small. Doing the entire Math character set we’re looking to achieve is a lot of work and I think we’re doing with the Serif but need to make a decision there (sans or serif?). I lean on serif as use case is typically within white papers and heavy documentation.

When I think of mathematical fonts, I think of Computer Modern Roman which is the standard of LaTeX.

IBM Plex Serif would be a good basis.

[tecosaur]

@mjabbink if you don't mind me chiming in:

• It's fantastic to hear that you're planning covering Maths seriously 🥳
• I would urge that serif be the basis for a comprehensive Maths character set, as that how I see the majority of maths typeset, and what I personally use for "serious maths stuff"
• Would it also be possible just to say just design Mathematical Operators block (U+2200 – U+22FF) in sans-serif? This would be a useful jump in support IMO, and I think it can be said that that single block would give you the most "bang for your buck".

[JimEBlevins]

@abrudz Cool project and yes it looks like Italic 12. The funding is not small. Doing the entire Math character set we’re looking to achieve is a lot of work and I think we’re doing with the Serif but need to make a decision there (sans or serif?). I lean on serif as use case is typically within white papers and heavy documentation.

Serif is standard in mathematics because readers need instantly to distinguish isolated glyphs, e.g., c from C (without being familiar with e.g., IBM Plex).

Earlier, you asked about desiderata for mathematical typography:

• Küster, Johannes. Fonts for Mathematics.
• Microsoft ClearType and Advanced Reading Technologies Group. Now Read this: The Microsoft ClearType Font Collection; Microsoft Corporation, 2004.
• Mills, Ross and John Hudson (editors), with contributions by Richard Lawrence and Murray Sargent. Mathematical Typesetting: Mathematical and Scientific Typesetting Solutions from Microsoft. Microsoft Corporation 2007.
• Rhatigan, Daniel (September 2007). Three Typefaces for Mathematics— The development of Times 4-line Mathematics Series569, AMS Euler, and Cambria Math (PDF). University of Reading (MA thesis).

Mathematics fonts have been designed for greater legibility under repeated photocopying and under coarse printing and displays and to help readers with visual impairments (e.g., age). Typography designers may find inspiration in these typefaces:

• AMS Euler (Hermann Zapf. Euler was reworked in Dr. Khaled Hosny's Neo Euler, since abandoned).
• Cambria and Cambria Math.
• STIX Two Text and Math (Stix2 Math and Stix2 Text) by David M. Jones.
• Libertinus Serif and Math (now led by Alerque, Caleb Maclennan, following Hosny).
• Minion Pro (Robert Slimbach) and Minion Math (Johannes Küster of Typoma).

Small caps are used in LaTeX and in the most important LaTeX style files by major mathematical publishers, e.g, the American Mathematical Society (AMS) and the Society for Industrial and Applied Mathematics (SIAM) --- perhaps unwisely!
IBM Plex has already increased the goodwill towards IBM among students of engineering and science. It would be difficult to overstate the desire of such students for a typeface that would have the breadth of typefaces of the Computer Modern family, e.g., with small caps.

[kenmcd]

Also useful: Designing Math Fonts, presentation by Johannes Küster of Typoma (he made Minion Math)
Designing.Math.Fonts.20040430-bachotex.pdf

[mjabbink]

Thanks for all the info @StatisticalProgrammer

@tecosaur — We plan on using Plex Serif as the basis but will explore your recommendation for the Sans for Mathematical Operators block (U+2200 – U+22FF)

[BoldMonday]

It will be an OpenType math font with a math table.

[apoorvpotnis]

Btw, this is not going to be a font with serif and sans serif glyphs mixed haphazardly, is it? This shall be a proper sans serif font, like fira sans math, and not the abomination that noto "sans" math is, right?

[BoldMonday]

Plex Math is based on Plex Serif. Similar to how STIX and Cambria are serif typefaces.

[apoorvpotnis]

Plex Math is based on Plex Serif. Similar to how STIX and Cambria are serif typefaces.

Thanks for the info. Request: Is it possible to have a true sans serif math typeface, if work has not already started? I can put forth two reasons.

1. There is a dearth of sans serif math fonts; only Fira Sans Math, GFS Neohellenic Math (almost sans), Lato Math (incomplete) come to mind. There is a pressing need of them as sans serif typefaces are often used in diagrams and figures, and section or chapter titles. Using sans for the text and serif for math symbols looks really bad. A lot of websites which use sans serif fonts, have to resort to using serif math.
2. IBM's own quantum computing site (Qiskit) uses IBM Plex Sans fonts for everything. The documentation has math. An IBM Plex Sans Math font would happily match the (now serif due to lack of Plex sans math) math used there. I am sure scientists and engineers at IBM need to use math in their documentation.

[BoldMonday]

Work on IBM Plex Math has already been underway since the end of last year. It is intended for a broad usage in scientific and academic papers. To cater in the best way for those applications we decided that a serif font is better suited than sans.

[apoorvpotnis]

Just one more thing, is there going to be a bold weight as well, for use in section/chapter titles?

[BoldMonday]

@apoorvpotnis Plex Math is one weight only (Regular) but Plex Serif has a range of eight weights.

[mjabbink]

@mpsmath We will soon have some testing for files and if you’re a willing tester, we would certainly appreciate it.

[sharadhr]

I'm happy to test Plex Maths, too! I have a fair few TeX documents that I would really like to re-type in Plex Serif and Plex Maths.

[apoorvpotnis]

I can offer assistance for testing as well, by testing on LaTeX.

[mjabbink]

@sharadhr @apoorvpotnis Attached find an IBM Plex Math Alpha file. Give it a whirl.

IBMPlexMath-Alpha230918.otf.zip

[apoorvpotnis]

@sharadhr @apoorvpotnis Attached find an IBM Plex Math Alpha file. Give it a whirl.

IBMPlexMath-Alpha230918.otf.zip

Does this contain only the glyphs as of now, and not a math table? Because I can see the glyphs in fontforge, but LuaLaTeX (with unicode-math) complains that the font does not contain the requested Script "Math". Thus, no LaTeX typesetting as of now.

[mpsmath]

@sharadhr @apoorvpotnis Attached find an IBM Plex Math Alpha file. Give it a whirl.

IBMPlexMath-Alpha230918.otf.zip

Thank you very much for the post, it looks like there are a lot of nice math glyphs inside.

As already mentioned, though, the font posted is lacking the necessary tables to make it into a "real" math font.

To add a bit more: Some slots usually come with variants and extensibles. Take the left parenthesis U+0028 for example. As of now I find extensibles (U+239B, U+239C, U+239D). But the base glyph U+0028 does not have a recipe that tells when these should kick in. Also, it will likely look a bit non-optimal if there are no variants that can be chosen step wise, before the extensible kicks in.

Once the necessary tables are added and extensible recipes are there, we can start the testing. (If you need help or more ideas regarding variants, extensibles and the many parameters to set, just tell.)

[abrudz]

@sharadhr @apoorvpotnis Attached find an IBM Plex Math Alpha file. Give it a whirl.

IBMPlexMath-Alpha230918.otf.zip

The APL glyphs should be more consistent:

• Where a space occurs, only glyphs to the left are regulary in use, but those on the right are prime candidates for adoption in future language extensions.
• The leftmost glyph is the prototypical one for the class.

Here's the raw text:

alphas:	⍺ ⍶
arrows-down:	↓ ⍗⍖
arrows-left	← ⍇⍅
arrows-right	→ ⍈⍆
arrows-up:	↑ ⍐⍏
asterisks:	*⍣⍟ ⋆
brackets	[]⌈⌊⌷
circles:	○⍥⍟⌽⍉⊖ ⍜⊙⌾
colons	:⍠÷⌹
commas:	,⍪; ⍮
dashes:	-÷⌹⌿⍀⍪ ⍏⍖
dels:	∇⍒⍫⍢
deltas:	∆⍙⍋ ⍍
diamonds:	⋄⌺ ⍚
diereses:	¨⍨⍥⍤⍣ ⍢⍡⍩
epsilons:	∊⍷
equals	=≠⌸
iotas	⍳⍸
jots:	∘⍤⍛⍝⍎⍕ ¤⌾
omegas:	⍵ ⍹
quads	⎕⌸⌹⌺ ⌻⌼⍁⍂⍃⍄⍇⍈⍌⍍⍐⍓⍯⍰
shoes-down	∪ ⍦
shoes-left	⊂⊆ ⍧
shoes-right	⊃⊇
shoes-up	∩ ⋔
slashes:	/⌿ ⍁%
slashes-back:	\⍀⍉ ⍂
stiles:	|⌽⍒⍋ ∥⍭⍦⍧
tacks-down:	⌶⊤⍕ ⍑⍡
tacks-up:	⌶⊥⍎ ⍊
tildes:	~⍬ ⍭
underscores:	_⍙⍷⍛⍸⊆⊇ ⍊⍜⍶⍹⍮⍚⍘
wedges-down	∨⍱ ⍌
wedges-left:	<≤ ⍃
wedges-right:	>≥ ⍄⍩
wedges-up:	∧⍲ ⍓

[BoldMonday]

@sharadhr @apoorvpotnis Attached find an IBM Plex Math Alpha file. Give it a whirl.
IBMPlexMath-Alpha230918.otf.zip

Does this contain only the glyphs as of now, and not a math table? Because I can see the glyphs in fontforge, but LuaLaTeX (with unicode-math) complains that the font does not contain the requested Script "Math". Thus, no LaTeX typesetting as of now.

This is a first Alpha build -- there is no Math table yet.

[BoldMonday]

The APL glyphs should be more consistent:

Where a space occurs, only glyphs to the left are regulary in use, but those on the right are prime candidates for adoption in future language extensions.

The leftmost glyph is the prototypical one for the class.

@abrudz Thank you for the very valuable feedback.

Two questions:

1. Do you the same example set in a font where the glyphs are correct according to your opinion?
2. Are there other mathematical fonts out there (STYX, Cambria, ...) that do a good job when setting APL? I get the impression that certain technical symbols have to be adapted very specifically for APL.

[abrudz]

APL doesn't require special adaption of symbols. Any consistency achievable is nice, but none of this is critical for use. Here are 3 proportional (including Stix) and 3 monospace samples:

Iosevka Etoile

https://typeof.net/Iosevka/

Stix Two Math

https://www.stixfonts.org/

Quivira

http://www.quivira-font.com/

DejaVu Sans Mono

https://dejavu-fonts.github.io/

APL385 Unicode

https://abrudz.github.io/APL386/

SAX2

https://abrudz.github.io/SAX2/

[BoldMonday]

Everyone: here is a new public alpha build of IBM Plex Math.

We addressed the comments from @abrudz about the APL glyphs as good as we could.
There is a brand new design for the Fraktur, Script and Typewriter glyphs.
Also lots of changes have happened in vertical positions and sizes of many symbols.
The math table is still in progress so typesetting of formulas might not be possible still.
But already the font contains well over 5,300 glyphs. Give it a try and let us know in the comments what you think.

IBMPlexMath-Alpha231127.otf.zip

[apoorvpotnis]

Is there a possibility of having regular (non-bold) sans Greek letters, in the private use area, say imported from the sans serif IBM fonts? I ask this since even though Unicode blocks do not have it, they might add it in the future. If there is bold sans serif Greek, why not regular? New Computer Modern, STIX2 and XITS provide these letters.

[abrudz]

Awesome.

1. The stars in ⍣ and ⍟ could really be the same size as ⋆:
   
2. ⌷ doesn't look like a merged []:
   
3. In general, the lines of APL glyps look thin compared to other mathematical symbols. It is especially noticable in the circles in ⍥⍟⌽⍉⌾ compared to ○⊖⊙:
   but also e.g. ÷ vs ⌹ (both the - and the ⎕):
   plus ⌸ and the outer ⎕ of ⍯ compared to =≠:
   and ∘ is thicker than the APL glyphs that contain it:
   
4. ⍜ appears very small, and easily confusable with ⍛:
   
5. ⍒⍋ are too low on the line compared to their brethren:
   
6. ⍷ should get its ∊ part from ∊:
   
7. ϼ is smaller than other Greek symbols:
   
8. ⟃⟄ seem smaller than plain ⊂⊃:
   
9. ⊤ looks much better than its derivations ⌶⍕⍑⍡ and the same goes for ⊥ vs ⌶⍎⍊:
   
10. ⍲ is mirrored:
    
11. ∨ and ∧ look much better than their derivations ⍱⍌ and ⍲⍓ which are both thinner and larger/taller:
    

[BoldMonday]

Is there a possibility of having regular (non-bold) sans Greek letters, in the private use area, say imported from the sans serif IBM fonts? I ask this since even though Unicode blocks do not have it, they might add it in the future. If there is bold sans serif Greek, why not regular? New Computer Modern, STIX2 and XITS provide these letters.

Not sure. In my opinion PUA unicodes are a hack, and never a good solution in the long term. It creates portability problems too. And if these glyphs are ever adopted by Unicode then they will get their own codepoints.

[BoldMonday]

Everyone: here is a first public beta version of IBM Plex Math.

This font contains nearly all glyphs (close to 6,000) that are scheduled for the official release.
But most importantly there is a math table now which allows typesetting of formulas.

Feel free to give it a try and let us know in the comments what you think.

IBMPlexMath-Beta240212.otf.zip

[JimEBlevins]

This Beta release compiled my current LaTeX mathematical-file flawlessly (which is based on a SIAM Journal style).

Already, IBM Plex Math allows the use of unicode symbols for basic mathematical operators (mathematical Greek, set-membership, black-board bold, etc.) that are still impossible for Latin Modern Math (!).

(Without the OpenMATH Table, the previous alpha releases of IBM Plex Math could not even be tested.)

Congratulations to the team!

[mjabbink]

Thanks for getting this up @BoldMonday. I am also sharing with IBM Research community.

[mpsmath]

Thank you! This now works as a real math font, and can be tested. Nice that there are many variants for delimiters. From a quick test I have a few comments:

• ssty is used for both smaller styles (script and scriptscript). Could be a two-step thing.
• The two sizes of the integrals do not look compatible. The small one is perhaps too small, and the big one maybe a bit bold.
  
  Nice that the integral is an extensible!
• Math fraktur I and J are very similar.
  
• The radicals might be considered badly located vertically. In other fonts they are placed vertically in such a way that the small index is correctly located (this can be fixed in macro packages, and in fact one could argue that it should have been clearer from the Opentype math spec). I suggest to have a look on how other fonts do this.
  
• The bar and double bar come with extensibles, but the triple bar (U+2980) does not (it comes as an extensible, though). It would be nice if that one also came with variants.
• The delimiters are not consistent in vertical size, they vary just slightly. Maybe that is by design, but I think it makes sense to have them sized uniformly. In the image below we can see a few of them (but not all!)
  
• The font parameters ScriptPercentScaleDown is set to 70 and ScriptScriptPercentScaleDown is set to 55. I got the impression that they are slightly too large. I tried with 65 and 50, respectively, and I think that looked a bit more balanced. I understand very well that this is highly subjective.
• In Unicode math there is a script alphabet, but no calligraphic one. Some other fonts, like Stix Two Math have one of them in these slots and the other as ss01. It is nice to have both types of alphabets available.

Again, thanks for making it available for testing.

[JimEBlevins]

@mpsmath (Mikael P. Sundqvist) has written recent articles on the development of mathematical typography through LaTeX:

TUGBOAT: (The Communications of the TeX Users Group)

• Articles by MPS

[sharadhr]

I notice the readme now says

Additionally, we have introduced IBM Plex® Math. This highly anticipated release includes over 5,000 new glyphs, covering a wide range of mathematical symbols such as alphanumeric, double-struck, Fraktur, operators, script, icons, arrows, Greek letters, phonetics, technical and geometric shapes — making it one of the most complete math fonts available today. IBM Plex Math provides a fresh and comprehensive alternative to STIX and Microsoft’s Cambria. Its compatibility with IBM Plex Serif Regular makes it an ideal choice for IBM researchers and mathematicians.

I suppose this means IBM Plex Math is now out of beta? I look forward to testing it in LaTeX!

[mjabbink]

Yes it does. Let us know what you think.

[mpsmath]

Yes it does. Let us know what you think.

Thanks! Well done! Almost all of the issues reported have been addressed (I realize one does not have to agree with all of them...). I will test the font a bit more and report if I find some problems.