The various Unicode characters for phi (Φ or φ or ϕ) display inconsistently between body and preview in Google Chrome.

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In particular, φ &phi and ϕ &#981 display reversed. It's obviously difficult to tell which (if either) is incorrect!

On its own, this isn't too much of an issue. However, when used in conjunction with phi characters in a MathJax equation (\phi \varphi), the result can be very confusing.

See this answer where I originally noticed the difference. Depending on whether you are editing or viewing, the variables in the equation have their definitions swapped!

I understand this is a well-documented problem when displaying between platforms, but as another example, all three characters display inconsistently between the iOS App, iOS Safari and Google Chrome (all the other Greek characters appear to display much more consistently).


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Screenshots from this post.


  • Google Chrome: Version 68.0.3440.106 on Windows 10, version 1803
  • iOS:
    • Device: iPhone 5S (Global)
    • iOS Version: Version 11.4.1 (Build 15G77)
    • App Version:
  • 3
    Reproducible in Firefox Nightly 63.0a1, Arch Linux with Gnome 3.28. – Sebastian Simon Aug 10 '18 at 15:12
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    Why are you sure this is an app or SE bug, rather than just a difference in fonts, which is where my first inclination runs? – Jeff Zeitlin Aug 10 '18 at 15:13
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    Stack Exchange uses the font Consolas for monospace text. This is the font that swaps phi and varphi. – Sebastian Simon Aug 10 '18 at 15:25
  • @JeffZeitlin you're right - I realise it's a difference between the two typefaces in body and preview, but I think we can all agree it's confusing to have the two characters swapped on the same page. – Jack Aug 10 '18 at 15:46
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    @Jack: But if it's a problem with the fonts, there's nothing SO can do about it. – Nicol Bolas Aug 10 '18 at 17:09
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    @NicolBolas Agreed, but there may potentially be other solutions. Either way, I feel it's still worth identifying as a piece of unexpected behaviour. – Jack Aug 10 '18 at 17:17
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    Phi, phi, fo, fum ..... – Rosinante Aug 11 '18 at 23:28
  • @NicolBolas they could use a different monospace that doesn't have inconsistencies with the font used for display. – Cave Johnson Jun 13 '20 at 15:09

According to "Writing mathematical expressions" by Jukka K. Korpela, page 128:

for [unspecified] historical reasons [...] many fonts have [φ and ϕ] reversed, such as Calibri, Consolas, Lucida Sans Unicode, Palatino Linotype, and Symbola. This means that its generally very risky to use φ and ϕ in different meanings.

Therefore, SE requires a feature that warns users when they use both symbols in the same post.

  • The first half of this post is good, the second part would be a feature request (which I would disagree with). Feature requsts should be made in their own questions. – Luuklag Jun 13 '20 at 10:00
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    @Luuklag OK, I posted it as an own question: meta.stackexchange.com/questions/349370/… – root Jun 13 '20 at 14:09

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