Page MenuHomePhabricator

'\phi' and '\varphi' not necessarily distinguished in Unicode
Closed, ResolvedPublic


Author: viric

Is it possible in unicode to show that difference of 'phi'?
I have a text, where I want \phi, and appears \varphi (when showin the formulæ
in unicode, in the mediawiki).
If I copy that unicode character (\phi) to different fonts, in some I get
\varphi, and in some I get \phi.

so, how to get those characters _always_ properly in unicode? maybe allowing
only PNG of them?

Version: unspecified
Severity: minor



Event Timeline

bzimport raised the priority of this task from to Medium.Nov 21 2014, 8:10 PM
bzimport added a project: Math.
bzimport set Reference to bz1347.
bzimport added a subscriber: Unknown Object (MLST). is affected by this: in Firefox on Ubuntu Edgy
(using Bitstream Vera Serif), the four variant glyphs for lowercase phi shown in
the lede are indistinguishable, in particular the TeX markup \phi is
indistinguishable from \varphi (they all look like the latter). Sometimes the
distinction is important, so I think the presence of \phi should always force
rendering of the png.

ayg wrote:

Unicode has a dedicated character for the stroked phi (GREEK PHI SYMBOL, U+03D5,
ϕ), but apparently no specific character for the loopy phi. Font authors get to
decide whether to render GREEK SMALL LETTER PHI, U+03C6, φ stroked or loopy. Of
course, there's also variation in displaying U+03D5. All in all it's probably
best to always use images when showcasing particular variants of a letter. But
if there's also a difference sometimes for general mathematical use, as Peter
Barry says, it would indeed be wise to always render phi to PNG. (When is there
a difference?)

bastian wrote:

I got confused by this when reading the "Michael Dummett" section in - the Phi is displayed differently in the "exists x.phi(x)"-term than in the "t of which phi holds"-term. The first one displays as the latin small letter, the second one as the greek one. I tested this with Ubuntu Feisty with both Firefox and Epiphany with different fonts. If you do not happen to know that both symbols should actually be the same one, that statement there does not make any sense.

We were discussing this issue again on VPT. We noticed that in html \phi is rendered as html "small letter phi" φ

Lexically this is seems correct, but in latex \phi should always be the small stroked version and \varphi should always be the loopy version of the character. (See )
Because in unicode, the small letter phi can be either loopy OR stroked, translating \phi as unicode small letter phi is not correct. \phi should therefore either be always rendered in PNG, or alternatively, we could render it with ϕ Since we always use \phi in a math context and ϕ is reserved for the small stroked math version of the phi symbol, this is a correct translation when convert math. I have attached patches for both alternative corrections.

Created attachment 6486
render as U+03D5


Created attachment 6487
render always as png


  • Bug 16438 has been marked as a duplicate of this bug. ***

Applied the PNG fix in r66580

At least that is consistent.