bugGNU Octave - Bugs: bug #42582, some TeX symbols don't work...


bug #42582: some TeX symbols don't work on-screen (fltk)

Submitter:  Hartmut <hardy>
Submitted:  Wed 18 Jun 2014 06:54:08 PM UTC
Category:  Plotting with OpenGL Severity:  1 - Wish
Priority:  3 - Low Item Group:  Feature Request
Status:  Postponed Assigned to:  None
Originator Name:  Open/Closed:  * Open
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Tue 27 Jul 2021 10:16:34 PM UTC, comment #12: 

@Rik thank you for looking into this.
So at least for 6.3 there has been no changes.

Closed octave, reopened, and now I get the same results as you.


Found the my error.
Copied from Hartmut's code and did not capture the %


Instead of


Tue 27 Jul 2021 09:17:08 PM UTC, comment #11: 

Latest version of Octave is 6.3.  When I run the code from comment #10 it shows that "\varphi" is unrecognized and so not interpreted as a TeX character.


Rik <rik5>
Group administrator
Tue 27 Jul 2021 08:55:23 PM UTC, comment #10: 

@Michael has there been any progress on this?

Using version 6.1.0 for mac

title('\varphi and \phi')

Look the same.

Sun 03 Sep 2017 11:01:14 PM UTC, comment #9: 

I looked up pgs. 434-438 of the TeXbook. It appears that
what is in the Manual is not what I thought I had done.
I intended to do all of Lists:
1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15.
I think that there may have been a problem with the missing symbols, but this was a long time ago.

The missing symbols from these lists should be included if

But, adding non-TeX symbols is not, I think, a good idea.
Some thought could go into a mechanism for users to create
their own symbols.

Michael Godfrey <godfrey>
Group Member
Sun 03 Sep 2017 09:34:38 PM UTC, comment #8: 

I have had a look what symbols TeX supports [1] and are not currently implemented in Octave [2]. From those I've picked the ones I personally have seen in scientific plots and consider them useful myself. So here is my suggested (and maybe very personal) list:

*** My personal wish list: ***
\varepsilon  (useful and common for any kind of formulas)
\varrho      (useful and common for any kind of formulas)
\varphi      (useful and common for any kind of formulas)
\hbar        (useful for Physics stuff)
\sqrt        (is this doable without excessiv effort?)
\sum         (but there is already \Sigma)
\prod        (but there is already \Pi)
\ominus      (because there is already \oplus in Octave)
\odot        (because there is already \otimes in Octave)
\ll          (this looks more professional as <<)
\gg          (this looks more professional as >>)
\parallel    (because there is already \perp in Octave)
\simeq       (currently there is only \sim in Octave)
\notin       (currently there seem to be no negationas at all in Octave, except for \neq)
\not=        (even if there is already \neq in Octave)
\Leftrightarrow      (currently there is only \leftrightarrow in Octave)
\mapsto      (useful arrow type for Math)
\rightleftharpoons   (useful for chemical stuff)
\Uparrow     (currently there is only \uparrow in Octave)
\Downarrow   (currently there is only \uparrow in Octave)

(alternate names for already existing TeX symbols in Octave:)

[1] http://www.math.union.edu/~dpvc/jsmath/symbols/welcome.html
This webpage claims to list „The symbols listed in Appendix F of The TeXbook“

[2] https://www.gnu.org/software/octave/doc/interpreter/Use-of-the-interpreter-Property.html

Here is the full list of TeX symbols in [1] which are not yet in Octave [2] (leftout stuff is marked with square brackets):

*** Full list of possibly missing TeX symbols ***
Greek Letters

Symbols of type Ord
\emptyset     (there is alreaddy \O )
\triangle      (there is already \Delta )


\sqrt        (is this doable without excessiv effort?)
\root 3\of

"Large" Operators
\sum       (but there is already \Sigma)
\prod      (but there is already \Pi)

Binary operations
\ominus      (because there is already \oplus in Octave)
\odot        (because there is already \otimes in Octave)

Relations and their Negations
\ll         (this looks more professional as <<)
\gg         (this looks more professional as >>)
\parallel   (because there is already \perp in Octave)
\simeq      (currently there is only \sim in Octave)

\notin        (currently there seem to be no negationas at all in Octave, except for \neq)
\not=         (even if there is already \neq in Octave)

\Leftrightarrow   (currently there is only \leftrightarrow in Octave)
\mapsto           (useful arrow type for Math)
\rightleftharpoons   (useful for chemical stuff)
\Uparrow            (currently there is only \uparrow in Octave)
\Downarrow          (currently there is only \uparrow in Octave)


Matrices and Arrays

Alternate Names and Non-Math Symbols

Hartmut <hardy>
Fri 01 Sep 2017 05:07:07 PM UTC, comment #7: 

If more symbols are added it would be good to make clear
that the current set is taken from the TeX book. Additional
symbols have been added for some specific reason.

In any case the result should be able to be processed by
TeX since this is sometimes done to produce results
suitable for publication, for instance.

Michael Godfrey <godfrey>
Group Member
Fri 01 Sep 2017 04:36:40 PM UTC, comment #6: 

Given that we like to view Octave as a superset of Matlab, I don't have an issue with adding some more symbols to the list.  But, I don't want to go overboard and add 1,000 new entries.

Would someone be willing to look at TeX and the Octave manual and come up with a list of additional symbols that would be useful?

Rik <rik5>
Group administrator
Tue 24 Jun 2014 08:24:43 PM UTC, comment #5: 

Updating bug priority and severity. And of course there is always full Unicode support as a long-term goal, which if/when done might obviate the need to support more named TeX math symbols.

Mike Miller <mtmiller>
Group Member
Wed 18 Jun 2014 11:28:49 PM UTC, comment #4: 

Table 15.1 is actually derived from the TeX Book.

I think that it is a good idea to adher to what is specified
by Knuth in his documentation.

There are other means of introducing TeX source code,
as explained in the Manual.

This was discussed about a year ago when Table 15.1 and
the code were updated to match the tables in the TeX Book.

Michael Godfrey <godfrey>
Group Member
Wed 18 Jun 2014 08:27:51 PM UTC, comment #3: 

We could change this into a wish list item, but currently Octave is only trying to match Matlab's character set.  It's not terrifically hard, but it does take some work to add a new character to the TeX interpreter so if we're mostly happy with the ones we have then I would make this a low priority item.

Rik <rik5>
Group administrator
Wed 18 Jun 2014 07:43:10 PM UTC, comment #2: 

Oh, sorry. Then I was mislead by the information in the mentioned book of jwe on "Octave 3" (link in my original post). Maybe that's a bit outdated now.

If those symbols currently are not mentioned in the Octave manual nor support by Matlab, then I personally wouldn't consider this to be a bug at all.

But now it's up to the TeX experts...

Hartmut <hardy>
Wed 18 Jun 2014 07:12:42 PM UTC, comment #1: 

Thanks for your bug report. I will have to let someone with more expertise on TeX support comment on whether or not this will be fixed. Setting status to "need info" until that is resolved.

However, the set of TeX symbols that Octave supports is explicitly intended to match the set that Matlab supports. Here is the Matlab set:


and here is the Octave set:


As you can see, the symbols you say are not working are not listed in either of these tables, so they are currently not expected to work. The only question is, should they be supported or do we strictly support only the same set of characters as Matlab?

Mike Miller <mtmiller>
Group Member
Wed 18 Jun 2014 06:54:08 PM UTC, original submission:  

Here is some sample script to show what I mean:

close all;
r = 'works: \alpha \approx \leftrightarrow ';
s = ', works not: \varphi \Leftrightarrow \Uparrow \Downarrow \notin \prod \diamond ';
t = '\bigrightriangledown';

If I run this on Octave 3.8.1 as well as on Octave 3.8.2-rc1 under Ubuntu Linux, then the TeX symbols in s and t are NOT shown on screen. This is using FLTK.

If I switch to Gnuplot, then most of those symbols appear on screen, just the one in t still does not appear.

I assumed that all of those symbols should work because of this reference: www.network-theory.co.uk/docs/octave3/octave_172.html

I don't know if this happens as well on Windows installations, but I would assume yes.

Hartmut <hardy>


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Attach Files:

Attached Files
file #51703:  varphi.png added by rik5 (12KiB - image/png)
file #51702:  test.png added by None (12KiB - image/png)


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    Follow 10 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-07-27 rik5 Attached File- Added varphi.png, #51703
    2021-07-27 None Attached File- Added test.png, #51702
    2014-06-24 mtmiller Severity3 - Normal 1 - Wish
        Priority5 - Normal 3 - Low
        Item GroupIncorrect Result Feature Request
        StatusNeed Info Postponed
        Release3.8.1 dev
        Operating SystemGNU/Linux Any
    2014-06-18 mtmiller CategoryPlotting Plotting with OpenGL
        StatusNone Need Info

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