r"""
.. redirect-from:: /tutorials/text/usetex

.. _usetex:

*************************
Text rendering with LaTeX
*************************

Matplotlib can use LaTeX to render text.  This is activated by setting
``text.usetex : True`` in your rcParams, or by setting the ``usetex`` property
to True on individual `.Text` objects.  Text handling through LaTeX is slower
than Matplotlib's very capable :ref:`mathtext <mathtext>`, but
is more flexible, since different LaTeX packages (font packages, math packages,
etc.) can be used. The results can be striking, especially when you take care
to use the same fonts in your figures as in the main document.

Matplotlib's LaTeX support requires a working LaTeX_ installation.  For
the \*Agg backends, dvipng_ is additionally required; for the PS backend,
PSfrag_, dvips_ and Ghostscript_ are additionally required.  For the PDF
and SVG backends, if LuaTeX is present, it will be used to speed up some
post-processing steps, but note that it is not used to parse the TeX string
itself (only LaTeX is supported).  The executables for these external
dependencies must all be located on your :envvar:`PATH`.

Only a small number of font families (defined by the PSNFSS_ scheme) are
supported.  They are listed here, with the corresponding LaTeX font selection
commands and LaTeX packages, which are automatically used.

=========================== =================================================
generic family              fonts
=========================== =================================================
serif (``\rmfamily``)       Computer Modern Roman, Palatino (``mathpazo``),
                            Times (``mathptmx``),  Bookman (``bookman``),
                            New Century Schoolbook (``newcent``),
                            Charter (``charter``)

sans-serif (``\sffamily``)  Computer Modern Serif, Helvetica (``helvet``),
                            Avant Garde (``avant``)

cursive (``\rmfamily``)     Zapf Chancery (``chancery``)

monospace (``\ttfamily``)   Computer Modern Typewriter, Courier (``courier``)
=========================== =================================================

The default font family (which does not require loading any LaTeX package) is
Computer Modern.  All other families are Adobe fonts.  Times and Palatino each
have their own accompanying math fonts, while the other Adobe serif fonts make
use of the Computer Modern math fonts.

To enable LaTeX and select a font, use e.g.::

    plt.rcParams.update({
        "text.usetex": True,
        "font.family": "Helvetica"
    })

or equivalently, set your :ref:`matplotlibrc <customizing>` to::

    text.usetex : true
    font.family : Helvetica

It is also possible to instead set ``font.family`` to one of the generic family
names and then configure the corresponding generic family; e.g.::

    plt.rcParams.update({
        "text.usetex": True,
        "font.family": "sans-serif",
        "font.sans-serif": "Helvetica",
    })

(this was the required approach until Matplotlib 3.5).

Here is the standard example,
:doc:`/gallery/text_labels_and_annotations/tex_demo`:

.. figure:: /gallery/text_labels_and_annotations/images/sphx_glr_tex_demo_001.png
   :target: /gallery/text_labels_and_annotations/tex_demo.html
   :align: center

Note that display math mode (``$$ e=mc^2 $$``) is not supported, but adding the
command ``\displaystyle``, as in the above demo, will produce the same results.

Non-ASCII characters (e.g. the degree sign in the y-label above) are supported
to the extent that they are supported by inputenc_.

.. note::
   For consistency with the non-usetex case, Matplotlib special-cases newlines,
   so that single-newlines yield linebreaks (rather than being interpreted as
   whitespace in standard LaTeX).

   Matplotlib uses the underscore_ package so that underscores (``_``) are
   printed "as-is" in text mode (rather than causing an error as in standard
   LaTeX).  Underscores still introduce subscripts in math mode.

.. note::
   Certain characters require special escaping in TeX, such as::

     # $ % & ~ ^ \ { } \( \) \[ \]

   Therefore, these characters will behave differently depending on
   :rc:`text.usetex`.  As noted above, underscores (``_``) do not require
   escaping outside of math mode.

PostScript options
==================

In order to produce encapsulated PostScript (EPS) files that can be embedded
in a new LaTeX document, the default behavior of Matplotlib is to distill the
output, which removes some PostScript operators used by LaTeX that are illegal
in an EPS file. This step produces results which may be unacceptable to some
users, because the text is coarsely rasterized and converted to bitmaps, which
are not scalable like standard PostScript, and the text is not searchable. One
workaround is to set :rc:`ps.distiller.res` to a higher value (perhaps 6000)
in your rc settings, which will produce larger files but may look better and
scale reasonably. A better workaround, which requires Poppler_ or Xpdf_, can
be activated by changing :rc:`ps.usedistiller` to ``xpdf``. This alternative
produces PostScript without rasterizing text, so it scales properly, can be
edited in Adobe Illustrator, and searched text in pdf documents.

.. _usetex-hangups:

Possible hangups
================

* On Windows, the :envvar:`PATH` environment variable may need to be modified
  to include the directories containing the latex, dvipng and ghostscript
  executables. See :ref:`environment-variables` and
  :ref:`setting-windows-environment-variables` for details.

* Using MiKTeX with Computer Modern fonts, if you get odd \*Agg and PNG
  results, go to MiKTeX/Options and update your format files

* On Ubuntu and Gentoo, the base texlive install does not ship with
  the type1cm package. You may need to install some of the extra
  packages to get all the goodies that come bundled with other LaTeX
  distributions.

* Some progress has been made so Matplotlib uses the dvi files
  directly for text layout. This allows LaTeX to be used for text
  layout with the pdf and svg backends, as well as the \*Agg and PS
  backends. In the future, a LaTeX installation may be the only
  external dependency.

.. _usetex-troubleshooting:

Troubleshooting
===============

* Try deleting your :file:`.matplotlib/tex.cache` directory. If you don't know
  where to find :file:`.matplotlib`, see :ref:`locating-matplotlib-config-dir`.

* Make sure LaTeX, dvipng and ghostscript are each working and on your
  :envvar:`PATH`.

* Make sure what you are trying to do is possible in a LaTeX document,
  that your LaTeX syntax is valid and that you are using raw strings
  if necessary to avoid unintended escape sequences.

* :rc:`text.latex.preamble` is not officially supported. This
  option provides lots of flexibility, and lots of ways to cause
  problems. Please disable this option before reporting problems to
  the mailing list.

* If you still need help, please see :ref:`reporting-problems`.

.. _dvipng: http://www.nongnu.org/dvipng/
.. _dvips: https://tug.org/texinfohtml/dvips.html
.. _Ghostscript: https://ghostscript.com/
.. _inputenc: https://ctan.org/pkg/inputenc
.. _LaTeX: http://www.tug.org
.. _Poppler: https://poppler.freedesktop.org/
.. _PSNFSS: http://www.ctan.org/tex-archive/macros/latex/required/psnfss/psnfss2e.pdf
.. _PSfrag: https://ctan.org/pkg/psfrag
.. _underscore: https://ctan.org/pkg/underscore
.. _Xpdf: http://www.xpdfreader.com/
"""
