| r""" | |
| .. redirect-from:: /tutorials/text/mathtext | |
| .. _mathtext: | |
| Writing mathematical expressions | |
| ================================ | |
| You can use a subset of TeX markup in any Matplotlib text string by placing it | |
| inside a pair of dollar signs ($). | |
| Note that you do not need to have TeX installed, since Matplotlib ships | |
| its own TeX expression parser, layout engine, and fonts. The layout engine | |
| is a fairly direct adaptation of the layout algorithms in Donald Knuth's | |
| TeX, so the quality is quite good (Matplotlib also provides a ``usetex`` | |
| option for those who do want to call out to TeX to generate their text; see | |
| :ref:`usetex`). | |
| Any text element can use math text. You should use raw strings (precede the | |
| quotes with an ``'r'``), and surround the math text with dollar signs ($), as | |
| in TeX. Regular text and mathtext can be interleaved within the same string. | |
| Mathtext can use DejaVu Sans (default), DejaVu Serif, the Computer Modern fonts | |
| (from (La)TeX), `STIX <http://www.stixfonts.org/>`_ fonts (which are designed | |
| to blend well with Times), or a Unicode font that you provide. The mathtext | |
| font can be selected via :rc:`mathtext.fontset` (see | |
| :ref:`customizing`) | |
| Here is a simple example:: | |
| # plain text | |
| plt.title('alpha > beta') | |
| produces "alpha > beta". | |
| Whereas this:: | |
| # math text | |
| plt.title(r'$\alpha > \beta$') | |
| produces ":mathmpl:`\alpha > \beta`". | |
| .. note:: | |
| Mathtext should be placed between a pair of dollar signs ($). To make it | |
| easy to display monetary values, e.g., "$100.00", if a single dollar sign | |
| is present in the entire string, it will be displayed verbatim as a dollar | |
| sign. This is a small change from regular TeX, where the dollar sign in | |
| non-math text would have to be escaped ('\\\$'). | |
| .. note:: | |
| While the syntax inside the pair of dollar signs ($) aims to be TeX-like, | |
| the text outside does not. In particular, characters such as:: | |
| # $ % & ~ _ ^ \ { } \( \) \[ \] | |
| have special meaning outside of math mode in TeX. Therefore, these | |
| characters will behave differently depending on :rc:`text.usetex`. See the | |
| :ref:`usetex tutorial <usetex>` for more information. | |
| .. note:: | |
| To generate html output in documentation that will exactly match the output | |
| generated by ``mathtext``, use the `matplotlib.sphinxext.mathmpl` Sphinx | |
| extension. | |
| Subscripts and superscripts | |
| --------------------------- | |
| To make subscripts and superscripts, use the ``'_'`` and ``'^'`` symbols:: | |
| r'$\alpha_i > \beta_i$' | |
| .. math:: | |
| \alpha_i > \beta_i | |
| To display multi-letter subscripts or superscripts correctly, | |
| you should put them in curly braces ``{...}``:: | |
| r'$\alpha^{ic} > \beta_{ic}$' | |
| .. math:: | |
| \alpha^{ic} > \beta_{ic} | |
| Some symbols automatically put their sub/superscripts under and over the | |
| operator. For example, to write the sum of :mathmpl:`x_i` from :mathmpl:`0` to | |
| :mathmpl:`\infty`, you could do:: | |
| r'$\sum_{i=0}^\infty x_i$' | |
| .. math:: | |
| \sum_{i=0}^\infty x_i | |
| Fractions, binomials, and stacked numbers | |
| ----------------------------------------- | |
| Fractions, binomials, and stacked numbers can be created with the | |
| ``\frac{}{}``, ``\binom{}{}`` and ``\genfrac{}{}{}{}{}{}`` commands, | |
| respectively:: | |
| r'$\frac{3}{4} \binom{3}{4} \genfrac{}{}{0}{}{3}{4}$' | |
| produces | |
| .. math:: | |
| \frac{3}{4} \binom{3}{4} \genfrac{}{}{0pt}{}{3}{4} | |
| Fractions can be arbitrarily nested:: | |
| r'$\frac{5 - \frac{1}{x}}{4}$' | |
| produces | |
| .. math:: | |
| \frac{5 - \frac{1}{x}}{4} | |
| Note that special care needs to be taken to place parentheses and brackets | |
| around fractions. Doing things the obvious way produces brackets that are too | |
| small:: | |
| r'$(\frac{5 - \frac{1}{x}}{4})$' | |
| .. math:: | |
| (\frac{5 - \frac{1}{x}}{4}) | |
| The solution is to precede the bracket with ``\left`` and ``\right`` to inform | |
| the parser that those brackets encompass the entire object.:: | |
| r'$\left(\frac{5 - \frac{1}{x}}{4}\right)$' | |
| .. math:: | |
| \left(\frac{5 - \frac{1}{x}}{4}\right) | |
| Radicals | |
| -------- | |
| Radicals can be produced with the ``\sqrt[]{}`` command. For example:: | |
| r'$\sqrt{2}$' | |
| .. math:: | |
| \sqrt{2} | |
| Any base can (optionally) be provided inside square brackets. Note that the | |
| base must be a simple expression, and cannot contain layout commands such as | |
| fractions or sub/superscripts:: | |
| r'$\sqrt[3]{x}$' | |
| .. math:: | |
| \sqrt[3]{x} | |
| .. _mathtext-fonts: | |
| Fonts | |
| ----- | |
| The default font is *italics* for mathematical symbols. | |
| .. note:: | |
| This default can be changed using :rc:`mathtext.default`. This is | |
| useful, for example, to use the same font as regular non-math text for math | |
| text, by setting it to ``regular``. | |
| To change fonts, e.g., to write "sin" in a Roman font, enclose the text in a | |
| font command:: | |
| r'$s(t) = \mathcal{A}\mathrm{sin}(2 \omega t)$' | |
| .. math:: | |
| s(t) = \mathcal{A}\mathrm{sin}(2 \omega t) | |
| More conveniently, many commonly used function names that are typeset in | |
| a Roman font have shortcuts. So the expression above could be written as | |
| follows:: | |
| r'$s(t) = \mathcal{A}\sin(2 \omega t)$' | |
| .. math:: | |
| s(t) = \mathcal{A}\sin(2 \omega t) | |
| Here "s" and "t" are variable in italics font (default), "sin" is in Roman | |
| font, and the amplitude "A" is in calligraphy font. Note in the example above | |
| the calligraphy ``A`` is squished into the ``sin``. You can use a spacing | |
| command to add a little whitespace between them:: | |
| r's(t) = \mathcal{A}\/\sin(2 \omega t)' | |
| .. Here we cheat a bit: for HTML math rendering, Sphinx relies on MathJax which | |
| doesn't actually support the italic correction (\/); instead, use a thin | |
| space (\,) which is supported. | |
| .. math:: | |
| s(t) = \mathcal{A}\,\sin(2 \omega t) | |
| The choices available with all fonts are: | |
| ========================= ================================ | |
| Command Result | |
| ========================= ================================ | |
| ``\mathrm{Roman}`` :mathmpl:`\mathrm{Roman}` | |
| ``\mathit{Italic}`` :mathmpl:`\mathit{Italic}` | |
| ``\mathtt{Typewriter}`` :mathmpl:`\mathtt{Typewriter}` | |
| ``\mathcal{CALLIGRAPHY}`` :mathmpl:`\mathcal{CALLIGRAPHY}` | |
| ========================= ================================ | |
| .. role:: math-stix(mathmpl) | |
| :fontset: stix | |
| When using the `STIX <http://www.stixfonts.org/>`_ fonts, you also have the | |
| choice of: | |
| ================================ ========================================= | |
| Command Result | |
| ================================ ========================================= | |
| ``\mathbb{blackboard}`` :math-stix:`\mathbb{blackboard}` | |
| ``\mathrm{\mathbb{blackboard}}`` :math-stix:`\mathrm{\mathbb{blackboard}}` | |
| ``\mathfrak{Fraktur}`` :math-stix:`\mathfrak{Fraktur}` | |
| ``\mathsf{sansserif}`` :math-stix:`\mathsf{sansserif}` | |
| ``\mathrm{\mathsf{sansserif}}`` :math-stix:`\mathrm{\mathsf{sansserif}}` | |
| ``\mathbfit{bolditalic}`` :math-stix:`\mathbfit{bolditalic}` | |
| ================================ ========================================= | |
| There are also five global "font sets" to choose from, which are | |
| selected using the ``mathtext.fontset`` parameter in :ref:`matplotlibrc | |
| <matplotlibrc-sample>`. | |
| ``dejavusans``: DejaVu Sans | |
| .. mathmpl:: | |
| :fontset: dejavusans | |
| \mathcal{R} \prod_{i=\alpha}^{\infty} a_i \sin\left(2\pi fx_i\right) | |
| ``dejavuserif``: DejaVu Serif | |
| .. mathmpl:: | |
| :fontset: dejavuserif | |
| \mathcal{R} \prod_{i=\alpha}^{\infty} a_i \sin\left(2\pi fx_i\right) | |
| ``cm``: Computer Modern (TeX) | |
| .. mathmpl:: | |
| :fontset: cm | |
| \mathcal{R} \prod_{i=\alpha}^{\infty} a_i \sin\left(2\pi fx_i\right) | |
| ``stix``: STIX (designed to blend well with Times) | |
| .. mathmpl:: | |
| :fontset: stix | |
| \mathcal{R} \prod_{i=\alpha}^{\infty} a_i \sin\left(2\pi fx_i\right) | |
| ``stixsans``: STIX sans-serif | |
| .. mathmpl:: | |
| :fontset: stixsans | |
| \mathcal{R} \prod_{i=\alpha}^{\infty} a_i \sin\left(2\pi fx_i\right) | |
| Additionally, you can use ``\mathdefault{...}`` or its alias | |
| ``\mathregular{...}`` to use the font used for regular text outside of | |
| mathtext. There are a number of limitations to this approach, most notably | |
| that far fewer symbols will be available, but it can be useful to make math | |
| expressions blend well with other text in the plot. | |
| For compatibility with popular packages, ``\text{...}`` is available and uses the | |
| ``\mathrm{...}`` font, but otherwise retains spaces and renders - as a dash | |
| (not minus). | |
| Custom fonts | |
| ~~~~~~~~~~~~ | |
| mathtext also provides a way to use custom fonts for math. This method is | |
| fairly tricky to use, and should be considered an experimental feature for | |
| patient users only. By setting :rc:`mathtext.fontset` to ``custom``, | |
| you can then set the following parameters, which control which font file to use | |
| for a particular set of math characters. | |
| ============================== ================================= | |
| Parameter Corresponds to | |
| ============================== ================================= | |
| ``mathtext.it`` ``\mathit{}`` or default italic | |
| ``mathtext.rm`` ``\mathrm{}`` Roman (upright) | |
| ``mathtext.tt`` ``\mathtt{}`` Typewriter (monospace) | |
| ``mathtext.bf`` ``\mathbf{}`` bold | |
| ``mathtext.bfit`` ``\mathbfit{}`` bold italic | |
| ``mathtext.cal`` ``\mathcal{}`` calligraphic | |
| ``mathtext.sf`` ``\mathsf{}`` sans-serif | |
| ============================== ================================= | |
| Each parameter should be set to a fontconfig font descriptor (as defined in the | |
| yet-to-be-written font chapter). | |
| .. TODO: Link to font chapter | |
| The fonts used should have a Unicode mapping in order to find any | |
| non-Latin characters, such as Greek. If you want to use a math symbol | |
| that is not contained in your custom fonts, you can set | |
| :rc:`mathtext.fallback` to either ``'cm'``, ``'stix'`` or ``'stixsans'`` | |
| which will cause the mathtext system to use | |
| characters from an alternative font whenever a particular | |
| character cannot be found in the custom font. | |
| Note that the math glyphs specified in Unicode have evolved over time, and many | |
| fonts may not have glyphs in the correct place for mathtext. | |
| Accents | |
| ------- | |
| An accent command may precede any symbol to add an accent above it. There are | |
| long and short forms for some of them. | |
| ============================== ================================= | |
| Command Result | |
| ============================== ================================= | |
| ``\acute a`` or ``\'a`` :mathmpl:`\acute a` | |
| ``\bar a`` :mathmpl:`\bar a` | |
| ``\breve a`` :mathmpl:`\breve a` | |
| ``\dot a`` or ``\.a`` :mathmpl:`\dot a` | |
| ``\ddot a`` or ``\''a`` :mathmpl:`\ddot a` | |
| ``\dddot a`` :mathmpl:`\dddot a` | |
| ``\ddddot a`` :mathmpl:`\ddddot a` | |
| ``\grave a`` or ``\`a`` :mathmpl:`\grave a` | |
| ``\hat a`` or ``\^a`` :mathmpl:`\hat a` | |
| ``\tilde a`` or ``\~a`` :mathmpl:`\tilde a` | |
| ``\vec a`` :mathmpl:`\vec a` | |
| ``\overline{abc}`` :mathmpl:`\overline{abc}` | |
| ============================== ================================= | |
| In addition, there are two special accents that automatically adjust to the | |
| width of the symbols below: | |
| ============================== ================================= | |
| Command Result | |
| ============================== ================================= | |
| ``\widehat{xyz}`` :mathmpl:`\widehat{xyz}` | |
| ``\widetilde{xyz}`` :mathmpl:`\widetilde{xyz}` | |
| ============================== ================================= | |
| Care should be taken when putting accents on lower-case i's and j's. Note that | |
| in the following ``\imath`` is used to avoid the extra dot over the i:: | |
| r"$\hat i\ \ \hat \imath$" | |
| .. math:: | |
| \hat i\ \ \hat \imath | |
| Symbols | |
| ------- | |
| You can also use a large number of the TeX symbols, as in ``\infty``, | |
| ``\leftarrow``, ``\sum``, ``\int``. | |
| .. math_symbol_table:: | |
| If a particular symbol does not have a name (as is true of many of the more | |
| obscure symbols in the STIX fonts), Unicode characters can also be used:: | |
| r'$\u23ce$' | |
| Example | |
| ------- | |
| Here is an example illustrating many of these features in context. | |
| .. figure:: /gallery/text_labels_and_annotations/images/sphx_glr_mathtext_demo_001.png | |
| :target: /gallery/text_labels_and_annotations/mathtext_demo.html | |
| :align: center | |
| """ | |