| 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 |
| """ |
|
|
