Subscripts and superscripts¶

To make subscripts and superscripts, use the '_' and '^' symbols:

r'$\alpha_i > \beta_i$'

Some symbols automatically put their sub/superscripts under and over the operator. For example, to write the sum of \(x_i\) from \(0\) to \(\infty\), you could do:

r'$\sum_{i=0}^\infty x_i$'

Fractions, binomials and stacked numbers¶

Fractions, binomials and stacked numbers can be created with the \frac{}{}, \binom{}{} and \stackrel{}{} commands, respectively:

r'$\frac{3}{4} \binom{3}{4} \stackrel{3}{4}$'

produces

Fractions can be arbitrarily nested:

r'$\frac{5 - \frac{1}{x}}{4}$'

produces

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'$(\frac{5 - \frac{1}{x}}{4})$'

The solution is to precede the bracket with \left and \right to inform the parser that those brackets encompass the entire object:

r'$\left(\frac{5 - \frac{1}{x}}{4}\right)$'

Radicals¶

Radicals can be produced with the \sqrt[]{} command. For example:

r'$\sqrt{2}$'

Any base can (optionally) be provided inside square brackets. Note that the base must be a simple expression, and can not contain layout commands such as fractions or sub/superscripts:

r'$\sqrt[3]{x}$'

Fonts¶

The default font is italics for mathematical symbols.

To change fonts, eg, to write “sin” in a Roman font, enclose the text in a font command:

r'$s(t) = \mathcal{A}\mathrm{sin}(2 \omega t)$'

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'$s(t) = \mathcal{A}\sin(2 \omega t)$'

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 caligraphy A is squished into the sin. You can use a spacing command to add a little whitespace between them:

s(t) = \mathcal{A}\/\sin(2 \omega t)

The choices available with all fonts are:

Command	Result
\mathrm{Roman}	\(\mathrm{Roman}\)
\mathit{Italic}	\(\mathit{Italic}\)
\mathtt{Typewriter}	\(\mathtt{Typewriter}\)
\mathcal{CALLIGRAPHY}	\(\mathcal{CALLIGRAPHY}\)

When using the STIX 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}}`

There are also three global “font sets” to choose from, which are selected using the mathtext.fontset parameter in matplotlibrc.

cm: Computer Modern (TeX)

stix: STIX (designed to blend well with Times)

stixsans: STIX sans-serif

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.

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	\(\acute a\)
\bar a	\(\bar a\)
\breve a	\(\breve a\)
\ddot a or \"a	\(\ddot a\)
\dot a or \.a	\(\dot a\)
\grave a or \`a	\(\grave a\)
\hat a or \^a	\(\hat a\)
\tilde a or \~a	\(\tilde a\)
\vec a	\(\vec a\)
\overline{abc}	\(\overline{abc}\)

In addition, there are two special accents that automatically adjust to the width of the symbols below:

Command	Result
\widehat{xyz}	\(\widehat{xyz}\)
\widetilde{xyz}	\(\widetilde{xyz}\)

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"$\hat i\ \ \hat \imath$"

Symbols¶

You can also use a large number of the TeX symbols, as in \infty, \leftarrow, \sum, \int.

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:

ur'$\u23ce$'

Example¶

Here is an example illustrating many of these features in context.