# Introductory example - Plotting sin#

This is a general example demonstrating a Matplotlib plot output, embedded rST, the use of math notation and cross-linking to other examples. It would be useful to compare the source Python file with the output below.

Source files for gallery examples should start with a triple-quoted header docstring. Anything before the docstring is ignored by Sphinx-Gallery and will not appear in the rendered output, nor will it be executed. This docstring requires a rST header, which is used as the title of the example and to correctly build cross-referencing links.

Code and embedded rST text blocks follow the docstring. The first block immediately after the docstring is deemed a code block, by default, unless you specify it to be a text block using a line of #’s or #%% (see below). All code blocks get executed by Sphinx-Gallery and any output, including plots will be captured. Typically, code and text blocks are interspersed to provide narrative explanations of what the code is doing or interpretations of code output.

Mathematical expressions can be included as LaTeX, and will be rendered with MathJax. To include displayed math notation, use the directive .. math::. To include inline math notation use the :math: role. For example, we are about to plot the following function:

$x \rightarrow \sin(x)$

Here the function $$\sin$$ is evaluated at each point the variable $$x$$ is defined. When including LaTeX in a Python string, ensure that you escape the backslashes or use a raw docstring. You do not need to do this in text blocks (see below).

# Code source: Óscar Nájera

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 2 * np.pi, 100)
y = np.sin(x)

plt.plot(x, y)
plt.xlabel(r'$x$')
plt.ylabel(r'$\sin(x)$')
# To avoid matplotlib text output
plt.show()


To include embedded rST, use a line of >= 20 #’s or #%% between your rST and your code (see Embed rST in your example Python files). This separates your example into distinct text and code blocks. You can continue writing code below the embedded rST text block:

print('This example shows a sin plot!')

This example shows a sin plot!


LaTeX syntax in the text blocks does not require backslashes to be escaped:

$\sin$

## Cross referencing#

You can refer to an example from any part of the documentation, including from other examples. Sphinx-Gallery automatically creates reference labels for each example. The label consists of the .py file name, prefixed with sphx_glr_ and the name of the folder(s) the example is in. Below, the example we want to cross-reference is in auto_examples (the gallery_dirs; see Configure and use Sphinx-Gallery), then the subdirectory no_output (since the example is within a sub-gallery). The file name of the example is plot_syntaxerror.py. We can thus cross-link to the example ‘SyntaxError’ using: :ref:sphx_glr_auto_examples_no_output_plot_syntaxerror.py.