>>> """
=================
Mathtext Examples
=================

Selected features of Matplotlib's math rendering engine.
"""
... import re
... import subprocess
... import sys
... 
... import matplotlib.pyplot as plt
... 
... 
... # Selection of features following "Writing mathematical expressions" tutorial,
... # with randomly picked examples.
... mathtext_demos = {
...     "Header demo":
...         r"$W^{3\beta}_{\delta_1 \rho_1 \sigma_2} = "
...         r"U^{3\beta}_{\delta_1 \rho_1} + \frac{1}{8 \pi 2} "
...         r"\int^{\alpha_2}_{\alpha_2} d \alpha^\prime_2 \left[\frac{ "
...         r"U^{2\beta}_{\delta_1 \rho_1} - \alpha^\prime_2U^{1\beta}_"
...         r"{\rho_1 \sigma_2} }{U^{0\beta}_{\rho_1 \sigma_2}}\right]$",
... 
...     "Subscripts and superscripts":
...         r"$\alpha_i > \beta_i,\ "
...         r"\alpha_{i+1}^j = {\rm sin}(2\pi f_j t_i) e^{-5 t_i/\tau},\ "
...         r"\ldots$",
... 
...     "Fractions, binomials and stacked numbers":
...         r"$\frac{3}{4},\ \binom{3}{4},\ \genfrac{}{}{0}{}{3}{4},\ "
...         r"\left(\frac{5 - \frac{1}{x}}{4}\right),\ \ldots$",
... 
...     "Radicals":
...         r"$\sqrt{2},\ \sqrt[3]{x},\ \ldots$",
... 
...     "Fonts":
...         r"$\mathrm{Roman}\ , \ \mathit{Italic}\ , \ \mathtt{Typewriter} \ "
...         r"\mathrm{or}\ \mathcal{CALLIGRAPHY}$",
... 
...     "Accents":
...         r"$\acute a,\ \bar a,\ \breve a,\ \dot a,\ \ddot a, \ \grave a, \ "
...         r"\hat a,\ \tilde a,\ \vec a,\ \widehat{xyz},\ \widetilde{xyz},\ "
...         r"\ldots$",
... 
...     "Greek, Hebrew":
...         r"$\alpha,\ \beta,\ \chi,\ \delta,\ \lambda,\ \mu,\ "
...         r"\Delta,\ \Gamma,\ \Omega,\ \Phi,\ \Pi,\ \Upsilon,\ \nabla,\ "
...         r"\aleph,\ \beth,\ \daleth,\ \gimel,\ \ldots$",
... 
...     "Delimiters, functions and Symbols":
...         r"$\coprod,\ \int,\ \oint,\ \prod,\ \sum,\ "
...         r"\log,\ \sin,\ \approx,\ \oplus,\ \star,\ \varpropto,\ "
...         r"\infty,\ \partial,\ \Re,\ \leftrightsquigarrow, \ \ldots$",
... }
... n_lines = len(mathtext_demos)
... 
... 
... def doall():
...     # Colors used in Matplotlib online documentation.
...     mpl_grey_rgb = (51 / 255, 51 / 255, 51 / 255)
... 
...     # Creating figure and axis.
...     fig = plt.figure(figsize=(7, 7))
...     ax = fig.add_axes([0.01, 0.01, 0.98, 0.90],
...                       facecolor="white", frameon=True)
...     ax.set_xlim(0, 1)
...     ax.set_ylim(0, 1)
...     ax.set_title("Matplotlib's math rendering engine",
...                  color=mpl_grey_rgb, fontsize=14, weight='bold')
...     ax.set_xticks([])
...     ax.set_yticks([])
... 
...     # Gap between lines in axes coords
...     line_axesfrac = 1 / n_lines
... 
...     # Plot header demonstration formula.
...     full_demo = mathtext_demos['Header demo']
...     ax.annotate(full_demo,
...                 xy=(0.5, 1. - 0.59 * line_axesfrac),
...                 color='tab:orange', ha='center', fontsize=20)
... 
...     # Plot feature demonstration formulae.
...     for i_line, (title, demo) in enumerate(mathtext_demos.items()):
...         print(i_line, demo)
...         if i_line == 0:
...             continue
... 
...         baseline = 1 - i_line * line_axesfrac
...         baseline_next = baseline - line_axesfrac
...         fill_color = ['white', 'tab:blue'][i_line % 2]
...         ax.fill_between([0, 1], [baseline, baseline],
...                         [baseline_next, baseline_next],
...                         color=fill_color, alpha=0.2)
...         ax.annotate(f'{title}:',
...                     xy=(0.06, baseline - 0.3 * line_axesfrac),
...                     color=mpl_grey_rgb, weight='bold')
...         ax.annotate(demo,
...                     xy=(0.04, baseline - 0.75 * line_axesfrac),
...                     color=mpl_grey_rgb, fontsize=16)
... 
...     plt.show()
... 
... 
... if '--latex' in sys.argv:
...     # Run: python mathtext_examples.py --latex
...     # Need amsmath and amssymb packages.
...     with open("mathtext_examples.ltx", "w") as fd:
...         fd.write("\\documentclass{article}\n")
...         fd.write("\\usepackage{amsmath, amssymb}\n")
...         fd.write("\\begin{document}\n")
...         fd.write("\\begin{enumerate}\n")
... 
...         for s in mathtext_demos.values():
...             s = re.sub(r"(?<!\\)\$", "$$", s)
...             fd.write("\\item %s\n" % s)
... 
...         fd.write("\\end{enumerate}\n")
...         fd.write("\\end{document}\n")
... 
...     subprocess.call(["pdflatex", "mathtext_examples.ltx"])
... else:
...     doall()
...