.. _pylab_examples-usetex_demo:

pylab_examples example code: usetex_demo.py
===========================================



.. plot:: /home/travis/build/jenshnielsen/matplotlib/doc/mpl_examples/pylab_examples/usetex_demo.py

::

    import matplotlib
    matplotlib.rc('text', usetex=True)
    import pylab
    import numpy as np
    
    # interface tracking profiles
    N = 500
    delta = 0.6
    X = np.linspace(-1, 1, N)
    pylab.plot(X, (1 - np.tanh(4.*X/delta))/2,    # phase field tanh profiles
               X, (X + 1)/2,                      # level set distance function
               X, (1.4 + np.tanh(4.*X/delta))/4,  # composition profile
               X, X < 0, 'k--',                   # sharp interface
               linewidth=5)
    
    # legend
    pylab.legend((r'phase field', r'level set', r'composition', r'sharp interface'), shadow=True, loc=(0.01, 0.55))
    
    ltext = pylab.gca().get_legend().get_texts()
    pylab.setp(ltext[0], fontsize=20, color='b')
    pylab.setp(ltext[1], fontsize=20, color='g')
    pylab.setp(ltext[2], fontsize=20, color='r')
    pylab.setp(ltext[3], fontsize=20, color='k')
    
    # the arrow
    height = 0.1
    offset = 0.02
    pylab.plot((-delta / 2., delta / 2), (height, height), 'k', linewidth=2)
    pylab.plot((-delta / 2, -delta / 2 + offset * 2), (height, height - offset), 'k', linewidth=2)
    pylab.plot((-delta / 2, -delta / 2 + offset * 2), (height, height + offset), 'k', linewidth=2)
    pylab.plot((delta / 2, delta / 2 - offset * 2), (height, height - offset), 'k', linewidth=2)
    pylab.plot((delta / 2, delta / 2 - offset * 2), (height, height + offset), 'k', linewidth=2)
    pylab.text(-0.06, height - 0.06, r'$\delta$', {'color': 'k', 'fontsize': 24})
    
    # X-axis label
    pylab.xticks((-1, 0, 1), ('-1', '0', '1'), color='k', size=20)
    
    # Left Y-axis labels
    pylab.ylabel(r'\bf{phase field} $\phi$', {'color': 'b',
                                              'fontsize': 20})
    pylab.yticks((0, 0.5, 1), ('0', '.5', '1'), color='k', size=20)
    
    # Right Y-axis labels
    pylab.text(1.05, 0.5, r"\bf{level set} $\phi$", {'color': 'g', 'fontsize': 20},
               horizontalalignment='left',
               verticalalignment='center',
               rotation=90,
               clip_on=False)
    pylab.text(1.01, -0.02, "-1", {'color': 'k', 'fontsize': 20})
    pylab.text(1.01, 0.98, "1", {'color': 'k', 'fontsize': 20})
    pylab.text(1.01, 0.48, "0", {'color': 'k', 'fontsize': 20})
    
    # level set equations
    pylab.text(0.1, 0.85,
               r'$|\nabla\phi| = 1,$ \newline $ \frac{\partial \phi}{\partial t}'
               r'+ U|\nabla \phi| = 0$',
               {'color': 'g', 'fontsize': 20})
    
    # phase field equations
    pylab.text(0.2, 0.15,
               r'$\mathcal{F} = \int f\left( \phi, c \right) dV,$ \newline '
               r'$ \frac{ \partial \phi } { \partial t } = -M_{ \phi } '
               r'\frac{ \delta \mathcal{F} } { \delta \phi }$',
               {'color': 'b', 'fontsize': 20})
    
    # these went wrong in pdf in a previous version
    pylab.text(-.9, .42, r'gamma: $\gamma$', {'color': 'r', 'fontsize': 20})
    pylab.text(-.9, .36, r'Omega: $\Omega$', {'color': 'b', 'fontsize': 20})
    
    pylab.show()
    

Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)