def test_latexformula():

       png = datadir.join("test.png")

       formula = r'$$Entropy(T) = - \sum^{m}_{j=1}  \frac{|T_j|}{|T|} \log \frac{|T_j|}{|T|}$$'

       #does not crash

->     latexformula2png(formula, png)

       assert png.check()

       png.remove()

   def __init__(self, formula, dest, temp=None):

       self.formula = formula

       try:

           import Image

           self.Image = Image

           self.scale = 2 # create a larger image

           self.upscale = 5 # create the image upscale times larger, then scale it down

       except ImportError:

           self.scale = 2

           self.upscale = 1

           self.Image = None

       self.output_format = ('pngmono', 'pnggray', 'pngalpha')[2]

       if temp is None:

           temp = py.test.ensuretemp("latexformula")

       self.temp = temp

       self.latex = self.temp.join('formula.tex')

       self.dvi = self.temp.join('formula.dvi')

       self.eps = self.temp.join('formula.eps')

       self.png = self.temp.join('formula.png')

->     self.saveas(dest)

   def saveas(self, dest):

       self.gen_latex()

       self.gen_dvi()

->     dvi2eps(self.dvi, self.eps)

       self.gen_png()

       self.scale_image()

       self.png.copy(dest)

   def dvi2eps(dvi, dest=None):

       if dest is None:

           dest = eps.new(ext=".eps")

       command = 'dvips -q -E -n 1 -D 600 -p 1 -o "%s" "%s"' % (dest, dvi)

->     if not py.path.local.sysfind("dvips"):

           raise SystemExit("ERROR: dvips not found")

       py.process.cmdexec(command)