docs: def ticks_format(value, index):
      """
      get the value and returns the value as:
         integer: [0,99]
         1 digit float: [0.1, 0.99]
         n*10^m: otherwise
      To have all the number of the same size they are all returned as latex strings
  
      http://stackoverflow.com/questions/17165435/matplotlib-show-labels-for-minor-ticks-also
      """
      exp = np.floor(np.log10(value))
      base = value/10**exp
      if exp == 0 or exp == 1:
          return '${0:d}$'.format(int(value))
      if exp == -1:
          return '${0:.1f}$'.format(value)
      else:
          return '${0:d}\\times10^{{{1:d}}}$'.format(int(base), int(exp))