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

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))