def write_heat_capacity_P_numerical(self, filename='Cp-temperature.dat'):
    w = open(filename, 'w')
    for i in range(self._len):
        w.write(('%20.15f %20.15f\n' % (self._temperatures[i], self._cp_numerical[i])))
    w.close()
def write_heat_capacity_P_numerical(self, filename='Cp-temperature.dat'):
    w = open(filename, 'w')
    for i in range(self._len):
        w.write(('%20.15f %20.15f\n' % (self._temperatures[i], self._cp_numerical[i])))
    w.close()