from carnahanstarling import CarnahanStarling
import numpy as np

eos = CarnahanStarling('AR,HE')
rho = 20000
x1 = 0.9
x = np.array([x1, 1 - x1])
n = x * rho
print(eos.compressibility(rho, x))
print((eos.dvdn_Tp(rho, n) - 1 / rho) / (1 / rho))