import numpy as np
import matplotlib.pyplot as plt

def CA(Mach):
    return np.where(Mach > 1.0, 0.02 + 0.03/Mach,
           np.where(Mach > 0.5, 0.02*(Mach-0.5) + 0.04, 0.04))


def main():
    Mach = np.linspace(0,5,100)
    plt.plot(Mach, CA(Mach))
    plt.xlabel("Mach number")
    plt.ylabel("CA")
    plt.savefig("axial_drag.png")
    plt.show()



if __name__ == "__main__":
    main()