import numpy as np
import scipy as sp
import matplotlib.pyplot as plt


def u(n):
    return np.heaviside(n, 1)


def ideal_lowpass(omega, omega_c):
    return np.where(np.abs(omega) <= omega_c, 1, 0)


def main():
    omega_c = 0.4*np.pi
    omega = np.arange(0, np.pi, 0.05*np.pi)

    h_lpf = ideal_lowpass(omega, omega_c)

    plt.plot(omega, h_lpf)
    plt.show()


if __name__ == "__main__":
    main()