Untitled

a = 1
fig = plt.subplots(figsize =(15, 5)) 
T_tau = [2, 4, 16]
X = np.arange(-20, 20, dtype=np.int32)
Y_1 = np.array([a*T_tau[0]/((math.pi * n)**2)*(1-math.cos(math.pi*n/T_tau[0])) if n != 0 else a/(2*T_tau[0]) for n in X], dtype=float)
Y_2 = np.array([a*T_tau[1]/((math.pi * n)**2)*(1-math.cos(math.pi*n/T_tau[1])) if n != 0 else a/(2*T_tau[1]) for n in X], dtype=float)
Y_3 = np.array([a*T_tau[2]/((math.pi * n)**2)*(1-math.cos(math.pi*n/T_tau[2])) if n != 0 else a/(2*T_tau[2]) for n in X], dtype=float)
plt.vlines(X, ymin=0, ymax=Y_1, color='green', alpha=0.7, linewidth=8)
plt.vlines(X, ymin=0, ymax=Y_2, color='orange', alpha=0.7, linewidth=5)
plt.vlines(X, ymin=0, ymax=Y_3, color='red', alpha=0.7, linewidth=2)
plt.scatter(X, Y_1, color='green', s=40, label="τ = T/2")
plt.scatter(X, Y_2, color='orange', s=25, label="τ = T/4")
plt.scatter(X, Y_3, color='red', s=10, label="τ = T/16")
plt.grid()
plt.legend()