import numpy as np
import matplotlib.pyplot as plt
from scipy.fft import fft, ifft
from scipy import signal

t=np.arange(0,100,0.1)
x= np.cos(2*np.pi*t)
y= fft(x)


p= np.linspace(0,1000,1,endpoint=True)
u = signal.square( np.pi*5*p)
e = np.fft.fft(u)
plt.plot(p,e)