fft.py

#!/usr/bin/python
import numpy as np
#import scipy.fftpack
#import scipy as sp
import matplotlib.pyplot as plt
import math

import time

def howlong(f):
    def tmp(*args, **kwargs):
        t = time.time()
        res = f(*args, **kwargs)
        print "time: %f" % (time.time()-t)
        return res

    return tmp
    
arrlen = 1024

x = []
y = []
z = []
@howlong
def operate():
    global x, y, z
    x = np.linspace(0, arrlen-1, arrlen)
    #x = np.arange(0, 1024, dtype=np.float)
    y = np.sin(x*(2*np.pi/arrlen)*500) + np.sin(x*(2*np.pi/arrlen)*250)
    z = np.absolute(np.fft.fft(y, arrlen))
    #np.allclose()


operate()

plt.plot(x, z)
plt.xlabel(r'$x$')
plt.ylabel(r'$f(x)$')
#plt.grid(1)

plt.show()