A flash question, I'm looking at the following code
from __future__ import division
import math
import time
def dft(x, inverse = False, verbose = False) :
t = time.clock()
N = len(x)
inv = -1 if not inverse else 1
X =[0] * N
for k in xrange(N) :
for n in xrange(N) :
X[k] += x[n] * math.e**(inv * 2j * math.pi * k * n / N)
if inverse :
X[k] /= N
t = time.clock() - t
if verbose :
print "Computed","an inverse" if inverse else "a","DFT of size",N,
print "in",t,"sec."
return X
and I'm wondering (I do not know python):
- what does the X =[0] * N line do?
- why the double asterisk ** ?