From 75b86e12526899cda4e901db9fb951e57d118b6e Mon Sep 17 00:00:00 2001
From: Travis Oliphant <oliphant@enthought.com>
Date: Thu, 28 Feb 2008 16:07:59 +0000
Subject: Try to speed up fftfreq a bit.

---
 numpy/fft/helper.py | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/numpy/fft/helper.py b/numpy/fft/helper.py
index 17a4a24dc..74f4e363b 100644
--- a/numpy/fft/helper.py
+++ b/numpy/fft/helper.py
@@ -6,8 +6,7 @@ Discrete Fourier Transforms - helper.py
 __all__ = ['fftshift','ifftshift','fftfreq']
 
 from numpy.core import asarray, concatenate, arange, take, \
-    integer
-from numpy import hstack
+    integer, empty
 import types
 
 def fftshift(x,axes=None):
@@ -63,4 +62,12 @@ def fftfreq(n,d=1.0):
       f = [0,1,...,(n-1)/2,-(n-1)/2,...,-1]/(d*n)   if n is odd
     """
     assert isinstance(n,types.IntType) or isinstance(n, integer)
-    return hstack((arange(0,(n-1)/2 + 1), arange(-(n/2),0))) / (n*d)
+    val = 1.0/(n*d)
+    results = empty(n, int)
+    N = (n-1)//2 + 1
+    p1 = arange(0,N,dtype=int)
+    results[:N] = p1
+    p2 = arange(-(n//2),0,dtype=int)
+    results[N:] = p2
+    return results * val
+    #return hstack((arange(0,(n-1)/2 + 1), arange(-(n/2),0))) / (n*d)
-- 
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