From: Francis Russell <francis@unchartedbackwaters.co.uk>
Date: Mon, 15 Apr 2013 17:57:01 +0000 (+0100)
Subject: Add script to compare NumPy's FFT and explicit DFT matrix.
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=1f96f6d40051ba56051302cee2c385120bb12920;p=francis%2Flta.git

Add script to compare NumPy's FFT and explicit DFT matrix.
---

diff --git a/misc/fourier.py b/misc/fourier.py
new file mode 100755
index 0000000..c13a9c0
--- /dev/null
+++ b/misc/fourier.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+
+from numpy import complex128, empty, e, pi
+from numpy.random import random
+from numpy.fft import fft
+from numpy.linalg import norm
+
+
+def constructDFT(size):
+    dft = empty([size, size], complex128)
+
+    for row in range(0, size):
+        for col in range(0, size):
+            dft[row, col] = e ** (- 2j * pi * row * col / size)
+
+    return dft
+
+
+size = 10
+signal = random(size) * 2 - 1
+dft = constructDFT(size)
+
+numpy_dft = fft(signal)
+explicit_dft = dft.dot(signal)
+
+print "Delta between DFTs: " + str(norm(numpy_dft - explicit_dft))