Changeset 1513

Timestamp:

09/29/08 09:10:26 (2 months ago)

Author:

cdavid

Message:

Add docstring for dctii.

Files:

• trunk/talkbox/scikits/talkbox/transforms/dct.py (modified) (1 diff)

trunk/talkbox/scikits/talkbox/transforms/dct.py

@@ -48 +48 @@
-
-def dctii(x):
+    """Compute a Discrete Cosine Transform, type II.
+
+    The DCT type II is defined as:
+
+        \forall u \in 0...N-1, 
+        dct(u) = a(u) sum_{i=0}^{N-1}{f(i)cos((i + 0.5)\pi u}
+
+    Where a(0) = sqrt(1/(4N)), a(u) = sqrt(1/(2N)) for u > 0
+
+    Parameters
+    ==========
+    x : array-like
+        input signal
+
+    Returns
+    =======
+    y : array-like
+        DCT-II
+    """
-    n = x.size
-    y = np.zeros(n * 4, x.dtype)