The Wavelet Digest Homepage
Return to the homepage
Search the complete Wavelet Digest database
Help about the Wavelet Digest mailing list
About the Wavelet Digest
The Digest The Community
 Latest Issue  Back Issues  Events  Gallery
The Wavelet Digest
   -> Volume 7, Issue 5

Answer: Error in Matlab manual (WD 7.4 #26)
images/spacer.gifimages/spacer.gif Reply into Digest
Previous :: Next  
Author Message
Paul Costa (

PostPosted: Tue Apr 21, 1998 8:37 pm    
Subject: Answer: Error in Matlab manual (WD 7.4 #26)
Reply with quote

#25 Answer: Error in Matlab manual (WD 7.4 #26)

Hello Wavelet Digest authors,

My name is Paul Costa and I work for The MathWorks. I would like to
answer a question which was posed in the Wavelet Digest, Vol. 07, Nr. 04.

Here is the question:

> Date: Sun, 12 Apr 1998 15:24:03 PKT
> From: "Awais M. Hussain" <>
> Subject: #26 Question: Error in Matlab wavelet toolbox manual?
> Question:
> The MATLAB wavelet toolbox manual on p.6-13 (1996) defines the DWT
> of a signal s(n) as:
> C(j,k) = sum_{n in Z} s(n) g_{j,k} (n)
> with
> g_{j,k}(n) = 2^{-j/2} g( 2^{-j} n - k)
> where g(n) is the wavelet filter's impulse response (discrete-
> time). Thus g_{j,k} are the dilations of the discrete filter?
> This does not appear to be the correct representation of the DWT. Can
> someone explain?
> Awais

Here is the Answer:

There is a typographical error on page 6-13 of the Wavelet Toolbox
User's Guide (March 1996). This error was also present in the MATLAB
5.0 version of this User's Guide (1997) on page 6-14.

The correct equation for g_{j,k}(n) should read:

g_{j,k}(n) = 2^{j/2} g( 2^{j} n - k)

Paul Costa
The MathWorks, Inc.
All times are GMT + 1 Hour
Page 1 of 1

Jump to: 

disclaimer -
Powered by phpBB

This page was created in 0.023725 seconds : 18 queries executed : GZIP compression disabled