On Tue, Oct 1, 2013 at 9:17 AM, anonymous <address@hidden> wrote:
Please use the bug tracker to post updates to a bug report. The mailing list is intended as a read-only notification stream. Info posted to this mailing list address won't appear in the tracker database where it is most useful.
URL:
<http://savannah.gnu.org/bugs/?40155>
Summary: Octave does not produce same results as Matlab for
iir scripts
Project: GNU Octave
Submitted by: None
Submitted on: Tue 01 Oct 2013 01:17:39 PM UTC
Category: Octave Forge Package
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Matlab Compatibility
Status: None
Assigned to: None
Originator Name: Mike Fontes
Originator Email: address@hidden
Open/Closed: Open
Discussion Lock: Any
Release: 3.6.4
Operating System: Microsoft Windows
_______________________________________________________
Details:
I am using the eziir32.m script designed by TI to create iir filter
coefficients for use with the TI libraries. They were designed to run under
Matlab, but they also run under Octave, using the signals package. There are
two problems I have noticed:
1. Some runs of the script cause errors in the Octave environment and produce
valid results in the Matlab environment.
2. Some runs of the script produce valid, but very different results in the
two environments.
My big issue is with choice number 2 because the results are very different,
and are causing representation and overflow issues in the code written using
the libraries. I have attached a file which contains the results of a Matlab
and an Octave run for the same script inputs. The Matlab run normalizes the
filter gain to 1 and scales the coefficients accordingly. The Octave run
gives me a gain of over 1100 and totally different coefficients.
I need to get the normalized output to keep the filter representation from
losing accuracy due to rounding. A few questions come to mind:
1. What is different between the two packages that cause the large differences
in the results created?
2. Are there steps that can be taken to normalize the Octave output and supply
a set of coefficients similar to those from Matlab?
3. Is the signal package compatible with Matlab, or similar to Matlab when
using the functions in the script.
Can someone please contact me to discuss this. I do not have Matlab and I am
relying on Octave to provide me with the coefficients for my filters. I need
to know how to successfully get workable values in a normalized form.
Sincerely,
Mike Fontes
address@hidden
Without trying the software and using filter theory, all you would have to do is divide all numerator coefficients by 1100
_______________________________________________________
File Attachments:
-------------------------------------------------------
Date: Tue 01 Oct 2013 01:17:39 PM UTC Name: eziir32.m Size: 7kB By: None
<http://savannah.gnu.org/bugs/download.php?file_id=29279>
-------------------------------------------------------
Date: Tue 01 Oct 2013 01:17:39 PM UTC Name: Octave and Matlab output and
files for IIR.doc Size: 306kB By: None
<http://savannah.gnu.org/bugs/download.php?file_id=29280>
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?40155>
_______________________________________________
Message sent via/by Savannah
http://savannah.gnu.org/