[Octave-bug-tracker] [bug #39314] The convn() function produces results that are different from Matlab.

[Alberto Andreotti]

URL:
  <http://savannah.gnu.org/bugs/?39314>

                 Summary: The convn() function produces results that are
different from Matlab.
                 Project: GNU Octave
            Submitted by: albertoandreotti
            Submitted on: Fri 21 Jun 2013 09:05:08 PM GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: AlbertoAndreotti
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: GNU/Linux

    _______________________________________________________

Details:

Hi,

the convn() function is returning results that are different from the ones
returned on Matlab. The error is small, but causes problems in some
applications.
To reproduce it, do,

>load octave_convn.m
>convn(zzz, hhh, 'valid')  - conv2d

zzz, hhh, are the input matrices, and conv2d the output of convn(zzz,hhh,
'valid') in Matlab. All this stuff comes in the file, and was generated in
Matlab. 
This, when run on Matlab, will return a matrix of zeros, and something like
this(error)when run in Octave,

  1.29912184192067e-005  1.28215490056687e-005  1.29375784844437e-005
  1.20384206842329e-005  1.60724929372802e-005  1.55126096841249e-005
  1.10716816072338e-005  1.79941888939234e-005  1.73947117905957e-005
  1.67516463603148e-005  2.38806994258701e-005  2.04159342070756e-005
  2.49735609200875e-005  2.98445469683259e-005  2.23170170254184e-005


the above response is of course truncated(two columns missing).
This represents the difference between Octave's computation and Matlabs.
Although the error is small, it is enough to prevent the convn() function to
be used in many applications. This was tested in Ubuntu and in Windows 7 with
the same results.





    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Fri 21 Jun 2013 09:05:08 PM GMT  Name: octave_convn.m  Size: 8kB   By:
albertoandreotti
the file was generated in Matlab.
<http://savannah.gnu.org/bugs/download.php?file_id=28380>

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?39314>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/