[Octave-bug-tracker] [bug #31730] chebwin() function gives wildly different results from matlab with low values of the 'at' parameter

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?31730>

                 Summary: chebwin() function gives wildly different results
from matlab with low values of the 'at' parameter
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Mon 22 Nov 2010 12:42:31 PM UTC
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Sidney Cadot
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.2.4
        Operating System: GNU/Linux

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Details:

In Octave:


octave:1> chebwin(10, 10.0)
ans =

   2.24051
   0.80130
   0.89683
   0.96473
   1.00000
   1.00000
   0.96473
   0.89683
   0.80130
   2.24051


Matlab:


>> chebwin(10, 10.0)

ans =

    1.0000
    0.3576
    0.4003
    0.4306
    0.4463
    0.4463
    0.4306
    0.4003
    0.3576
    1.0000


It is unclear to me which of these results is correct, I hope that someone
with more signal processing experience will be able to establish that.

The problem occurs mainly when the attenuation parameter is not too high. For
at >= 100, for example, the differences become negligible.




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