[Octave-bug-tracker] [bug #30905] Var sample size normalisation default incorrect

[Nicholas Holmes]

URL:
  <http://savannah.gnu.org/bugs/?30905>

                 Summary: Var sample size normalisation default incorrect
                 Project: GNU Octave
            Submitted by: npholmes
            Submitted on: Mon Aug 30 10:21:17 2010
                Category: None
                Severity: 3 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Nicholas Holmes
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.2.3
        Operating System: GNU/Linux

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Details:

the function var should default to var(x,0) (normalising by N-1) when the
second argument is missing, but it seems to default to var(x,1) (normalising
by N), opposite to Matlab and the Octave help text, and opposite to the std
function.

Thus,
x=1:10;

var(x)  = 8.25
var(x,0)= 9.167
var(x,1)= 8.25

whereas:

std(x)  = 3.0277
std(x,0)= 3.0277
std(x,1)= 2.8723

I'm using QtOctave & Octave 3.2.3-1 in Ubuntu 10.04 LTS

cheers,
nick




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