[Octave-bug-tracker] [bug #42062] normrnd returns NaN for sigma=0

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?42062>

                 Summary: normrnd returns NaN for sigma=0
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Sun 06 Apr 2014 11:09:25 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Matt
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: Microsoft Windows

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Details:

Can reproduce by using command:


octave:1> normrnd(1,0)
ans = NaN


normrnd should return mu when sigma=0, not NaN

Output expected:

ans = 1


This is inconsistent with the definition of the normal distribution, and also
inconsistent with Matlab's results.

I think the problem is in the normrnd.m file when testing whether sigma has a
valid value. It does not include 0, only >0.

Specifically the parts of the code below

if (!isnan (mu) && !isinf (mu) && (sigma > 0) && (sigma < Inf))
should be 
if (!isnan (mu) && !isinf (mu) && !(sigma < 0) && (sigma < Inf))


and


k = isnan (mu) | isinf (mu) | !(sigma > 0) | !(sigma < Inf);
 should be
k = isnan (mu) | isinf (mu) | (sigma < 0) | !(sigma < Inf);






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