[Octave-bug-tracker] [bug #39838] str2double ('') gives [](0x1) instead of NaN

[Philip Nienhuis]

URL:
  <http://savannah.gnu.org/bugs/?39838>

                 Summary: str2double ('') gives [](0x1) instead of NaN
                 Project: GNU Octave
            Submitted by: philipnienhuis
            Submitted on: Wed 21 Aug 2013 03:14:49 PM CEST
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Philip Nienhuis
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

According to the Octave docs, str2double(S) "...returns NaN for elements of S
which cannot be converted".

However, in Octave 3.7.5 (and I also saw this in Octave 3.4.3):

debug> str2double('')
ans = [](0x1)
debug> str2double([])
ans = [](0x0)
debug> str2double(' ')
ans = NaN
debug> str2double('a')
ans = NaN
debug> str2double({})
ans = [](0x0)
debug> str2double({''})
ans = NaN
debug> str2double({[]})
ans = NaN
debug>


...so str2double doesn't always behave as the docs say it does.
(Note I hit this while debugging Matlab scripts at work)

Matlab r2012a gives: (empty lines removed)

>> str2double('')
ans =
   NaN
>> str2double([])
ans =
   NaN
>> str2double(' ')
ans =
   NaN
>> str2double('a')
ans =
   NaN
>> str2double({})
ans =
     []
>> str2double({''})
ans =
   NaN
>> str2double({[]})
ans =
   NaN
>>


...so also Matlab sometimes gets confused, e.g., str2double({}) (Matlab docs
claim it should return NaN there, in wording similar to Octave)





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