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Re: sum() behaving erratically?

From: Francesco Potorti`
Subject: Re: sum() behaving erratically?
Date: Thu, 7 Oct 2004 03:10:33 -0500

>> If I let a=[1,2;3,4]; and then ask for sum(a), sum(a,1) and sum(a,2), I
>> get the answers
>> 4 6     4 6     3
>>                 7
>> respectively. Now I let a=[1,2]; and do the same. I now get
>> 3       1 2     3
>> indicating that in the second case sum(a) != sum(a,1), in direct
>> violation of the documentation in the manual. Is this supposed to be
>> like this and didn't I understand things, or is it a bug? (Octave is
>> 2.1.57.)

>This is a case of bug-for-bug compatibility.

In fact, it is a bug in the manual and the help.  Here is a patch:

  -- Built-in Function:  sum (X, DIM)
      Sum of elements along dimension DIM.  If DIM is omitted, it
!     defaults to 1 (column-wise sum).
!     defaults to 1 (column-wise sum) unless the argument is a
+     vector, in which case the sum of elements is returned.

Or, one could specify "unless the argument is a row vector".

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