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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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