Re: why two indexes in 1d cell array ? (octave-3.4.2) ... how about more dimensions ?

[Sergei Steshenko]

--- On Wed, 8/10/11, Ben Abbott <address@hidden> wrote:

> From: Ben Abbott <address@hidden>
> Subject: Re: why two indexes in 1d cell array ? (octave-3.4.2) ... how about 
> more dimensions ?
> To: "Sergei Steshenko" <address@hidden>
> Cc: address@hidden
> Date: Wednesday, August 10, 2011, 2:06 PM
> On Aug 10, 2011, at 3:18 PM, Sergei
> Steshenko wrote:
> 
> > c =
> > {
> >  [1,1] = a string
> >  [1,2] =
> > "
> > 
> > I see _two_ indexes, i.e. "[1,1]...", "[1,2]", though
> to me it looks like
> > created a _1d_ (just _one_ dimension) cell array;
> 
> Matlab originated from Fortran code. Thus, arrays were/are
> column-major.
> 
>     http://en.wikipedia.org/wiki/Row-major_order#Column-major_order
> 
> When the source code switched to C, Matlab maintained the
> default column-major storage order for arrays. This means
> that A = 1:5 produces a single row with 5 columns.
> 
> However, since C is row-major ...
> 
>     http://en.wikipedia.org/wiki/Row-major_order#Row-major_order
> 
> ... a 1D array requires two indices. The fist specifies the
> row [1], and the second the column.
> 
> For compatibility with Matlab, Octave adopted the same
> approach.
> 
> > Is this all expected and documented behavior ?
> 
> Yes this is expected and deliberate. If you search the
> manual. you'll find a few instances where the effect of
> "column-major" ordering is mentioned.
> 
> Ben
> 
> 

Let's again have a look at documentation:

http://www.gnu.org/software/octave/doc/interpreter/Basic-Usage-of-Cell-Arrays.html#Basic-Usage-of-Cell-Arrays
.

I am going to repeat actions described in the documentation:

1a) documentation:
c = {"a string", rand(2, 2)};

1b) me:
"
c = {"a string", rand(2, 2)}
c =
{
  [1,1] = a string
  [1,2] =

     0.64730   0.79055
     0.40904   0.54691

}
"
- 'octave' prints differently, but I didn't put ';' at the end of my input,
so IMO in this case 'octave' behaves as expected;


2a) documentation:
"
c{1:2}
          ⇒ ans =
     
               (,
                 [1] = a string
                 [2] =
     
                    0.593993   0.627732
                    0.377037   0.033643
     
               ,)
"
2b) me:
"
c{1:2}
ans = a string
ans =

   0.64730   0.79055
   0.40904   0.54691
".

In '2b)' _no_ indexes.

Why the discrepancy between actual behavior and the documentation ?

Thanks,
  Sergei.