Re: senseless warning in octave-3.6.2

[Nicholas Jankowski]

On Tue, Jul 3, 2012 at 11:14 AM, Sergei Steshenko <address@hidden> wrote:
>
>
>
>
> ----- Original Message -----
>> From: c. <address@hidden>
>> To: Sergei Steshenko <address@hidden>
>> Cc: Jordi Gutiérrez Hermoso <address@hidden>; Octave users list 
>> <address@hidden>
>> Sent: Tuesday, July 3, 2012 12:26 AM
>> Subject: Re: senseless warning in octave-3.6.2
>>
>>
>> Il giorno 02/lug/2012, alle ore 01.53, Sergei Steshenko ha scritto:
>>
>>>  As wrote much much earlier, essentially column vector vs row vector is a
>> nuisance - one type of vector would suffice.
>> In a sense, Octave, as Matlab, does not have either row or column vectors, 
>> nor
>> it has scalars, it just uses 2-index matrices for all those types.
>> You might consider this a very exotic and probably annoying (and maybe even
>> stupid) design choice, and I might even, partly, agree.
>> But it is at the very root of the design of the Matlab language, so it 
>> cannot be
>> abandoned.
>> The best option, if you cannot live with the way data-types are used in
>> Octave/Matlab, is to switch to a different language.
>>
>> c.
>
> <<<You might consider this a very exotic and probably annoying (and maybe 
> even stupid) design choice, and I might even, partly, agree. But it is at the 
> very root of the design of the Matlab language, so it cannot be abandoned>>>
>
> Huh ?!!!!!!!!!
>
> Here is a simple Octave session:
>
> "
> octave:1> N=100
> N =  100
> octave:2> row_sin = sin(2 * pi * (0:N-1)/10);
> octave:3> size(row_sin)
> ans =
>
>      1   100
>
> octave:4> col_sin = row_sin';
> octave:5> size(col_sin)
> ans =
>
>    100     1
>
> octave:6> plot((0:N-1)', row_sin, 0:N-1, col_sin);
> octave:7>
> ".
>
> As everybody can see, the behavior does _not_ _at_ _all_ depend on the fact 
> whether an entity is a row or a column vector.
>
> So, vector differentiation depending on row/column property can _definitely_ 
> be abandoned - as the above example shows.
>
> Instead Octave developers in their "infinite wisdom" introduce outlandish
>
> row_vec OP col_vec -> matrix
>
> behavior and even make it default. Instead of, say, fixing (by first properly 
> defining functionality) 'pkg.m'. Strangely enough, in VLSI design my 
> mentoring managers taught me that first bugs are fixed, and then new features 
> are introduced.
>
> In this case a whole layer of new bugs has been introduced.
>
> --Sergei.
> _______________________________________________
> Help-octave mailing list
> address@hidden
> https://mailman.cae.wisc.edu/listinfo/help-octave

jumping into the deep  without a real appreciation for 'broadcasting',
but it seems that basic matrix math cares whether something is a row
or column matrix

octave:1> a = 1:4
a =

   1   2   3   4

octave:2> b = a
b =

   1   2   3   4

octave:3> a*b
error: operator *: nonconformant arguments (op1 is 1x4, op2 is 1x4)
octave:3> b*a
error: operator *: nonconformant arguments (op1 is 1x4, op2 is 1x4)
octave:3> a'*b'
error: operator *: nonconformant arguments (op1 is 4x1, op2 is 4x1)
octave:4> a'*b
ans =

    1    2    3    4
    2    4    6    8
    3    6    9   12
    4    8   12   16

octave:5> a*b'
ans =  30

as the last two cases show, basic rules of matrix multiplication
(forget what Matlab wanted) and linear algebra specify the inner and
outer product multiplications and being equivalent to vector products
that either produce a scalar (dot product) or tensor.  In Matlab,
(_matrix_ laboratory) everything is a matrix, and it's easier to
represent vectors and tensors using the same 2d construct, especially
when that construct preserves necessary 'orientation' information.
Sure it can be referenced using single indices as it is stored in
memory, (a convenience rather than a necessity), and Octave maintained
that behavior, but it never throws away orientation information.

While certain functions (like the sine function) shouldn't care if
you're using a row or column vector, Please don't abandon basic matrix
algebra.

http://en.wikipedia.org/wiki/Tensor_product