resize

[David Bateman]

Francesco Potorti` wrote:
> What does the resize function do?
>
> Its help string makes one think that it does the same as reshape, only
> in place:
>  -- Built-in Function:  resize (X, M, N)
>      Destructively resize X.
>
>      *Values in X are not preserved as they are with `reshape'.*
>
>      If only M is supplied and it is a scalar, the dimension of the
>      result is M-by-M.  If M is a vector, then the dimensions of the
>      result are given by the elements of M.  If both M and N are
>      scalars, then the dimensions of the result are M-by-N.
>
>      See also: reshape.
>
> However, it does not do that:
>
> octave> resize((1:3*4)',[3 4])
> ans =
>
>    1   0   0   0
>    2   0   0   0
>    3   0   0   0
>
> Is it a sort of truncation?
>
>   
It seems to do what it says it does to me.. That is in your example it 
takes a 12x1 matrix and converts it to a 3x4 matrix keeping the 
overlapping parts of the matrix assuming that the [0,0] index is the same.

The original reason this function was created was that some user types 
might have additional attributes associated with them and so a 
zeros(m,n) couldn't be used in many functions, but a
resize(resize (x, 0, 0), m, n) could and keep the attributes of x. An 
example is the primitive polynomial of a galois field user type.

Regards
David

-- 
David Bateman                                David.Bateman at motorola.com
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
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