[Insight-developers] Octree representation

[Luis Ibanez]

Hi Mark,

There is an historic reason.

Originally in VNL, the vnl_fixed_vector derived from vnl_vector.
So, it was fixed size but had the overhead of an integer for counting
components and a pointer to the memory allocated for the components.
This extra 8 bytes were undesirable in classes deriving from the
FixedArray like the itk::Point, itk::Vector,itk::CovariantVector and
the itk::RGBPixel.

The most recent version of VNL (in ITK) does not have this overhead.
vnl_vector_fixed do not derive from vnl_vector anymore. So, in principle
now we could derive from it.   However, I don't see any advantage in
doing so, now that the Fixed array is fully implemented in ITK style.


Luis



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Mark Foskey wrote:
> 
> Incidentally, is there a reason we wrap vnl_vector for our Array type, 
> but don't wrap vnl_vector_fixed for our FixedArray type?
>