Boost logo

Ublas :

From: Gunter Winkler (guwi17_at_[hidden])
Date: 2008-05-28 17:03:18

Hongzheng Wang schrieb:
> Hi,
> I have some questions. Since they may not be related each other, such
> a title is used. I'm sorry for its oversimplification.
> First, is there some circular shift operation been defined for
> uBLAS::vector (even matrix)?
This operation is not implemented. An efficient implementation would be
to create a new vector_proxy (similar to vector_range and vector_slice)
that does the index calculation.
> Secondly, what's the purpose of the compose function of basic_range
> and basic_slice? Is it just an internally used helper method, or
> something which the users could reliably use?
When you create a range from a range then the resulting type should
simply be a range and not a range_of_range. Thus ranges have to be
"composed". (like the function f(g(x)) is the composition of f and g)

> Thirdly, is there any easy and efficient way to construct
> vector/matrix from other data object, e.g. C array, tr1::array,
> valarray or something else? I think there would be one, but I cannot
> find it yet. I googled array_adaptor, shallow_array_adaptor, and they
> are probably the answer, but I'm not sure.
These adaptors are the answer, however the code is still experimental.
This means the documentation is very sparse and the use can lead to
unexpected surprises.

maybe this thread helps: