Re: [eigen] matrix::linspace

[Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>]

Ok, I am done. I have the whole patch ready for review. Since I have
no idea what else to do for reviewing larger commits, I am posting
here.

The main new functionality offered is

  DenseBase::setLinSpace(Scalar l,Scalar h,int s)

which computes for each vector index

  a(i) = l + i*(h-l)/(s-1)

Now to the changes this involves.

a) I added a new packet op ei_plset(Scalar a). It creates packages [a,
a+1, ..., a+packet_size]. The nice part as opposed to ei_pset(...) is
that for all types (float, double, int) there is only a single
argument and not a varying number of arguments. This also allows to
offer a GenericPacketMath implementation where this operator acts as
identity.

b) I added new constraints for functors that are meant to be used with
CwiseNullaryOp. They are now required to offer a vector indexing
operator()(int). For minimal invasive modifications, I simply changed
existing ones by defining operator()(int,int) as operator()(int,int =
0) - where it was appropriate. That was already partially done.

c) As discussed, ei_linspace_op_impl has two specializations one for
random access and one for sequential or linear access. The vectorized
sequential versions are much faster than non-vectorized ones and the
random access versions seem to perform equally fast and faster (at
least not worse).

d) I introduced a new proxy ojbect ei_unaligned_assign_impl. It
performs a simple loop assignment when required and it does not
inline. Preventing the inlining was crucial in order to allow MSVC to
perform proper optimization of packet ops. Maybe this should be
guarded by a pre-processor define and activated only for MSVC.

If I am not wrong, this is all. Any comments, or am I good to synch?

- Hauke

Attachment: linspace.patch
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