Re: [eigen] [Review] Pull request 66, Huge Tensor module improvements

[Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>]

On 11.06.2014 19:53, Benoit Steiner wrote:
> I use std::array in order to encode ordered lists of dimensions. I am not
> convinced that using Eigen::Array instead is a good choice:
>   * Eigen Array is a 2d object. Users will always wonder if they need to
> order their coefficients in a row or a column.

Currently, at many places row vectors and column vectors are 
automatically converted to each other, so that should be possible here 
as well.

>   * The Array class lacks nice to have cxx11 features such as initialization
> lists. This is syntactic sugar, but if I can use a recent compiler I'd
> rather write:
>      Tensor<float, 3> T({1,2,3})
> than
>      Array<ptrdiff_t, 3, 1> dims;
>      coeffs << 1, 2, 3;
>      Tensor<float, 3> T(dims);

For that (simple) case it would just be
  Tensor<float, 3> T(Array3i(1,2,3));
That's with integers instead of ptrdiff, but so was your C++11 example. 
And it is currently limited to 4 dimensions.
I do agree that the C++11 syntax is nicer, and I would definitely not 
object supporting std::array if it is available -- my question was 
basically, if there is a need to partially re-implement std::array if it 
does not give additional features compared to Eigen::Array.

Christoph




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Dipl.-Inf., Dipl.-Math. Christoph Hertzberg
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