Hello,

I found a way how to correctly implement multidimensional functional map for ndslices and for packed ndslices (tensors composed of tensors). It allows
 1. a compiler to use vectorisation with SIMD instructions like `fabs` or `sqrt` for example. But first [1] should be merged
 2. to manage mapped ndslices as common ndslices.
In additional the future ndmap abstraction has zero computational cost.

The are 6 ndslice PRs, which should be merged first [1]. Please help to review and merge this. They does not contain any new API names, but optimizations and small API enhancements, which was delayed before because I wanted to get enough experience with ndslice first.

ndslice is in experimental and it is the most generic package in Phobos along with new regex. Regex has a lot CTFE-able magic, ndslice operates with abstract entities. Feel free to ask questions if you want to have more detailed imagination about implementation.

[1] https://github.com/dlang/phobos/pulls?q=is%3Aopen+is%3Apr+author%3A9il+label%3Andslice

Thank you and best regards,
Ilya

On Sunday, 24 July 2016 at 17:30:24 UTC, Ilya Yaroshenko wrote:
> Hello,
>
> I found a way how to correctly implement multidimensional functional map for ndslices and for packed ndslices (tensors composed of tensors). It allows
>  1. a compiler to use vectorisation with SIMD instructions like `fabs` or `sqrt` for example. But first [1] should be merged
>  2. to manage mapped ndslices as common ndslices.
> In additional the future ndmap abstraction has zero computational cost.
>


I'm a little confused. Why not just use slice.byElement.map!f?

Anyway, I hope this work is related to multi-dimensional folding, as mentioned here
https://github.com/libmir/mir/issues/209

On Monday, 25 July 2016 at 17:12:08 UTC, jmh530 wrote:
> On Sunday, 24 July 2016 at 17:30:24 UTC, Ilya Yaroshenko wrote:
>> Hello,
>>
>> I found a way how to correctly implement multidimensional functional map for ndslices and for packed ndslices (tensors composed of tensors). It allows
>>  1. a compiler to use vectorisation with SIMD instructions like `fabs` or `sqrt` for example. But first [1] should be merged
>>  2. to manage mapped ndslices as common ndslices.
>> In additional the future ndmap abstraction has zero computational cost.
>>
>
>
> I'm a little confused. Why not just use slice.byElement.map!f?
>
> Anyway, I hope this work is related to multi-dimensional folding, as mentioned here
> https://github.com/libmir/mir/issues/209

1. ndmap is N-Dimensional Slice composed of lazy elements. a user can use all nslice package to manage it.
2. byElement can not be vectorized
3. byElement adds few additional operations for each element, it is slower than direct index access.

Just opened PR for ndmap : https://github.com/dlang/phobos/pull/4652


[1] https://github.com/dlang/phobos/pull/4652