ndslice, using a slice in place of T[] in template parameters

[Ilya Yaroshenko via Digitalmars-d-learn]

On Monday, 11 January 2016 at 00:39:04 UTC, Jay Norwood wrote:
> On Sunday, 10 January 2016 at 23:31:47 UTC, Ilya Yaroshenko 
> wrote:
>> Just use normal arrays for buffer (median accepts array on 
>> second argument for optimisation reasons).
>
> ok, I think I see. I created a slice(numTasks, bigd) over an 
> allocated double[] dbuf, but slb[task] will be returning some 
> struct instead of the double[] that i need in this case.
>
> If I add .array to the Slice, it does compile, and executes, 
> but slower than using the buffer directly.
>
> medians[i] = median(vec, slb[task].array);
> parallel time medians msec:113
>
> original version using the computed slice of the original 
> allocated dbuf.
> medians[i] = median(vec,dbuf[j .. k]);
> parallel time medians msec:85
>
> The .array appears to make a copy. Is there some other call in 
> ndslice to return the double[] slice of the original array?

I will add such function. But it is not safe to do so (Slice can 
have strides not equal to 1). So it is like a hack (&ret[0, 0, 
0])[0 .. ret.elementsCount]).

Have you made comparison between my and yours parallel versions?
https://github.com/9il/examples/blob/parallel/image_processing/median-filter/source/app.d
-- Ilya