Mir Blog: Writing efficient numerical code in D

[Andrei Alexandrescu via Digitalmars-d-announce]

On 12/12/16 4:58 PM, Relja Ljubobratovic wrote:
> Hey guys,
>
> We have just published another post on "Writing efficient numerical code
> in D", to Mir's Blog[1]. In this post we are focusing on
> mir.ndslice.algorithm usage in DCV[2], computer vision library that has
> recently joined libmir organization. We've had great success in
> optimizing DCV's algorithms mostly by replacing loop-style code with
> mir.ndslice.algorithm multidimensional iteration utilities[3], and we
> thought it was worth blogging about.
>
> Any grammar (or any other type of) fix report is greatly appreciated!
>
> Also, we'd like to ask Mike Parker to forward this to reddit if it's not
> too much trouble? :) Maybe only wait few days so we could weed out some
> mistakes from the text.
>
> Cheers,
> Relja
>
> [1]
> http://blog.mir.dlang.io/ndslice/algorithm/optimization/2016/12/12/writing-efficient-numerical-code.html
>
> [2] https://github.com/libmir/dcv
> [3] https://github.com/libmir/dcv/pull/58

This is awesome! Mike, could you please post to reddit about 11 hours 
from now if possible.

I'm about to fall asleep, but I made a quick pass through the piece. 
Here are a few nits:

* "In this post I’d like give" -> "This post gives"

* "module equipped with" -> "module that provides"

* "it’s usage" -> "its usage"

* "Note: It is assumed the reader is already somewhat familiar with 
ndslice package [1]." -> "This article assumes the reader has a cursory 
understanding of the ndslice package. If not, please consult this 
post/doc/webpage/etc before returning here."

* "What does it offer?" -> "What does mir.ndslice.algorithm offer?"

* "its integrated seamlessly" -> "it is integrated seamlessly"

* "by that allowing more natural flow of processing pipeline" -> "which 
makes for elegantly flowing processing pipelines"

* "One of key components to make code based" -> "One key component that 
makes code based"

* "LLVM based D compiler" -> "the LLVM based D compiler"

* "kernels you write" -> "computation kernels written by the end user"

* "else turned on" -> "turned on"

* ", by Johan Engelen" -> remove the comma

* "we’ve been actively refactoring" -> define the team; so far the 
article referred to the author as a single person

* "with mir.ndslice.algorithm equivalent" -> "with mir.ndslice.algorithm 
equivalents"

* align numbers in html tables to the right

* "As you can see, speedups" -> "Speedups"

* "as I’ll show you in this post" -> "as shown below"

* "take a look at PR" -> "take a look at the pull request"

* "Discalmer" -> "Disclaimer"

* "mind DCV project" -> "mind the DCV project"

* "showing power" -> "showing the power"

* "dive into implementation" -> "dive into the implementation"

* "without extensive optimization techniques applied" -> "without 
extensive optimizations"

* "In future we’ll focus" -> "A future post will focus"

* "first we’ll take a look" -> "first let's take a look"

* "basic principle how it can efficiently replace loop-based code" -> 
"basic principle of replacing loop-based code with pipelines efficiently"

* "… This code" -> "This code"

* "apply given kernel" -> "apply the given kernel"

* "To bring this example more down to earth" -> "To make the example 
more concrete"

* "As you can see, we are replacing" -> "The pipeline version replaces"

* "with few magic calls" -> "with a few magic calls"

* "And as you may have noticed, at" -> "At"

* "I get ~10x speedup" -> there's been a bunch of "we" and now getting 
back to "I" is surprising. You may want to make a pass making sure the 
use of person is consistent.

* "that variant written" -> "that the variant written"

* "syntax, and are" -> "syntax and are"

* "this is most basic binarization" -> "this is a most basic binarization"

* "Special part to care about, related to lockstep, is that byElement 
call on each input Slice" -> "The call to byElement inside lockstep is 
worth special attention"

* "We can notice right away there’s a change" -> "First off, there's a 
change"

* "requires this so" -> "assumes that is the case"

* "We can also notice byElement" -> "Notably, byElement"

* "examine performance differences" -> "compare the impact of these 
changes on performance"

* "On my machine" -> "On a Core i7 laptop with xyz GB or RAM and xyz 
other relevant parameters..."

* "result is following" -> "the results are as follows"

* "with very little effort using" -> "with very little effort by using"

* "and it’s submodules" -> "and its submodules"

* "coming for some numerical computing" -> "having an interest in 
numerical computing"

* "would have to be introduced to ndslice" -> "should take a close look 
at ndslice"

I suggest making two passes through the piece: (a) one pass should 
reduce fillers that are abundant ("as you can see", "as I'll show you", 
"as said in the docs"...) A few are fine (perhaps 2-3 in the whole 
article. Then (b) one pass looking for unified use of "I" (most likely: 
the author, use sparingly), "you" (the reader, use sparingly), and "we" 
(most likely: the author and reader looking together at something).

The results are terrific, congrats Ilya and Relja!


Andrei