Re: [boost] RFC: runtime-flexible arrays

Subject: Re: [boost] RFC: runtime-flexible arrays
From: Larry Evans (cppljevans_at_[hidden])
Date: 2012-02-16 07:40:08

On 02/16/12 01:17, Mathias Gaunard wrote:
> On 02/16/2012 02:42 AM, Bjoern Andres wrote:
>> Hi everyone,
>>
>> I have written a header for runtime-flexible multi-dimensional views and
>> arrays and would love to get comments and feedback from the boost
>> community:
>>
>> tutorial code        : http://tinyurl.com/7hdldc9
>> main website         : http://www.andres.sc/marray.html
>> doxygen reference doc: http://www.andres.sc/marray/doc/index.html
>> git repository       : https://github.com/bjoern-andres/marray
>> tech report          : http://arxiv.org/pdf/1008.2909v1
>>
[snip]
> Something else, what we do in NT2 is that we use an iliffe index as
> described in the NRC (Numerical Recipes for C) book. This allows us to
> make a view that extracts an arbitrary rectangle or hypercube and to add
> padding between lines without extra modulo operations.
How would NT2 do a transpose like the one on line 00201 of:

http://www.andres.sc/marray/doc/tutorial_8cxx_source.html

?  Judging from a brief look at:

  http://en.wikipedia.org/wiki/Array_data_structure

which suggests an iliffe data structure contains pointer
to subarrays, I'd guess that would be more difficult than
if a dope vector data structure, described on the same
web page, were used.  With a dope vector, a transpose
would just mean reversing the dope vector.  I'm guessing
marray using something like a dope vector. However,
with the iliffe data structure, I'd guess you'd have
to recalculate several pointers.  Right?

-regards,
Larry