Gunter,
 I implemented both your thinking (to my understanding) and mine. I think that yours reflects the symmetry of indexing (i.e. a row by row banded matrix is stored row by row, while a column-by column is stored column by column) while my original thinking doesn't  (i.e. a column by column  banded matrix as per netlib is either stored in a  row-major or a column-major container (as per the template argument).

I got both implementations running but I think I prefer your idea after all. I will apply the patch after the transition to github is complete.

-Nasos

Gunter,
I am working on this bug, but based on the test case I am wondering why should the expected row-major data layout be:

0, 0, 11, 12, 0, 21, 22, 23, 31, 32, 33, 34, 42, 43, 44, 45, 53, 54, 55, 0 

And not

0, 12, 23, 34, 45, 11, 22, 33, 44, 55, 21, 32, 43, 54, 0, 31, 42, 53, 0, 0 ?

For the moment I got the column-major implementation working as expected, but I need to add some more tests cases to make sure it is working for non-square matrices as well.

Regards,

-Nasos



On 10/21/2012 04:57 PM, Gunter Winkler wrote:
Hello,

Am Monday 15 October 2012 schrieb Rutger ter Borg:

On 2012-10-15 18:09, Gunter Winkler wrote:

Could you please provide a simple test program which checks the
storage format? Then we (or maybe you) can create a new ticket.

mfg
Gunter

thanks for the response. I've attached a test program, its output is
shown below. I haven't created a ticket yet, because I would like to
make sure the test is correct first. I double-checked the 'expected
data()' values, to me they seem to be correct.

I agree, the mapping from (i,j) to storage location is weird. I created 
an issue: https://svn.boost.org/trac/boost/ticket/7549

Now we only need a volunteer to fix it ...

mfg
Gunter




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