Re: [vhdl-200x] Please Review Matrix Math Package

On 06/26/2014 10:09 PM, tgingold@free.fr wrote:
> Hello,
>
> I am slightly confused by the representation.  In the ug:
>
> As a concession to C, all matrices are assumed to be in column, row format, and starting at index “0”. Thus for the matrix:
> Z := ((1.0, 2.0, 3.0),
>        (4.0, 5.0, 6.0),
>        (7.0, 8.0, 9.0));
> Z (0,2) = 7.0
>
>
> I suppose we all agree that Z should be:
> [ 1 2 3
>    4 5 6
>    7 8 9 ]
>
> So the first dimension is the number of lines and the second dimension is the number of columns.
> This is natural both from a point of view of the VHDL language and from classical math style.
>
> But in that case and following the above excerpt, Z (0, 2) is 3.0 !
>
> BTW, I am not sure that starting at index "0" is the best choice.  This is
> neither the matlab conversion (which is heavily used) nor the math choice.
When I create a matrix, I do it as:
   type real_matrix is array (NATURAL range <>, NATURAL range <>) of 
REAL;  -- real matrix
Which follows from:
   type real_vector is array (NATURAL range <>) of REAL;
Which is part of VHDL-2008.

So what you really have is array of arrays.   In order to load the 
array, I have to do:

Z := ((1.0, 2.0, 3.0),
       (4.0, 5.0, 6.0),
       (7.0, 8.0, 9.0));

which reversed rows and columns as it loads.....


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