From: Olaf on
Hello,

I'm trying to solve the diophantine equation using the sylvester matrix.
On matlab's homepage I found a m-script sylvester.m

The core of this is:

function M = sylvester(P,Q)
....
NP = numel(P) ;
NQ = numel(Q) ;
....
MP = toeplitz([P(:) ; zeros(NQ-1,1)],zeros(NQ,1)) ;
MQ = toeplitz([Q(:) ; zeros(NP-1,1)],zeros(NP,1)) ;
M = [MP MQ].' ;

Well, the sylvester matrix shouldn't be square? which isn't here (from
doc of this):

P = [1 2 3 4] ; Q = [6 7] ;
size( sylvester(P,Q) )

ans =
6 5

What's wrong here? Do I miss something here?

Thanks,
Olaf
From: Roger Stafford on
Olaf <noreplay(a)inder.net> wrote in message <hphiqo$53c$1(a)fuerst.cs.uni-magdeburg.de>...
> Hello,
>
> I'm trying to solve the diophantine equation using the sylvester matrix.
> On matlab's homepage I found a m-script sylvester.m
>
> The core of this is:
>
> function M = sylvester(P,Q)
> ...
> NP = numel(P) ;
> NQ = numel(Q) ;
> ...
> MP = toeplitz([P(:) ; zeros(NQ-1,1)],zeros(NQ,1)) ;
> MQ = toeplitz([Q(:) ; zeros(NP-1,1)],zeros(NP,1)) ;
> M = [MP MQ].' ;
>
> Well, the sylvester matrix shouldn't be square? which isn't here (from
> doc of this):
>
> P = [1 2 3 4] ; Q = [6 7] ;
> size( sylvester(P,Q) )
>
> ans =
> 6 5
>
> What's wrong here? Do I miss something here?
>
> Thanks,
> Olaf
----------
There are apparently two differing notions of a "sylvester matrix". The version mentioned in wikipedia:

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

which is associated with two polynomials is indeed square. However elsewhere on the internet I see references to sylvester matrices in conjunction with diophantine equations which are definitely not square, as for example at:

http://homepages.laas.fr/henrion/Papers/6-43-13-16.pdf

and

http://www2.imm.dtu.dk/pubdb/views/edoc_download.php/3646/pdf/imm3646.pdf

Roger Stafford