Re: new FFM_mul (and FlxqM_mul, FqM_mul, ...)

[Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>]

* Bill Allombert [2014-01-14 14:35]:
> On Tue, Jan 14, 2014 at 12:32:39PM +0100, Karim Belabas wrote:
> > * Bill Allombert [2014-01-14 11:48]:
> > > Do you know how to compute the square of a matrix faster than by using M*M ?
> > 
> > Obviously for matrices of size 1, we do :-)
> > 
> > For size 2 as well (2 squares + 4 multiply) :
> > 
> > (12:15) gp > [a,b;c,d]^2
> > %1 = 
> > [a^2 + c*b b*a + d*b]
> > 
> > [c*a + d*c c*b + d^2]
> > 
> > =
> > 
> > [a^2 + c*b b*(a + d)]
> > 
> > [c*(a + d) c*b + d^2]
> 
> This is only 2 squares and 3 multiply :)

Agreed. Call that a typo :-)

    K.B.
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite Bordeaux 1          Fax: (+33) (0)5 40 00 69 50
351, cours de la Liberation    http://www.math.u-bordeaux1.fr/~kbelabas/
F-33405 Talence (France)       http://pari.math.u-bordeaux1.fr/  [PARI/GP]
`