On Jan 4, 12:50 pm, "Ondrej Certik" <[EMAIL PROTECTED]> wrote:
> On Jan 4, 2008 10:01 AM, William Stein <[EMAIL PROTECTED]> wrote:
Hi,
> > On Jan 3, 2008 12:13 PM, Ondrej Certik <[EMAIL PROTECTED]> wrote:
>
> > > Hi,
>
> > > I posted my thoughts on the curent status and the future of Sage.calculus
> > > here:
>
> > >http://planet.sagemath.org/
>
> > > direct link is:
>
> > >http://ondrejcertik.blogspot.com/2008/01/sympysympycore-pure-python-u...
>
> > > If you have some thoughts on that, let's discuss it. Unfortunately, I
> > > am very busy at school,
> > > so I myself cannot help a lot, but my hope is that there could be some
> > > google summer of
> > > code projects for improving Sage.calculus.
>
> > Definitely.
>
> > By the way, in your blog post you have this example:
>
> > "
> > sympycore:
> > >>> from sympy import *
> > >>> x,y,z=map(Symbol,'xyz')
> > >>> xx=((x+y+z)**20).expand()
> > >>> yy=((x+y+z)**21).expand()
> > >>> %time e=(xx*yy).expand()
> > CPU times: user 2.21 s, sys: 0.10 s, total: 2.32 s
> > Wall time: 2.31
> > swiginac:
> > >>> xx=((x+y+z)**20).expand()
> > >>> yy=((x+y+z)**21).expand()
> > >>> %time e=(xx*yy).expand()
> > CPU times: user 0.30 s, sys: 0.00 s, total: 0.30 s
> > Wall time: 0.30
> > maxima:
> > (%i44) xx:expand((x+y+z)^20)$
> > (%i45) yy:expand((x+y+z)^21)$
> > (%i46) t0:elapsed_real_time ()$ expand (xx*yy)$ elapsed_real_time ()-t0;
> > (%o48) 0.57999999999993
> > "
>
> > Sage can do the benchmark above muh faster than all the other
> > systems you've time, including swiginac:
>
> > sage: R.<x,y,z> = QQ[]
> > sage: xx = (x+y+z)^20; yy = (x+y+z)^21
> > sage: time e=xx*yy
> > CPU times: user 0.03 s, sys: 0.00 s, total: 0.03 s
> > Wall time: 0.03
>
> > Note that expanding automatically happens for arithmetic in
> > multivariate polynomial
> > rings in Sage. Also the above timing is on a 2.6Ghz 32-bit OSX computer.
> > The underlying library that does the arithmetic is libsingular (i.e.,
> > Martin's singular
> > library).
>
> Right, that is interesting. It would be nice, if you did just
>
> sage: xx = (x+y+z)^20; yy = (x+y+z)^21
> sage: time e=expand(xx*yy)
>
> in Sage.calculus and it would automatically recognize it's a
> polynomial and used libsingular.
The same applies to #1617, i.e. when factoring polynomials. If x and y
are symbolic we use maxima, which is obviously a bad idea.
>
> > If you wanted to work modulo a prime (you probably don't since you're
> > a physicist),
>
> Such a think didn't even occur to me. :)
>
> Ondrej
Cheers,
Michael
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