grouping the variables in a certain way



On Fri, Jun 15, 2007 at 11:02:51PM -0400, Kamaraju S Kusumanchi wrote:
> Richard Fateman wrote:
> 
> > ratsubst(q,x/D^2,a);
> > factor(%);
> > ratsubst(x/D^2,q,%);
> >  
> > Does it. Gives
> > -(x/D-1)*(x/D+1)/(3*x/D+1)^4
...
> Doesnot seem to work. I am getting
> 
> (%i4) ratsubst(x/D^2,q,%);
>                                    4    2  2
>                                   D  - x  D
> (%o4)             ------------------------------------------
>                    4         3       2  2        3         4
>                   D  + 12 x D  + 54 x  D  + 108 x  D + 81 x

if you replace the second ratsubst with subst(q=x/D^2,%) it works for
me.



-- 
Daniel Lakeland
dlakelan at street-artists.org
http://www.street-artists.org/~dlakelan