>
> On Monday 17 September 2007, Stavros Macrakis wrote:
> How did you determine the 5 in the for loop, can't this be done
> automatically?
>
> > You can write a loop do this systematically, e.g.
> >
> > substabn(ex):=
> > block([newex],
> > for i: 1 thru 5 do
> > while denom(newex: ex*(a+b+i)!/((a+b+i)*(a+b+i-1)!))=1
> > do ex:newex,
> > ex)
>
Everything can be generalized arbitrarily and done automatically. How much
do you want to generalize? Do you want to convert (XX+1)*XX! => (XX+1)! for
all XX, or only for XX of the form a+b+<integer>? I was just giving the
sketch of a solution.
You might think that this sort of thing could be done using the pattern
matcher, but I don't think it can -- at least not straightforwardly. RJF
may have some thoughts on this.
-s