newbie question



On 3/9/2013 2:59 PM,  andre maute wrote:
> On 03/09/2013 11:14 PM, Paul J. Ste. Marie wrote:
>> cx = -((b^2-1)*y2+(1-b^2)*y1-2*b*x2-2*b*x1)/(4*b
>
> okay let's try:
>
> display2d : false;
> h :-((b^2-1)*y2+(1-b^2)*y1-2*b*x2-2*b*x1)/(4*b);
> h : ratsubst(b2m1,b^2-1,h);
> h : factorsum(h);

ratsubst is definitely an improvement over subst's behavior!

It still doesn't gather the terms, though.  I wind up with

(%o118) cx = -(b2m1*y2-b2m1*y1-2*b*x2-2*b*x1)/(4*b)