assign numerical value from a previous line



On Wednesday 14 of July 2010 18:39:22 William Porter wrote:
> Hello,
>
>
>
> I am a new user and having difficulty finding a method to assign a value
> from a previous line.

(%i1) e1: x^2+d*y*4+d^2*(-4);
                          2      2
(%o1)            4 d y + x  - 4 d
(%i2) e2: subst([y=0,d=5], e1);
                  2
(%o2)            x  - 100
(%i3) e3: solve(e2, x);
(%o3)            [x = - 10, x = 10]
(%i4) %phi[1] : -x/(2*d);
                    x
(%o4)            - ---
                   2 d
(%i5) %phi[2] : -x/(2*d);
                    x
(%o5)            - ---
                   2 d
(%i6) subst([e3[1], d=5],%phi[1]);
(%o6)            1
(%i7) subst([e3[2], d=5],%phi[2]);
(%o7)            - 1

Zbigniew