source: CGBLisp/examples/pappus.macsyma@ 1

if get('geometry2, 'version)=false then load(geometry2);
/* Specifications */
x1:0;
y1:0;
x2:1;
y2:0;
y3:0;

X:[x1,y1]; Y:[x2,y2]; Z:[x3,y3]; /* First line */
P:[u1,v1]; Q:[u2,v2]; R:[u3,v3]; /* Second line */
U:[z1,w1]; V:[z2,w2]; W:[z3,w3]; /* Intersection points */

params:cons(s,listofvars(append(X,Y,Z,U,V,W)));
vars:listofvars(append(P,Q,R));
concl: collinear(P,Q,R);
eqns:
[
        collinear(X,Y,Z),
        collinear(X,P,V),
        collinear(U,P,Y),
        collinear(Y,R,W),
        collinear(Z,R,V),
        collinear(U,Q,Z),
        collinear(X,Q,W),
        collinear(U,V,W),
        1-s*concl
];

cover: [[],[]];

eqns:expand(eqns);
cover:expand(cover);
stringout("pappus.out",eqns,vars,params,cover);