Symbol m,x,y,z,[(4*m^2-q.q)^2*q.q];
Indices rho,nu,mu;
Vectors p1,p2,P,q,k,l;

Local Ma=-d_(rho,nu)*g_(1,rho)*(g_(1,q)+g_(1,k)+m)*g_(1,mu)*(g_(1,k)+m)*g_(1,nu);
Local F2a1=g_(1,mu)*(g_(1,p2)+m)*Ma*(g_(1,p1)+m);
Local F2a2=P(mu)/m*(g_(1,p2)+m)*Ma*(g_(1,p1)+m);
Local F2a=(F2a1*P.P-(q.q+2*m*m)*F2a2)*m^2/[(4*m^2-q.q)^2*q.q];

Trace4,1;

id k=-y*q+z*p1;
id P=p1+p2;
id p2=q+p1;
id p1.p1=m*m;
id p1.q=-q.q/2;
id q.q^3=[(4*m^2-q.q)^2*q.q]+8*m^2*q.q^2-16*m^4*q.q;

Bracket m;

Print;
.end;