K := proc(x1,x2,y1,y2,p1,p2,q1,q2) local xx,yy,pp,qq,r0,r1,r2, A,B,L0,L1,L2,m01,m12,m20,apb,amb; xx:=x1^2+x2^2; yy:=y1^2+y2^2; pp:=p1^2+p2^2; qq:=q1^2+q2^2; r0:=xx*yy; r1:=((x1-y2)^2+(x2+y1)^2)*((x1+y2)^2+(x2-y1)^2)/4; r2:=((x1+y1)^2+(x2+y2)^2)*((x1-y1)^2+(x2-y2)^2)/4; A:=2*(p1*q1+p2*q2)*(x1*y1+x2*y2); B:=2*(p2*q1-p1*q2)*(x2*y1-x1*y2); apb:=A+B: amb:=A-B: L0:=r0*(pp*xx+qq*yy-apb); L1:=r1*(pp*yy+qq*xx-amb); L2:=r2*(pp*yy+qq*xx+amb); m01 := m0*m1; m12 := m1*m2; m20 := m2*m0; L0/32/m0+L1/32/m1+L2/32/m2-m01*r0*r1-m12*r1*r2-m20*r2*r0 -EE*r0*r1*r2; end: