53.x1(k)=ptr(1,k-1)+c2/st*(ptr(1,k)-ptr(1,k-1));54.y1(k)=ptr(2,k-1)+c2/st*(ptr(2,k)-ptr(2,k-1));55.z1(k)=ptr(3,k-1)+c2/st*(ptr(3,k)-ptr(3,k-1));56.x(k)=pmr(1,k-1)+sm/c1*(x1(k)-pmr(1,k-1));57.y(k)=pmr(2,k-1)+sm/c1*(y1(k)-pmr(2,k-1));58.z(k)=pmr(3,k-1)+sm/c1*(z1(k)-pmr(3,k-1));