OFF ECHO;
COMMENT A LA FEYNMAN III, P. 17-16;

MATRIX HALFZ(2,2),HALFY(2,2),ONEZ(3,3),ONEY(3,3);

HALFZ:=MAT((E↑(+I*PHI/2),0),(0,E↑(-I*PHI/2)));
HALFY:=MAT((COS(THETA/2),SIN(THETA/2)),(-SIN(THETA/2),COS(THETA/2)));

ONEZ:=MAT((E↑(+I*PHI),0,0),(0,1,0),(0,0,E↑(-I*PHI)));
ONEY:=MAT(((1/2)*(1+COS(THETA)),((1/2)↑(1/2))*SIN(THETA),
           (1/2)*(1-COS(THETA))),
          (-((1/2)↑(1/2))*SIN(THETA),COS(THETA),
            ((1/2)↑(1/2))*SIN(THETA)),
          ((1/2)*(1-COS(THETA)),-((1/2)↑(1/2))*SIN(THETA),
           (1/2)*(1+COS(THETA))));

END;