out tt;
%off nat;

depend ro,z;

h:=mat((1,0),(0,-1));
xp:=mat((0,1),(0,0));
xm:=mat((0,0),(1,0));

AP:=(1/4)*df(ro,z)*h + exp(ro/2)*xp;
AM:=-(1/4)*df(ro,z)*h + exp(ro/2)*xm;



com:=AP*AM - AM*AP;
AMP:=AM-AP;

matrix mder(2,2);
for ii:=1:2 do for jj:=1:2 do mder(ii,jj):=df(amp(ii,jj),z);

mder;

mder + com;

shut tt;
bye;
end;