R = ZZ/11[x,y,z]
A = matrix {{x,0,x*z},{z,y,x^2},{x^2,y,z}}
B = matrix {{2*x,3,y*z},{z^4,1,z^3},{y^2,x,y}}
C = matrix table(3,3,(i,j)->random(i+j,R))
A^4
A+B
D=A*C
U=exteriorPower(2,A)
transpose B
rank A
trace A
toString D