kill(all)$

van=facebook.com/LearningCalculus;

x:[a,b,c]$
y:[d,e,f]$

f[i,j]:=if i = j then 1 else y[i]/x[i]$
g[i,j]:=if i = j then 1 else x[i]/y[j]$

A:genmatrix(f,3,3);

B:genmatrix(g,3,3);

A.B;

B.A;

is(equal(A.B,B.A));

e^(A+B)=e^A*e^B;