A = [-0.2762, 0.0060, 0.4593; 0.2513, 0.1991, 0.0472;
            -0.2449, 0.3909, -0.3614]

    B=expm(A)
B =
    0.7244    0.0834    0.3299
    0.2364    1.2375    0.0935
   -0.1333    0.3604    0.6706

    C = expm(-A)
C =
    1.2344    0.0976   -0.6208
   -0.2651    0.8213    0.0158
    0.3878   -0.4220    1.3593

B*C and C*B are, of course, the unit diagonal matrix (i.e. eye(3) to the
working precision).

    eye(3)+A+A^2/2+A^3/6+A^4/24+A^5/120
ans =
    0.7244    0.0835    0.3298
    0.2363    1.2375    0.0935
   -0.1333    0.3604    0.6706

    trace(A)
ans =
   -0.4385

    sum(diag(A))
ans =
   -0.4385