EXPM(X) is the matrix exponential of X. EXPM is computed using
a scaling and squaring algorithm with a Pade approximation.
Although it is not computed this way, if X has a full set
of eigenvectors V with corresponding eigenvalues D, then
[V,D] = EIG (X) and EXPM(X) = V*diag(exp(diag(D)))/V.
See EXPM1 , EXPM2 and EXPM3 for alternative methods.
EXP (X) (that's without the M) does it element-by-element.