math problem: matrix exponential not following the rules in ML or Octave?

[Nicholas Jankowski]

wrote it up over at stackexchange. would appreciate it if anyone could take a look and give me their thoughts.  basically, having trouble taking a matrix to a fractional exponent and getting the 'expected' value. it involves solving an eigenvalue problem internally, i've tried verifying via Maxima, and it 'should work' but I don't know what I'm missing with how Octave/ML handle the fractional exponent... is it a normalization thing, etc.

http://math.stackexchange.com/questions/1383443/matrix-with-fractional-exponent-not-getting-expected-output-in-matlab-octave