Holonomic Gradient Descent for the Fisher-Bingham Distribution on the   $d$-dimensional Sphere
  We propose an accelerated version of the holonomic gradient descent and apply it to calculating the maximum likelihood estimate (MLE) of the Fisher-Bingham distribution on a $d$-dimensional sphere. We derive a Pfaffian system (an integrable connection) and a series expansion associated with the normalizing constant with an error estimation. These enable us to solve some MLE problems up to dimension $d=7$ with a specified accuracy. 
Tamio Koyama, Hiromasa Nakayama, Kenta Nishiyama, Nobuki Takayama
math.ST stat.TH