GP Efficiency and Evaluators

[sanderson77]

What was the design decision behind separating evaluation and the Jacobian function:

  /// Get the curve Jacobians.
  /// This is the main interface for GTSAM
  virtual void getJacobians(unsigned derivativeOrder, ...

I ask because in the case of GP's, my jacobians essentially double as the interpolation coefficients (similar to alpha and 1-alpha in the case of linear interpolation). I know Paul mentioned previously that it is not good to store the Jacobian's because they take too much memory, so I am doing them functionally, but at the moment I have to do it twice (once for evaluation and once for getJacobians).