Under "Fit" use "Save to workspace" and use "Save fit to MATLAB object named" . You do not need the other two possible outputs for this purpose.
The fittedmodel output that generates has a property named "p" which is a piecewise polynomial structure such as is made by mkpp . You can use unmkpp to pull it apart, or you can just access its fields to gets its breaks and its coefficients.
computed splines are not often written out as mathematical functions because they become a whole mess of dirac deltas and heaviside functions. The boundary conditions are especially a nuisance as there are competing definitions of the value of HeaviSide(0)
