Local maxima and minima of a pp spline

Determine the locations of local maxima and minima in a pp spline generated by pp = spline(x,Y);

This function uses vectorised methods to determine the locations of maxima and minima where they exist within a piecewise spline fit. The matlab built-in functions for determining the maxima and minima, by differentiating the pp spline and finding its zeros (using the Spline toolbox), are quite slow, and are given as comment at the end of the m-file for reference.